Role of Vitamin D in Athletes and Their Performance: Current Concepts and New Trends

International society of sports nutrition position stand: nutrition and weight cut strategies for mixed martial arts and other combat sports

Following an extensive literature review, the International Society of Sports Nutrition (ISSN) has developed an official position on nutritional and weight cut strategies for combat sports. The type of combat sport, length of the fight camp, and time between weigh-in and competition are factors influencing nutritional and weight cut strategies. The following 16 points constitute the Position Statement of the Society; the Research Committee has approved them. 1. Combat sports have differing weight categories, official weigh-in times, and competition frequencies, influencing the nutritional and weight cut strategies for training and competition. 2. As the duration of a combat match increases, >4 min, contribution of the aerobic system can rise to >70%, yet anaerobic alactic pathways and anaerobic glycolytic pathways support high-output bursts. 3. During the off camp/general preparation phase, athletes should maintain a weight ranging 12% to 15% above the weight division requirement. 4. Supplements including creatine, beta-alanine, beta-hydroxy-beta-methylbutyrate, and caffeine have been shown to enhance performance and/or recovery during preparation phases, competition, and post-competition. 5. During fight camp, strategic decreases in calorie intake are necessary for an efficient longitudinal weight descent. Individual caloric needs can be determined using indirect calorimetry or validated equations such as Mifflin St. Jeor or Cunningham. 6. Protein should be prioritized during longitudinal weight descents to preserve lean body mass, and the timely delivery of carbohydrates supports training demands. Macronutrients should not drop below the following: carbohydrates 3.0-4.0 g/kg, protein 1.2-2.0 g/kg, and fat 0.5 to 1.0 g/kg/day. 7. Suitable losses in body mass range from 6.7% at 72 h, 5.7% at 48 h, and 4.4% at 24 h, prior to weigh-in. 8. Sodium restriction and water loading are effective for inducing polyuria and acute water loss. 9. During fight week, water-bound glycogen stores can be depleted through exercise and carbohydrate restriction, facilitating a 1% to 2% loss in body mass, with equivalent losses from a low-fiber intake of <10 g/day for 4 days. 10. During fight week, acute water loss strategies, including sauna, hot water immersion, and mummy wraps, can be used effectively with appropriate supervision (optimally ~2-4% of body mass within 24 h of weigh-in). 11. Post-weigh-in, rapid weight gain strategies are utilized to recover lost body fluid/mass before competition with the intent of gaining a competitive advantage. 12. Oral rehydration solutions (1 to 1.5 liters/h) combined with a sodium range of 50-90 mmol/dL should take precedence immediately post-weigh-in. 13. Fast-acting carbohydrates at a tolerable rate of ≤ 60 g/h should follow oral rehydration solutions. Post weigh-in intake of fiber should be limited to avoid gastrointestinal distress. 14. Post-weigh-in carbohydrate intake at 8-12 g/kg may be appropriate for combat athletes that undertook significant glycogen depletion strategies during fight week. About 4-7 g/kg may be suitable for modest carbohydrate restriction. 15. Post weigh-in, rehydration/refueling protocols should aim to regain ≥10% of body mass to mitigate declines in performance and the negative effects of rapid weight loss. 16. The long-term effects of frequent weight cuts on health and performance are unknown, necessitating further research.

Annual Vitamin D Status of World-Class British Swimmers Following a Standardised Supplementation Protocol for Three Years

Background/objectives: British swimmers are at a heightened risk of vitamin D deficiency (serum 25-hydroxyvitamin D (25(OH)D): <50 nmol∙L-1) as their large indoor training volumes often restrict sunlight exposure, especially during the winter when daylight hours are reduced in the United Kingdom. Previous research has recommended supplementation with 4000 IU∙day-1 vitamin D3 from October to March to offset vitamin D losses. However, no current study has analysed this approach over multiple seasons to assess if this is an appropriate strategy. Methods: Using a quasi-experimental design, twenty-nine world-class British swimmers (aged 16-30 years) provided a 10 mL venous blood sample (fasted) as part of their routine haematological screening in the September of three consecutive years (2018, 2019, and 2020). Serum 25(OH)D was determined by radioimmunoassay, and this result determined the length of the standardised vitamin D3 protocol (<30 nmol∙L-1: 4000 IU∙day-1 from September to March; 30-79 nmol∙L-1: 4000 IU∙day-1 from October to March; >75 nmol∙L-1: no supplementation). Results: Mean serum 25(OH)D concentrations increased each year (2018: 76.4 ± 28.4 nmol∙L-1, 2019: 91.5 ± 24.8 nmol∙L-1, 2020: 115.0 ± 36.6 nmol∙L-1, p < 0.001), which coincided with the eradication of vitamin D deficiency after one season (prevalence, 2018: 10%, 2019: 0%, 2020: 0%). In September 2020, 35% of swimmers had a serum 25(OH)D > 125 nmol∙L-1, although it is currently debated whether this is a concern or a benefit for athletic populations. Conclusions: Supplementing with 4000 IU∙day-1 of vitamin D3 throughout the winter can increase the vitamin D status of swimmers. However, more frequent testing may be required to ensure that serum 25(OH)D remains within the sufficient range across the season (75-125 nmol∙L-1).

Nutrition for optimising immune function and recovery from injury in sports

The immune system, sports injuries, physical activity and clinical sports nutrition are closely linked. Inadequate nutrition and intense stress in athletes increase the risk of immune dysfunction, injury and disease, while injury reduces the positive effects of physical activity, creating a vicious cycle affecting health and performance. Nutritional support is key to reducing the risk of injury, speeding up recovery and shortening rehabilitation. The intake of energy, protein, carbohydrates, fats and micronutrients should be adapted to the needs following injury. Quality nutrition is preferred over the use of dietary supplements, which are limited to cases of identified deficiencies (e.g. vitamin D or iron deficiencies). Health professionals with knowledge of clinical nutrition have a key role to play in injury prevention, treatment and rehabilitation, and nutritional interventions are an indispensable part of a holistic approach to athletes' health.

Vitamin D and thyroid function of pregnant women in a sunny region: is there any connection?

OBJECTIVE

The aim of this study was to investigate the relationship between vitamin D serum concentrations and thyroid hormones of pregnant women living in a sunny region of Northeast Brazil.

METHODS

This is a cross-sectional secondary analysis of a study that evaluated the iodine status of pregnant women attending prenatal consultations in a tertiary hospital. Consecutive patients (>18 years) were conveniently sampled. Blood samples were collected for the study, including measurements of vitamin D, anti-TPO, and anti-Tg antibodies, thyroid-stimulating hormone, total and free thyroxine (TT4, FT4), and total and free triiodothyronine (TT3, FT3). Vitamin D levels <20 ng/mL were considered deficient. Between 20 and 30 ng/mL were classified as insufficient, and >30 ng/mL were sufficient. Additional data on urinary iodine concentrations, anthropometry, sociodemographic, and gestational features were also collected.

RESULTS

A total of 562 pregnant women were included, with a median age of 29 years. Most of them (47.9%) were in the first gestational semesters. Only 3.9% of subjects presented with vitamin D deficiency, while 81% had insufficient values and 15.1% had sufficient levels. Vitamin D levels were not significantly correlated or associated with thyroid hormones or body mass index (all p-values >0.05).

CONCLUSION

Our study adds to the growing body of evidence highlighting the importance of assessing the status of both vitamin D and thyroid hormones in population- and region-specific contexts, as it may vary accordingly.

Assessment of Micro- and Macronutrient Intake in Male Competitive Athletes Using the Epic-Norfolk Food Frequency Questionnaire

This study aimed to investigate diet quality in a population of male competitive athletes by comparing their total energy and macro- and micronutrients intake assessed by a food frequency questionnaire (FFQ) to current nutritional recommendations for this specific population. An additional goal was to assess athletes' sodium-to-potassium (Na-to-K) ratio. This cross-sectional study involved 31 healthy competitive male athletes. Subjects' body mass index, body composition, arterial blood pressure, as well as red blood count (RBC) and serum lipid profile measurements showed that all subjects were lean and normotensive and had normal RBC and serum lipid levels. All subjects completed a cross-culturally adapted, translated, and validated EPIC-Norfolk FFQ. The total energy intake reported in the FFQ was below the recommended values; however, 71% of subjects were classified as low energy reporters (LERs). Energy intake from proteins was within and from carbohydrates was below the recommended interval, while the total energy intake from fats (and also saturated fatty acids) exceeded the recommendations. Suboptimal intakes of vitamin D and folate were observed, indicating the necessity for monitoring (and supplementing) in this population. High Na intake, which despite adequate K intake resulted in a higher Na-to-K ratio, highlighted concerns over excessive salt consumption, but also accentuated the need for monitoring sodium (and potassium) intake in competitive athletes with consideration for sweat-related losses.

Are there Effective Vegan-Friendly Supplements for Optimizing Health and Sports Performance? a Narrative Review

PURPOSE OF REVIEW

Veganism, characterized by the exclusion of all animal-derived products, has grown in popularity due to ethical, environmental, and health considerations. However, vegan athletes often face unique nutritional challenges related to dietary deficiencies of critical nutrients such as proteins, vitamin B12, iron, calcium, and omega-3 fatty acids, among others. This narrative review aims to explore the efficacy and benefits of vegan-friendly supplements specifically tailored to athletic performance, focusing on essential micronutrients, ergogenic aids, and nutrient bioavailability.

RECENT FINDINGS

Nineteen key supplements are discussed, including protein powders, creatine, beta-alanine, caffeine, vitamin B12, vitamin D, omega-3 fatty acids, zinc, calcium, iron, iodine, vitamin K2, selenium, probiotics, nitrates, electrolytes (including sodium and potassium), taurine, vitamin A, and magnesium. Evidence suggests that the integration of these supplements into personalized nutrition plans can bridge dietary gaps while addressing specific performance needs, potentially leveling the competitive field for vegan athletes. Recent studies also highlight research gaps in sex-specific needs, synergistic effects, and strategies to enhance the bioavailability of nutrients from whole foods. Vegan diets, while conferring various benefits, require careful consideration of nutrient intake for athletes seeking optimal performance. Personalized biochemical assessments should be considered when possible for tailoring specific nutritional guidelines for each case. This narrative review provides practical guidelines for clinicians, nutritionists, trainers, sports scientists, and athletes to design personalized supplementation strategies that address common nutritional shortfalls, enhance performance, and serve as a foundation for future research in vegan sports nutrition.

