Contributions of sunlight and diet to vitamin D status

Clinical Practice Guidelines of the Latin American Federation of Endocrinology for the use of vitamin D in the maintenance of bone health: recommendations for the Latin American context

INTRODUCTION

These guidelines aim to provide evidence-based recommendations for the supplementation of Vitamin D in maintaining bone health. An unmet need persists in Latin American regarding the availability of clinical and real-world data for rationalizing the use of vitamin D supplementation. The objective of these guidelines is to establish clear and practical recommendations for healthcare practitioners from Latin American countries to address Vitamin D insufficiency in clinical practice.

METHODS

The guidelines were developed according to the GRADE-ADOLOPMENT methodology for the adaptation or adoption of CPGs or evidence-based recommendations. A search for high quality CPGs was complemented through a comprehensive review of recent literature, including randomized controlled trials, observational studies, and systematic reviews evaluating the effects of Vitamin D supplementation on bone health. The evidence to decision framework proposed by the GRADE Working Group was implemented by a panel of experts in endocrinology, bone health, and clinical research.

RESULTS

The guidelines recommend Vitamin D supplementation for individuals aged 18 and above, considering various populations, including healthy adults, individuals with osteopenia, osteoporosis patients, and institutionalized older adults. These recommendations offer dosing regimens depending on an individualized treatment plan, and monitoring intervals of serum 25-hydroxyvitamin D levels and adjustments based on individual results.

DISCUSSION

The guidelines highlight the role of Vitamin D in bone health and propose a standardized approach for healthcare practitioners to address Vitamin D insufficiency across Latin America. The panel underscored the necessity for generating local data and stressed the importance of considering regional geography, social dynamics, and cultural specificities when implementing these guidelines.

Interplay between Vitamin D and Sphingolipids in Cardiometabolic Diseases

Sphingolipids (SLs) are structural, bioactive molecules with several key cellular roles, whereas 1,25-dihydroxyvitamin D (1,25(OH)D), the active form of vitamin D, is considered the major regulator of calcium homeostasis, although it also exerts other extraskeletal effects. Many studies reported the physiological connection between vitamin D and SLs, highlighting not only the effects of vitamin D on SL metabolism and signaling but also the influence of SLs on vitamin D levels and function, thus strongly suggesting a crosstalk between these molecules. After a brief description of 1,25(OH)D and SL metabolism, this review aims to discuss the preclinical and clinical evidence on the crosstalk between SLs and 1,25(OH)D, with a special focus on cardiometabolic diseases.

Impact of ultraviolet radiation on cardiovascular and metabolic disorders: The role of nitric oxide and vitamin D

BACKGROUND/PURPOSE

Ultraviolet (UV) radiation has both harmful and beneficial effects on human skin and health. It causes skin damage, aging, and cancer; however, it is also a primary source of vitamin D. Additionally, UV radiation can impact energy metabolism and has protective effects on several cardiovascular and metabolic disorders in mice and humans. However, the mechanisms of UV protection against these diseases have not been clearly identified.

METHODS

This review summarizes the systemic effects of UV radiation on hypertension and several metabolic diseases such as obesity, diabetes, and nonalcoholic fatty liver disease (NAFLD) in mice, and we also consider the mechanisms of action of the related regulators nitric oxide (NO) and vitamin D.

RESULTS

UV exposure can lower blood pressure and prevent the development of cardiovascular diseases and metabolic disorders, such as metabolic syndrome, obesity, and type 2 diabetes, primarily through mechanisms that depend on UV-induced NO. UV radiation may also effectively delay the onset of type 1 diabetes through mechanisms that rely on UV-induced vitamin D. UV-induced NO and vitamin D play roles in preventing and slowing the progression of NAFLD.

CONCLUSION

UV exposure is a promising nonpharmacological intervention for cardiovascular and metabolic disorders. NO and vitamin D may play a crucial role in mediating these effects. However, further investigations are required to elucidate the exact mechanisms and determine the optimal dosage and exposure duration of UV radiation.

Correlation between vitamin D levels in serum and the risk of dental caries in children: a systematic review and meta-analysis

BACKGROUND

Vitamin D plays a crucial role in oral health, and its deficiency is associated to significant changes in oral health diseases. We aimed to explore the relationship between levels of 25-hydroxyvitamin D (25(OH) D) and dental caries in children.

METHODS

Four electronic databases were searched by two investigators including PubMed, Embase, Web of Science, and Cochrane Library. Dental caries results were presented as either prevalence or based on the index of primary and permanent teeth/surfaces with decaying, missing, and filled areas, while vitamin D levels were determined through laboratory testing. Two researchers independently selected studies, collected information, assessed risk of bias, and evaluated the study quality. Any disagreements were resolved through discussion.

RESULTS

A total of 13 studies were included, comprising 5 cross-sectional studies, 5 cohort studies, 3 case-control studies, all of which had high methodological quality. Our meta-analysis showed that children with vitamin D deficiency had a 22% higher risk of dental caries than those with normal vitamin D levels, with a relative risk (RR) of 1.22 and a 95% confidence interval (CI) of 1.18 to 1. 25. Further subgroup analysis according to the three types of studies showed that the risk of dental caries in children with vitamin D deficiency was higher than that in normal vitamin D level group (cohort studies: 62%; cross-sectional studies, 19%; and case-control studies, 5%). Additionally, according to age, subgroup analysis also showed that the risk of dental caries in children with vitamin D deficiency was higher than that in normal vitamin D level group (permanent teeth studies, 28%; deciduous teeth studies, 68%; and mixed dentition studies 8%).

CONCLUSIONS

Levels of 25 (OH) D have been found negatively associated with dental caries in children, indicating that low vitamin D levels may be considered a potential risk factor to this dental disease.

Assessment, treatment and prevention of vitamin D deficiency

Vitamin D deficiency is prevalent among various groups in the UK, and can result from insufficient sunlight exposure and dietary intake. There is a population-wide recommendation of 10 micrograms (400 international units) of vitamin D per day, with a daily supplement advised. However, supplement use is often suboptimal, compounding the risk of deficiency. Long-term vitamin D deficiency can cause rickets in children and osteomalacia or osteoporosis in adults. Therefore, it is important that nurses recognise which groups are at increased risk of vitamin D deficiency and understand how to assess people's vitamin D status. Nurses also need to be able to support the prevention and treatment of low vitamin D levels, which typically involves supplementation and lifestyle changes.

Associations between vitamin D levels and dietary patterns in patients with Hashimoto's thyroiditis

Introduction

Vitamin D insufficiency is a global health problem affecting healthy and diseased individuals, including patients with Hashimoto's thyroiditis (HT). Identifying dietary factors that may affect vitamin D levels and providing dietary guidelines accordingly can alleviate this problem. We therefore aimed to identify still unknown associations of dietary patterns, assessed through the Food Frequency Questionnaire (FFQ) with vitamin D blood levels.

Materials and methods

FFQ was collected from 459 patients from Croatian Biobank of Patients with Hashimoto's thyroiditis (CROHT), while total 25(OH)D was measured from their stored serum samples. We performed linear regression analysis between vitamin D levels and weekly intake of 24 food groups in 459 patients with HT (ALL), and in two disease-severity groups (MILD and OVERT).

Results

The main results of our study are observations of: (1) an inverse association between vitamin D levels and coffee consumption (ALL: β = -0.433, p = 0.005; OVERT: β = -0.62, p = 0.008); (2) an inverse association between vitamin D levels and sweets consumption (ALL: β = -0.195, p = 0.034; OVERT: β = -0.431, p = 0.006); (3) positive association between vitamin D levels and vegetable consumption (ALL: β = 0.182, p = 0.019; OVERT, β = 0.311, p = 0.009). Importantly, effect sizes of all three associations were more prominent in HT patients with prolonged and more severe disease (OVERT).

