Influence of vitamin D mushroom powder supplementation on exercise-induced muscle damage in vitamin D insufficient high school athletes

Safety of vitamin D2 mushroom powder as a Novel food pursuant to Regulation (EU) 2015/2283 (NF 2020/2226)

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on vitamin D2 mushroom powder as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is produced from Agaricus bisporus mushroom powder that has been exposed to ultraviolet (UV) irradiation to induce the conversion of provitamin D2 (ergosterol) to vitamin D2 (ergocalciferol). The NF contains concentrations of vitamin D in the form of vitamin D2 in the range of 245-460 μg/g. The information provided on the production process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF as an ingredient in a variety of foods and beverages in amounts that result in either 1.2 or 2.4 μg vitamin D2 per 100 g or 100 mL of the food as consumed. The applicant also intends to add the NF in food supplements at a maximum of 15 μg vitamin D2/day for individuals above 1 year of age, as well as in foods for special medical purposes (FSMPs). The estimates for combined intake of vitamin D from the NF, the background diet and fortified foods, were below the ULs for vitamin D as established previously by the NDA Panel for children, adolescents and adults, i.e. 50 and 100 μg/day. The estimated combined vitamin D intake in infants (6-12 months) is also below the UL for vitamin D of 35 μg/day. The Panel considers that taking into account the composition of the NF and the proposed conditions of use, the consumption of the NF is not nutritionally disadvantageous for the proposed target population. The Panel concludes that the NF is safe under the proposed conditions of use.

Effects of vitamin D3 supplementation on strength of lower and upper extremities in athletes: an updated systematic review and meta-analysis of randomized controlled trials

Background

Coaches and athletes are increasingly interested in understanding athletes' serum vitamin D levels, their impact on strength, physical performance, and athletic outcomes. Previous meta-analyses were reported with limited sample size and no significant overall effect was found. Hence, it is crucial to conduct a thorough and up-to-date systematic examination and meta-analysis to elucidate the potential advantages of supplementing with vitamin D3 in enhancing muscle strength for athletes.

Methods

We performed a thorough investigation, spanning three databases (PubMed, EBSCO, and Cochrane Library), seeking randomized controlled trials (RCTs) in all languages. These trials delved into the influence of vitamin D3 supplementation on the changes of pre- and post-intervention muscle strength in healthy athletes. Our systematic examination and meta-analysis took into account serum 25(OH)D levels exceeding 30 ng/mL as a marker of adequacy.

Results

Ten RCTs, comprising 354 athletes (185 in the vitamin D3 group and 169 in the placebo group), fulfilled the inclusion criteria. During the study, 36 athletes were lost to follow-up, leaving 318 athletes (166 in the vitamin D3 group and 152 in the placebo group) with documented complete results. In comparison with the placebo group, there is a significant increase between the changes of pre- and post-intervention serum 25(OH)D levels among athletes following a period of vitamin D3 supplementation (MD 14.76, 95% CI: 8.74 to 20.77, p < 0.0001). Overall effect of four strength measurements including handgrip, one repetition maximum Bench Press (1-RM BP), vertical jump, and quadriceps contraction was not significantly improved (SMD 0.18, 95% CI: -0.02 to 0.37, p = 0.08), but there was a significant increase in quadriceps contraction (SMD 0.57, 95% CI: 0.04 to 1.11, p = 0.04).

Conclusion

This updated meta-analysis indicates the potential benefits of vitamin D supplementation for enhancing muscle strength in athletes when analyzing its quantitatively synthesized effects. With limited available studies for the quantitative synthesis, it cannot warrant significant overall enhancements in muscle strength when athletes attain adequate serum 25(OH)D levels through supplementation.

Strategic food vehicles for vitamin D fortification and effects on vitamin D status: A systematic review and meta-analysis of randomised controlled trials

There has been growing interest in the potential of vitamin D food fortification in Europe as a means of addressing low vitamin D status. The WHO-FAO suggest that choosing a suitable food vehicle and ensuring the combination of the food vehicle and the fortificant will be efficacious and effective are of key importance to a successful food fortification programme. Our key objective was to conduct a systematic review and meta-analysis to investigate the effect of various animal- and plant-based food vehicles fortified with vitamin D (as D3 or D2) on circulating 25-hydroxyvitamin D [25(OH)D] concentrations. A list of prioritised food vehicles was established and we searched PubMed, Embase, Scopus and Web of Science for randomised controlled trials (RCTs) which used these vehicles individually, and which met prespecified criteria. The searches identified 49 papers which described suitable RCTs using vitamin D-fortified bread/savoury biscuits (n = 5), orange juice (n = 5), UV-mushrooms (n = 8), cheese (n = 3), yogurt (n = 5), fluid milk (n = 13), powdered milk (n = 5), eggs (n = 2), edible oils (n = 4), or breakfast cereal (n = 1). No suitable RCTs were identified for rice, maize flour, butter, margarine or dairy spreads, plant-based milk or yogurt alternatives. Random-effects meta-analyses of each food vehicle individually indicated weighted mean differences (WMD) in 25(OH)D in the range ∼9-35 nmol/L (3-15 RCT arms, depending on vehicle), and all statistically significant (P < 0.01-0.0001), with the exception of UV-mushrooms (P = 0.06). Heterogeneity was variable (I2 =33-99%, depending on vehicle), but subgroup analysis based on vitamer and dose reduced it in some instances. Sub-group analysis on the basis of whether the food vehicles were from plant-based or animal-based origin showed no significant difference in WMD (15.2 versus 15.9 nmol/L, respectively; P = 0.48). These results support the use of various animal- and plant-based food vehicles for vitamin D fortification to improve circulating 25(OH)D concentrations in populations. This work was registered with PROSPERO as CRD42023439883.

Jakyak-gamcho-tang, a decoction of Paeoniae Radix and Glycyrrhizae Radix et Rhizoma, ameliorates dexamethasone-induced muscle atrophy and muscle dysfunction

BACKGROUND

Although chronic treatment with glucocorticoids, such as dexamethasone, is frequently associated with muscle atrophy, effective and safe therapeutics for treating muscle atrophy remain elusive. Jakyak-gamcho-tang (JGT), a decoction of Paeoniae Radix and Glycyrrhizae Radix et Rhizoma, has long been used to relieve muscle tension and control muscle cramp-related pain. However, the effects of JGT on glucocorticoid-induced muscle atrophy are yet to be comprehensively clarified.

PURPOSE

The objective of the current study was to validate the protective effect of JGT in dexamethasone-induced muscle atrophy models and elucidate its underlying mechanism through integrated in silico - in vitro - in vivo studies.

STUDY DESIGN AND METHODS

Differential gene expression was preliminarily analyzed using the RNA-seq data to determine the effects of JGT on C2C12 myotubes. The protective effects of JGT were further validated in dexamethasone-treated C2C12 myotubes by assessing cell viability, myotube integrity, and mitochondrial function or in C57BL/6 N male mice with dexamethasone-induced muscle atrophy by evaluating muscle mass and physical performance. Transcriptomic pathway analysis was also performed to elucidate the underlying mechanism.

RESULTS

Based on preliminary gene set enrichment analysis using the RNA-seq data, JGT regulated various pathways related to muscle differentiation and regeneration. Dexamethasone-treated C2C12 myotubes and muscle tissues of atrophic mice displayed substantial muscle protein degradation and muscle loss, respectively, which was efficiently alleviated by JGT treatment. Importantly, JGT-mediated protective effects were associated with observations such as preservation of mitochondrial function, upregulation of myogenic signaling pathways, including protein kinase B/mammalian target of rapamycin/forkhead box O3, inhibition of ubiquitin-mediated muscle protein breakdown, and downregulation of inflammatory and apoptotic pathways induced by dexamethasone.

CONCLUSION

To the best of our knowledge, this is the first report to demonstrate that JGT could be a potential pharmaceutical candidate to prevent muscle atrophy induced by chronic glucocorticoid treatment, highlighting its known effects for relieving muscle spasms and pain. Moreover, transcriptomic pathway analysis can be employed as an efficient in silico tool to predict novel pharmacological candidates and elucidate molecular mechanisms underlying the effects of herbal medications comprising diverse biologically active ingredients.

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.