Challenges Posed by Osteoporosis in Arthroscopy and Sports Injury Management

Background

Osteoporosis, whether generalized or localized, presents significant challenges in arthroscopic procedures, particularly in surgeries such as ligament reconstructions and rotator cuff repairs, which depend on fixation through interference screws and/or anchors. These challenges are especially pronounced in women, the elderly, and individuals with chronic injuries. The literature discusses various techniques to mitigate these issues.

Objective

Despite the recognition of these challenges, there is no clear consensus on the most effective methods to address them. Current literature lacks comprehensive information on the specific difficulties surgeons encounter when managing sports injuries in osteoporotic bones, particularly around the knee. This manuscript aims to outline and describe various treatment strategies to manage sports injuries in patients with osteoporotic bones.

Current Knowledge

Numerous studies acknowledge the heightened risk of fixation failure in osteoporotic bones. Surgeons have described various techniques to address these fixation issues, such as alternative fixation methods, preserved insertion techniques, bone bridge techniques, larger diameter screws, and supplementary fixation strategies. Techniques such as transosseous equivalent (TOE) repair, special suture configurations, multiple fixation points, medial anchor placement in subchondral bone, and bone cement augmentation are among the methods used to improve anchor fixation in osteoporotic bone.

Literature Gap

Although multiple surgical techniques are available for graft and tendon fixation in osteoporotic bones, there is no clear guideline on which method offers the best combination of biological and mechanical superiority. This article reviews the various fixation techniques and explores innovative approaches to graft fixation. In addition, the authors emphasize the importance of medical management of osteoporosis in patients undergoing surgical interventions, highlighting the role of bisphosphonate, teriparatide, denosumab. Medical therapy not only reduces the risk of fixation failure but also plays a crucial role in post-operative recovery.

Conclusions

With the growing emphasis on healthy lifestyles, increasing numbers of elderly patients are participating in sports activities. As a result, more patients with low bone mineral density (BMD) are seeking treatment for sports injuries. Anticipating the issue of regional low BMD is essential, even in younger patients, to ensure that alternative fixation techniques are employed when necessary.

The relationship between serum vitamin D, bone mineral density, and injury in collegiate acrobatics and tumbling athletes

Background: Medical staff for indoor aesthetic sports such as acrobatics and tumbling (A&T) is often concerned with athletes' bone mineral density (BMD), serum vitamin D (SvD), and associated injury risks. Aim: To evaluate the relationship between BMD, SvD, and injury among A&T athletes. Methods: 42 (19 tops, 23 bases) female A&T athletes aged 19.6 (±1.17) years participated. Two samples of SvD were taken. Injury and BMD data were provided by support staff. Bivariate and multivariate analysis assessed relationships between and among variables. Results: Participants experienced a decrease in SvD (6.093 ± 10.973). Spine BMD was significantly higher in bases compared to tops (p = 0.039). BMD and SvD did not differ based on injuries sustained. Conclusion: Relationships between SvD, BMD, and injury were not identified. Positional differences in BMD may be related to the demands of each role. Participants possessed low SvD and high BMDs, which may provide useful information for medical staff.

Exploring factors associated with vitamin D nutritional status in Japanese baseball players

BACKGROUND

Vitamin D is a nutrient necessary for conditioning athletes. This cross-sectional study aimed to determine the nutritional status of vitamin D in farm-league professional baseball players to examine vitamin D requirements.

METHODS

This study included 35 players enrolled in farm team A of the Nippon Professional Baseball Organization in the spring of 2022. The survey items included anthropometric measurements, serum 25-hydroxyvitamin D [25(OH)D] levels as an indicator of vitamin D nutritional status, a simple questionnaire for predicting vitamin D deficiency in Japanese adults, mean daily sun exposure duration, and body surface area (BSA).

RESULTS

The serum 25(OH)D level was 29.8±1.8 ng/mL, and 17 (49%) participants were vitamin D deficient (<30 ng/mL). The serum 25(OH)D levels showed positive correlations with body height (r=0.459, P<0.01), fat-free mass (r=0.347, P<0.05), muscle mass (r=0.341, P<0.05), and BSA (r=0.434, P<0.01). Furthermore, the consumption frequency of fish with high vitamin D levels in regular diets, BSA, and body fat mass were identified as predictors of the serum nutritional status of vitamin D.

CONCLUSIONS

Athletes engaged in outdoor sports, such as the study participants, had inadequate vitamin D levels. In addition, the frequency of consumption of fish with high vitamin D levels in regular diets, BSA, and body fat mass were identified as predictors of the serum nutritional status of vitamin D. Further studies of the relationship between vitamin D supplementation and performance are needed.

Body composition, exercise-related performance parameters and associated health factors of transgender women, cisgender women and cisgender men volleyball players

OBJECTIVE

The inclusion of transgender athletes in competitive sports has promoted significant dialogue and controversy among exercise-related professionals. The objective of this study was to investigate body composition, exercise-related performance parameters and associated health-related factors of transgender women (TW), cisgender women (CW) and cisgender men (CM) amateur volleyball players.

METHODS

This was a cross-sectional study comprising TW, CW and CM amateur volleyball players eligible with the following characteristics: 'gender incongruent' (for TW only); age between 18 and 35 years; body mass index (BMI) between 18.0 and 29.9 kg/m2; 'very active' according to the International Physical Activity Questionnaire, and engaged in regular volleyball training for at least 1 year. All participants were assessed for body composition, blood biomarkers, handgrip strength, countermovement jump height (CMJ), squat jump height (SQJ) and maximum oxygen consumption (V̇O2max).

RESULTS

69 amateur volleyball players were initially evaluated, but only 23 met the inclusion criteria and were included in the study (7 TW, 8 CW and 8 CM). Age (p=0.07) and BMI (p=0.26) were similar between groups. Estradiol (p=0.47), total testosterone (p=1.00) and haemoglobin (p=1.00) levels did not differ between TW and CW. However, analysis not adjusted by confounding variables showed that CM presented higher testosterone levels (p<0.001), haemoglobin levels (p=0.03), lean body mass (p=0.03), handgrip strength (p<0.001), CMJ (p<0.001), SQJ (p=0.012) and V̇O2max (mL/min) (p=0.001) compared with TW. When adjusted by confounding variables, all p values were <0.05, except for SQJ (p=0.062).

CONCLUSION

TW athletes displayed similar exercise performance and biomarkers compared with CW but lower results compared with CM.

Vitamin D and its relationship to performance and health during a competitive period in elite women's basketball and volleyball players

Vitamin D [25(OH)D] is a key nutrient, although its level is often low in the general population. To investigate the relationship between vitamin D levels and muscle performance, and to analyze how vitamin D changes during a 16-week competitive season and its relationship to the performance tests performed. Participant characteristics: age 25.1 ± 4.7 years; height 1.8 ± 0.1 m, and body mass 73.9 ± 15.4 kg. Vitamin D levels (ng/mL) were at T1 (September): 33.7 ± 14.7 (n = 23), and at T2 (January): 26.1 ± 7.3 (n = 23). Over 16 weeks of competition, participants' blood was analyzed to determine their vitamin D levels. Their athletic abilities were evaluated through various tests: vertical jumps (standing jump and countermovement jump); 20-m sprint without direction changes; and intermittent endurance test; the vitamin D level decreased from T1 to T2 by -22. 40% [p < 0.05] but performance improved in all tests performed (SJ: 4.57%; CMJ: 6.94%; VO2max: 4.99% [p < 0.05]; 20 m: -1.83%). There is a relationship between vitamin D levels and physical performance in female indoor athletes. The results suggest that increased training load may also negatively affect vitamin D levels in elite female indoor athletes.

Potential of Vitamin D and l-Cysteine Co-supplementation to Downregulate Mammalian Target of Rapamycin: A Novel Therapeutic Approach to Diabetes

Diabetes, a metabolic disease associated with an increased health care burden and mortality, is currently on the rise. Both upregulation of the mammalian target of rapamycin (mTOR) and decreased levels of vitamin D (VD) and l-cysteine (LC) have been associated with diabetes. The overactivation of mTOR leads to insulin desensitization and metabolic dysfunction including uncontrolled hyperglycemia. This review summarizes various studies that have shown an inhibitory effect of VD or LC on mTOR activity. Findings from preclinical studies suggest that optimizing the VD and LC status in patients with diabetes can result in mTOR suppression, which has the potential to protect these individuals from microvascular and macrovascular complications while enhancing the regulation of their blood glucose. Given this information, finding ways to suppress mTOR signaling and also increasing VD and LC status is a possible therapeutic approach that might aid patients with diabetes. Future clinical trials are needed to investigate whether VD and LC co-supplementation can successfully downregulate mTOR and can be used as adjuvant therapy in patients with diabetes.