Conclusion

Further research into the functional and causal relationships of the observed associations is important to provide guidance regarding coffee/sugar intake on vitamin D status. A well-balanced diet can help prevent vitamin D deficiency and improve the quality of life of patients with HT, especially those in later stages of disease characterized by greater metabolic imbalance.

Prevalence of an insufficient vitamin D status at the onset of a spinal cord injury - a cross-sectional study

STUDY DESIGN

A cross-sectional study.

OBJECTIVE

This study aimed to investigate the vitamin D status after acute spinal cord injury (SCI) onset.

SETTING

Specialized SCI rehabilitation center in Switzerland.

METHODS

Patients admitted to the center after an acute SCI onset were included. The prevalence of a deficient (25(OH)D ≤ 50 nmol/l), insufficient (50 < 25(OH)D ≤ 75 nmol/l) and sufficient (25(OH)D > 75 nmol/l) vitamin D status were determined after admission. Vitamin D status was compared between different patient groups based on demographic and SCI characteristics. The occurrence of bed rest, falls and pressure injuries were also assessed.

RESULTS

In total, 87 patients (median (interquartile range); 53 (39-67) years, 25 females, 66 traumatic SCI, 54 paraplegia) were included. Assessed a median of 15 (9-22) days after SCI onset, median vitamin D status was 41 (26-57) (range 8-155) nmol/l. The majority of patients had a deficient (67%, 95% confidence interval (95% CI) 0.56-0.76) or insufficient (25%, 95% CI 0.17-0.36) vitamin D status. A moderate negative correlation was found between vitamin D status and body mass index (p = 0.003). A moderate positive correlation was found between vitamin D and calcium status (p = 0.01).

CONCLUSION

A deficient or insufficient vitamin D status directly after SCI onset is highly prevalent. Vitamin D status should be carefully observed during acute SCI rehabilitation. We recommend that all patients with recent SCI onset should receive vitamin D supplementation with a dosage depending on their actual vitamin D status.

Determinants and Effects of Vitamin D Supplementation in Postmenopausal Women: A Systematic Review

Hormonal fluctuations, excessive clothing covering, sunscreen use, changes in body fat composition, a vitamin D-deficient diet, and a sedentary lifestyle can all predispose postmenopausal women to vitamin D deficiency. An effective supplementation plan requires a thorough understanding of underlying factors to achieve the desired therapeutic concentrations. The objective of this study was to conduct a systematic review of the predictors that affect vitamin D status in postmenopausal women. From inception to October 2022, we searched MEDLINE, Embase, Web of Science, Scopus, and clinical trial registries. Randomized clinical trials of postmenopausal women taking supplements of vitamin D with serum 25-hydroxyvitamin D (25(OH)D) measurement as the trial outcome were included. Two independent reviewers screened selected studies for full-text review. The final assessment covered 19 trials within 13 nations with participants aged 51 to 78. Vitamin D supplementation from dietary and pharmaceutical sources significantly increased serum 25(OH)D to optimal levels. Lower baseline serum 25(OH)D, lighter skin color, longer treatment duration, and prolonged skin exposure were all associated with a better response to vitamin D supplementation in postmenopausal women.

Metabolic bone health considerations in giant cell arteritis and polymyalgia rheumatica

Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are two common systemic inflammatory conditions with a combined lifetime risk of approximately 3.5% in women and 1.5% in men. They are intimately associated with the aging process, virtually never occurring prior to 50 years of age and becoming more common over time. The reasons for this are unclear, but likely relate in part to factors related to aging of the immune system. The treatment of both GCA and PMR is traditionally based on glucocorticoids, frequently requiring a prolonged treatment course over long periods of time. Other medications are belatedly entering our treatment armamentarium, but their exact place in treatment algorithms remains to be fully defined and it is likely glucocorticoids will remain a cornerstone of our treatment in GCA and PMR for the foreseeable future. As a result, people with GCA and PMR will continue to be exposed to a significant cumulative glucocorticoid burden with all of the attendant potential adverse events, including osteoporosis. The predominantly post-menopausal female population that most commonly develops PMR and GCA is also the population that is most affected by osteoporosis. Given the risk of glucocorticoid-induced osteoporosis and subsequent fragility fractures, a planned treatment approach from glucocorticoid initiation is needed in these conditions. For the majority of patients, this will entail ensuring sufficiency of calcium and vitamin D as well as antiresorptive treatments. In this article, we discuss considerations around optimisation of metabolic bone health in GCA and PMR.

Knowledge about Vitamin D among Women in the United Arab Emirates

Vitamin D deficiency is a significant public health issue as it affects almost 90% of the United Arab Emirates (UAE) population. A bigger portion of this percentage is women due to the physiological changes throughout their life cycle. This study aims to assess the knowledge about vitamin D among women in the UAE. This is a quantitative cross-sectional study. Using snowball sampling, an electronic questionnaire was sent to women aged 18 years and above. Overall, 1537 women completed the questionnaire. The participants had mean scores of 49.4 ± 10.7 and 59.6 ± 14.6 for general and nutritional knowledge, respectively. Factors associated with higher scores included older age, marriage, higher educational level, and having tested their vitamin D levels. Factors associated with lower scores included the history of a chronic illness and being employed. Findings indicate that women in this study showed a low level of vitamin D knowledge specifically regarding the non-skeletal benefits of vitamin D and factors that affect vitamin D synthesis. Therefore, health education and promotion programs must be implemented across the UAE to improve overall awareness about vitamin D.

Comprehensive Analysis of Seasonal and Geographical Variation in UVB Radiation Relevant for Vitamin D Production in Europe

Dermal synthesis, following sun exposure, is the main source of vitamin D. This study characterizes ambient UVB radiation relevant for vitamin D production in Europe. A biological weighing function was applied to data from the Tropospheric Emissions Monitoring Internet Service (TEMIS) for 46 capital cities over an 18-year period (2004-2021) to isolate wavelengths relevant for vitamin D production (D-UVB). Cumulative and weighted D-UVB (CW-D-UVB) were calculated to approximate seasonal vitamin D accumulation and diminution. Monthly 25(OH)D concentration measurements were extracted from published reports. All data were analyzed by location and time. Despite a moderate latitudinal range (35-64° N), we observed large-up to five-fold-regional differences: the highest mean diurnal D-UVB dose of 5.57 kJ/m² (SD = 3.55 kJ/m²) was observed in Nicosia (Cyprus) and the lowest in Reykjavik (Iceland, 1.16 ± 1.29 kJ/m²). Seasonal differences in diurnal D-UVB dose were even more pronounced, with a median 36-fold difference between annual peak and trough depending on a location (range: 10- to 525-fold). The mean duration of "vitamin D winter" was 126 days but varied widely (4 to 215 days). Monthly CW-D-UVB and 25(OH)D changes were very strongly correlated: the changes in 25(OH)D concentration increased by 12.6 nmol/L for every 100 kJ/m² increment of CW-D-UVB in population-based studies (r² = 0.79, p-value = 1.16 × 10^-37). Understanding the differences in D-UVB radiation can help understand determinants of vitamin D status and guide region- and season-specific safe and effective sunlight exposure recommendations and vitamin D supplementation guidelines.