Exploring the Relationship between Micronutrients and Athletic Performance: A Comprehensive Scientific Systematic Review of the Literature in Sports Medicine

The aim of this systematic review is twofold: (i) to examine the effects of micronutrient intake on athletic performance and (ii) to determine the specific micronutrients, such as vitamins, minerals, and antioxidants, that offer the most significant enhancements in terms of athletic performance, with the goal of providing guidance to athletes and coaches in optimizing their nutritional strategies. The study conducted a systematic search of electronic databases (i.e., PubMed, Web of Science, Scopus) using keywords pertaining to micronutrients, athletic performance, and exercise. The search involved particular criteria of studies published in English between 1950 and 2023. The findings suggest that vitamins and minerals are crucial for an athlete's health and physical performance, and no single micronutrient is more important than others. Micronutrients are necessary for optimal metabolic body's functions such as energy production, muscle growth, and recovery, which are all important for sport performance. Meeting the daily intake requirement of micronutrients is essential for athletes, and while a balanced diet that includes healthy lean protein sources, whole grains, fruits, and vegetables is generally sufficient, athletes who are unable to meet their micronutrient needs due to malabsorption or specific deficiencies may benefit from taking multivitamin supplements. However, athletes should only take micronutrient supplements with the consultation of a specialized physician or nutritionist and avoid taking them without confirming a deficiency.

Immunologic, Anti-Inflammatory, and Anti-Muscle Damage Profile of Supplemented Vitamin D3 in Healthy Adults on Strenuous Endurance Exercise

Reportedly, strenuous endurance exercise can depress the immune system and induce inflammation and muscle damage. Therefore, this double-blinded, matched-pair study aimed to investigate the impact of vitamin D₃ supplementation on immune response (leukocyte, neutrophil, lymphocyte, CD4⁺, CD8⁺, CD19⁺, and CD56⁺ counts), inflammatory profile (TNF-α and IL-6), muscle damage (CK and LDH levels), as well as aerobic capacity after strenuous endurance exercise in 18 healthy men taking 5000 IU of vitamin D₃ (n = 9) or placebo (n = 9) daily for 4 weeks. Total and differential blood leukocyte counts, levels of cytokines, and muscle damage biomarkers were determined before, immediately after, and 2, 4, and 24 h after exercise. The IL-6, CK, and LDH levels were significantly lower in vitamin D₃ group at 2, 4, and 24 h post exercise (p < 0.05). Maximal and average heart rates during exercise were also significantly lower (p < 0.05). In the vitamin D₃ group, the CD4⁺/CD8⁺ ratio after 4 weeks of supplementation was only significantly lower at post-0 than at baseline and significantly higher at post-2 than at baseline and post-0 (all p < 0.05). Taken together, 5000 IU of daily vitamin D₃ supplementation for 4 weeks exhibited positive effects in terms of increased blood 25(OH)D levels, CD4⁺/CD8⁺ ratio (immune response), and aerobic capacity while inhibiting inflammatory cytokines and CK and LDH (muscle damage) in people performing strenuous endurance exercise.

Vitamin D from UV-Irradiated Mushrooms as a Way for Vitamin D Supplementation: A Systematic Review on Classic and Nonclassic Effects in Human and Animal Models

Recent literature has shown that vitamin D, in addition to its well-known activity on the skeleton, has many positive effects on health. Unfortunately, it is not easy to meet intake needs solely with food. Mushrooms could provide a valid way to achieve this goal, because they are one of the few sources of vitamin D. The aim of this systematic review was to summarize what has been reported in the literature on the treatment of animal and human models with irradiated commercial mushrooms, with particular attention paid to the effects on clinical outcomes associated with the classical and nonclassical vitamin D functions. A total of 18 articles were selected. Six studies were conducted on human samples, while twelve were focused on animal models. The six studies conducted in humans involved a large number of subjects (663), but the treatment period was relatively short (1–6 months). Furthermore, the treatment dosage was different in the various groups (600–3800 IU/day). Probably for this reason, the studies did not demonstrate clinical efficacy on the parameters evaluated (cognitive functions, muscle system/function, metabolic syndrome). Indeed, those studies demonstrated an efficacy in increasing the blood levels of 25(OH)D2, but not in increasing the levels of 25(OH)D total. In 9 of 12 studies conducted on the animal model, however, a clinical efficacy on bone metabolism, inflammation, and cognitive performance was demonstrated. The results of this systematic review indicate that the intake of vitamin D from irradiated mushrooms could possibly help to meet vitamin D needs, but the dosage and the time of treatment tested need to be evaluated. Therefore, studies conducted in humans for longer periods than the studies carried out up to now are necessary, with defined dosages, in order to also evaluate the clinical efficacy demonstrated in animal models both for the classical (bone metabolism) and nonclassical (muscle function, cognitive performance, anti-inflammatory, and antioxidant activities) effects of vitamin D.

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.

Nutritional Compounds to Improve Post-Exercise Recovery

The metabolic and mechanical stresses associated with muscle-fatiguing exercise result in perturbations to bodily tissues that lead to exercise-induced muscle damage (EIMD), a state of fatigue involving oxidative stress and inflammation that is accompanied by muscle weakness, pain and a reduced ability to perform subsequent training sessions or competitions. This review collates evidence from previous research on a wide range of nutritional compounds that have the potential to speed up post-exercise recovery. We show that of the numerous compounds investigated thus far, only two-tart cherry and omega-3 fatty acids-are supported by substantial research evidence. Further studies are required to clarify the potential effects of other compounds presented here, many of which have been used since ancient times to treat conditions associated with inflammation and disease.

Influences of Vitamin D and Iron Status on Skeletal Muscle Health: A Narrative Review

There is conflicting evidence of the roles vitamin D and iron have in isolation and combined in relation to muscle health. The purpose of this narrative review was to examine the current literature on the roles that vitamin D and iron have on skeletal muscle mass, strength, and function and how these nutrients are associated with skeletal muscle health in specific populations. Secondary purposes include exploring if low vitamin D and iron status are interrelated with skeletal muscle health and chronic inflammation and reviewing the influence of animal-source foods rich in these nutrients on health and performance. PubMed, Scopus, SPORT Discus, EMBAE, MEDLINE, and Google Scholar databases were searched to determine eligible studies. There was a positive effect of vitamin D on muscle mass, particularly in older adults. There was a positive effect of iron on aerobic and anaerobic performance. Studies reported mixed results for both vitamin D and iron on muscle strength and function. While vitamin D and iron deficiency commonly occur in combination, few studies examined effects on skeletal muscle health and inflammation. Isolated nutrients such as iron and vitamin D may have positive outcomes; however, nutrients within food sources may be most effective in improving skeletal muscle health.

Safety of vitamin D2 mushroom powder as a Novel food pursuant to Regulation (EU) 2015/2283 (NF 2019/1471)

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on vitamin D₂ mushroom powder as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is produced from Agaricus bisporus mushroom that has been exposed to ultraviolet (UV) irradiation to induce the conversion of provitamin D₂ (ergosterol) to vitamin D₂ (ergocalciferol). The NF contains levels of vitamin D in the form of vitamin D₂ in the range of 125-375 µg/g. The information provided on the production process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF as an ingredient in a variety of foods and beverages in amounts that result in either 1.125 or 2.25 µg vitamin D₂ per 100 g or 100 mL of the food as consumed. The applicant also intends to add the NF in food supplements, for infants from 7 to 11 months at a maximum of 10 µg vitamin D₂/day and of 15 µg vitamin D₂/day for individuals aged 1 year or older, as well as in foods for special medical purposes (FSMPs) and total and meal diet replacement for weight control. For the adult population, the maximum intended use level in FSMPs is 15 µg vitamin D₂/day and 5 µg vitamin D₂/meal in total and meal diet replacement for weight control. The Panel concludes that the NF is safe under the proposed conditions of use. The Panel notes uncertainty regarding the calculated combined exposures to vitamin D for the general population, given the fact that the range of foods fortified with vitamin D has increased over the years, as well as the marketing of high-dose vitamin D supplements.