A Strengths-Based Approach to Increasing Nutrition Knowledge in Student-Athletes: The 'Eat 2 Win' Pilot Program

Background and Objectives: Proper nutrition and hydration are essential for the health, growth, and athletic performance of student-athletes. Adequate energy availability and sufficient intake of macro- and micronutrients support adolescent development, prevent nutrient deficiencies, and reduce the risk of disordered eating. These challenges are particularly relevant to student-athletes, who are vulnerable to nutrition misinformation and often exhibit limited nutrition knowledge. This study aimed to evaluate the feasibility and acceptability of the 'Eat 2 Win' nutrition education pilot program for high school student-athletes and assess changes in nutrition knowledge using the Nutrition for Sport Knowledge Questionnaire-Adolescents (NSKQ-a). Methods: Fifty-five high school student-athletes (14.1 ± 2.2 years; 53% male, 47% female) from the Bremer State High School Sports Academy participated in the 'Eat 2 Win' program. The curriculum was tailored to align with the nutritional needs of Australian high school student-athletes and included three interactive workshops on sports nutrition concepts, practical cooking classes, and online learning modules. Sessions were delivered onsite at the school over three consecutive weeks, once per week. Twenty-four participants (43.6%) completed all program components. Results: The program was feasible and well-accepted by participants. Nutrition knowledge, assessed in 16 participants using the NSKQ-a, revealing an overall knowledge increase of 9.7%, with sub-category improvements ranging from 3.1% to 34.4%. Conclusions: The 'Eat 2 Win' pilot program improved student-athletes' nutrition knowledge, particularly in macronutrients and hydration. Participant feedback highlighted enjoyment and positive impacts. Targeted nutrition education programs like 'Eat 2 Win' can empower student-athletes to make informed dietary choices by addressing knowledge gaps, debunking nutrition myths, and fostering positive dietary behaviours. Future programs should emphasize energy intake, practical skills, and accessible, actionable information.

Vitamin D status and its determinants in German elite athletes

PURPOSE

This study investigated elite German athletes to (1) assess their serum 25(OH)D levels and the prevalence of insufficiency, (2) identify key factors influencing serum 25(OH)D levels, and (3) analyze the association between serum 25(OH)D levels and handgrip strength.

METHODS

In this cross-sectional study, a total of 474 athletes (231 female), aged 13-39 years (mean 19.3 years), from ten Olympic disciplines were included. Serum 25(OH)D levels were analyzed via liquid chromatography-mass spectrometry, and 17 single nucleotide polymorphisms (SNPs) related to vitamin D metabolism were determined using leukocyte DNA. Grip strength was measured unimanually using a hand-held dynamometer. Multiple linear regressions were used to analyze the influence of SNPs, age, sex, season (summer vs. winter), and discipline (indoor vs. outdoor) on 25(OH)D status. Linear regression analyzed the relationship between handgrip strength and serum 25(OH)D levels.

RESULTS

In total, 55.5% (n = 263) of athletes demonstrated insufficient serum 25(OH)D levels (< 30 ng/mL, < 75 nmol/L), with 16% (n = 76) showing levels below 20 ng/mL (50 nmol/L). After correction for multiple testing, significant influences on 25(OH)D levels were observed for the C allele of VDBP rs7041 (AC Genotype: β ^  = 7.46, p < .001; CC Genotype: β ^  = 6.23, p = .001). Age (all p < .01) and discipline (indoor vs. outdoor; all p < .05) also influenced serum 25(OH)D levels. Furthermore, serum 25(OH)D was positively associated with handgrip strength ( β ^ = 0.01, p < .001).

CONCLUSION

A high prevalence of insufficient 25(OH)D levels (< 30 ng/mL, < 75 nmol/L) was observed. We identified certain genetic variants as well as age and discipline as predictors of serum 25(OH)D levels. This knowledge may guide individualized diagnostic, nutritional, and supplementation strategies.

Associations of co-exposure to polycyclic aromatic hydrocarbons and vitamin D with early lung dysfunction: Mediating roles of metabolic score-visceral adiposity index

BACKGROUND

Preserved ratio impaired spirometry (PRISm) and airflow obstruction are recognized as critical early signs of chronic obstructive pulmonary disease (COPD). While these conditions arise from concurrent exposure to toxicants and essential nutrients, how vitamin D modifies the pulmonary toxicity induced by polycyclic aromatic hydrocarbons (PAHs) and the metabolic mechanisms involved is still unclear.

METHODS

Based on the National Health and Nutrition Examination Survey (NHANES) 2007-2012, data on urinary PAH metabolites (ΣOH-PAHs), serum vitamin D metabolite levels [Σ25(OH)D], and pulmonary function tests [forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and FEV1/FVC] from 2189 participants, including 369 subjects with early lung dysfunction, defined as PRISm or airflow obstruction. Multiple metabolic disorder indicators were calculated using biochemical markers. The interaction effects between vitamin D and PAHs were evaluated using multiple linear and logistic regression models. Causal mediation analyses and structural equation modeling were employed to investigate the mediating roles of metabolic indicators.

RESULTS

PAHs and vitamin D had opposite effects on lung function parameters [FEV1: β (95 CIs) = -0.01 (-0.02, -0.01) vs. 0.01 (0.01, 0.04); FVC: β (95 CIs) = -0.01 (-0.02, 0.01) vs. 0.04 (0.01, 0.06)] and risk of early lung dysfunction [OR (95 CIs) = 1.22 (1.06, 1.40) vs. 0.52 (0.37, 0.73)]. Decreased associations of ΣOH-PAHs with FEV1, FVC, and early lung dysfunction, as well as with metabolic score-visceral adiposity index (MSV) were visualized with increased Σ25(OH)D among subjects with body mass index (BMI) < 28 kg/m2. Furthermore, 2.18 %, 18.20 %, 5.70 %, and 4.70 % of the associations of co-exposure to ΣOH-PAHs and Σ25(OH)D with FEV1, FVC, FEV1/FVC, and early lung dysfunction disease were mediated by MSV.

CONCLUSIONS

Our findings indicated that vitamin D antagonizes the hazardous effects of PAHs on early lung dysfunction by metabolic alteration, providing new insight into the identification of the underlying high-risk populations and accessible prevention and intervention measures for attenuating PAH-induced lung dysfunction.

Association of vitamin D deficiency with post-exercise hypotension and arterial stiffness following prolonged endurance exercise in healthy young men

BACKGROUND

Vitamin D is associated with vascular function; however, the impact of different vitamin D levels on vascular elasticity following prolonged exercise remains uncertain. The primary objective of this study was to investigate the association of vitamin D levels with changes in peripheral pulse wave velocity (pPWV) and the magnitude of acute post-exercise hypotension (PEH) following prolonged endurance exercise in healthy young men.

METHODS

All the participants were divided into two groups: the 25-hydroxyvitamin D (25(OH)D) sufficiency group (25(OH)D ≧50 nmol/L) and the deficiency group (25(OH)D < 50 nmol/L). A cardiopulmonary exercise test for maximal oxygen uptake (V . O2max) was performed on the graded cycling. The prolonged exercise was set at 60% V . O2max for 120 min of continuous riding on a stationary bicycle. The pPWV and blood pressure were measured at baseline and 0, 15, 30, 45, 60 min after prolonged endurance exercise.

RESULTS

Post hoc analysis revealed that the vitamin D sufficient group had a greater magnitude of PEH than the deficiency group at post-45 min. Multiple linear regression analyses showed a significant correlation between 25(OH)D and both pPWV (p = 0.036) and PEH (p = 0.007), after adjusting for V . O2max, weight, height, and physical activity. In addition, the 25(OH)D deficiency group also had higher pPWV at post-15 min (5.41 ± 0.93 vs 4.84 ± 0.75 m/s), post-30 min (5.30 ± 0.77 vs 4.87 ± 0.50 m/s), post-45 min (5.56 ± 0.93 vs 5.05 ± 0.68 m/s) than the sufficiency group.

CONCLUSIONS

There was a positive correlation between 25(OH)D levels and systolic PEH following prolonged endurance exercise. Individuals with sufficient 25(OH)D status may have better vascular elasticity and more efficient blood pressure regulation during exercise.

The Role of Vitamin D Deficiency in Hepatic Encephalopathy: A Review of Pathophysiology, Clinical Outcomes, and Therapeutic Potential

Hepatic encephalopathy (HE) is a neuropsychiatric condition frequently associated with cirrhosis and portosystemic shunting (PSS). It imposes a significant clinical and economic burden, with increasing attention toward identifying modifiable factors that could improve outcomes. Emerging evidence suggests that vitamin D deficiency (VDD), prevalent in patients with cirrhosis, may contribute to the development and severity of HE. This review explores the association between VDD and HE by analyzing the underlying pathophysiology, including oxidative stress, ammonia accumulation, and impaired hepatic function. Additionally, we summarize recent studies highlighting the correlation between low serum 25-hydroxy vitamin D (25-OHD) levels and worsening grades of HE. Despite strong observational data, interventional studies on vitamin D (VD) supplementation for HE remains limited. Current evidence suggests that VD's antioxidant properties may alleviate oxidative stress in HE, with potential benefits in mitigating disease severity. Future research should focus on longitudinal studies and randomized controlled trials to evaluate the clinical impact of VD supplementation on HE outcomes and explore VD's role in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) procedures. Understanding the therapeutic potential of VD could lead to improved management strategies for HE and cirrhotic patients at large.

Nutrition, hydration and supplementation considerations for mountaineers in high-altitude conditions: a narrative review

Staying and climbing in high mountains (>2,500 m) involves changes in diet due to poor access to fresh food, lack of appetite, food poisoning, environmental conditions and physiological changes. The purpose of this review is to summarize the current knowledge on the principles of nutrition, hydration and supplementation in high-altitude conditions and to propose practical recommendations/solutions based on scientific literature data. Databases such as Pubmed, Scopus, ScienceDirect and Google Scholar were searched to find studies published from 2000 to 2023 considering articles that were randomized, double-blind, placebo-controlled trials, narrative review articles, systematic reviews and meta-analyses. The manuscript provides recommendations for energy supply, dietary macronutrients and micronutrients, hydration, as well as supplementation recommendations and practical tips for mountaineers. In view of the difficulties of being in high mountains and practicing alpine climbing, as described in the review, it is important to increase athletes' awareness of nutrition and supplementation in order to improve well-being, physical performance and increase the chance of achieving a mountain goal, and to provide the appropriate dietary care necessary to educate mountaineers and personalize recommendations to the needs of the individual.