Vitamin D3 supplementation alleviates chemically-induced cirrhosis-associated hepatocarcinogenesis

Vitamin D₃ (VD₃) deficiency has been associated with increased risk for cirrhosis and hepatocellular carcinoma, a highly incident malignant neoplasia worldwide. On the other hand, VD₃ supplementation has shown some beneficial effects in clinical studies and rodent models of chronic liver disease. However, preventive effects of dietary VD₃ supplementation in cirrhosis-associated hepatocarcinogenesis is still unknow. To investigate this purpose, male Wistar rats submitted to a combined diethylnitrosamine- and thioacetamide-induced model were concomitantly supplemented with VD₃ (5,000 and 10,000 IU/kg diet) for 25 weeks. Liver samples were collected for histological, biochemical and molecular analysis. Serum samples were used to measure 25-hydroxyvitamin D [25(OH)D] and alanine aminotransferase levels. Both VD₃ interventions decreased hepatic collagen deposition and pro-inflammatory p65 protein levels, while increased hepatic antioxidant catalase and glutathione peroxidase activities and serum 25(OH)D, without a clear dose-response effect. Nonetheless, only the highest concentration of VD₃ increased hepatic protein levels of VD receptor, while decreased the number of large preneoplastic glutathione-S-transferase- (>0.5 mm²) and keratin 8/18-positive lesions, as well the multiplicity of hepatocellular adenomas. Moreover, this intervention increased hepatic antioxidant Nrf2 protein levels and glutathione-S-transferase activity. In summary, dietary VD₃ supplementation - in special the highest intervention - showed antifibrotic and antineoplastic properties in chemically-induced cirrhosis-associated hepatocarcinogenesis. The positive modulation of Nrf2 antioxidant axis may be mechanistically involved with these beneficial effects, and may guide future clinical studies.

A Nutraceutical Formula Is Effective in Raising the Circulating Vitamin and Mineral Levels in Healthy Subjects: A Randomized Trial

Low levels of nutrient intake are common in industrialized countries. This has negative implications on health and is associated with chronic diseases. Supplementation of vitamins, minerals, and key nutrients to optimal levels may, therefore, be beneficial for individual health and for the health economy. Although the use of supplements has become very common, due to a lack of monitoring, there is very limited data on the efficacy of supplementation with different formulas. In this study, we present the results of a randomized controlled study on the efficacy of a novel formulated nutraceutical, N247, in 250 healthy volunteers aged 26-75 years and a placebo control group (n = 35). The broad-spectrum formulation of N247 includes essential vitamins, minerals, and trace elements that are adequately balanced in regard to synergies and related metabolic functions. Moreover, tolerance, safety, and nutrient availability is an important aspect of daily, long-term use of N247. After 3 months of regular N247 use, levels of vitamins and minerals in serum were significantly increased in the N247 group compared with the control group and a placebo group, with excellent compliance rates. Coupled with additional natural ingredients that aim to increase the potency of the nutrients, N247 may represent a novel and beneficial supplement for individuals with nutritional deficiencies. Clinical Trial Registration:https://clinicaltrials.gov/, identifier: NCT04054505.

Essential sufficiency of zinc, ω-3 polyunsaturated fatty acids, vitamin D and magnesium for prevention and treatment of COVID-19, diabetes, cardiovascular diseases, lung diseases and cancer

Despite the development of a number of vaccines for COVID-19, there remains a need for prevention and treatment of the virus SARS-CoV-2 and the ensuing disease COVID-19. This report discusses the key elements of SARS-CoV-2 and COVID-19 that can be readily treated: viral entry, the immune system and inflammation, and the cytokine storm. It is shown that the essential nutrients zinc, ω-3 polyunsaturated fatty acids (PUFAs), vitamin D and magnesium provide the ideal combination for prevention and treatment of COVID-19: prevention of SARS-CoV-2 entry to host cells, prevention of proliferation of SARS-CoV-2, inhibition of excessive inflammation, improved control of the regulation of the immune system, inhibition of the cytokine storm, and reduction in the effects of acute respiratory distress syndrome (ARDS) and associated non-communicable diseases. It is emphasized that the non-communicable diseases associated with COVID-19 are inherently more prevalent in the elderly than the young, and that the maintenance of sufficiency of zinc, ω-3 PUFAs, vitamin D and magnesium is essential for the elderly to prevent the occurrence of non-communicable diseases such as diabetes, cardiovascular diseases, lung diseases and cancer. Annual checking of levels of these essential nutrients is recommended for those over 65 years of age, together with appropriate adjustments in their intake, with these services and supplies being at government cost. The cost:benefit ratio would be huge as the cost of the nutrients and the testing of their levels would be very small compared with the cost savings of specialists and hospitalization.

Sunlight activated film forming adhesive polymers

Stimuli-sensitive biomaterials that are activated by light are in need of formulations that are stable under indoor lighting yet can be activated under direct sunlight. Carbene-based bioadhesives are a new generation of film-forming polymers that are stable under indoor lighting yet are rapidly activated with low-energy UVA light, but have never been evaluated under sunlight exposure. Previous investigations have evolved two flexible carbene-based platforms, where aryl-diazirine is grafted on to polyamidoamine dendrimers (PAMAM-NH₂; generation-5) or hydrophobic liquid polycaprolactone tetrol to yield G5-Dz_x and CaproGlu, respectively. For the first time the activation of G5-Dz_x and CaproGlu is investigated by natural sunlight with intensities up to 10 mW·cm^-2. Structure-property relationships of bioadhesion are investigated by: (1) joules dose of sunlight; (2) bioadhesive polymer structure; and (3) optical concentrators of magnifying glass and Fresnel lens. Using only natural sunlight, adhesion strength could be tuned from 20 to 150 kPa with crosslinking achieved in under 1 min. The results show that carbene-based polymers are a class of stimuli-sensitive biomaterials that are stable to indoor lighting, yet can be rapidly activated under direct sunlight, which may be useful for topical film forming polymers or as active ingredients in sunscreen formulations.

Vitamin D status, vitamin D intake, and sunlight exposure in adults adhering or not to periodic religious fasting for decades

We investigated whether periodic abstinence from foods of animal origin and a conservative lifestyle, with reduced sunlight exposure, affect vitamin D status. In a cross-sectional design, we measured the serum 25-hydroxyvitamin D concentration and assessed dietary vitamin D intake and sunlight exposure in 200 adults adhering to religious fasting for decades and in 200 non-fasters, with no differences between groups in bone mineral density. Fasters showed lower 25-hydroxyvitamin D concentration than non-fasters in winter and spring. Vitamin D intake and some indices of sunlight exposure (including two related to winter and spring) were lower in fasters, and 378 of the 400 participants exhibited vitamin D insufficiency or deficiency. In conclusion, individuals following a religious lifestyle had lower vitamin D intake, sunlight exposure and, at times, serum 25-hydroxyvitamin D concentration than controls, although these differences did not impact bone health.

NUTRITION AND MINERAL CONTENT IN HUMAN TEETH THROUGH THE CENTURIES

OBJECTIVES

The objectives of the study were: (i) to compare mineral values of calcium, phosphorus, magnesium, zinc and their ratios, in teeth from Croatian populations that lived in different historical periods, namely the Medieval period, the early 20th century, and the 21 st century; and (ii) to elucidate the influence of diet and lifestyle on tooth quality in these groups.

DESIGN

Determination of mineral content (Ca, Mg, P and Zn) in 294 teeth from three different periods of history (Medieval Period [G1], Second World War period [G2] and the contemporary period [G3]) using atomic absorption spectrometer and UV/VIS spectrometer methods.

RESULTS

Our results showed that the mineral content in teeth has changed over the centuries. Between analysed samples from all groups, there were significant differences in the elemental content as well as in the interrelationship of the elements. The largest differences were observed in the mean values of magnesium and zinc concentrations while smaller differences were observed for changes in calcium and phosphorus.

CONCLUSIONS

From the obtained results, it is evident that there are changes in the tooth mineral composition in specimens centuries apart that could be a reflection of changes in eating habits, food quality and the environment. In addition to differences in individual elements, differences in their mutual ratios were also observed.