Vitamin D Supplementation Improves Handgrip Strength in Postmenopausal Women: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

INTRODUCTION

In postmenopausal women, vitamin D deficiency (as defined by the circulating level of 25(OH)D being below 20 ng/ml (50 nmol/L)) is a regular occurrence. The effect of vitamin D supplementation on the muscle function of postmenopausal women has been controversial. This systematic review and meta-analysis of randomized controlled trials (RCTs) examines and summarizes the effects of vitamin D supplementation on the muscular strength and mobility of postmenopausal women.

METHODS

RCTs that met the inclusion criteria for this study were identified by searching PubMed, EMBASE, and the Cochrane Library. Postmenopausal women who were included in the study were exposed to RCTs assessing the effectiveness of vitamin D supplements. Meta-analysis data were extracted by two independent reviewers and screened for methodological quality. RCTs that did not meet the minimum requirement for assessment were excluded. In the meta-analysis, the effect size (weighted mean differences, WMD) of handgrip strength (HGS) and timed-up and go test (TUG) with a 95% confidence interval (CI) was obtained to compare reported results across the included RCTs.

RESULTS

A total of 19 trials were included in this systematic review, among which 13 trials were eligible for the meta-analysis. In the 13 included studies, supplementing with vitamin D produced a weighted mean difference of 0.876 kg (95% CI = 0.180 to 1.571, P = 0.014, I² = 68.5%) for HGS, a measurement of muscle strength. However, an insignificant decrease of 0.044 s was observed after analyzing the TUG (95% CI = -0.979 to 0.892, P = 0.927, I² = 95%). According to subgroup analysis, vitamin D supplementation increased HGS in patients over the age of 60 (P = 0.001), in those without calcium supplementation (P = 0.032), and in those whose baseline vitamin D level was greater than 75 nmol/L (30 ng/ml) (P = 0.003).

CONCLUSIONS

Taking into account the studies in this systematic review, vitamin D supplementation improved muscle strength in postmenopausal women. However, an insignificant result was demonstrated in terms of mobility after vitamin D supplementation.

Medicinal mushrooms: Clinical perspective and challenges

Mushrooms are valued by humans worldwide as food, but also for their medicinal properties. Over 130 medicinal effects of mushrooms have been reported, including anti-diabetic, antioxidant, antimicrobial, anticancer, prebiotic, immunomodulating, anti-inflammatory and cardiovascular benefits. Several mushrooms have been tested in phase I, II, or III clinical trials for various diseases, including cancers, as well as to modulate immunity. Here, we review clinical studies on medicinal mushrooms or preparations (but not pure compounds) derived thereof. Overall, few phase III trials have been performed, and in many cases, these trials included a relatively small number of patients. Therefore, despite the promising published clinical data, especially on immune modulation, more work is required to clarify the therapeutic value of mushrooms.

Effects of Vitamin D in Post-Exercise Muscle Recovery. A Systematic Review and Meta-Analysis

Vitamin D is a key micronutrient modulating function and health in skeletal muscle. Therefore, we sought to systematically review the role of vitamin D in muscle recovery. A search in different databases (PubMed/MEDLINE, WOS, Google Scholar, and Scopus) was carried out following PRISMA^® and PICOS. The search period was from inception to April 2020. Changes in post-exercise muscle damage were quantified comparing experimental group vs. placebo in each study by using number of participants, standardized mean difference (SMD), and standard error of the SMD. Hedges’s g was used to calculate the SMDs for each study group and biased by the inverse of variance that allows calculating an overall effect and the 95% confidence interval (CI). The net vitamin D supplementation effect was calculated by subtracting the placebo SMD from SMD of the experimental group. The DerSimonian and Laird method was used as a random effect model, taking into account that the effect of vitamin D on muscular damage may vary according to the dose administered and additional moderators. Six studies were selected. In conclusion, regarding circulating levels of muscle biomarkers and additional limitations of the studies, it cannot be concluded that vitamin D supplementation exerts an effect in post-exercise muscle recovery. Likely, the anti-inflammatory action of vitamin D is quicker than the recovery of tissue structure and function. This aspect is pending verification in future research.

Vitamin D3 supplementation reduces serum markers of bone resorption and muscle damage in female basketball players with vitamin D inadequacy

This study aimed to investigate the effect of vitamin D₃ supplementation at a dose of 4,000 IU/day for 6 weeks on serum levels of: 25-hydroxyvitamin D [25(OH)D], bone turnover [osteocalcin and carboxy-terminal telopeptides of crosslinks of type I collagen (CTx-I)], and muscle damage [lactate dehydrogenase (LDH) and creatine kinase (CK)] in middle adolescent (15-18 years) and late-adolescent to early adulthood (19-30 years) female basketball players with inadequate vitamin D status. Participants (N=24) were randomly assigned in a double-blind manner into a vitamin D or placebo group. Data were analyzed using separate 2×2x2 mixed ANOVAs with one within-subjects factor (time) and two between-subjects factors (condition and age). When a significant interaction was observed, the intra-group changes were assessed using paired t tests and Hedge's g. Paired t-tests comparing intra-group changes in the vitamin D condition revealed a non-significant large improvement in 25(OH)D (p = 0.06; g = 0.86), non-significant small decreases in CTx-I (p = 0.13; g = -0.22) and CK (p = 0.07; g = -0.26), as well as a significant moderate decrease in LDH (p = 0.004; g = -0.74). Paired t-tests comparing intra-group changes in the placebo condition revealed a significant moderate decline in 25(OH)D (p <0.001; g = -0.77), as well as significant small increases in CTx-I (p = 0.04; g = 0.47) and CK (p = 0.04; g = 0.36). Vitamin D₃ supplementation at 4,000 IU/day could be effective in reducing bone resorption and muscle damage in female basketball players with inadequate baseline vitamin D, irrespective of age.

The future is bright: Biofortification of common foods can improve vitamin D status

Vitamin D deficiency is a global concern, linked to suboptimal musculoskeletal health and immune function, with status inadequacies owing to variations in UV dependent cutaneous synthesis and limited natural dietary sources. Endogenous biofortification, alongside traditional fortification and supplement usage is urgently needed to address this deficit. Evidence reviewed in the current article clearly demonstrates that feed modification and UV radiation, either independently or used in combination, effectively increases vitamin D content of primary produce or ingredients, albeit in the limited range of food vehicles tested to date (beef/pork/chicken/eggs/fish/bread/mushrooms). Fewer human trials have confirmed that consumption of these biofortified foods can increase circulating 25-hydroxyvitamin D [25(OH)D] concentrations (n = 10), which is of particular importance to avoid vitamin D status declining to nadir during wintertime. Meat is an unexplored yet plausible food vehicle for vitamin D biofortification, owing, at least in part, to its ubiquitous consumption pattern. Consumption of PUFA-enriched meat in human trials demonstrates efficacy (n = 4), lighting the way for exploration of vitamin D-biofortified meats to enhance consumer vitamin D status. Response to vitamin D-biofortified foods varies by food matrix, with vitamin D₃-enriched animal-based foods observing the greatest effect in maintaining or elevating 25(OH)D concentrations. Generally, the efficacy of biofortification appears to vary dependent upon vitamer selected for animal feed supplementation (vitamin D₂ or D₃, or 25(OH)D), baseline participant status and the bioaccessibility from the food matrix. Further research in the form of robust human clinical trials are required to explore the contribution of biofortified foods to vitamin D status.

Vitamin D in athletes: focus on physical performance and musculoskeletal injuries

PURPOSE

The aim of this review was to discuss the effects of vitamin D on physical performance and musculoskeletal injuries in athletes and provide information on the field applications of vitamin D.

METHODS

A systematic review was conducted to identify studies on vitamin D in athletes that assessed serum vitamin D levels, vitamin D and physical performance, vitamin D and musculoskeletal injuries, and practical guidelines for supplementation of vitamin D.

RESULTS

Several studies reported that a high proportion of athletes had vitamin D insufficiency or deficiency. Low serum levels of vitamin D in athletes were more pronounced in winter than in other seasons, and indoor athletes had lower serum vitamin D levels than outdoor athletes. Low vitamin D levels have been demonstrated to have negative effects on muscle strength, power, and endurance; increase stress fractures and other musculoskeletal injuries; and affect acute muscle injuries and inflammation following high-intensity exercises. Therefore, periodic assessment and monitoring of vitamin D levels are necessary in athletes; the recommended serum level of 25(OH)D is &gt; 32 ng/mL and the preferred level is &gt; 40 ng/mL (-1). In those with low levels of vitamin D, exposure to sunlight and an improved diet or supplements may be helpful. Particularly, 2000-6000 IU of supplemental vitamin D3 can be consumed daily.