Youth and Adolescent Athlete Musculoskeletal Health: Dietary and Nutritional Strategies to Optimise Injury Prevention and Support Recovery

Background: Despite the well-documented benefits of exercise and sports participation, young athletes are particularly vulnerable to musculoskeletal injuries. This is especially true during periods of rapid growth, sports specialisation, and high training loads. While injuries are an inevitable aspect of sports participation, the risk can be minimised by promoting the development of strong, resilient tissues through proper nutrition and injury prevention strategies. Moreover, targeted nutrition strategies can accelerate recovery and rehabilitation, allowing for a quicker return to sports participation. Methods: This narrative review synthesises scientific evidence with practical insights to offer comprehensive dietary recommendations aimed at strengthening tissues and supporting the healing process during recovery and rehabilitation. The selection of all sources cited and synthesised in this narrative review were agreed upon by contributing author consensus, experts in sports nutrition (R.A., H.V., B.D.) and exercise and sports medicine (M.H.). Results: Key topics include factors that contribute to injury susceptibility, general dietary recommendations for growth and development, sports nutrition guidelines, and nutrition considerations during injury and rehabilitation. This review also addresses external factors that may lead to suboptimal nutrition, such as food literacy and eating disorders. Conclusions: By highlighting these factors, this article aims to equip coaches, nutritionists, dietitians, athletic trainers, physical therapists, parents/guardians, sporting organisations, and schools with essential knowledge to implement effective nutritional strategies for injury prevention, recovery, and rehabilitation, ultimately enhancing long-term health and athletic performance.

A sustainable nutritional solution for fattening pigs based on 25-hydroxycholecalciferol and triterpenoids added to a low Ca diet containing phytase improves growth performance via the activation of muscle protein synthesis without compromising bone mineralization

In the current climate of sustainable animal agriculture, nutritional strategies that support fattening swine growth performance and bone mineralization whilst reducing environmental impacts are much sought after. This study evaluated the effect of supplementing 25(OH)D3 with triterpenoids to a Ca-reduced diet containing phytase during the grower-finisher phase. Growth performance, bone composition, plasma metabolites and muscle gene expression were evaluated. Sixty crossbreed boar pigs (initial body weight (BW) 42.0 ± 5.1 kg at 12 wk of age) were assigned to three treatments with 20 pigs/treatment in a completely randomized design. Treatments comprised: 1) a standard commercial grower-finisher diet (positive control (PC)) containing 1,500 IU/kg vitamin D3 [3,585 kcal/kg digestible energy, 16.19% CP, 0.70% Ca, 0.29% standardized total tract digestible P]; 2) a negative control (NC) based on the PC with reduction in Ca and P (minus 30% and 10%, respectively); 3) the NC with vitamin D3 replaced by a commercially available compounds combination containing 25(OH)D3 and triterpenoids, dosed at 500 mg per kg of feed (TRT). All diets were provided ad libitum for 7 wk, and feed intake was recorded individually via electronic feeder stations. For the overall period, average daily gain and average daily feed intake were increased (P < 0.05) in TRT vs. NC or PC (+ 13.0% and + 8.3%, respectively, vs. NC); final BW was 7.8% higher vs. NC (+ 5.2% vs. PC; P < 0.05). Whole-body DXA-scanning at 19 wk of age showed that bone mineral density, content and percentage were reduced in NC vs. PC and equivalent to PC in TRT. Plasma 25(OH)D3 and P levels were raised in TRT (+ 33 ng/ml or 2.6-fold and + 0.55 mg/dL or 5.9%, respectively, vs. NC). The combination of 25(OH)D3 with triterpenoids was found to activate several biological pathways involved in muscle growth, including pathways that activate mTOR, a key central regulator of cell metabolism, growth, proliferation and survival when the gene expression was measured in the muscle tissue at 19 wk of age. These results suggest that the dietary combination of 25(OH)D3 with triterpenoids has the potential for use, alongside phytase, in supporting a reduction in Ca and P in the diet to reduce nutrient waste and improve the sustainability of production by promoting muscle growth and maintaining bone composition.

Micro- and Macronutrients in Endometrial Cancer-From Metallomic Analysis to Improvements in Treatment Strategies

Endometrial cancer is reported to be one of the most prevalent cancers of the female reproductive organs worldwide, with increasing incidence and mortality rates over the past decade. Early diagnosis is critical for effective treatment. Recently, there has been a growing focus on the role of nutrition and micronutrient and macronutrient status in patients with gynecologic cancers, including endometrial cancer. In the following paper, we have conducted an in-depth narrative literature review with the aim of evaluating the results of metallomic studies specifically concerning the micro- and macronutrient status of patients with endometrial cancer. The main objective of the paper was to analyze the results regarding the nutritional status of endometrial cancer patients and describe the role of chosen elements in the onset and progression of endometrial carcinogenesis. Further, we have focused on the evaluation of the usage of the described elements in the potential treatment of the abovementioned cancer, as well as the possible prevention of cancer considering proper supplementation of chosen elements in healthy individuals. Calcium supplementation has been proposed to reduce the risk of endometrial cancer, although some studies offer conflicting evidence. Deficiencies in phosphorus, selenium, and zinc have been inversely associated with endometrial cancer risk, suggesting they may play a protective role, whereas excessive levels of iron, copper, and cadmium have been positively correlated with increased risk. However, the molecular mechanisms by which these elements affect endometrial carcinogenesis are not fully understood, and current findings are often contradictory. Further research is needed to clarify these relationships and to evaluate the potential of nutritional interventions for the prevention and treatment of endometrial cancer.

Serum iron and ferritin levels in female patients with gingivitis and periodontitis

AIM

The aim of the study was to compare serum ferritin and iron levels and periodontal status in pre- and post-menopausal female patients.

MATERIALS AND METHODS

A total of 108 systemically healthy patients were included in the study, 63 patients in the pre-menopause group and 45 patients in the post-menopause group. The periodontal diagnosis was made according to the new periodontal disease classification of the American Academy of Periodontology and the European Federation of Periodontology Serum Iron (μg/dL) and Serum Ferritin (ng/mL) values were analysed in patients divided into groups according to menopausal status and periodontal status.

RESULT

The mean ferritin in pre-menopausal women (34.96 ± 27.87 ng/mL) was lower than the mean ferritin in post-menopausal women (64.24 ± 36.05 ng/mL), and this difference was found to be statistically significant (P<0.001). There was no statistically significant difference between the averages of iron and ferritin according to periodontal diagnosis in pre-menopausal women (P = 0.200 and P = 0.858). A statistically significant difference was found between serum ferritin averages according to periodontal diagnosis in post-menopausal women (P < 0.001). Serum ferritin at % Interdental bone loss = 0 in Post-M was 33.93 ± 8.65 ng/mL; 47.51 ± 16.17 ng/mL in Stage 1 periodontitis; 72.66 ± 18.12 ng/mL in Stage 2 periodontitis; It was found to be 87.4 ± 47.1 ng/mL in Stage 3-4 periodontitis.

CONCLUSION

Serum ferritin values might vary depending on the presence or severity of periodontitis in post-menopausal women.

Characteristics of Vitamin D Concentration in Elite Israeli Olympic Athletes

BACKGROUND

The prevalence of vitamin D deficiency has been a growing concern in recent years. Vitamin D is important in many of the body's physiological systems, such as the musculoskeletal, cardiovascular and immune functions. A deficiency of vitamin D in athletes may negatively impact both muscle functions and recovery and, thus, affect performance and increase the risk of injury. Many studies assessed the prevalence of vitamin D deficiency in athletes; however, as of today, there are no official recommendations/protocols for screening vitamin D levels in athletes, and only a few studies were performed in male and female elite athletes (i.e., Olympic level), in different sport disciplines.

METHOD

We investigated the prevalence of vitamin D deficiency among athletes entering the Israeli Olympic team. A total of 761 samples of Vitamin D(OH)25 from 334 athletes were analyzed. For this analysis, we used the first test the athlete had performed when joining the Olympic team. The prevalence of vitamin D deficiency (<50 nmol/L, as defined by the Endocrine Society Committee) was investigated according to gender, types of sports and outdoor vs. indoor sports through the different seasons of the Israeli Olympic team athletes.

RESULT

Twenty-five athletes (7.5%) were diagnosed with vitamin D deficiency. One hundred and thirty-one athletes (39.2%) had insufficient levels of vitamin D (50-75 nmol/L). The highest incidence of vitamin D deficiency was found amongst gymnastics and combat sport athletes. A significant difference was also found in vitamin D concentration between seasons. Vitamin D average concentration in the winter was 74.1 nmol/L compared to 86.4 nmol/L in the Summer (p < 0.0005).

CONCLUSIONS

Due to the importance of vitamin D to athletic performance and the high prevalence of deficiency and insufficiency, we suggest careful and frequent monitoring of groups at risk, including elite athletes, especially in susceptible sports and during the winter. Future studies are necessary to investigate the effectiveness of Vitamin D supplementation in athletes with low baseline vitamin D levels.