Physical Determinants of Vitamin D Photosynthesis: A Review

Vitamin D synthesis by exposure of skin to solar ultraviolet radiation (UVR) provides the majority of this hormone that is essential for bone development and maintenance but may be important for many other health outcomes. This process, which is the only well-established benefit of solar UVR exposure, depends on many factors including genetics, age, health, and behavior. However, the most important factor is the quantity and quality of UVR reaching the skin. Vitamin D synthesis specifically requires ultraviolet B (UVB) radiation that is the minority component (<5%) of solar UVR. This waveband is also the most important for the adverse effects of solar exposure. The most obvious of which is sunburn (erythema), but UVB is also the main cause of DNA damage to the skin that is a prerequisite for most skin cancers. UVB at the Earth's surface depends on many physical and temporal factors such as latitude, altitude, season, and weather. Personal, cultural, and behavioral factors are also important. These include skin melanin, clothing, body surface area exposed, holiday habits, and sunscreen use. There is considerable disagreement in the literature about the role of some of these factors, possibly because some studies have been done by researchers with little understanding of photobiology. It can be argued that vitamin D supplementation obviates the need for solar exposure, but many studies have shown little benefit from this approach for a wide range of health outcomes. There is also increasing evidence that such exposure offers health benefits independently of vitamin D: the most important of which is blood-pressure reduction. In any case, public health advice must optimize risk versus benefit for solar exposure. It is fortunate that the individual UVB doses necessary for maintaining optimal vitamin D status are lower than those for sunburn, irrespective of skin melanin. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

The influence of omega-3 supplementation on vitamin D levels in humans: a systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND

Inconsistencies exist with regard to the influence of omega-3 supplementation on 25-hydroxyvitamin D (25(OH)D) levels, which could be attributed to many factors, such as the duration and dose of omega-3 supplementation, and individuals' baseline 25(OH)D levels. Therefore, to address the inconsistencies, we conducted a systematic review and dose-response meta-analysis to accurately determine the effect of omega-3 supplementation on 25(OH)D levels in humans.

METHODS

We performed a comprehensive literature search in Web of Science, PubMed/Medline, Scopus, and Embase databases from inception up to January 2020. We included only randomized controlled trials (RCTs). We used weighted mean difference (WMD) with 95% confidence interval (CI) to assess the influence of omega-3 supplementation on serum 25(OH)D levels using the random-effects model.

RESULTS

Our pooled results of 10 RCTs demonstrated an overall significant increase in 25(OH)D levels following omega-3 intake (WMD = 3.77 ng/ml, 95% CI: 1.29, 6.25). In addition, 25(OH)D levels were significantly increased when the intervention duration lasted >8 weeks and when the baseline serum 25(OH)D level was ˂20 ng/ml. Moreover, omega-3 intake ≤1000 mg/day resulted in higher 25(OH)D levels compared to omega-3 intake >1000 mg/day.

CONCLUSION

In conclusion, omega-3 supplementation increased 25(OH)D concentrations, particularly with dosages ≤1000 mg/day and intervention durations >8 weeks.

Zinc, ω-3 polyunsaturated fatty acids and vitamin D: An essential combination for prevention and treatment of cancers

Zinc, ω-3 polyunsaturated fatty acids (PUFAs) and vitamin D are essential nutrients for health, maturation and general wellbeing. Extensive literature searches have revealed the widespread similarity in molecular biological properties of zinc, ω-3 PUFAs and vitamin D, and their similar anti-cancer properties, even though they have different modes of action. These three nutrients are separately essential for good health, especially in the aged. Zinc, ω-3 PUFAs and vitamin D are inexpensive and safe as they are fundamentally natural and have the properties of correcting and inhibiting undesirable actions without disturbing the normal functions of cells or their extracellular environment. This review of the anticancer properties of zinc, ω-3 PUFAs and vitamin D is made in the context of the hallmarks of cancer. The anticancer properties of zinc, ω-3 PUFAs and vitamin D can therefore be used beneficially through combined treatment or supplementation. It is proposed that sufficiency of zinc, ω-3 PUFAs and vitamin D is a necessary requirement during chemotherapy treatment and that clinical trials can have questionable integrity if this sufficiency is not checked and maintained during efficacy trials.

Vitamin D and the hepatitis B vaccine response: a prospective cohort study and a randomized, placebo-controlled oral vitamin D3 and simulated sunlight supplementation trial in healthy adults

Purpose

To determine serum 25(OH)D and 1,25(OH)₂D relationship with hepatitis B vaccination (study 1). Then, to investigate the effects on hepatitis B vaccination of achieving vitamin D sufficiency (serum 25(OH)D ≥ 50 nmol/L) by a unique comparison of simulated sunlight and oral vitamin D₃ supplementation in wintertime (study 2).

Methods

Study 1 involved 447 adults. In study 2, 3 days after the initial hepatitis B vaccination, 119 men received either placebo, simulated sunlight (1.3 × standard-erythema dose, 3 × /week for 4 weeks and then 1 × /week for 8 weeks) or oral vitamin D₃ (1000 IU/day for 4 weeks and 400 IU/day for 8 weeks). We measured hepatitis B vaccination efficacy as percentage of responders with anti-hepatitis B surface antigen immunoglobulin G ≥ 10 mIU/mL.

Results

In study 1, vaccine response was poorer in persons with low vitamin D status (25(OH)D ≤ 40 vs 41–71 nmol/L mean difference [95% confidence interval] − 15% [− 26, − 3%]; 1,25(OH)₂D ≤ 120 vs ≥ 157 pmol/L − 12% [− 24%, − 1%]). Vaccine response was also poorer in winter than summer (− 18% [− 31%, − 3%]), when serum 25(OH)D and 1,25(OH)₂D were at seasonal nadirs, and 81% of persons had serum 25(OH)D < 50 nmol/L. In study 2, vitamin D supplementation strategies were similarly effective in achieving vitamin D sufficiency from the winter vitamin D nadir in almost all (~ 95%); however, the supplementation beginning 3 days after the initial vaccination did not effect the vaccine response (vitamin D vs placebo 4% [− 21%, 14%]).

Conclusion

Low vitamin D status at initial vaccination was associated with poorer hepatitis B vaccine response (study 1); however, vitamin D supplementation commencing 3 days after vaccination (study 2) did not influence the vaccination response.

Clinical trial registry number

Study 1 NCT02416895; https://clinicaltrials.gov/ct2/show/study/NCT02416895; Study 2 NCT03132103; https://clinicaltrials.gov/ct2/show/NCT03132103.

Electronic supplementary material

The online version of this article (10.1007/s00394-020-02261-w) contains supplementary material, which is available to authorized users.

Impact of dietary vitamin D on initiation and progression of oral cancer

Calcitriol, the active metabolite of vitamin D, has been widely studied for its preventive and therapeutic activity against several cancers including oral squamous cell carcinoma (OSCC). However, the impact of dietary vitamin D supplementation on initiation and progression of OSCC is unclear. To address this gap in knowledge, we conducted preclinical trials using the 4-nitroquinoline-1-oxide 4NQO carcinogen model of oral carcinogenesis. Female C57BL/6 mice were maintained on one of three vitamin D diets [25 IU, 100 IU, 10,000 IU] and exposed to 4NQO in drinking water for 16 weeks followed by regular water for 10 weeks. Body weight measurements obtained through the study duration did not reveal any differences between the three diets. Animals on 100 IU diet showed lower incidence of high-grade dysplasia/OSCC and higher CD3 + T cells compared to animals on 25 IU and 10,000 IU diets. Serum 25OHD₃ levels were highest in animals on 10,000 IU diet at week 0 prior to carcinogen exposure but showed ∼50 % reduction at week 26. Histologic evaluation revealed highest incidence of OSCC in animals maintained on 10,000 IU diet. Animals on 100 IU and 10,000 IU diets showed higher vitamin D receptor VDR and CYP24A1 immunostaining in high-grade dysplastic lesions and OSCC compared to normal tongue. Validation studies performed in a 4NQO-derived OSCC model showed that short-term treatment of animals on a 25 IU diet with calcitriol significantly inhibited tumor growth compared to controls but did not affect tumor growth in animals on reference diet 1000 IU. Collectively, our results highlight the complex dynamics between vitamin D status and oral carcinogenesis. Our observations also suggest that therapeutic benefits of short-term calcitriol treatment may be more pronounced in vitamin D deficient hosts.