CONCLUSION

Vitamin D is a potential nutritional factor that can significantly affect physical performance and musculoskeletal injuries in athletes. The importance and role of vitamin D in athletes should be emphasized, and the current levels of vitamin D should be assessed. Therefore, it is essential to periodically evaluate and monitor serum vitamin D levels in athletes.

Safety of Vitamin D2 mushroom powder (Agaricus bisporus) as a Novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on vitamin D2 mushroom powder as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is an ingredient produced from Agaricus bisporus mushroom powder that has been exposed to ultraviolet (UV) irradiation to induce the conversion of provitamin D2 (ergosterol) to vitamin D2 (ergocalciferol). The NF contains concentrations of vitamin D provided by vitamin D2 in the ranges of 580-595 μg/g. The information provided on the manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF in a variety of foods and beverages, including food for special medical purposes and food supplements. The target population is the general population except for food supplements and Foods for Special Medical Purposes (FSMPs), for which the target population is individuals above 1 year of age. The Panel concludes that the NF, used as an ingredient, is safe for the general population at the proposed condition of use in foods and beverages and that the NF used as a food supplement, is safe for individuals above 1 year.

Vitamin D, sport and health: a still unresolved clinical issue

Vitamin D metabolites have a pleiotropic role in human physiology, both in static and dynamic conditions, and a lot of vitamin D-related biological effects could influence physical and sport performances in athletes. Probably due to different factors (e.g., drugs, doping, nutrition, ultraviolet B radiation exposure), in athletes a very high prevalence of vitamin D inadequacy (i.e., deficiency or insufficiency) has been observed. Vitamin D inadequacy in athletes could be associated with specific health risks and to alterations of functional capacities, potentially influencing the fine adjustment of physical performances during training and sport competitions. When risk factors for vitamin D inadequacy exist, a preventive vitamin D supplementation is indicated, and if a vitamin D inadequacy is diagnosed, its supplementation is recommended. Unfortunately, on these issues many concerns remain unresolved. Indeed, it is not clear if athletes should be classified as a special population at increased risk for vitamin D inadequacy; moreover, in comparison to the non-athletic population, it is still not clear if athletes should have different reference ranges and different optimal target levels for serum vitamin D, if they have additional health risks, and if they need different type of supplementations (doses) for prevention and/or replacement therapy. Moreover, in athletes also the abuse of vitamin D supplements for ergogenic purposes raise different ethical and safety concerns. In this review, the main physio-pathological, functional and clinical issues that relate vitamin D to the world of athletes are described.

Assessing the impact of a mushroom-derived food ingredient on vitamin D levels in healthy volunteers

BACKGROUND

Prevalence of vitamin D insufficiency/deficiency has been noted in athletic populations, although less is known about recreationally active individuals. Biofortification of natural food sources (e.g. UV radiated mushrooms) may support vitamin D status and is therefore of current scientific and commercial interest. The aim of this study was to assess the impact of a mushroom-derived food ingredient on vitamin D status in recreationally active, healthy volunteers.

METHODS

Twenty-eight participants were randomly assigned to either: 25 μg (1000 IU) encapsulated natural mushroom-derived vitamin D₂; matched-dose encapsulated vitamin D₃ or placebo (PL) for 12 weeks. Venous blood samples were collected at baseline, week 6 and 12 for analysis of serum 25(OH)D₂ and 25(OH)D₃ using liquid chromatography mass spectrometry. Habitual dietary intake and activity were monitored across the intervention.

RESULTS

Vitamin D status (25(OH)D_TOTAL) was significantly increased with vitamin D₃ supplementation from 46.1 ± 5.3 nmol·L^- 1 to 88.0 ± 8.6 nmol·L^- 1 (p < 0.0001) across the intervention, coupled with an expected rise in 25(OH)D₃ concentrations from 38.8 ± 5.2 nmol·L^- 1 to 82.0 ± 7.9 nmol·L^- 1 (p < 0.0001). In contrast, D₂ supplementation increased 25(OH)D₂ by + 347% (7.0 ± 1.1 nmol·L^- 1 to 31.4 ± 2.1 nmol·L^- 1, p < 0.0001), but resulted in a - 42% reduction in 25(OH)D₃ by week 6 (p = 0.001). A net + 14% increase in 25(OH)D_TOTAL was established with D₂ supplementation by week 12 (p > 0.05), which was not statistically different to D₃. Vitamin D status was maintained with PL, following an initial - 15% reduction by week 6 (p ≤ 0.046 compared to both supplement groups).

CONCLUSIONS

The use of a UV radiated mushroom food ingredient was effective in maintaining 25(OH)D_TOTAL in healthy, recreationally active volunteers. This may offer an adjunct strategy in supporting vitamin D intake. However, consistent with the literature, the use of vitamin D₃ supplementation likely offers benefits when acute elevation in vitamin D status is warranted.

The effect of vitamin D supplementation on the muscle damage after eccentric exercise in young men: a randomized, control trial

Background

Vitamin D contributes to the optimal functioning of muscles. This study was designed to determine the modulating effect of vitamin D supplementation on the degree of muscle cell damage caused by eccentric exercise in young men.

Methods

60 male volunteers (20–24 years old) taking part in this study were divided in two groups - with suboptimal (S) and optimal (O;) 25(OH)D plasma levels. These groups were randomly subdivided into groups with vitamin D supplementation (experimental: SE and OE) and controls (SC and OC). Before the supplementation (Test I) and after 3 months (Test II), participants were subjected to two rounds of eccentric exercise tests on a declined treadmill (running speed corresponded 60% VO2peak determined in each subject in incremental exercise test). During each test, blood samples used for determination of 25(OH)D, Il-1β, myoglobin (Mb) levels and CK, LDH activity were taken at three timepoints: before the test, 1 h and 24 h after it ended.

After distribution normality testing (Saphiro-Wilk test), statistical analyses were performed. Non-parametric: Kruskal-Wallis test and the Wilcoxon test were applied, and the Dunn-Bonferroni test as a post-hoc test.

Results

In all groups, after 3 months, higher concentrations of 25(OH)D were indicated (SE p = 0.005; SC p = 0.018; OE p = 0.018; OC p = 0.028). SE and SC groups showed higher baseline concentrations of Il-1β and significantly higher concentrations of this interleukin after 1 h compared to groups with an optimal 25(OH)D level. After supplementation, the SE group reacted with a similar jump in concentration of Il-1β as the OC and OE groups. The change after 1 h after exercise in Test II was significantly different from that from Test I (p = 0.047) in SE group. Lower Mb concentrations indicated 1 h after exercise in Test II for SC and SE groups were indicated. CK activity did not differentiate the studied groups. Plasma calcium and phosphate disorders were also not indicated.

Conclusions

The study has shown that vitamin D doses determined from the plasma concentration of 25(OH)D of individuals to match their specific needs can significantly reduce muscle cell damage induced by eccentric exercise.

Vitamin D Supplementation Does Not Impact Resting Metabolic Rate, Body Composition and Strength in Vitamin D Sufficient Physically Active Adults

Supplementation with the most efficient form of Vitamin D (VitD3) results in improvements in energy metabolism, muscle mass and strength in VitD deficient individuals. Whether similar outcomes occur in VitD sufficient individuals' remains to be elucidated. The aim of this study is to determine the effect of VitD3 supplementation on resting metabolic rate (RMR), body composition and strength in VitD sufficient physically active young adults. Participants completed pre-supplementation testing before being matched for sunlight exposure and randomly allocated in a counterbalanced manner to the VitD3 or placebo group. Following 12 weeks of 50 IU/kg body-mass VitD3 supplementation, participants repeated the pre-supplementation testing. Thirty-one adults completed the study (19 females and 12 males; mean ± standard deviation (SD); age = 26.6 ± 4.9 years; BMI = 24.2 ± 4.1 kg·m²). The VitD group increased serum total 25(OH)D by 30 nmol/L while the placebo group decreased total serum concentration by 21 nmol/L, reaching 123 (51) and 53 (42.2) nmol/L, respectively. There were no significant changes in muscle strength or power, resting metabolic rate and body composition over the 12-week period. Physically active young adults that are VitD sufficient have demonstrated that no additional physiological effects of achieving supraphysiological serum total 25(OH)D concentrations after VitD3 supplementation.

