Figure 1 summarizes the search and selection process. After reviewing titles and abstracts, 21 articles were selected for full-text article review. Of the 21 articles, five RCTs were included in this meta-analysis. For example, of the excluded articles, research from Jastrzebska M.

et al. Figure 2 presents the funnel plot of the included trials for within study mean difference of serum vitamin D status between groups at baseline. The horizontal axis presents within study mean difference of serum 25 OH D between intervention and placebo for each trial at the baseline [ 28 , 29 , 30 , 31 , 32 ].

Funnel plot for within study serum 25 OH D difference between intervention and placebo for each trial at baseline. SE, standard error; MD, mean difference of serum 25 OH D between intervention and placebo. Close a included 2 different vitamin D3 dosage intervention groups in their study [ 28 ].

Methodological quality of the trials and introduced risk of bias are shown in Fig. Five included studies are all placebo controlled and double blinded studies. Cochrane risk of bias assessment.

Baseline characteristics of subjects from all five included RCTs for analytical and quantitative synthesis are presented in Tables 1 and 2.

Three studies were from UK, one from Korea and one from New Zealand. Athletes were engaged in different sports, and four out of the five trials included males only. Wyon et al. Close et al. In another study, Close et al. For both studies carried out by Close et al. Jung et al. Fairbairn et al.

Both Tables 3 and 4 demonstrate mean serum 25 OH D concentration at the baseline and follow-up for each study. For those athletes with insufficient serum 25 OH D at the baseline, vitamin D3 supplementation improved their vitamin D status.

Table 3 Fig. From this sensitivity analysis in Fig. Total sample size in this study is including both intervention and placebo. Table 5 shows the strength changes between pre and post- vitamin D3 intervention for one repetition maximum Bench Press 1-RM BP and maximal quadriceps contraction.

After generating the forest plot for different strength tests subgroups in Fig. And, furthermore, no overall effect on muscle strength was observed based on included RCTs SMD From Figs.

The sensitivity analysis also observed an overall beneficial effects of vitamin D3 supplementation on serum 25 OH D.

In order to generate consistent result for pooled mean difference between post-intervention results and baseline profile, each subgroup included two to three trials that contributed to the pooling of standard mean difference of the strength measurement. Neither Wyon et al.

PRISMA criteria of Cochrane reviews were used to ensure quality and rigorous methodology. The selection and review process was independently conducted by two reviewers.

Our conclusions are made based on findings from up-to-date officially published RCTs to ensure the quality of this systematic reviews and meta-analyses. With limited RCTs available after screening and selection assessment process for this meta-analysis, this study only has data from five RCTs of certain variables inherent to meta-analysis including different supplementation dosage, outcome measurements, sports and training routines, which may introduce confounders with limited subjects.

Our study has certain limitations inherent to systematic reviews and meta-analysis and cannot be disregarded, such as year-round indoors training like Judo and Taekwondo may significantly reduce serum 25 OH D compared with outdoors sports. Furthermore, muscle strength can be more important in certain sports since taekwondo and judo athletes pay more attention to enhancing strength then soccer players.

With limited RCTs observed vitamin D3 supplementations on muscle strength, it is therefore not feasible to adjust for different variables, like measurement performed during different season of the year, sport professions, sunlight exposure, specific age groups, genders, type of diets such as Mediterranean diet, vegan diet, Ketogenic diet , etc.

The finding of having no overall effect of vitamin D3 on muscle strength in this study could due to small sample size and not being able to stratify included athletes for better control when pooling and summarizing each outcome.

The level of current evidence of this meta-analysis is estimated as moderate to high for elevating serum 25 OH D concentrations with appropriate dosage and duration, but, low evidence for enhancing muscle strength have been observed. The sample sizes in these included trials were small [ 28 , 29 , 30 , 31 , 32 ], varying from 10 to 57, and between-study baseline serum 25 OH D status heterogeneity was large.

The populations that been studied were very diverse with different sport professions, nationalities, living latitudes, and there were only 5 athletes received vitamin D3 intervention in a study [ 31 ].

Sport activities that athletes undertook were also varied within one study which included mixed athletes from both football and rugby [ 28 ].