The relationship between molar incisor hypomineralization, dental caries, socioeconomic factors, and polymorphisms in the vitamin D receptor gene: a population-based study

OBJECTIVES

The purpose of this cross-sectional study was to investigate whether polymorphisms in vitamin D receptor (VDR) genes increase the prevalence of dental caries, molar incisor hypomineralization (MIH), and hypomineralized primary second molars (HPSM).

MATERIAL AND METHODS

A representative population-based sample of 731 schoolchildren, 8 years of age, was randomly selected in Curitiba, Paraná, Brazil. MIH, HPSM, and dental caries were clinically assessed by four calibrated examiners (kappa > 0.80) using European Academy of Pediatric Dentistry (2003) criteria, the modified Developmental Defects of Enamel (DDE) index, and the Decayed, Missing, or Filled Teeth (DMFT) index by the World Health Organization (2013), respectively. The VDR rs739837 and rs2228570 polymorphisms were genotyped using real-time polymerase chain reaction. Associations were analyzed by Poisson regression with robust variance (α = 0.05).

RESULTS

Schoolchildren with MIH presented a higher prevalence of dental caries (DMFT > 1, PR = 2.52, confidence interval = 1.60-3.97, p ≤ 0.001). No association was observed between MIH, HPSM, and dental caries, with rs739837 and rs2228570 polymorphisms. Individuals with the GT/GG genotype in rs739837 polymorphism presented a higher prevalence of MIH in molars and incisors than individuals TT (PR = 2.34, confidence interval = 1.08-5.07, p = 0.03).

CONCLUSION

Children with MIH presented a significant higher prevalence of dental caries than children without MIH. To carry at least one G allele in rs739837 was associated to higher prevalence of MIH in molars and incisors.

CLINICAL RELEVANCE

Our findings suggested that more severe cases with incisors affected by MIH could be associated with polymorphism in VDR gene.

Impact of Vitamin D on Physical Efficiency and Exercise Performance-A Review

Vitamin D deficiency amongst athletes and the general population seems to be a prominent problem. The most recognized role of vitamin D is its regulation of calcium homeostasis; there is a strong relationship between vitamin D and bone health. Moreover, its concentrations are associated with muscle function and immune response in both the general and athletic populations. Vitamin D level is strongly connected with the presence of VDRs (vitamin D receptors) in most human extraskeletal cells. Expression of multiple myogenic transcription factors enhancing muscle cell proliferation and differentiation is caused by an exposure of skeletal muscles to vitamin D. The aim of this review is to summarize current understanding of the significance of vitamin D on exercise performance and physical efficiency, as well to analyze the impact of vitamin D on multiple potential mechanisms. More high-quality research studies, considering free 25(OH)D as a better marker of vitamin D status, the baseline level of 25(OH)D and multiple pathways of vitamin D acting and usage in athletes are required.

Association between vitamin D and hypertension in people coming for health check up to a tertiary care centre in South India

INTRODUCTION

Vitamin D has many effects apart from its role in calcium metabolism and bone health. Vitamin D is derived from endogenous ultraviolet-B induced vitamin D synthesis in the skin, and the current high prevalence of vitamin D deficiency in India, can be attributed to lifestyle related low sunlight exposure. Identification of the vitamin D receptor (VDR) in almost all human cells, suggests a role in extra skeletal diseases. Studies have shown that vitamin D deficiency is an independent risk factor for hypertension.

AIM

To evaluate the association between vitamin D and hypertension in people coming for health check up to a tertiary care center in South India.

MATERIALS AND METHODS

Study was carried out as a cross sectional study in a tertiary care hospital in South India. Participants (520) were both males and females (337 males and 183 females), between the age group of 20-60 years attending the comprehensive health check up clinic of our hospital.

STATISTICAL ANALYSIS

Statistical analysis was done using IBM SPSS statistics 20.0.

RESULTS

Severe vitamin D deficiency was highly prevalent in people with hypertension than in people without hypertension (P value <0.001).

CONCLUSION

Since India is a tropical country, till recently it was believed that vitamin D deficiency and its ill effects are uncommon. But it was found that, vitamin D deficiency was highly prevalent in people with hypertension in South India, emphasizing the need of early vitamin D supplementation. Therefore, to reduce cardiovascular morbidity, early identification of vitamin D deficiency and appropriate vitamin D supplementation may be of primary importance in population, especially like ours, having high prevalence.

Predictive Factors for Vitamin D Concentrations in Swiss Athletes: A Cross-sectional Study

Vitamin D concentrations corresponding to 75 nmol/L 25(OH)D have been associated with maintained muscle function, growth and regeneration, optimal bone health and immunology in athletes. The objective of this study was to investigate the prevalence and predictors of insufficient 25(OH)D concentrations in athletes. Six hundred three Swiss athletes were assessed. 25(OH)D was analysed by high-performance liquid chromatography (HPLC). A standardized questionnaire was used to gather information about potential predictors for 25(OH)D concentrations; 50.5% showed insufficient 25(OH)D concentrations. Differences in predicted probability of insufficient 25(OH)D were found for those vitamin D supplemented (42%) versus not supplemented (52%), in those performing indoor (58%) versus outdoor sports (43%), and during the sun-deprived seasons of fall (49%), winter (70%) and spring (57%) compared with summer (17%). Higher BMI z-scores and age were associated with higher 25(OH)D concentrations. In conclusion, insufficient 25(OH)D concentrations were common among athletes especially at a younger age, among those not supplemented, in athletes who trained indoors, and during the sun-deprived seasons. Because the prevalence of insufficient 25(OH)D concentrations in this study was high, regular supplementation in athletes may be indicated, except perhaps during the summer season. Further research is needed to determine which 25(OH)D concentrations lead to optimal health and performance in athletes.

Creatine or vitamin D supplementation in individuals with a spinal cord injury undergoing resistance training: A double-blinded, randomized pilot trial

PURPOSE

Determine whether creatine or vitamin D supplementation improves muscle strength in individuals with spinal cord injury undergoing resistance training.

METHODS

Thirteen male and one female with spinal cord injury, from two Portuguese rehabilitation centers, were randomized to creatine (3g daily), vitamin D (25000 IU each two weeks) or placebo group in a double-blind design. All participants performed progressive resistance training during eight weeks. The outcome measures, obtained at baseline and after intervention, included: Sum of four skinfolds; Corrected arm muscle area; Seated medicine ball throw; Handgrip strength with dynamometer; Manual wheelchair slalom test and one repetition maximum for Chest press, Triceps, Pec deck and Lat pulldown. Vitamin D levels were obtained in all participants before and after intervention.

RESULTS

71.4% of participants had deficit values of vitamin D. The corrected arm muscle area improved significantly (p<0.05) in creatine group relatively to the control group. There was a significant correlation (p<0.05) between the one repetition maximum Pec deck and levels of vitamin D.

CONCLUSIONS

Supplementation with creatine may improve muscle strength parameters in individuals with spinal cord injury. Vitamin D deficiency is highly prevalent in this population. It is recommended an initial screening of vitamin D levels at the beginning of the physical rehabilitation process.