Vitamin D Supplementation Improves Physical Performance in Athletes and Healthy Aging in Physically Active Adults

Vitamin D deficiency is a significant global public health issue, even in regions with all year sun exposure. Currently, the scientific community has not yet reached a unanimous agreement regarding the optimum levels of vitamin D and the precise threshold values. Additional efforts are required to standardize the evaluation of vitamin D insufficiency and deficiency and to provide uniform treatment guidelines. Epidemiological studies have identified a broad spectrum of estimated prevalences in athletes. Their performance when participating in sports. depend on their muscles, heart and lung function. It seems that athletes have significantly lower levels of vitamin D compared to the general population. However, there is a lack of comprehensive studies and systematic reviews on this subject, making it challenging to reach conclusions due to variations in laboratory techniques and cut-off values. While there is an abundant of research on the supplementation of vitamin D and its benefits, it is challenging to provide general recommendations for athletes due to the limitations of extrapolation. However, there is a rather high occurrence of Vitamin D deficiency among individuals who engage in regular physical activity. Supplementing with Vitamin D helps prevents osteoporosis, bone fractures, enhances muscle strength, avoids lung infections, heart failure, and arrhythmias. It is generally safe when used in appropriate quantities, given its wide therapeutic range. Athletes can decrease the occurrence of training dropouts caused by infection, arrhythmias, muscular weakness and potentially prevent the inability to participate in competitions through correct nutrition and vitamin D supplementation. Keywords: vitamin D; sports; muscle; heart, athletes rehabilitation, vitamin D, ventricular premature contractions, physical activity

Current Aspects of Selected Factors to Modulate Brain Health and Sports Performance in Athletes

This review offers a comprehensive evaluation of current aspects related to nutritional strategies, brain modulation, and muscle recovery, focusing on their applications and the underlying mechanisms of physiological adaptation for promoting a healthy brain, not only in athletes but also for recreationally active and inactive individuals. We propose that applying the rule, among others, of good sleep, regular exercise, and a properly balanced diet, defined as "SPARKS", will have a beneficial effect on the function and regeneration processes of the gut-brain-muscle axis. However, adopting the formula, among others, of poor sleep, stress, overtraining, and dysbiosis, defined as "SMOULDER", will have a detrimental impact on the function of this axis and consequently on human health as well as on athletes. Understanding these dynamics is crucial for optimizing brain health and cognitive function. This review highlights the significance of these factors for overall well-being, suggesting that adopting the "SPARKS" approach may benefit not only athletes but also older adults and individuals with health conditions.

Evaluation of the relationship between body composition and dietary habits of physically active people with disabilities

Physical activity offers numerous physical and mental health benefits for individuals with disabilities, while nutrition plays a crucial role in maintaining bodily homeostasis. This study aimed to assess the relationship between body composition and dietary habits among physically active people with disabilities. Fifty-five participants aged 16 to 61, including 28 with disabilities and 27 without, were included in the study. The FFQ-6 questionnaire, Tanita body composition analyzer, and Stadiometer were utilized. No significant differences in BMI were observed between the two groups. However, individuals with disabilities showed higher body fat, metabolic age, or pulse values, whereas the control group exhibited higher muscle mass, muscle quality, body type, or bone mass. Participants with disabilities were more likely to consume vegetables (p = 0.004) and animal fats (p = 0.027), while those without disabilities were more inclined to consume fast food, instant products (p = 0.006), sweetened beverages (p < 0.001), and alcohol (p < 0.001). People with disabilities often have a higher percentage of body fat, cautioning against the consumption of processed fruits, dried fruits, fast food, and red meat. Conversely, in non-disabled individuals, frequent consumption of eggs, animal fats, sugar, and sweets is not recommended due to the potential for increased body fat, visceral fat, and higher BMI.

Seasonal Variation in Vitamin D Status Does Not Interfere with Improvements in Aerobic and Muscular Endurance in Conscripts during Basic Military Training

Considering a lack of respective data, the primary objective of this study was to assess whether seasonal variation in vitamin D status (D-status) affects the extent of improvement in physical performance (PP) in conscripts during basic military training (BMT). D-status, PP and several blood parameters were measured repeatedly in conscripts whose 10-week BMT started in July (cohort S-C; n = 96) or in October (cohort A-C; n = 107). D-status during BMT was higher in S-C compared to A-C (overall serum 25(OH)D 61.4 ± 16.1 and 48.5 ± 20.7 nmol/L, respectively; p < 0.0001). Significant (p < 0.05) improvements in both aerobic and muscular endurance occurred in both cohorts during BMT. Pooled data of the two cohorts revealed a highly reliable (p = 0.000) but weak (R2 = 0.038-0.162) positive association between D-status and PP measures both at the beginning and end of BMT. However, further analysis showed that such a relationship occurred only in conscripts with insufficient or deficient D-status, but not in their vitamin D-sufficient companions. Significant (p < 0.05) increases in serum testosterone-to-cortisol ratio and decreases in ferritin levels occurred during BMT. In conclusion, a positive association exists between D-status and PP measures, but seasonal variation in D-status does not influence the extent of improvement in PP in conscripts during BMT.

Evolution of Vitamin D Status and Vitamin D Receptor Gene Expression Among Professional Handball Athletes During a Competitive Period. Relationship with Body Composition, Calcium, Magnesium and Phosphorous

INTRODUCTION

A generalized risk of vitamin D deficiency exists worldwide affecting also professional and elite athletes. This study assesses the evolution of vitamin D status and vitamin D receptor (VDR) gene expression and their relationship with body composition, calcium (Ca), magnesium (Mg) and phosphorous (P) among professional handball athletes during a competitive period.

METHODS

A total of 26 male subjects were recruited: 13 professional handball athletes and 13 non-athlete controls. An observational follow-up study was conducted in 2 time points over a 16-week period. Nutritional intake, body composition, and routinary biochemical parameters were measured via 24-hours recall, bioimpedance and enzyme immunoassay, respectively. Ca and Mg were measured by flame atomic absorption spectrophotometry and P was determined with the colorimetric method of Fiske-Subbarow. 25-hydroxyvitamin-D (25(OH)D) levels and its forms (i.e., 25(OH)D3 and 25(OH)D2) were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS), whereas VDR gene expression was measured by quantitative real time-polymerase chain reaction (qRT-PCR).

RESULTS

A total of 54% of the athletes showed deficient vitamin D status. Moreover, a prevalence of insufficient vitamin D status in handball players affected 46% at baseline, reaching 61% after 16 weeks. Vitamin D showed no evolution during the competitive period and no differences between groups were observed (all p ≥ 0.05). Handball players increased the VDR expression, enhanced body composition, Ca and Mg levels at 16-weeks follow-up (all p < 0.05). VDR gene expression was positively related with body mass and body mass index at follow-up in athletes (all p ≤ 0.038; r ≥ 0.579) and with Ca at baseline in controls (p = 0.026; r = 0.648). Finally, 25(OH)D2 form was directly associated with P in athletes at 16 weeks of study (p = 0.034; r = 0.588).

CONCLUSION

Players of indoor team sports such as handball would be a population at risk of vitamin D deficiency. The 16-weeks competition improved VDR gene expression, body composition, Ca and Mg levels. The associations observed between VDR gene expression and the variables of the study evidenced the importance of this receptor as a marker involved in health status in handball athletes despite vitamin D - although in a deficient status -, Ca, Mg and P showed no remarkable changes during the competition period.

Metabolic disorders in prediabetes: From mechanisms to therapeutic management

Diabetes, one of the world's top ten diseases, is known for its high mortality and complication rates and low cure rate. Prediabetes precedes the onset of diabetes, during which effective treatment can reduce diabetes risk. Prediabetes risk factors include high-calorie and high-fat diets, sedentary lifestyles, and stress. Consequences may include considerable damage to vital organs, including the retina, liver, and kidneys. Interventions for treating prediabetes include a healthy lifestyle diet and pharmacological treatments. However, while these options are effective in the short term, they may fail due to the difficulty of long-term implementation. Medications may also be used to treat prediabetes. This review examines prediabetic treatments, particularly metformin, glucagon-like peptide-1 receptor agonists, sodium glucose cotransporter 2 inhibitors, vitamin D, and herbal medicines. Given the remarkable impact of prediabetes on the progression of diabetes mellitus, it is crucial to intervene promptly and effectively to regulate prediabetes. However, the current body of research on prediabetes is limited, and there is considerable confusion surrounding clinically relevant medications. This paper aims to provide a comprehensive summary of the pathogenesis of pre-diabetes mellitus and its associated therapeutic drugs. The ultimate goal is to facilitate the clinical utilization of medications and achieve efficient and timely control of diabetes mellitus.

Vitamin D/Bone Mineral Density and Triglyceride Paradoxes Seen in African Americans: A Cross-Sectional Study and Review of the Literature

Vitamin D is known to have a positive effect on bone health. Despite the greater frequency of vitamin D deficiency in African Americans (AA), they have a higher bone mineral density (BMD) compared to whites, demonstrating a disconnect between BMD and vitamin D levels in AA. Another intriguing relationship seen in AA is the triglyceride (TG) paradox, an unusual phenomenon in which a normal TG status is observed even when patients house conditions known to be characterized by high TG levels, such as Type II diabetes. To the best of our knowledge, no study has examined whether these two paradoxical relationships exist simultaneously in AA subjects with Type II diabetes. In this study, we compared levels of blood markers, including HbA1c, TG, and vitamin D, measured as serum 25-hydroxyvitamin D [25(OH)VD] µM/mL, [25(OH)VD]/TG, calcium, and BMD in AA (n = 56) and white (n = 26) subjects with Type II diabetes to see whether these relationships exist concurrently. We found that AA subjects had significantly lower TG and [25(OH)VD] levels and a significantly higher BMD status compared to white subjects, even when the ages, BMI, duration of diabetes, HbA1c, and calcium levels were similar between the two groups. This demonstrates that these two paradoxical relationships exist simultaneously in Type II diabetic AA subjects. In addition to these findings, we discuss the current hypotheses in the literature that attempt to explain why these two intriguing relationships exist. This review also discusses four novel hypotheses, such as altered circulating levels and the potential role of estrogen and hydrogen sulfide on BMD and HMG-CoA reductase as a possible contributor to the TG paradox in AA subjects. This manuscript demonstrates that there are still many unanswered questions regarding these two paradoxical relationships and further research is needed to determine why they exist and how they can be implemented to improve healthcare.

Evaluation of normal range of serum 25 hydroxyvitamin d in iraqi healthy adults: demographic and socioeconomic effects

OBJECTIVE

Aim: To determine the normal range of serum levels of total 25(OH)VD in Iraqi healthy adult subjects and to relate its level with demographic profile and socioeconomic status..

PATIENTS AND METHODS

Materials and Methods: This cross sectional study was carried out at Iraq and the samples were collected during the period from August 2019 to January 2020. It included 649 adult subjects apparently healthy, from three governorates (Baghdad, Al-Anbar and Al-Basrah), Investigations included serum measurement of total 25(OH)D in all included individuals by using ELISA technique. Age, gender, marital state, blood pressure, smoking, sunshine exposure (%), hours of exposure/day, percentage of body surface area exposed, body mass index (BMI) subgroups, waist circumference (WC) subgroups, diet type, sport type and time, geographic factor (governorate) were measured and / or calculated and the levels of 25(OH)D were studied according to each of these factors.