Sunlight exposure is considered to be crucial for human body vitamin D synthesis under the skin [ 33 ], and athletes [ 34 ] with weight management protocols and limited sunlight ultraviolet exposure, for example, figure skating athletes [ 35 ] and ice hockey players [ 36 , 37 , 38 ], were reported to have high prevalence of vitamin D deficiency.

In the process of RCTs selection from fully assessed articles, nine studies [ 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ] reported vitamin D supplementation had beneficial effect on elevating serum 25 OH D, but not establishing any association between vitamin D3 supplementation and muscle strength.

There are three studies [ 43 , 44 , 45 ] indicating that vitamin D2 supplementation significantly increased serum 25 OH D2 concentration, but decreased serum 25 OH D3 concentration and had no overall effects on strength tests.

In mice models restricted to either vitamin D2 alone or vitamin D3 alone in its diet, vitamin D2 fed mice had superior bone health regarding bio-markers compared with vitamin D3 fed mice by the week 16 [ 48 ].

In contrast, vitamin D2 supplementation was less effective than vitamin D3 in maintaining healthy serum 25 OH D status reported by other researchers [ 49 , 50 , 51 , 52 , 53 ].

The Longitudinal Aging Study Amsterdam [ 54 ] indicates that down-regulated vitamin D and elevated parathyroid hormone levels can indicate loss of muscle strength. Though, vitamin D3 supplementation was reported to improve physical fitness [ 54 , 55 , 56 , 57 ], high-quality RCTs of vitamin D3 supplementation for athletes are still badly in need.

This meta-analysis looked at up-to-date vitamin D3 supplementation effect on serum 25 OH D and muscle strength from RCTs. After quantitative synthesis in this systematic review and meta-analysis, we have clearly showed that there was a small effect size and little evidence for improved muscle strength with vitamin D3 intervention.

Therefore, even though we observed improved 25 OH D in this meta-analysis, we cannot make the conclusion that vitamin D3 supplementation have beneficial effect on muscle strength. For the future, well-designed RCTs are still needed to look at the impact of vitamin D3 supplementation among different athletes in the aspect of muscle strength and athletic performance.

Paxton GA, Teale GR, Nowson CA, Mason RS, McGrath JJ, Thompson MJ, Siafarikas A, Rodda CP, Munns CF. Australian and New Zealand Bone and Mineral Society. Vitamin D and health in pregnancy, infants, children and adolescents in Australia and New Zealand: A position statement.

Med J Aust. Article PubMed Google Scholar. Cherniack EP, Levis S, Troen BR. Hypovitaminosis D: a widespread epidemic. PubMed Google Scholar. Winzenberg T, Jones G. Vitamin D and bone health in childhood and adolescence. Calcif Tissue Int. Article CAS PubMed Google Scholar.

Holick MF, Chen TC. Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr. Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes B. Estimation of optimal serum concentrations of hydroxyvitamin D for multiple health outcomes. Tomlinson PB, Joseph C, Angioi M.

Effects of vitamin D supplementation on upper and lower body muscle strength levels in healthy individuals. A systematic review with meta-analysis.

J Sci Med Sport. Thacher TD, Clarke BL. Vitamin D insufficiency. Mayo Clin Proc. Article CAS PubMed PubMed Central Google Scholar. DeLuca HF. Overview of general physiologic features and functions of vitamin D. Yoshizawa T, Handa Y, Uematsu Y, Takeda S, Sekine K, Yoshihara K, Kawakami T, Arioka K, Sato H, Uchiyama Y, et al.

Mice lacking the vitamin D receptor exhibit impaired bone formation, uterine hypoplasia and growth retardation after weaning. Nat Genet. Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad MH, Weaver CM, Endocrine Society. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline.

J Clin Endocrinol Metab. Institute of Medicine. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: The National Academies Press; Google Scholar.

Ogan D, Pritchett K. Vitamin D and the athlete: risks, recommendations, and benefits. Article CAS Google Scholar. Holick MF. Vtamin D is not as toxic as was once thought: a historical and an up-to-date perspective. Francesca MT, Paola C, Marta AS, Francesco P, Giuseppe M.

Impact of Western and Mediterranean diets and vitamin D on muscle fibers of sedentary rats. Oku Y, Tanabe R, Nakaoka K, Yamada A, Noda S, Hoshino A, Haraikawa M, Goseki-Sone M.