Serum 25-hydroxyvitamin D deficiency predicts poor outcome among acute ischemic stroke patients without hypertension

25-Hydroxyvitamin D (25(OH)D) deficiency is a frequent condition in patients who suffer acute ischemic stroke (AIS), and several studies suggested that it may be associated with a poorer prognosis. Whether this association is affected by hypertension is unclear. Our aim was to investigate the association between 25(OH)D levels and both clinical severity and outcome after 3 months in AIS patients stratified by the history of hypertension. Consecutive first-ever AIS patients admitted to the Third Affiliated Hospital of Sun Yat-sen University, China were identified. Clinical information was collected. Serum 25(OH)D levels were measured at baseline. Stroke severity was assessed at admission using the National Institutes of Health Stroke Scale (NIHSS) score. Functional outcome was evaluated after 3 months of onset using the modified Rankin Scale (mRS). Multivariate analyses were performed using logistic regression models. During the study period, 377 patients were diagnosed as AIS and were included in the analysis. 25(OH)D deficiency was not associated with the risk of NIHSS at admission and 3 months mRS both in total patients and the hypertension subgroup. Among AIS without hypertension, 25(OH)D deficiency subjects had a significantly higher of NIHSS at admission and 3 months mRS compared with those with 25(OH)D ≥ 50 nmol/L. The odds ratios (95% confidence interval) were 5.51(1.83-16.60) and 4.63(1.53-14.05) in the multivariable adjusted model (P for linear trend < 0.05). Serum lower 25(OH)D levels can be seen as an independent prognostic factor of functional outcome in AIS without hypertension. Additional studies about improving prognosis of AIS by vitamin D supplementation could be first applied to these patients.

Evolution of Serum 25OHD in Response to Vitamin D3-Fortified Yogurts Consumed by Healthy Menopausal Women: A 6-Month Randomized Controlled Trial Assessing the Interactions between Doses, Baseline Vitamin D Status, and Seasonality

BACKGROUND

Adequate vitamin D status contributes to bone fragility risk reduction and possibly other pathological conditions that occur with aging. In response to pharmaceutical vitamin D3 supplements, several studies have documented the influence of doses, baseline status, and seasonality on serum 25-hydroyvitamin D (s25OHD).

OBJECTIVE

Using fortified yogurt, we investigated in one randomized controlled trial how both baseline status, as assessed by measuring s25OHD prior the onset of the trial, and the season of enrollment quantitatively influenced the response to the supplemented (Suppl.) of vitamin D3 (VitD3) in healthy community-dwelling women.

METHODS

A 24-week controlled trial was conducted in menopausal women (mean age: 61.5). Participants were randomized into 3 groups (Gr): Gr.Suppl.0, time controls maintaining dietary habits; Gr.Suppl.5 and Gr.Suppl.10 consuming one and two 125-g servings of VitD3-fortified yogurts with 5- and 10-µg daily doses, respectively. The 16 intervention weeks lasted from early January to mid-August, the 8 follow-up weeks, without product, from late August to mid-October. Before enrollment, subjects were randomized into 2 s25OHD strata: low stratum (LoStr): 25-50 nmol/L; high stratum (HiStr): >50-75 nmol/L.

RESULTS

All enrolled participants adhered to the protocol throughout the 24-week study: Gr.Suppl.0 (n = 45), Gr.Suppl.5 (n = 44), and Gr.Suppl.10 (n = 44). Over the 16 intervention and 8 follow-up weeks, s25OHD increased in both supplemented groups, more in Gr.Suppl.10 than in Gr.Suppl.5. At the end of the intervention, the subject proportion with s25OHD ≥ 50 nmol/L was 37.8, 54.5, and 63.6% in Gr.Suppl.0, Gr.Suppl.5, and Gr.Suppl.10, respectively. The constant rate of s25OHD per supplemental VitD3 microgram was greater in LoStr than HiStr. The s25OHD increase was greater with late (mid-March) than early (mid-January) inclusion.

CONCLUSION

This randomized trial demonstrates (1) a dose-dependent s25OHD improvement related to fortified yogurt consumption; (2) an inversely baseline-dependent increase in s25OHD; and (3) a seasonal effect that highlights the importance of VitD3-fortified foods during winter, even at 5 µg/d, in healthy menopausal women.

Sun exposure in pigs increases the vitamin D nutritional quality of pork

There is a high prevalence of vitamin D insufficiency and deficiency worldwide likely because of both limited sun-exposure and inadequate dietary intake. Meat, including pork, is not typically considered a dietary source of vitamin D, possibly because of management practices that raise pigs in confinement. This experiment determined the vitamin D content of loin and subcutaneous adipose tissue in sun-exposed finisher pigs. Two separate groups of pigs were used. The first group (28 white Landrace-Duroc) was assigned at random to either sunlight exposure (SUN) in spring and summer or confinement per standard practice (Control). The second (24 Yorkshire-Duroc-Landrace) underwent the same exposure protocol but was exposed in summer and fall or assigned to control (Control). A subsample of five SUN and four Control pigs, matched for weight and body condition score, was selected for slaughter from each group. Pigs (n = 10 SUN, n = 8 Control) had blood drawn for analysis of 25(OH)D₃ concentration before/after sun exposure or control, and tissue samples were taken at slaughter for analysis of tissue vitamin D3 and 25(OH)D₃ concentration. Three random samples from a single loin chop and surrounding adipose were collected and analyzed. Serum concentrations of 25(OH)D₃ did not differ (P≥0.376) between treatments prior to sun exposure in either group, but was increased (time*treatment interaction, P<0.001) with SUN exposure. Total vitamin D content (D3 plus 25(OH)D₃) of loin tissue was increased (P < 0.001) with sun exposure and averaged 0.997±0.094 μg/100g and 0.348±0.027 μg/100g for sun and control pigs, respectively. While exposure to sunlight increased (P = 0.003) tissue content of 25(OH) D in subcutaneous adipose tissue, vitamin D₃ content was similar between treatments (P = 0.56). Sunlight exposure in pigs increased the vitamin D content of loin, and may provide an additional source of dietary vitamin D.

25-Hydroxyvitamin D as a Biomarker of Vitamin D Status and Its Modeling to Inform Strategies for Prevention of Vitamin D Deficiency within the Population

There is substantial evidence that the prevalence of vitamin D deficiency is unacceptably high in the population, and this requires action from a public health perspective. Circulating 25-hydroxyvitamin D [25(OH)D] is a robust and reliable marker of vitamin D status and has been used by numerous agencies in the establishment of vitamin D dietary requirements and for population surveillance of vitamin D deficiency or inadequacy. In a wider context, modeling of serum 25(OH)D data and its contributory sources, namely dietary vitamin D supply and UVB availability, can inform our understanding of population vitamin D status. The aim of this review is to provide the current status of knowledge in relation to modeling of such vitamin D-relevant data. We begin by highlighting the importance of the measurement of 25(OH)D and its standardization, both of which have led to new key data on the prevalence of vitamin D deficiency and inadequacy in North America and Europe. We then overview how state-of-the-art modeling can be used to inform our understanding of the potential effect of ergocalciferol and 25(OH)D on vitamin D intake estimates and how meteorological data on UVB availability, when coupled with other key data, can help predict population serum 25(OH)D concentration, even accounting for seasonal fluctuations, and lastly, how these in silico approaches can help inform policymakers on strategic options on addressing low vitamin D status through food-based approaches and supplementation. The potential of exemplar food-based solutions will be highlighted, as will the possibility of synergies between vitamin D and other dairy food-based micronutrients, in relation to vitamin D status and bone health. Lastly, we will briefly consider the interactions between season and vitamin D supplements on vitamin D status and health.