Examining the health effects and bioactive components in Agaricus bisporus mushrooms: a scoping review

There is evidence from both in vitro and animal models that the consumption of edible mushrooms has beneficial effects on health. It is unclear whether similar effects exist in humans and which bioactive compounds are present. This review synthesises the evidence on the world's most commonly consumed mushroom, Agaricus bisporus to (i) examine its effect on human health outcomes; and (ii) determine the nutrient density of its bioactive compounds, which may explain their health effects. A systematic literature search was conducted on the consumption of A. bisporus, without date and study design limits. Bioactive compounds included ergosterol, ergothioneine, flavonoids, glucans and chitin. Two authors independently identified studies for inclusion and assessed methodological quality. Beneficial effects of A. bisporus on metabolic syndrome, immune function, gastrointestinal health and cancer, with the strongest evidence for the improvement in Vitamin D status in humans, were found. Ultraviolet B (UVB) exposed mushrooms may increase and maintain serum 25(OH)D levels to a similar degree as vitamin D supplements. A. bisporus contain beta-glucans, ergosterol, ergothioneine, vitamin D and an antioxidant compound usually reported as flavonoids; with varying concentrations depending on the type of mushroom, cooking method and duration, and UVB exposure. Further research is required to fully elucidate the bioactive compounds in mushrooms using vigorous analytical methods and expand the immunological markers being tested. To enable findings to be adopted into clinical practice and public health initiatives, replication of existing studies in different population groups is required to confirm the impact of A. bisporus on human health.

Nutritional interventions for reducing the signs and symptoms of exercise-induced muscle damage and accelerate recovery in athletes: current knowledge, practical application and future perspectives

PURPOSE

This review provides an overview of the current knowledge of the nutritional strategies to treat the signs and symptoms related to EIMD. These strategies have been organized into the following sections based upon the quality and quantity of the scientific support available: (1) interventions with a good level of evidence; (2) interventions with some evidence and require more research; and (3) potential nutritional interventions with little to-no-evidence to support efficacy.

METHOD

Pubmed, EMBASE, Scopus and Web of Science were used. The search terms 'EIMD' and 'exercise-induced muscle damage' were individually concatenated with 'supplementation', 'athletes', 'recovery', 'adaptation', 'nutritional strategies', hormesis'.

RESULT

Supplementation with tart cherries, beetroot, pomegranate, creatine monohydrate and vitamin D appear to provide a prophylactic effect in reducing EIMD. β-hydroxy β-methylbutyrate, and the ingestion of protein, BCAA and milk could represent promising strategies to manage EIMD. Other nutritional interventions were identified but offered limited effect in the treatment of EIMD; however, inconsistencies in the dose and frequency of interventions might account for the lack of consensus regarding their efficacy.

CONCLUSION

There are clearly varying levels of evidence and practitioners should be mindful to refer to this evidence-base when prescribing to clients and athletes. One concern is the potential for these interventions to interfere with the exercise-recovery-adaptation continuum. Whilst there is no evidence that these interventions will blunt adaptation, it seems pragmatic to use a periodised approach to administering these strategies until data are in place to provide and evidence base on any interference effect on adaptation.

Effects of vitamin D3 supplementation on serum 25(OH)D concentration and strength in athletes: a systematic review and meta-analysis of randomized controlled trials

Background

The purpose of this systematic review and meta-analysis is to investigate the effects of vitamin D3 supplementation on skeletal muscle strength in athletes. Vitamin D3 supplements or vitamin D3 fortified foods always have claims for bringing people health benefits including bone and muscle health. An up-to-date rigorous systematic review and meta-analysis is important to better understand the effect of vitamin D3 supplementation on muscle strength.

Methods

English written randomized controlled trials (RCTs) that looked at effects of vitamin D3 supplementation on muscle strength in healthy athletes were searched using three databases (PubMed, Embase and Cochrane Library). Serum 25(OH)D above 30 ng/mL is considered to be sufficient in this systematic review and meta-analysis.

Results

Five RCTs with 163 athletes (vitamin D3 n = 86, placebo n = 77) met inclusion criteria. Fourteen athletes were lost to follow-up and 149 athletes (vitamin D3 n = 80, placebo n = 69) were documented with complete result. Among athletes with baseline serum 25(OH)D values suggesting insufficiency, vitamin D3 daily dosage at 5000 IU for over 4 weeks led to a serum 25(OH)D concentration of 31.7 ng/mL. Athletes with sufficient serum 25(OH)D level at baseline were recruited in only one study, and the participants of which were assigned to either vitamin D3 at a daily dosage of 3570 IU or placebo for 12 weeks, their serum 25(OH)D sufficiency (VD: 37.2 ± 7.6 vs. 45.6 ± 7.6; PL: 38 ± 6.8 vs. 32 ± 8.4) was well maintained above the cut-off boundary. One repetition maximum Bench Press (1-RM BP) was not improved significantly (SMD 0.07, 95% CI: − 0.32 to 0.47, P = 0.72) and there was no significant increase in maximal quadriceps contraction (SMD -2.14, 95% CI: − 4.87 to 0.59, P = 0.12). Furthermore, there was no significant overall effect of vitamin D3 intervention on muscle strength in this meta-analysis (SMD -0.75, 95% CI: − 1.82 to 0.32, P = 0.17).

Conclusion

Although, serum 25(OH)D concentrations after supplementation reached sufficiency was observed, muscle strength did not significantly improve at this point of current meta-analysis. Additional well-designed RCTs with large number of participants examined for the effect of vitamin D3 supplementation on serum 25(OH)D concentrations, muscle strength in a variety of sports, latitudes and diverse multicultural populations are needed.

A single mega dose of vitamin D3 improves selected physical variables in vitamin D-deficient young amateur soccer players: a randomized controlled trial

This randomized controlled trial aimed to test whether vitamin D (VD) supplementation affects measures of physical performance in VD-deficient, mildly trained children. Thirty-six recreationally soccer player boys were randomly assigned to single dose (200 000 IU) of VD3 (n = 19) or placebo (n = 17). Plasma 25-hydroxyvitamin D (25-OHD) was assessed and measures of physical performance (i.e., vertical and standing broad jumps, triple hop, 10-m and 30-m sprints, shuttle run) were performed before and 12 weeks after the loading dose. Mixed ANCOVA models were performed and effect size was estimated by partial eta squared (η_p²). Baseline 25-OHD and physical variables were equivalent in the 2 groups. Twelve weeks after VD loading, plasma 25-OHD increased and physical variables improved only in the VD group. There was a significant interaction effects for group by time for vertical jump (F = 14.9, p = 0.001, η_p² = 0.394), triple hop jump (F = 24.2, p < 0.001, η_p² = 0.513), 10-m (F = 4.46, p = 0.046, η_p² = 0.162) and 30-m (F = 6.56, p = 0.017, η_p² = 0.222) sprints, and shuttle run (F = 13.4, p = 0.001, η_p² = 0.369). In conclusion, a single bolus of VD3 resulted in significant improvements in jumping ability, agility, and running speed in mildly trained children that are deficient in VD. The findings suggest that correcting VD deficit might be beneficial for physical performance. Novelty A mega dose of VD3 improves jumping ability, agility, and running speed in VD-deficient, mildly trained children. Effect of VD on measures of physical performance is noticeable 3 months after the loading dose.

Physical performance is not improved with vitamin D repletion: a randomized trial

BACKGROUND

Studies enrolling physically active participants have used various vitamin D dosing strategies which can result in diverse post supplementation vitamin D status due to individual body weight and initial vitamin D status. Emerging evidence suggests serum 25(OH)D levels of 100-120 nmol/L are optimal for peak performance, however, studies generally administer the same dose for all participants regardless of initial 25(OH)D status and body weight. This approach will not likely get all participants to the optimal 25(OH)D level proposed for optimal physical performance. Therefore, it's important to enroll vitamin D insufficient/deficient participants to observe the effects of vitamin D supplementation on physical performance. We assessed vitamin D repletion on markers of anaerobic performance in physically active adults by replenishing insufficient/deficient vitamin D to the target of 100-120 nmol/L suggested for optimal physical performance.