Influences of dietary vitamin D restriction on bone strength, body composition, and muscle in rats fed a high-fat diet: involvement of mRNA expression of MyoD in skeletal muscle. J Nutr Biochem.

Chang E, Kim Y. Vitamin D decreases adipocyte lipid storage and increases NAD-SIRT1 pathway in 3T3-L1 adipocytes. Farrokhyar F, Tabasinejad R, Dao D, Peterson D, Ayeni OR, Hadioonzadeh R, Bhandari M.

Prevalence of vitamin D inadequacy in athletes: a systematic-review and meta-analysis. Sports Med. The vitamin D epidemic and its health consequences. J Nutr. Nykjaer A, Dragun D, Walther D, Vorum H, Jacobsen C, Herz J, Melsen F, Christensen EI, Willnow TE.

An Endocytic pathway essential for renal uptake and activation of the steroid OH vitamin D. Orysiak J, Mazur-Rozycka J, Fitzgerald J, Starczewski M, Malczewska-Lenczowska J, Busko K. Vitamin D status and its relation to exercise performance and iron status in young ice hockey players.

PLoS One. Chiang CM, Ismaeel A, Griffis RB, Weems S. Effects of vitamin D supplementation on muscle strength in athletes a systematic review. J Strength Cond Res.

Farrokhyar F, Sivakumar G, Savage K, Koziarz A, Jamshidi S, Ayeni OR, Peterson D, Bhandari M. Effects of vitamin D supplementation on serum Hydroxyvitamin D concentrations and physical performance in athletes: a systematic review and meta-analysis of randomized controlled trials.

Tenforde AS, Sayres LC, Sainani KL, Fredericson M. Evaluating the relationship of calcium and vitamin D in the prevention of stress fracture injuries in the young athlete: a review of the literature. Dahlquist DT, Dieter BP, Koehle MS. Plausible ergogenic effects of vitamin D on athletic performance and recovery.

J Int Soc Sports Nutr. Moher D, Liberati A, Tetzlaff J, Douglas GA, for the PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. Int J Surg. Review Manager RevMan [Computer program]. Version 5. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, Jastrzebska M, Kaczmarczyk M, Jastrzebski Z.

The effect of vitamin d supplementation on training adaptation in well trained soccer players. Close GL, Leckey J, Patterson M, Bradley W, Owens DJ, Fraser WD, Morton JP. The effects of vitamin D3 supplementation on serum total 25[OH]D concentration and physical performance: a randomised dose-response study.

Br J Sports Med. Wyon MA, Wolman R, Nevill AM, Cloak R, Metsios GS, Gould D, Ingham A, Koutedakis Y. Acute effects of vitamin D3 supplementation on muscle strength in judoka athletes: a randomized placebo-controlled, double-blind trial.

Clin J Sport Med. Jung HC, Seo MW, Lee S, Jung SW, Song JK. Correcting vitamin D insufficiency improves some, but not all aspects of physical performance during winter training in taekwondo athletes.

Int J Sport Nutr Exerc Metab. Fairbairn KA, Ceelen IJ, Skeaff CM, Cameron CM, Perry TL. Vitamin D3 supplementation does not improve Sprint performance in professional Rugby players: a randomised, placebo-controlled double blind intervention study.

Close GL, Russell J, Cobley JN, Owens DJ, Wilson G, Gregson W, Fraser WD, Morton JP. Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK: implications for skeletal muscle function.

J Sports Sci. Holick MF, Matsuoka LY, Wortsman J. Age, vitamin D, and solar ultraviolet. Michael EA, Albert OG, Michael S, Russell FW, Scott AR. Am J Sports Med. Article Google Scholar. Ziegler PJ, Nelson JA, Jonnalagadda SS. Nutritional and physiological status of U. National Figure Skaters.

Int J Sport Nutr. Fitzgerald JS, Orysiak J, Wilson PB, Mazur-Rozycka J, Obminski Z. Association between vitamin D status and testosterone and cortisol in ice hockey players. Biol Sport. Article PubMed PubMed Central Google Scholar.

Fitzgerald JS, Peterson BJ, Warpeha JM, Johnson SC, Ingraham SJ. Association between vitamin D status and maximal-intensity exercise performance in junior and collegiate hockey players.