RESULTS

Results: The mean ± SD level of 25(OH)D in total (n=649) studied Iraqi subjects was (16.29 ± 8.22 ng/ml), with women were significantly deficient than men (15.76 ± 6.89 ng/ml, 17.14 ± 6.85 ng/ml; p < 0.01 respectively). However, there was no significant differences in mean values of serum 25(OH)D levels among studied governorates, subgroups of BMI, WC, marital status, smokers and nonsmoker and subgroups of age. The mean value of serum 25(OH)D was found to be decreased in January, October and November as well as according to diet and sport types. There was significant positive correlation between total 25(OH)D and sun exposed surface area, sun exposure duration and with sun exposure area.

CONCLUSION

Conclusions: The mean (±SD) value of serum total 25(OH)D in Iraqi healthy subjects was 16.29 ng/ml (±8.22) reflecting the actual body status of this vitamin with lower concentration in women than in men. Type and time of sport and diet type were the major vitamin D dependent factors.

Effects of Vitamin D Supplementation in Elite Athletes: A Systematic Review

Background

Deficiency in vitamin D has been shown to increase the risk of injury.

Purpose

To synthesize current placebo-controlled randomized trials investigating the effect of vitamin D supplementation in elite athletes on (1) aerobic capacity; (2) anaerobic measures, such as strength, speed, and anaerobic power; (3) serum biomarkers of inflammation; and (4) bone health.

Study Design

Systematic review; Level of evidence, 1.

Methods

A literature search was conducted on November 30, 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included were randomized, placebo-controlled studies of longer than 2 weeks on subjects with active participation in organized sport. Excluded were nonrandomized controlled trial study designs, vitamin D administration routes other than oral, studies that did not use vitamin D supplementation as the sole intervention, and studies with nonathletic or military populations.

Results

Out of 2331 initial studies, 14 studies (482 athletes) were included. Of the 3 studies that assessed aerobic capacity, 2 demonstrated significantly greater improvements in maximal oxygen uptake and physical working capacity-170 (P < .05) in supplemented versus nonsupplemented athletes. Measurements of anaerobic power and strength were consistently increased in supplemented groups compared with nonsupplemented groups in 5 out of the 7 studies that assessed this. Of the 6 studies that assessed sprint speed, 4 found no significant difference between supplemented and nonsupplemented groups. Aside from 1 study that found significantly lower interleukin-6 levels in supplemented athletes, measures of other inflammatory cytokines were not affected consistently by supplementation. The 4 studies that assessed markers of bone health were conflicting regarding benefits of supplementation. One study found demonstrated improvements in bone mineral density in response to supplementation (P = .02) compared with control whereas another found no significant difference between supplemented and nonsupplemented groups. However, in 3 other studies, serum biomarkers of bone turnover such as bone-specific alkaline phosphatase, parathyroid hormone, and N-terminal telopeptide appeared to be higher in subjects with lower serum vitamin D levels (P < .05).

Conclusion

Results of this systematic review indicated that the greatest benefit of vitamin D supplementation in elite athletes may be improving aerobic endurance, anaerobic power, and strength. More research is needed to determine the effect of vitamin D supplementation on bone health and injury risk in this population.

Combined Administration of Metformin and Vitamin D: A Futuristic Approach for Management of Hyperglycemia

Diabetes is a series of metabolic disorders that can be categorized into three types depending on different aspects associated with age at onset, intensity of insulin resistance, and beta- cell dysfunction: Type 1 and 2 Diabetes, and Gestational Diabetes Mellitus. Type 2 Diabetes Mellitus (T2DM) has recently been found to account for more than 85% of diabetic cases. The current review intends to raise awareness among clinicians/researchers that combining vitamin D3 with metformin may pave the way for better T2DM treatment and management. An extensive literature survey was performed to analyze vitamin D's role in regulating insulin secretion, their action on the target cells and thus maintaining the normal glucose level. On the other side, the anti-hyperglycemic effect of metformin as well as its detailed mechanism of action was also studied. Interestingly both compounds are known to exhibit the antioxidant effect too. Literature supporting the correlation between diabetic phenotypes and deficiency of vitamin D was also explored further. To thoroughly understand the common/overlapping pathways responsible for the antidiabetic as well as antioxidant nature of metformin and vitamin D3, we compared their antihyperglycemic and antioxidant activities. With this background, we are proposing the hypothesis that it would be of great interest if these two compounds could work in synergy to better manage the condition of T2DM and associated disorders.

Consumption of ultra-processed products is associated with vitamin D deficiency in Brazilian adults and elderly

Although studies show that the intake of ultra-processed products (UPP) has a negative impact on health, diet quality and dietary vitamin D, its influence on serum concentrations of this vitamin remains unknown; therefore, it is essential to verify the association between the UPP consumption and vitamin D deficiency. This is a cross-sectional, household, population-based study, carried out with 229 individuals aged 20 years or older, residents of the city of Teresina, Piauí, Brazil. Socio-demographic, lifestyle, food consumption and anthropometric data were collected. Food consumption was obtained using a 24-h food recall, and foods were grouped according to the NOVA classification. Plasma concentrations of calcidiol-25 (OH) D3 were determined by HPLC. Crude and adjusted binary logistic regression was applied to estimate the association between UPP consumption and vitamin D deficiency. Most individuals aged 20-39 years were vitamin D deficient (52·1 %). UPP contributed 19·9 % to the energetic intake of the participant's diet. This contribution was higher for individuals with vitamin D deficiency (22·5 %, P = 0·04). In addition, a high intake of UPP was associated with twice the risk of vitamin D deficiency in comparison with low consumption of UPP (OR: 2·05; CI 1·06, 4·50; P: 0·04). Our results suggest that the consumption of UPP may have a negative impact on serum concentrations of vitamin D; more studies are needed.

Association between the Serum Vitamin D Concentration and All-Cause and Cancer-Specific Mortality in Individuals with Cancer

We aimed to explore the association between the serum 25-hydroxyvitamin D concentration and all-cause and cancer-specific mortality in 2,463 adult patients with cancer from the National Health and Nutrition Examination Survey 2007-2018. We linked mortality data from the survey to the National Death Index records up to December 31, 2019. During a median follow-up period of 70 months, 567 patients died, of whom 194 died due to cancer. Multivariate adjustment was performed for demographic characteristics, lifestyle, dietary factors, 25-hydroxyvitamin D testing period, and cancer site. Higher serum 25-hydroxyvitamin D concentrations up to 75 nmol/L significantly reduced the risk of all-cause and cancer-specific mortality. When 25-hydroxyvitamin D quartiles were compared, the multivariable-adjusted hazard ratios were 0.59 (95% confidence interval: 0.42, 0.84) for all-cause mortality (P for trend <0.001) and 0.48 (95% confidence interval: 0.29, 0.79) for cancer-specific mortality (P for trend = 0.037) in quartile 3 (79.3-99.2 nmol/L). A threshold of 75 nmol/L for serum 25-hydroxyvitamin D may represent an intervention target to reduce mortalities in patients with cancer, and maintaining 25(OH)D concentrations within range (79.3-99.2 nmol/L) is beneficial for reducing all-cause and cancer-specific mortality.

A Diagnosis of Vitamin D Deficiency Is Associated With Increased Rates of Anterior Cruciate Ligament Tears and Reconstruction Failure

PURPOSE

To characterize the association between a diagnosis of hypovitaminosis D and primary anterior cruciate ligament (ACL) tear, primary anterior cruciate ligament reconstruction (ACLR), and revision ACLR in different sex and age cohorts.

METHODS

In this retrospective cohort study of the PearlDiver claims database, records were queried between January 1, 2011, and October 31, 2018 for all patients aged 10 to 59 years who received a diagnosis of hypovitaminosis D. Rates of primary ACL tears, primary reconstruction, and revision reconstruction were calculated for sex- and age-specific cohorts and compared with a control of patients without a diagnosis of hypovitaminosis D. Incidence rates for primary ACL injuries were calculated, and multivariable logistic regression was used to compare rates of ACL injury, primary reconstruction, and revision reconstruction while controlling for age, sex, Charlson Comorbidity Index, and several other comorbidities.

RESULTS

Among the 328,011 patients (mean age 41.9 ± 12.6 years, 65.8% female) included in both the hypovitaminosis D and control cohorts, the incidence of ACL tears was 115.2 per 100,000 person-years (95% confidence interval [CI] 107.2-123.7) compared with 61.0 (95% CI 55.2-67.2) in the demographic- and comorbidity-matched control cohort. The study cohort was significantly more likely to suffer an ACL tear over a 1- (aOR 1.67, 95% CI 1.41-1.99, P < .001) and 2-year (aOR 1.81, 95% CI 1.59-2.06, P < .001) period. This trend remained for both male patients at the 1- (aOR 1.66, 95% CI 1.29-2.14, P < .001) and 2-year (aOR 1.68, 95% CI 1.37-2.06, P < .001) mark and female patients at the 1- (aOR 1.69, 95% CI 1.33-2.14, P < .001) and 2-year (aOR 1.80, 95% CI 1.51-2.14, P < .001) mark. Finally, patients with vitamin D deficiency had a significantly increased likelihood of undergoing a revision ACLR within 2 years of a primary reconstruction (aOR 1.28, 95% CI 1.05-1.55, P = .012).

CONCLUSIONS

This study reports an association between patients previously diagnosed with hypovitaminosis D and significantly increased rates of both index ACL tears (81% increase within 2 years of diagnosis) and revision ACLR (28% within 2 years). These results identify a population with increased odds of injury and provide valuable knowledge as we expand our understanding of the relationship between vitamin D and musculoskeletal health.

LEVEL OF EVIDENCE

Level III, retrospective database study.