Low vitamin D status and obesity: Role of nutritionist

Low vitamin D status and obesity have concomitantly reached epidemic levels worldwide. Up to now the direction of the association between low vitamin D status and obesity, the exact mechanisms responsible for this association and the clinical usefulness to increase vitamin D status for reducing adiposity still warrant further evaluation. The aim of the present review was to examine the current evidence linking low vitamin D status and obesity in relation to the role of the nutritionist. On the one side, considering obesity as a causal factor, low sun exposure in obese individuals due to their sedentary lifestyle and less outdoor activity, vitamin D sequestration in adipose tissue, and volumetric dilution of ingested or cutaneously synthesized vitamin D₃ in the large fat mass of obese patients, might represent some of the factors playing a major role in the pathogenesis of the low vitamin D status. On the other side, the expression of both vitamin D₃ receptors and enzymes responsible for vitamin D₃ metabolism in adipocytes depicted a role for the low vitamin D status per se in the development of obesity by modulating adipocyte differentiation and lipid metabolism. Nutritionists need to accurately address the aspects influencing the low vitamin D status in obesity and the vitamin D supplementation in obese individuals.

Low serum vitamin D-status, air pollution and obesity: A dangerous liaison

The aim of this review is to provide a general overview of the possible associations among the vitamin D status, air pollution and obesity. Sunlight exposure accounts in humans for more than 90 % of the production of vitamin D. Among emerging factors influencing sunlight-induced synthesis of vitamin D, prospective and observational studies proved that air pollution constitutes an independent risk factor in the pathogenesis of vitamin D hypovitaminosis. In addition, environmental pollutants can affect risk of obesity when inhaled, in combination with unhealthy diet and lifestyle. In turn, obesity is closely associated with a low vitamin D status and many possible mechanisms have been proposed to explain this association. The associations of air pollution with low vitamin D status on the hand and with obesity on the other hand, could provide a rationale for considering obesity as a further link between air pollution and low vitamin D status. In this respect, a vicious cycle could operate among low vitamin D status, air pollution, and obesity, with additive detrimental effects on cardio-metabolic risk in obese individuals. Besides vitamin D supplementation, nutrient combination, used to maximize the protective effects against air pollution, might also contribute to improve the vitamin D status by attenuating the "obesogen" effects of air pollution.

Vitamin D receptor gene polymorphisms and cognitive decline in Parkinson's disease

We and others have suggested that vitamin D receptor gene (VDR) polymorphisms influence susceptibility for Parkinson's disease (PD), Alzheimer's disease (AD), mild cognitive impairment (MCI) or overall cognitive functioning. Here we examine VDR polymorphisms and cognitive decline in patients with PD. Non-Hispanic Caucasian PD patients (n=190) in the Parkinson Environment Gene (PEG) study were successfully genotyped for seven VDR polymorphisms. Cognitive function was assessed with the Mini-Mental State Exam (MMSE) at baseline and at a maximum of three follow-up exams. Using repeated-measures regression we assessed associations between VDR SNP genotypes and change in MMSE longitudinally. PD cases were on average 67.4years old at diagnosis and were followed for an average of 7.1years into disease. Each additional copy of the FokI A allele was associated with a 0.115 decrease in the total MMSE score per year of follow-up (β=-0.115, SE(β)=0.05, p=0.03) after adjusting for age, sex, education and PD duration. The effect on MMSE by the FokI A allele was comparable in absolute magnitude to the effect for disease duration in years prior to first interview (β=-0.129 per year, SE(β)=0.08, p=0.13), and years of education (β=0.118 per year, SE(β)=0.03, p<0.001). When LD/LED use and PD subtype were added to the model, the effect of the FokI A allele on total MMSE score was magnified (β=-0.141, SE(β)=0.05, p=0.005). Results point to Fokl, a functional VDR polymorphism, as being associated with cognitive decline in PD. Future studies examining the contributions of the vitamin D metabolic pathway to cognitive dysfunction in PD are needed.

Ultraviolet radiation and effects on humans: the paradigm of maternal vitamin D production during pregnancy

Current evidence indicates that neonates born of mothers with vitamin D deficiency during pregnancy have greater risk for developing hypocalcemia, rickets and extra-skeletal disorders. Despite the classic knowledge that ultraviolet-B (UVB) exposure is the most efficient way for a future mother to obtain optimal vitamin D concentrations, no current consensus or clinical recommendations exist regarding the duration and timing of UVB exposure for pregnant women. This article offers a narrative review of available data regarding how UVB exposure affects maternal vitamin D production during pregnancy, along with a discourse on clinical implications of this public health issue. Future studies would benefit from adopting UVB exposure estimates to recommend appropriate UVB exposure to pregnant women. Doing so could provide a more holistic and practical approach in managing maternal hypovitaminosis D during pregnancy.

Free 25-hydroxyvitamin D is low in obesity, but there are no adverse associations with bone health

BACKGROUND

The mechanism and clinical significance of low circulating 25-hydroxyvitamin D [25(OH)D] in obese people are unknown. Low total 25(OH)D may be due to low vitamin D-binding proteins (DBPs) or faster metabolic clearance. However, obese people have a higher bone mineral density (BMD), which suggests that low 25(OH)D may not be associated with adverse consequences for bone.

OBJECTIVE

We sought to determine whether 1) vitamin D metabolism and 2) its association with bone health differ by body weight.

DESIGN

We conducted a cross-sectional observational study of 223 normal-weight, overweight, and obese men and women aged 25-75 y in South Yorkshire, United Kingdom, in the fall and spring. A subgroup of 106 subjects was also assessed in the winter. We used novel techniques, including an immunoassay for free 25(OH)D, a stable isotope for the 25(OH)D3 half-life, and high-resolution quantitative tomography, to make a detailed assessment of vitamin D physiology and bone health.

RESULTS

Serum total 25(OH)D was lower in obese and overweight subjects than in normal-weight subjects in the fall and spring (geometric means: 45.0 and 40.8 compared with 58.6 nmol/L, respectively; P < 0.001) but not in the winter. Serum 25(OH)D was inversely correlated with body mass index (BMI) in the fall and spring and in the winter. Free 25(OH)D and 1,25-dihydroxyvitamin D [1,25(OH)2D] were lower in obese subjects. DBP, the DBP genotype, and the 25(OH)D3 half-life did not differ between BMI groups. Bone turnover was lower, and bone density was higher, in obese people.

CONCLUSIONS

Total and free 25(OH)D and 1,25(OH)2D are lower at higher BMI, which cannot be explained by lower DBP or the shorter half-life of 25(OH)D3 We speculate that low 25(OH)D in obesity is due to a greater pool of distribution. Lower 25(OH)D may not reflect at-risk skeletal health in obese people, and BMI should be considered when interpreting serum 25(OH)D as a marker of vitamin D status.

Vitamin D in patients with chronic kidney disease: a position statement of the Working Group "Trace Elements and Mineral Metabolism" of the Italian Society of Nephrology

In the late 1970s, calcitriol was introduced into clinical practice for the management of secondary renal hyperparathyroidism in chronic kidney disease (CKD). Since then, the use of calcifediol or other native forms of vitamin D was largely ignored until the publication of the 2009 Kidney Disease Improving Global Outcomes (KDIGO) recommendations. The guidelines suggested that measurement of circulating levels of 25(OH)D (calcifediol) and its supplementation were to be performed on the same basis as for the general population. This indication was based on the fact that the precursors of active vitamin D had provided to CKD patients considerable benefits in survival, mainly due to their pleiotropic effects on the cardiovascular system. However, despite the long-term use of various classes of vitamin D in CKD, a clear definition is still lacking concerning the most appropriate time for initiation of therapy, the best compound to prescribe (active metabolites or analogs), the proper dosage, and the most suitable duration of therapy. The aim of this position statement is to provide and critically appraise the current plentiful evidence on vitamin D in different clinical settings related to CKD, particularly focusing on outcomes, monitoring and treatment-associated risks. However, it should be taken in account that position statements are meant to provide guidance; therefore, they are not to be considered prescriptive for all patients and, importantly, they cannot replace the judgment of clinicians.

Study of the Determinants of Vitamin D Status in Pediatric Patients With Osteogenesis Imperfecta

OBJECTIVE

Vitamin D is essential to the development and maintenance of the skeleton, especially for children with bone disorders such as osteogenesis imperfecta (OI). We evaluated serum 25-hydroxyvitamin D (25-OHD) levels to assess the relationship between determinants of vitamin D status in pediatric patients with OI.