METHODS

We conducted a double-blind randomized control trial in 42 physically active participants, 18-42 years of age in the winter months. Physically active participants with insufficient/deficient 25(OH)D status (<75 nmol/L) were supplemented with an individualized dosing strategy to achieve 25(OH)D of 120 nmol/L with eight weeks of supplementation using the following formula: Dose (IU)=40•[Target 25(OH)D3 - Initial 25(OH)D3]•Body Weight (kg). A modified Wingate test, 10m and 40m sprints, vertical jump, hand grip strength, pushups, and isokinetic knee flexion and extension were assessed before and after repletion of 25(OH)D.

RESULTS

Thirty-nine out of 42 participants completed the study. Twenty-seven participants in the vitamin D group significantly increased 25(OH)D from 61 nmol/L to 123 nmol/L (P<0.001). 12 participants in the Placebo group had a significant decrease in 25(OH)D from 98 nmol/L to 83 nmol/L (P=0.02). Despite these changes in 25(OH)D status in each group, no significant changes in anaerobic performance markers were found.

CONCLUSIONS

These findings indicate that vitamin D repletion to levels sufficient for optimal physical performance does not improve anaerobic physical performance.

Vitamin D, Skeletal Muscle Function and Athletic Performance in Athletes-A Narrative Review

The active form of vitamin D (calcitriol) exerts its biological effects by binding to nuclear vitamin D receptors (VDRs), which are found in most human extraskeletal cells, including skeletal muscles. Vitamin D deficiency may cause deficits in strength, and lead to fatty degeneration of type II muscle fibers, which has been found to negatively correlate with physical performance. Vitamin D supplementation has been shown to improve vitamin D status and can positively affect skeletal muscles. The purpose of this study is to summarize the current evidence of the relationship between vitamin D, skeletal muscle function and physical performance in athletes. Additionally, we will discuss the effect of vitamin D supplementation on athletic performance in players. Further studies are necessary to fully characterize the underlying mechanisms of calcitriol action in the human skeletal muscle tissue, and to understand how these actions impact the athletic performance in athletes.

Effect of vitamin D supplementation on upper and lower limb muscle strength and muscle power in athletes: A meta-analysis

BACKGROUND

Vitamin D may play a role in skeletal muscle because of the discovery of VDR in skeletal muscle. However, vitamin D deficiency is a global problem, including athletes. Studies examining the effect of vitamin D supplementation on muscle function in athletes have inconsistent results. Therefore, we aimed to quantitatively summarize the evidence for the effect of vitamin D supplementation on skeletal muscle strength and explosive power of athletes using a meta-analysis.

METHODS

PubMed, EMBASE, Cochrane Library, and Web of Science were searched for studies to identify randomized controlled trials or controlled trials meeting the inclusion criteria. By a meta-analysis, effect sizes (standardized mean differences, SMD) with 95% confidence intervals (CI) was calculated to compare reported outcomes across studies, I2 index was used to assessing heterogeneity, and heterogeneity factors were identified by regression analysis. The potential publication and sensitivity analyses were also assessed.

RESULTS

Eight RCTs involving 284 athletes were included. The protocols used to evaluate the muscle strength of athletes were inconsistent across the included studies, and muscle explosive power was assessed via vertical jump tests. The results indicated that vitamin D supplementation had no impact on overall muscle strength outcomes (SMD 0.05, 95% CI: -0.39 to 0.48, p = 0.84). In subgroup analysis, vitamin D supplementation had an effect on lower-limb muscle strength (SMD 0.55, 95% CI:0.12 to 0.98, p = 0.01) but not upper-limb muscle strength (SMD -0.19, 95% CI:-0.73 to 0.36, p = 0.50) or muscle explosive power (SMD 0.05, 95% CI:-0.24 to 0.34, p = 0.73). Vitamin D supplementation was more effective for athletes trained indoors (SMD 0.48, 95% CI:0.06 to 0.90, p = 0.02).

CONCLUSIONS

Vitamin D supplementation positively affected lower limb muscle strength in athletes, but not upper limb muscle strength or muscle power. Different muscle groups and functions may respond differently to vitamin D supplementation. Additional studies should focus on determining the appropriate vitamin D supplementation methods and optimal serum 25(OH)D levels for athletes.

REGISTRATION

The protocol for our study is registered in the international prospective register of systematic reviews (PROSPERO registration number CRD42016045872).

Effect of vitamin D3 seasonal supplementation with 1500 IU/day in north Italian children (DINOS study)

Background

The appropriate dose of vitamin D supplementation in children is still debated. We calculated that the recommended dose of 600–1000 IU vitamin D3/day is not sufficient to reach a serum 25-hydroxyvitamin D (25-OH-D) level of at least 30 ng/ml (75 nmol/l) in north Italian children > 12 months. The aim of this study was to analyse the effect of seasonal supplementation with 1500 IU (=37.5 μg) vitamin D3/day.

Methods

DINOS (D-vitamIN Oral Supplementation) study was a pilot, monocentric, non-random case-control register study. It was conducted in a paediatric primary care setting near Padova (North Italy, 45°N latitude). The data of 203 children (girls:boys 1:1,33) aged 2–15 years, collected between November 2010 and January 2015, were analysed. Active group A (n = 82) were given 1500 IU vitamin D3/day from November to April; control Group B (n = 121) received no supplementation. The serum 25-OH-D test was part of a laboratory tests panel and performed using a chemiluminescence immunoassay method.

Results

Serum 25-OH-D mean level + standard deviation throughout the period was 32 + 13 ng/ml (80 + 32 nmol/l) in group A vs 22 + 10 ng/ml (55 + 25 nmol/l) in group B. In group A 12% had vitamin D deficiency 25-OH-D < 20 ng/ml (50 nmol/l) and 1.2% severe vitamin D deficiency 25-OH-D < 10 ng/ml (25 nmol/l). In group B 46% had vitamin D deficiency and 9% severe deficiency (P <  0.001). In group A mean levels were normal or near-normal all the year except in May. Group B reached mean 25-OH-D levels close to 30 ng/ml (75 nmol/l) only in late summer. The active group mean 25-OH-D level was normal in preschoolers and schoolers but not in adolescents. Non-white children had a three-times vitamin D deficiency probability despite supplementation.

Conclusions

Vitamin D supplementation with at least 1500 IU vitamin D3/day from November to April was found appropriate for children in North Italy. A prolongation until May could be useful. Higher doses and/or prolonged periods could be more appropriate especially in adolescents and in non-white children.

Study registration

DINOS gained the approval of Padova Ethics Committee (n. 3960/U16/2016).

Electronic supplementary material

The online version of this article (10.1186/s13052-018-0590-x) contains supplementary material, which is available to authorized users.

Nutritional and Supplementation Strategies to Prevent and Attenuate Exercise-Induced Muscle Damage: a Brief Review

Exercise-induced muscle damage (EIMD) is typically caused by unaccustomed exercise and results in pain, soreness, inflammation, and reduced muscle function. These negative outcomes may cause discomfort and impair subsequent athletic performance or training quality, particularly in individuals who have limited time to recover between training sessions or competitions. In recent years, a multitude of techniques including massage, cryotherapy, and stretching have been employed to combat the signs and symptoms of EIMD, with mixed results. Likewise, many varied nutritional and supplementation interventions intended to treat EIMD-related outcomes have gained prominence in the literature. To date, several review articles have been published that explore the many recovery strategies purported to minimize indirect markers of muscle damage. However, these articles are very limited from a nutritional standpoint. Thus, the purpose of this review is to briefly and comprehensively summarize many of these strategies that have been shown to positively influence the recovery process after damaging exercise. These strategies have been organized into the following sections based on nutrient source: fruits and fruit-derived supplements, vegetables and plant-derived supplements, herbs and herbal supplements, amino acid and protein supplements, vitamin supplements, and other supplements.