Competitive season effects on polyunsaturated fatty acid content in erythrocyte membranes of female football players

BACKGROUND

An optimal and correctly balanced metabolic status is essential to improve sports performance in athletes. Recent advances in omic tools, such as the lipid profile of the mature erythrocyte membranes (LPMEM), allow to have a comprehensive vision of the nutritional and metabolic status of these individuals to provide personalized recommendations for nutrients, specifically, the essential omega-3 and omega-6 fatty acids, individuating deficiencies/unbalances that can arise from both habitual diet and sportive activity. This work aimed to study the LPMEM in professional female football players during the football season for the first time and compare it with those defined as optimal values for the general population and a control group.

METHODS

An observational study was carried out on female football players from the Athletic Club (Bilbao) playing in the first division of the Spanish league. Blood samples were collected at three points: at the beginning, mid-season, and end of the season for three consecutive seasons (2019-2020, 2020-2021, and 2021-2022), providing a total of 160 samples from 40 women. The LPMEM analysis was obtained by GC-FID by published method and correlated to other individual data, such as blood biochemical parameters, body composition, and age.

RESULTS

We observed a significant increase in docosahexaenoic acid (DHA) (p 0.048) and total polyunsaturated fatty acid (PUFA) (p 0.021) in the first season. In the second season, we observed a buildup in the membrane arachidonic acid (AA) (p < .001) and PUFA (p < .001) contents when high training accumulated. In comparison with the benchmark of average population values, 69% of the football players showed lower levels of omega-6 dihomo-γ-linolenic acid (DGLA), whereas 88%, 44%, and 81% of the participants showed increased values of AA, eicosapentaenoic acid (EPA), and the ratio of saturated and monounsaturated fatty acids (SFA/MUFA), respectively. Regarding relationships between blood biochemical parameters, body composition, and age with LPMEM, we observed some mild negative correlations, such as AA and SFA/MUFA ratio with vitamin D levels (coefficient = -0.34 p = .0019 and coefficient = -.25 p = .042); DGLA with urea and cortisol (coefficient = -0.27 p < .006 and coefficient = .28 p < .0028) and AA with age (coefficient = -0.33 p < .001).

CONCLUSION

In conclusion, relevant variations in several fatty acids of the membrane fatty acid profile of elite female football players were observed during the competitive season and, in comparison with the general population, increased PUFA contents were confirmed, as reported in other sportive activities, together with the new aspect of DGLA diminution, an omega-6 involved in immune and anti-inflammatory responses. Our results highlight membrane lipidomics as a tool to ascertain the molecular profile of elite female football players with a potential application for future personalized nutritional strategies (diet and supplementation) to address unbalances created during the competitive season.

Effects of an Individualized vs. Standardized Vitamin D Supplementation on the 25(OH)D Level in Athletes

Vitamin D is crucial to the health and performance of athletes. Although the exact vitamin D requirements for athletes have not been established, maintaining a 25(OH)D level of at least 40 ng/mL is considered beneficial. This randomized controlled intervention study aimed to determine whether an individual loading dose formula for vitamin D supplementation is more effective than standardized supplementation and suitable enough for athletes to meet a target value of 40 ng/mL. In a 10-week supplementation study conducted during the winter months in Germany, 90 athletes with insufficient vitamin D levels (25(OH)D < 30 ng/mL) were randomly assigned to receive either a universal dose of 2000 IU/day of vitamin D or a loading dose of 4000 IU/day, followed by a maintenance dose of 1000 IU/day. The total 25(OH)D concentration was measured from dried blood spots at three time points: at baseline, at the computed date of 40 ng/mL, and after the 10-week period. Additionally, a vitamin-D-specific questionnaire was issued. On the day when 25(OH)D blood concentrations of 40 ng/mL were calculated to prevail, the individualized group had a significantly higher 25(OH)D level than the standardized group (41.1 ± 10.9 ng/mL vs. 32.5 ± 6.4 ng/mL, p < 0.001). This study demonstrated that the examined formula is suitable enough for athletes to achieve a 25(OH)D concentration of 40 ng/mL. This indicates that a personalized approach is more effective than a one-size-fits-all approach in restoring adequate vitamin D levels in athletes.

Vitamin D deficiency contributes to overtraining syndrome in excessive trained C57BL/6 mice

Overtraining syndrome is a condition resulting from excessive training load associated with inadequate recovery and poor sleep quality, leading to performance decrements and fatigue. Here we hypothesized that vitamin D (VitD) deficiency is a lead factor in the development of the overtraining syndrome. To test this hypothesis, two groups of 60-week-old C57BL/6 mice followed a 16-week excessive eccentric-based overtraining by excessive downhill running with or without dietary VitD depletion (EX and EX-D- groups). Two control groups were trained by uphill running at the same load with or without VitD depletion (CX and CX-D- groups). Handgrip strength decreased throughout the protocol for all groups but the decrease was sharper in EX-D- group (VitD × training, p = 0.0427). At the end of the protocol, the mass of Triceps brachii muscle, which is heavily stressed by eccentric contractions, was reduced in eccentric-trained groups (training effect, p = 0.0107). This atrophy was associated with a lower concentration of the anabolic myokine IL-15 (training effect, p = 0.0314) and a tendency to a higher expression of the atrogene cathepsin-L (training effect, p = 0.0628). VitD depletion led to a 50% decrease of the fractional protein synthesis rate in this muscle (VitD effect, p = 0.0004) as well as decreased FGF21 (VitD effect, p = 0.0351) and increased osteocrin (VitD effect, p = 0.038) concentrations that would lead to metabolic defects. Moreover, the proportion of anti-inflammatory Th2 lymphocytes was significantly decreased by the combination of eccentric training with VitD depletion (vitD × training, p = 0.0249) suggesting a systemic inflammation. Finally, exploratory behavior time of mice was decreased by VitD depletion (VitD effect, p = 0.0146) suggesting a cognitive dysfunction. Our results suggest that VitD deficiency exacerbates the effects of overtraining.

Effects of vitamin D supplementation on maximal strength and power in athletes: a systematic review and meta-analysis of randomized controlled trials

Background

Vitamin D is thought to be a powerful modulator of skeletal muscle physiology. However, available data on the effects of vitamin D supplementation on muscle function in athletes are limited and with mixed results. This meta-analysis therefore, aimed to quantitatively summarize the up-to-date literature assessing the effects of vitamin D supplementation on muscle strength and power in athletes.

Methods

Sport Discus, PubMed, Cochrane Library and Web of Science were searched to identify randomized controlled trials (RCTs) that used one-repetition maximum (1RM) tests to assess maximal strength, and vertical jump to assess muscle power in athletes. The Cochrane Risk of Bias tool was used to evaluate the included RCTs for sources of bias. The standardized mean difference (SMD) was used as the effect size, interpreted together with its 95% confidence intervals (CI). The effect sizes were calculated on the changes from baseline between vitamin D and placebo groups for maximal strength results by upper body and lower body, and for power results.

Results

Eleven RCTs involving 436 athletes were included. The results indicated that if baseline serum 25(OH)D concentration was < 75 nmol/L, the treatment had a small effect on upper body muscle strength [SMD 0.25, 95% CI: (-0.44, 0.95), p = 0.47] and on lower body muscle strength [SMD 0.26, 95% CI: (-0.13, 0.65), p = 0.19]; if the baseline serum 25(OH)D concentration was ≥ 75 nmol/L, the treatment had a trivial effect on muscle power [SMD 0.15, 95% CI: (-0.42, 0.72), p = 0.61].

Discussion

This meta-analysis demonstrated that there is not a statistically significant effect of vitamin D supplementation on improving maximum strength and power, but highlights that further research is required addressing the key limitations in previous studies before definitive conclusions can be made.

Oxidative Stress and Performance after Training in Professional Soccer (European Football) Players

Vitamins, hormones, free radicals, and antioxidant substances significantly influence athletic performance. The aim of this study was to evaluate whether these biological mediators changed during the season and if this was associated with the rate of improvement in performance after training, assessed by means of a standardized test. Professional male soccer players took part in the study. Two evaluations were performed: the first in the pre-season period and the second at the mid-point of the official season, after about 6 months of intensive training and weekly matches. Blood levels of vitamins D, B12, and folic acid, testosterone and cortisol, free radicals, and antioxidant substances were measured. Two hours after breakfast, a Yo-Yo test was performed. The relationships between the biological mediators and the rate of improvement after training (i.e., the increase in meters run in the Yo-Yo test between the pre-season and mid-season periods) were evaluated by means of a linear mixed models analysis. Results: Eighty-two paired tests were performed. The athletes showed better performance after training, with an increase in the meters run of about 20%. No significant relationships between the vitamin and hormone values and the gain in the performance test were observed. Plasmatic levels of free radicals increased significantly, as did the blood antioxidant potential. An indirect relationship between oxidative stress and the improvement in performance was observed (free radicals β ± SE: = -0.33 ± 0.10; p-value = 0.001), with lower levels of oxidative stress being associated with higher levels of performance in the Yo-Yo test. Monitoring the measures of oxidative stress could be a useful additional tool for coaches in training and/or recovery programs tailored to each player.

Thoroughbred Racehorses in Hong Kong Require Vitamin D Supplementation to Mitigate the Risk of Low Vitamin D Status

There is a paucity of data relating to the vitamin D status of racehorses. We hypothesised that the management of racehorses in Hong Kong (HK) predisposes to low vitamin D status unless they receive dietary supplementation. Serum concentrations of 25-hydroxyvitamin D₂ (25OHD₂), 25-hydroxyvitamin D₃ (25OHD₃) and total 25-hydroxyvitamin D (total 25OHD) for 79 non-grazing HK racehorses were compared with those for 22 racehorses training in the United Kingdom (UK) that grazed for ≥1 h/d, and for which published data exists. A nested group of 41 HK horses was sampled twice to determine the effect of the duration in HK on vitamin D status. The HK horses had significantly lower serum concentrations of total 25OHD and 25OHD₂ than the UK horses; 25OHD₂ was undetectable in 15/79 HK sera and serum concentrations of 25OHD₂ declined with the duration in HK. The main determinants of vitamin D status were assessed using linear regression; the retained variables were the 25OHD₃ concentration and the duration in HK. The inverse relationship between the serum concentrations of 25OHD₂ and 25OHD₃, previously identified in humans, was observed for the first time in horses. In conclusion, HK racehorses have low serum 25OHD₂ and total 25OHD concentrations and rely on D₃ supplementation to maintain adequate vitamin D status. Further study is required to determine the optimal form of dietary vitamin D supplementation for Thoroughbred racehorses.