METHODS

This cross-sectional study evaluated sex, age, weight, height, body mass index, OI type, sunscreen use, season of assessment, sun exposure, vitamin D and calcium supplementation, bisphosphonate treatment, bone mineral density (BMD), milk and soda consumption, mobility, and time of sedentary activity. Levels of serum 25-OHD, calcium, parathyroid hormone (PTH), phosphorus, and alkaline phosphatase (ALP) were analyzed. Serum levels of 25-OHD were classified according to sufficient (>30 ng/ml or 75 nmol/L), insufficient (20-30 ng/ml or 50-75 nmol/L), moderately deficient (20-10 ng/ml or 50-25 nmol/L), and severely deficient (<10 ng/ml or 25 nmol/L).

RESULTS

Fifty-two patients were included and 46 (88.4%) were classified as having insufficient or deficient 25-OHD. An inverse correlation between serum 25-OHD and time of sedentary activity (r = -0.597, p < 0.001) and a positive correlation with height (r = 0.521, p = 0.046) and whole body BMD (r = 0.586, p = 0.022) were observed. A significant difference between the number of glasses of milk consumed (p = 0.010) was observed.

CONCLUSION

To optimize bone health, patients with OI need to be educated regarding habits that can improve serum 25-OHD levels, such as a reduction in periods of inactivity, the importance of sun exposure, and increasing consumption of milk and fortified dairy products.

Predicted vitamin D status during pregnancy in relation to offspring forearm fractures in childhood: a study from the Danish National Birth Cohort

In a prospective cohort study, the association between maternal vitamin D status during pregnancy and offspring forearm fractures during childhood and adolescence was analysed in 30 132 mother and child pairs recruited to the Danish National Birth Cohort between 1996 and 2002. Data on characteristics, dietary factors and lifestyle factors were collected on several occasions during pregnancy. We analysed the association between predicted vitamin D status, based on a subsample with 25-hydroxyvitamin D (25(OH)D) biomarker measurements (n 1497) from gestation week 25, and first-time forearm fractures among offspring between birth and end of follow-up. Diagnoses were extracted from the Danish National Patient Register. Multivariable Cox regression models using age as the underlying time scale indicated no overall association between predicted vitamin D status (based on smoking, season, dietary and supplementary vitamin D intake, tanning bed use and outdoor physical activity) in pregnancy and offspring forearm fractures. Likewise, measured 25(OH)D, tanning bed use and dietary vitamin D intake were not associated with offspring forearm fractures. In mid-pregnancy, 91 % of the women reported intake of vitamin D from dietary supplements. Offspring of women who took >10 µg/d in mid-pregnancy had a significantly increased risk for fractures compared with the reference level of zero intake (hazard ratios (HR) 1·31; 95 % CI 1·06, 1·62), but this was solely among girls (HR 1·48; 95 % CI 1·10, 2·00). Supplement use in the peri-conceptional period exhibited similar pattern, although not statistically significant. In conclusion, our data indicated no protective effect of maternal vitamin D status with respect to offspring forearm fractures.

Sun Exposure and Protection Habits in Pediatric Patients with a History of Malignancy

BACKGROUND

Survivors of childhood cancer are at high risk for developing non-melanoma skin cancer and therefore are firmly advised to avoid or minimize sun exposure and adopt skin protection measures. We aimed to compare sun exposure and protection habits in a cohort of pediatric patients with a history of malignancy to those of healthy controls.

METHODS

Case-control study of 143 pediatric patients with a history of malignancy (aged 11.2±4.6 y, Male = 68, mean interval from diagnosis 4.4±3.8 y) and 150 healthy controls (aged 10.4±4.8 y, Male = 67). Sun exposure and protection habits were assessed using validated questionnaires.

RESULTS

Patients and controls reported similar sun exposure time during weekdays (94±82 minutes/day vs. 81±65 minutes/day; p = 0.83), while during weekends patients spent significantly less time outside compared to controls (103±85 minutes/day vs. 124±87 minutes/day; p = 0.02). Time elapsed from diagnosis positively correlated with time spent outside both during weekdays (r = 0.194, p = 0.02) and weekends (r = 0.217, p = 0.01), and there was a step-up in sun exposure starting three years after diagnosis. There was no significant difference regarding composite sun protection score between patients and controls. Age was positively correlated with number of sunburns per year and sun exposure for the purpose of tanning, and was negatively correlated with the use of sun protection measures.

CONCLUSIONS

Although childhood cancer survivors are firmly instructed to adopt sun protection habits, the adherence to these instructions is incomplete, and more attention should be paid to improve these habits throughout their lives. Since sunlight avoidance may results in vitamin D deficiency, dietary supplementation will likely be needed.

Vitamin D receptor gene polymorphisms and Parkinson's disease in a population with high ultraviolet radiation exposure

INTRODUCTION

A high prevalence of vitamin D deficiency has been reported in Parkinson's disease (PD). Epidemiologic studies examining variability in genes involved in vitamin D metabolism have not taken into account level of exposure to ultraviolet radiation (UVR). We examined whether exposure to UVR (as a surrogate for vitamin D levels) and variations in the vitamin D receptor gene (VDR) are associated with PD.

METHODS

Within a geographical information system (GIS) we linked participants' geocoded residential address data to ground level UV data to estimate historical exposure to UVR. Six SNPs in VDR were genotyped in non-Hispanic Caucasian subjects.

RESULTS

Average lifetime UVR exposure levels were >5000 Wh/m(2), which was higher than levels for populations in previous studies, and UVR exposure did not differ between cases and controls. Homozygotes for the rs731236 TT (major allele) genotype had a 31% lower risk of PD risk (OR=0.69; 95% CI=0.49, 0.98; p=0.04 for TT vs. TC+CC). The rs7975232 GG (minor allele) genotype was also associated with decreased risk of PD (OR=0.63; 95% CI=0.42, 0.93; p=0.02 for GG vs. TG+TT). The association between PD risk and a third locus, rs1544410 (BsmI), was not statistically significant after adjustment for covariates, although there was a trend for lower risk with the GG genotype.

CONCLUSIONS

This study provides initial evidence that VDR polymorphisms may modulate risk of PD in a population highly exposed to UVR throughout lifetime.

Elevated serum 25(OH)-vitamin D levels are negatively correlated with molar-incisor hypomineralization

To date, the precise etiology of molar-incisor hypomineralization (MIH) is uncertain. Vitamin D plays a key role in hard tissue formation. Therefore, this study aimed to analyze the relationship between serum 25-hydroxy-vitamin D (25(OH)D) status and dental health data obtained from 1,048 children in a 10-year follow-up of the Munich GINIplus and LISAplus birth cohorts. The dental examination included the diagnosis of MIH and recording of (non-)cavitated caries lesions in primary and permanent teeth. Serum 25(OH)D concentrations were taken from blood samples of the 10-year investigation and measured with a fully automated, modular system. Different logistic regression and Poisson hurdle models were calculated. MIH was diagnosed in 13.6% of the study population. Approximately 16.4% of the children demonstrated caries-related defects (D3-4MFS > 0). The mean season-adjusted concentration of 25(OH)D was 75.8 nmol/l (standard deviation 22.0 nmol/l). After adjusting for sex, age, body mass index, parental education, equivalent income, and television/personal computer (TV/PC) viewing hours, a 10 nmol/l increase in serum 25(OH)D concentrations was significantly associated with a lower odds ratio of having MIH (OR = 0.89; P = 0.006). Furthermore, higher 25(OH)D values were associated with a lower number of caries-affected permanent teeth. It is concluded that elevated serum 25(OH)D concentrations were associated with better dental health parameters.