Mehran N, Schulz BM, Neri BR, Robertson WJ, Limpisvasti O. Prevalence of vitamin D insufficiency in professional hockey players.

Orthop J Sports Med. Backx EM, Tieland M, Maase K, Kies AK, Mensink M, van Loon LJ, de Groot LC. The impact of 1-year vitamin D supplementation on vitamin D status in athletes: a dose-response study.

Eur J Clin Nutr. Guillemant J, Le HT, Maria A, Allemandou A, Pérès G, Guillemant S. Wintertime vitamin D deficiency in male adolescents: effect on parathyroid function and response to vitamin D3 supplements.

Osteoporos Int. He CS, Fraser WD, Tang J, Brown K, Renwick S, Rudland-Thomas J, Teah J, Tanqueray E, Gleeson M. The effect of 14 weeks of vitamin D3 supplementation on antimicrobial peptides and proteins in athletes.

Lewis RM, Redzic M, Thomas DT. The effects of season-long vitamin D supplementation on collegiate swimmers and divers.

Shanely RA, Nieman DC, Knab AM, Gillitt ND, Meaney MP, Jin F, Sha W, Cialdella-Kam L. Influence of vitamin D mushroom powder supplementation on exercise-induced muscle damage in vitamin D insufficient high school athletes.

Nieman DC, Gillitt ND, Shanely RA, Dew D, Meaney MP, Luo B. Vitamin D2 supplementation amplifies eccentric exercise-induced muscle damage in NASCAR pit crew athletes. Stephensen CB, Zerofsky M, Burnett DJ, Lin YP, Hammock BD, Hall LM, McHugh T. Ergocalciferol from mushrooms or supplements consumed with a standard meal increases hydroxyergocalciferol but decreases hydroxycholecalciferol in the serum of healthy adults.

Silk LN, Greene DA, Baker MK, Jander CB. Tibial bone responses to 6-month calcium and vitamin D supplementation in young male jockeys: a randomised controlled trial. Storlie DM, Pritchett K, Pritchett R, Cashman L. Int J Health Nutr. Rene FC, Ivan H, Renata P, Leon S, Tonnie H, Rui Z, Nancy QL, Albert S, Miriam G, Mallya SM, John SA, Martin H.

Differential Responses to Vitamin D2 and Vitamin D3 Are Associated With Variations in Free Hydroxyvitamin D. Trang HM, Cole DE, Rubin LA, Pierratos A, Siu S, Vieth R. Evidence that vitamin D3 increases serum hydroxyvitamin D more efficiently than does vitamin D2.

Jones G. Extrarenal vitamin D activation and interactions between vitamin D3, vitamin D2, and vitamin D analogs. Annu Rev Nutr. There are two forms of vitamin D available in supplement form. Vitamin D3 is the over-the-counter supplement available, while vitamin D2 is the prescription form.

Surprisingly, research consistently indicates that the over-the-counter form vitamin D3 is more easily absorbed by the body and the best form to take by athletes and the general population. Vitamin D has an important role in supporting many body systems, including the muscles, the nervous system, and the immune system [8].

This makes vitamin D of particular importance to athletes. Vitamin D also plays a critical role in the absorption of calcium [9] , which is important for building strong bones; if you do not get enough vitamin D, you cannot absorb and utilize calcium, which has lasting implications [10].

Scientific research indicates that adequate vitamin D intake throughout life helps prevent stress fractures [11] , muscle injuries [12] , sick days [13] , and long term diseases [14]. Furthermore, athletes who are vitamin D deficient and engage in long term training are at high risk of skeletal injuries, autoimmune diseases [15] , and arthritis [20].

Due to the significant benefits of vitamin D to athletes, slightly higher levels of vitamin D in the blood are recommended for athletes than non-athletes. In addition, studies indicate that athletes have increased risk of developing vitamin D deficiency during training, due to changes in body composition.

Your risk factor for being Vitamin D deficient is based on where you live, your lifestyle, your genetics, and other factors. Vitamin D is also known as the sunshine vitamin because your body can make this vitamin from ultraviolet B rays.

However, it takes a lot of sunshine year-round for the body to make enough of this vitamin. If you live in a climate that has four seasons, or you exercise indoors at a gym for most of the year, you will probably be missing out on vitamin D, and will have some a vitamin D deficiency for all or part of the year.