Low Energy Availability (LEA) and Hypertension in Black Division I Collegiate Athletes: A Novel Pilot Study

The purpose of this study was to investigate the relationship between low energy availability (LEA) and nutritional content with high blood pressure (HBP) in African American Division I athletes. Twenty-three D1 African American pre-season athletes were recruited to participate. HBP was defined as >120 systolic blood pressure (BP) and <80 diastolic BP. Athletes self-reported nutritional intake using a non-consecutive 3-day food recall which was then reviewed by a sports dietitian. LEA was evaluated as total energy intake-total daily energy expenditure (TDEE), which was predicted. Additionally, micronutrients were evaluated. A statistical analysis relied on Spearman correlation (R), standardized mean difference with 95% confidence interval, mean ± SD, and odds ratios (OR). Correlation values were categorized: 0.20-0.39 = low; 0.40-0.69 = moderate; 0.70-1.0 = strong. A moderate relationship was observed between HBP and LEA (R = 0.56) with 14/23 having HBP. Of the 14 athletes observed with HBP, 78.5% (11/14) were calorically deficient (-529 ± 695 kcal) with an OR of 7.2. Micronutrient intake deficiencies were ubiquitous among the 23 HBP athletes: poly-unsaturated fatty acid -29.6%; omega-3 -26.0%; iron -46.0%; calcium -25.1%; and sodium -14.2%, amongst others. LEA and micronutrient deficiencies may contribute to HBP in Black D1 athletes, which has been shown to be the most common modifiable risk factor to decrease the risk of sudden cardiac death.

The roles of hepatokine and osteokine in liver-bone crosstalk: Advance in basic and clinical aspects

Both the liver and bone are important secretory organs in the endocrine system. By secreting organ factors (hepatokines), the liver regulates the activity of other organs. Similarly, bone-derived factors, osteokines, are created during bone metabolism and act in an endocrine manner. Generally, the dysregulation of hepatokines is frequently accompanied by changes in bone mass, and osteokines can also disrupt liver metabolism. The crosstalk between the liver and bone, particularly the function and mechanism of hepatokines and osteokines, has increasingly gained notoriety as a topic of interest in recent years. Here, based on preclinical and clinical evidence, we summarize the potential roles of hepatokines and osteokines in liver-bone interaction, discuss the current shortcomings and contradictions, and make recommendations for future research.

The VegPlate for Sports: A Plant-Based Food Guide for Athletes

Background: Nutrition strategies improve physiological and biochemical adaptation to training, facilitate more intense workouts, promote faster recoveries after a workout in anticipation of the next, and help to prepare for a race and maintain the body’s hydration status. Although vegetarianism (i.e., lacto-ovo and veganism) has become increasingly popular in recent years, the number of vegetarian athletes is not known, and no specific recommendations have been made for vegetarian dietary planning in sports. Well-planned diets are mandatory to obtain the best performance, and the available literature reports that those excluding all types of flesh foods (meat, poultry, game, and seafood) neither find advantages nor suffer from disadvantages, compared to omnivorous diets, for strength, anaerobic, or aerobic exercise performance; additionally, some benefits can be derived for general health. Methods: We conceived the VegPlate for Sports, a vegetarian food guide (VFG) based on the already-validated VegPlate facilitating method, designed according to the Italian dietary reference intakes (DRIs). Results: The VegPlate for Sports is suitable for men and women who are active in sports and adhere to a vegetarian (i.e., lacto-ovo and vegan) diet, and provides weight-based, adequate dietary planning. Conclusions: The VegPlate for Sports represents a practical tool for nutrition professionals and gives the possibility to plan diets based on energy, carbohydrate (CHO), and protein (PRO) necessities, from 50 to 90 Kg body weight (BW).

Body Composition and Nutritional Status of the Spanish National Breaking Team Aspiring to the Paris 2024 Olympic Games

Breaking is a sports dance modality that will debut for the first time at the Paris 2024 Olympic Games. This dance form combines street dance steps with acrobatics and athletic elements. It complies with gender equality, maintains aesthetic appeal, and is practised indoors. The objective of this study is to assess the characteristics of body composition and nutritional status of the athletes that make up the Breaking national team. This national team was recruited, and they underwent an analysis of body composition using bioimpedance measurement and a nutritional interview status with the completion of a survey on the frequency of the consumption of sports supplements and ergogenic aids. In addition, they completed a consumption questionnaire for a series of food groups with specified protein, lipid, and carbohydrate content. After that, parameters were analyzed in relation to their nutritional status during a complete medical examination at the Endocrinology and Nutrition Service of the Sports Medicine Center of CSD. A descriptive analysis of the results obtained was carried out to find the mean values of the variables analyzed. The analytical parameters described an adequate nutritional status, except for the mean capillary determination of 25-OH-vitamin D3, which was 24.2 ng/dL (SD: 10.3). Bone mineral density values were higher than those of the general population. This is the first time that a study of these characteristics has been carried out on Breakers, so it is highly relevant to increase knowledge in this area in order to conduct nutritional interventions aimed at improving the sports performance of these athletes.

Determination of a Serum 25-Hydroxyvitamin D Reference Ranges in Japanese Adults Using Fully Automated Liquid Chromatography-Tandem Mass Spectrometry

BACKGROUND

Despite an increasing interest in vitamin D status, a reference range of the nutrient has not been fully established. This is partly due to a paucity of standardized measuring systems with high throughput. In addition, the range may vary by populations and may change with modernization of lifestyles.

OBJECTIVES

This study aims to calculate the current reference concentration of 25-hydroxyvitamin D (25(OH)D) among healthy people living in an urban area in Japan.

METHODS

A newly developed fully automated liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) system was used to measure serum 25(OH)D concentrations. Reproducibility was assessed by measuring standardized samples. Accuracy was validated by comparing with commercially available immunoassays. Then, mass screening was conducted targeting participants who received medical checkups in Tokyo from April 2019 to March 2020, and the reference ranges were calculated.

RESULTS

The coefficients of variations of interoperator and interday reproducibility were 4.1%-8.5% and 3.7%-8.0% for 25-hydroxyvitamin D₂ (25(OH)D2) and 4.7%-7.0% and 4.0%-6.9% for 25-hydroxyvitamine D3, respectively. The measured total 25(OH)D concentrations correlated well with those measured by immunoassays. In total, 5518 participants were measured for 25(OH)D concentrations, among whom 98% showed inadequate concentrations (<30 ng/mL). The reference ranges of total 25(OH)D for female, male, and total participants were 7-30 ng/mL, 5-27 ng/mL, and 6-29 ng/mL, respectively. After excluding those with abnormal renal and liver function, the range was 6-30 ng/mL.

CONCLUSIONS

The high prevalence of vitamin D insufficiency among seemingly healthy population may be attributed to lifestyle characteristics of people living in urban areas of Japan, including spending less time outdoors and lower intake of traditional foods. Longitudinal follow-up and mass screenings targeting different population will help elucidate reasons for discrepancies between official guidelines and the observed concentrations, to which the well-validated measurement system is essential.

The Level of Selected Blood Parameters in Young Soccer Players in Relation to the Concentration of 25(OH)D at the Beginning and End of Autumn

This study aimed to demonstrate the changes of selected blood parameters in relation to 25(OH)D concentration during the autumn period in young soccer players. A total of 35 participants’ results (age: 17.5 ± 0.6 years, body mass 71.3 ± 6.9 kg) were tested twice: in mid-September and in mid-December and divided into subgroups with regard to two criteria. First, according to the initial level of the 25(OH)D concentration (optimal group—ODG, suboptimal group—SDG), second, according to drops in 25(OH)D concentration (high drop group—HDG, low drop group—LDG). A significant decrease (p < 0.001) in the 25(OH)D concentration was reported in the total group (TGr) and in all subgroups. Blood parameters such as white blood cells, red blood cells, haemoglobin and haematocrit increased significantly (p < 0.05) in TGr during the analysed period of time. The analysis of changes in the lipid profile did not expose significant differences except triglycerides. The asparagine amino transferase and creatine kinase activity decreased significantly after autumn in all analysed groups. The declining level of 25(OH)D concentration should be compensated (e.g., with vitamin D supplementation) during autumn. Applied training loads could also influence the blood parameters variability in young soccer players. Regular measurements of 25(OH)D concentration are helpful in identifying potential drops and allows for the preparation of individual supplementation plans for the players.

Vitamin D Fortification and Its Effect on Athletes' Physical Improvement: A Mini Review

Poor vitamin D status is a widespread problem regardless of age and sex, emphasizing the necessity of new food sources to improve vitamin D levels. Currently, approximately 60% of dietary vitamin D consumption occurs via fortified foods. Vitamin D insufficiency (50-90%) is widespread according to age and region, despite different levels of sunlight exposure. The food industry must identify more effective strategies to increase normal dietary vitamin D intake and improve overall health. Strategies for vitamin D fortification include bioaddition, wherein a vitamin D-rich food source is added to staple foods during processes. These bioadditive strategies expand the range of vitamin D-containing foods and appeal to different preferences, cultures, and economic statuses. In several countries, vitamin D deficiency places athletes at a high risk of disease susceptibility. Due to low sun exposure, athletes in countries with higher and lower levels of sunlight have similar risks of vitamin D deficiency. In this review, we summarize recent technical advances to promote vitamin D utilization by humans during sports activities and in relation to the normal practices of athletes.