Effects of Vitamin D Supplementation on Serum 25-Hydroxyvitamin D Concentrations and Physical Performance in Athletes: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

There is currently no systematic review examining the effects of vitamin D supplementation among athletes. A rigorous systematic review and meta-analysis is important to provide a balanced view of current knowledge on the effect of vitamin D on serum 25-hydroxyvitamin D [25(OH)D] concentrations and physical performance.

OBJECTIVES

This systematic review of randomized controlled trials (RCTs) evaluated the effects of oral vitamin D supplementation on serum 25(OH)D concentrations and physical performance in athletes.

METHODS

Multiple electronic databases were searched, and study eligibility, methodological quality assessment, and data extraction were completed independently and in duplicate. Studies were stratified by baseline vitamin D sufficiency, season, and latitude. A cut-off of 30 ng/ml (75 nmol/l) of 25(OH)D was used for sufficiency. Absolute mean differences (AMDs) between vitamin D and placebo using random effects analysis, and heterogeneity using Q statistic and I ² index, were calculated. AMD with 95% confidence interval (CI), p value, and I ² are reported.

RESULTS

In total, 13 RCTs (2005-2016) with 532 athletes (vitamin D 311, placebo 221) were eligible. A total of 433 athletes (vitamin D 244, placebo 189) had complete outcome data. Among athletes with baseline values suggesting insufficiency, vitamin D supplementation led to significant increases from 3000 IU (AMD 15.2 ng/ml; 95% CI 10.7-19.7, p < 0.0001, I ² = 0%) and 5000 IU (AMD 27.8 ng/ml; 95% CI 16.9-38.8, p < 0.0001, I ² = 78%) per day at >45° latitudes. Both doses led to sufficiency concentrations during winter months. Among athletes with baseline vitamin D suggesting sufficiency, serum 25(OH)D sufficiency was maintained from different doses at both latitudes. Of 13 included trials, only seven measured different physical performances and none demonstrated a significant effect of vitamin D supplementation during 12 weeks of follow-up.

CONCLUSION

Despite achieving sufficiency in vitamin D concentrations from ≥3000 IU supplementation, physical performance did not significantly improve. Between-study heterogeneity was large, and well-designed RCTs examining the effect of vitamin D supplementation on serum 25(OH)D concentrations, physical performance, and injuries in different sports, latitudes, ethnicities, and vitamin D status are needed.

Vitamin D in pediatric age: consensus of the Italian Pediatric Society and the Italian Society of Preventive and Social Pediatrics, jointly with the Italian Federation of Pediatricians

Vitamin D plays a pivotal role in the regulation of calcium-phosphorus metabolism, particularly during pediatric age when nutritional rickets and impaired bone mass acquisition may occur.Besides its historical skeletal functions, in the last years it has been demonstrated that vitamin D directly or indirectly regulates up to 1250 genes, playing so-called extraskeletal actions. Indeed, recent data suggest a possible role of vitamin D in the pathogenesis of several pathological conditions, including infectious, allergic and autoimmune diseases. Thus, vitamin D deficiency may affect not only musculoskeletal health but also a potentially wide range of acute and chronic conditions. At present, the prevalence of vitamin D deficiency is high in Italian children and adolescents, and national recommendations on vitamin D supplementation during pediatric age are lacking. An expert panel of the Italian Society of Preventive and Social Pediatrics reviewed available literature focusing on randomized controlled trials of vitamin D supplementation to provide a practical approach to vitamin D supplementation for infants, children and adolescents.

Vitamin D3 Supplementation Does Not Improve Sprint Performance in Professional Rugby Players: A Randomized, Placebo-Controlled, Double-Blind Intervention Study

Vitamin D insufficiency is common in athletes and may lower physical performance. Many cross-sectional studies associate vitamin D status with physical performance in athletes; however, there have been few prospective randomized controlled trials with adequate statistical power to test this relationship, and none in the southern hemisphere. Thus, a prospective double-blind, randomized, placebo-controlled intervention trial was conducted involving 57 professional rugby union players in New Zealand. Participants were randomized to receive 50,000 IU of cholecalciferol (equivalent to 3,570 IU/day) or placebo once every two weeks over 11-12 weeks. Serum 25(OH)D concentrations and physical performance were measured at baseline, weeks 5-6, and weeks 11-12. Mean (SD) serum 25(OH)D concentrations for all participants at baseline was 94 (18) nmol/L, with all players above 50 nmol/L. Vitamin D supplementation significantly increased serum 25(OH)D concentrations compared to placebo, with a 32 nmol/L difference between groups at 11-12 weeks (95% CI, 26-38; p < 0.001). Performance in five of the six tests at study completion, including the primary outcome variable of 30-m sprint time, did not differ between the vitamin D supplemented and placebo groups (p > 0.05). Performance on the weighted reverse-grip chin up was significantly higher in players receiving vitamin D compared with placebo, by 5.5 kg (95% CI, 2.0-8.9; p = 0.002). Despite significantly improving vitamin D status in these professional rugby union players, vitamin D supplementation had little impact on physical performance outcomes. Thus, it is unlikely that vitamin D supplementation is an ergogenic aid in this group of athletes.

Effect of Vitamin D Supplementation on Training Adaptation in Well-Trained Soccer Players

Jastrzębska, M, Kaczmarczyk, M, and Jastrzębski, Z. Effect of vitamin D supplementation on training adaptation in well-trained soccer players. J Strength Cond Res 30(9): 2648-2655, 2016-There is growing body of evidence implying that vitamin D may be associated with athletic performance, however, studies examining the effects of vitamin D on athletic performance are inconsistent. Moreover, very little literature exists about the vitamin D and training efficiency or adaptation, especially in high-level, well-trained athletes. The purpose of the current study was to investigate the effect of vitamin D supplementation on training adaptation in well-trained football players. The subjects were divided into 2 groups: the placebo group (PG) and the experimental group (SG, supplemented with vitamin D, 5,000 IU per day). Both groups were subjected to High Intensity Interval Training Program. The selection to the groups was based on peak power results attained before the experiment and position on the field. Blood samples for vitamin D level were taken from the players. In addition, total work, 5, 10, 20, and 30 m running speed, squat jump, and countermovement jump height were determined. There were no significant differences between SG and PG groups for any power-related characteristics at baseline. All power-related variables, except the 30 m sprint running time, improved significantly in response to interval training. However, the mean change scores (the differences between posttraining and pretraining values) did not differ significantly between SG and PG groups. In conclusion, an 8-week vitamin D supplementation in highly trained football players was not beneficial in terms of response to High Intensity Interval Training. Given the current level of evidence, the recommendation to use vitamin D supplements in all athletes to improve performance or training gains would be premature. To avoid a seasonal decrease in 25(OH)D level or to obtain optimal vitamin D levels, the combination of higher dietary intake and vitamin D supplementation may be necessary.

A Systematic Review of the Role of Vitamin D on Neuromuscular Remodelling Following Exercise and Injury

Vitamin D is important for skeletal muscle health and deficiency is associated with clinical neuromuscular symptoms of poor strength and gait. Supplementation can independently increase muscle strength in chronically deficient populations. However, the regulatory role of vitamin D on neuromuscular remodelling and adaptation subsequent to exercise conditioning or injury has not been systematically reviewed.

OBJECTIVE

to systematically review the available evidence of the role of vitamin D on neuromuscular remodelling following exercise conditioning, exercise- or experimentally induced injury. We searched Medline (OVID platform), PubMed, Embase and Web of Science for randomised controlled trials (RCTs) including measures of neuromuscular function, injury and/or inflammation; a physiologically stressful intervention involving exercise conditioning, exercise- or experimentally induced injury and; vitamin D supplementation. Nine RCTs met the inclusion criteria. Significant heterogeneity of methodological approaches and outcomes meant that meta-analysis of data was limited. Qualitative findings indicated that vitamin D may be an effective accelerant of neuromuscular remodelling in animal models (24-140 % improved recovery vs. control); the effects in humans are inconclusive and likely influenced by baseline vitamin D and supplementation strategy. Results of the meta-analyses indicated no effect of vitamin D supplementation on muscle strength adaptation following resistance training [standardised mean difference (SMD): 0.74, P = 0.42] or muscle damage (SMD: -0.03, P = 0.92), although inflammatory markers were elevated in the latter (SMD: 0.56, P = 0.04). Data from animal models offer promising and plausible mechanisms for vitamin D as an agent for neuromuscular adaptation. Further high-quality research is needed to offer clearer insight into the influential role of vitamin D in human populations.

Effect of Ultraviolet Light-Exposed Mushrooms on Vitamin D Status: Liquid Chromatography-Tandem Mass Spectrometry Reanalysis of Biobanked Sera from a Randomized Controlled Trial and a Systematic Review plus Meta-Analysis

BACKGROUND

Randomized controlled trial (RCT) data on the response of serum total 25-hydroxyvitamin D [25(OH)D] in healthy participants consuming UV light-exposed edible mushrooms are limited and mixed.

OBJECTIVE

The objective was to undertake a systematic review and meta-analysis of responses of serum 25(OH)D [and serum 25-hydroxyergocalciferol, 25(OH)D2, and serum 25-hydroxycholecalciferol, 25(OH)D3, if available] to consumption of UV-exposed mushrooms by healthy participants. Biobanked sera from one RCT (originally analyzed by immunoassay) were reanalyzed by LC-MS/MS to generate serum 25(OH)D2 and serum 25(OH)D3 data.

METHODS

Ovid MEDLINE, EMBASE, and Cochrane CENTRAL were searched for RCTs of UV-exposed mushrooms and data on serum 25(OH)D. Studies were screened for eligibility, and relevant data were extracted. Serum 25(OH)D data were re-analyzed by ANOVA and paired t tests.

RESULTS

Our structured search yielded 6 RCTs meeting our inclusion criteria. Meta-analysis of all 6 RCTs showed serum 25(OH)D was not significantly increased (P = 0.12) by UV-exposed mushrooms, but there was high heterogeneity (I(2) = 87%). Including only the 3 European-based RCTs [mean baseline 25(OH)D, 38.6 nmol/L], serum 25(OH)D was increased significantly by UV-exposed mushrooms [weighted mean difference (WMD): 15.2 nmol/L; 95% CI: 1.5, 28.8 nmol/L, P = 0.03, I(2) = 88%], whereas there was no significant effect in the 3 US-based RCTs [P = 0.83; mean baseline 25(OH)D: 81.5 nmol/L]. Analysis of serum 25(OH)D2 and serum 25(OH)D3 (n = 5 RCTs) revealed a statistically significant increase (WMD: 20.6 nmol/L; 95% CI: 8.0, 33.3 nmol/L, P = 0.001, I(2 =) 99%) and decrease (WMD: -13.3 nmol/L; 95% CI: -15.8, -10.7 nmol/L, P < 0.00001, I(2) = 0%) after supplementation with UV-exposed mushrooms.

CONCLUSIONS

Consumption of UV-exposed mushrooms may increase serum 25(OH)D when baseline vitamin D status is low via an increase in 25(OH)D2 (24.2 nmol/L) and despite a concomitant but relatively smaller reduction in 25(OH)D3 (-12.6 nmol/L). When baseline vitamin D status is high, the mean increase in 25(OH)D2 (18.3 nmol/L) and a relatively similar reduction in 25(OH)D3 (-13.6 nmol/L) may explain the lack of effect on serum 25(OH)D.

Prevalence of vitamin D inadequacy in athletes: a systematic-review and meta-analysis

BACKGROUND

Vitamin D is essential for maintaining optimal bone health. The prevalence of vitamin D inadequacy in athletes is currently unclear.

OBJECTIVE

The objective of this study is to determine the prevalence of vitamin D inadequacy in athletes.

METHODS

We conducted a systematic review and meta-analysis. Multiple databases were searched and studies assessing serum 25-hydroxyvitamin D [25(OH)D] status in athletes were identified. Serum 25(OH)D is measured to clinically determine vitamin D status. Reviewers independently selected the eligible articles, assessed the methodological quality, and extracted data. Disagreements were resolved by consensus. Weighted proportions of vitamin D inadequacy [serum 25(OH)D <32 ng/mL] were calculated (DerSimonian-Laird random-effects model) and compared using Chi-squared (χ (2)) test. Subgroup analyses were conducted and risk ratios (RRs) with 95 % confidence intervals (CIs) were reported.

RESULTS

Twenty-three studies with 2,313 athletes [mean (standard deviation) age 22.5 (5.0) years, 76 % male] were included. Of 2,313 athletes, 56 % (44-67 %) had vitamin D inadequacy that significantly varied by geographical location (p < 0.001). It was significantly higher in the UK and in the Middle East. The risk significantly increased for winter and spring seasons (RR 1.85; 95 % CI 1.27-2.70), indoor sport activities (RR 1.19; 95 % CI 1.09-1.30), and mixed sport activities (RR 2.54; 95 % CI 1.03-6.26). The risk was slightly higher for >40°N latitude [RR 1.14 (95 % CI 0.91-1.44)] but it increased significantly [RR 1.85 (1.35-2.53)] after excluding the Middle East as an outlier. Seven studies with 359 athletes reported injuries. The prevalence of injuries in athletes was 43 % (95 % CI 20-68) [bone related = 19 % (95 % CI 7-36); muscle and soft-tissue = 37.5 % (95 % CI 11.5-68.5)].

CONCLUSION

Despite the limitations of the current evidence, the prevalence of vitamin D inadequacy in athletes is prominent. The risk significantly increases in higher latitudes, in winter and early spring seasons, and for indoor sport activities. Regular investigation of vitamin D status using reliable assays and supplementation is essential to ensure healthy athletes. The prevalence of injuries in athletes is notable but its association with vitamin D status is unclear. A well-designed longitudinal study is needed to answer this possible association.

Vitamin D and skeletal muscle function in athletes

PURPOSE OF REVIEW

To highlight recently published data about the vitamin D status of athletes, and effect of vitamin D supplementation on muscle strength and performance in the athletic population.The vitamin D receptor exists in skeletal muscle, and muscle weakness has been reported in individuals who are severely deficient [25(OH)D <25 nmol/l]. Experimental findings reveal the cellular and genomic mechanisms implicating vitamin D in muscle mass, strength and function, and raise questions about the role of vitamin D in the achievement of optimum athletic performance.

RECENT FINDINGS

Athletes appear to have the same risk of vitamin D deficiency and seasonal variance in status as nonathletic members of the same population, with the exception of athletes who train and compete indoors whose risk of deficiency is somewhat greater. Interventions with vitamin D supplements have had mixed results, with a positive effect on muscle function observed only in participants with insufficient status [25(OH)D <50 nmol/l].

SUMMARY

There have been relatively few robust interventions with vitamin D supplementation in athletic populations who are vitamin D deficient, and none which have been able to establish the ideal 25(OH)D concentration for optimum performance.

Vitamin D2 supplementation amplifies eccentric exercise-induced muscle damage in NASCAR pit crew athletes

This study determined if 6-weeks vitamin D₂ supplementation (vitD₂, 3800 IU/day) had an influence on muscle function, eccentric exercise-induced muscle damage (EIMD), and delayed onset of muscle soreness (DOMS) in National Association for Stock Car Auto Racing (NASCAR) NASCAR pit crew athletes. Subjects were randomized to vitD₂ (n = 13) and placebo (n = 15), and ingested supplements (double-blind) for six weeks. Blood samples were collected and muscle function tests conducted pre- and post-study (leg-back and hand grip dynamometer strength tests, body weight bench press to exhaustion, vertical jump, 30-s Wingate test). Post-study, subjects engaged in 90 min eccentric-based exercise, with blood samples and DOMS ratings obtained immediately after and 1- and 2-days post-exercise. Six weeks vitD₂ increased serum 25(OH)D₂ 456% and decreased 25(OH)D₃ 21% versus placebo (p < 0.001, p = 0.036, respectively), with no influence on muscle function test scores. The post-study eccentric exercise bout induced EIMD and DOMS, with higher muscle damage biomarkers measured in vitD₂ compared to placebo (myoglobin 252%, 122% increase, respectively, p = 0.001; creatine phosphokinase 24 h post-exercise, 169%, 32%, p < 0.001), with no differences for DOMS. In summary, 6-weeks vitD₂ (3800 IU/day) significantly increased 25(OH)D₂ and decreased 25(OH)D₃, had no effect on muscle function tests, and amplified muscle damage markers in NASCAR pit crew athletes following eccentric exercise.