Most people in the United States, Canada, and Europe live too far north of the equator for their bodies to make adequate vitamin D from sun for most of the year.

Regardless of the sport they participate in, the majority of athletes in the US are Vitamin D deficient. This may be shown by an increased incidence of inflammation, poor jumping velocity and power, lowered strength, and increased risk of fractures and stress fractures.

Athletes living near the equator are the least likely to be deficient; people living north of the equator have varying risk of deficiency, depending on how far north they live and time spent in the sun. If you are wondering how high your risk is of having a Vitamin D deficiency based on your location in the United States, look at a map.

If you live in a city north of Los Angeles or north of 35 degrees latitude , you have a high risk of vitamin D deficiency. If you have darker skin, you have an additional risk of being Vitamin D deficient, regardless of where you live.

Darker skin blocks a lot of the UV rays that the body needs to synthesize Vitamin D. Studies indicate that So, if you have dark skin or even sun tanned skin , you are at increased risk and may want to discuss vitamin D supplementation with your doctor. In addition, lifestyle factors can also contribute to your particular risk factor of having a vitamin D deficiency.

This could include how much time you spend in the sun and whether you wear sunscreen to protect your skin from aging and skin cancer. You can get some vitamin D in foods you eat, particularly fatty fish and some fortified dairy products.

However, food sources are insufficient to maintain a healthy Vitamin D level. Based on the many risk factors associated with low levels of Vitamin D, it is highly recommended that all athletes consider Vitamin D supplementation.

In particular, athletes living above 35 degrees latitude [20] should take vitamin D daily. Studies focusing on the dosage for athletes in particular point to the optimal dose being 4, IU to 5, IU daily.

In addition, the rigors of training and related changes in body mass add additional risk of vitamin D deficiency to the athlete. If you want to become a better athlete, make sure you are getting sufficient Vitamin D.

With vitamin D 3 proving more efficacious, the optimal dosage varies depending on the individual and the institution providing the guidelines. The definitions of hypo vitaminosis or hyper vitaminosis are more controversial. However, recent reviews have suggested that this is more of a theoretical concern [ 72 , 83 , 84 , 90 ].

The optimal vitamin D dosage and level are clearly controversial [ 88 , 91 ]. Furthermore, the optimal levels needed for athletic performance have not yet been determined.

Furthermore, this dosage would be unattainable from natural UVB exposure during the months of October to April when residing in latitudes of Recently, an accidental overdose of 2,, IU of vitamin D 3 in two elderly patients did not cause adverse effects and only elevated blood calcium levels slightly [ ].

RANKL in turn stimulates mineralization and bone resorption via osteoclastogenesis. Any discussion of vitamin D toxicity merits mention of vitamin K. As with calcium, vitamin K works synergistically with vitamin D to regulate bone resorption, activation and distribution [ ].

Vitamin K carboxylates the newly-formed ostecalcin proteins that are produced in mature bone cells and are tightly regulated by vitamin D [ ]. Once the protein is carboxylated, it interacts with calcium ions in bone tissue [ ] and has a significant effect on bone mineralization, formation, the prevention of bone loss, and potentially the stoppage of fractures in women [ , — ].

However, when levels of vitamin K are inadequate, the ostecalcin production is not suppressed [ ]. This situation facilitates a build-up of un-carboxylated inactive ostecalcin proteins in bone, leading to a potential increase in calcium release from bone and the deposition of calcium into soft tissues causing arterial calcification [ , ].

Thus, vitamin D 3 toxicity might occur only in the absence of sufficient vitamin K stores. Recommended dosages of vitamin K range from 50 mcg to mcg [ ]. However, these recommendations are controversial since vitamin K stores are rapidly depleted without constant supply [ ] and like vitamin D, vitamin K also has two variants: K 1 and K 2.

Sources of vitamin K can be found in pharmacological analogues and naturally in the diet. Vitamin K 2 , the more bioavailable form of vitamin K [ ], comes in a variety of fish, offal, meat, dairy products, fermented cheese e.

Specifically, vitamin K 1 has a key role in the carboxylation of various blood clotting proteins, where vitamin K 2 is essential for the carboxylation and activation of osteocalcin and matrix Gla protein MGP an essential protein needed to prevent soft tissue calcification [ ].

More importantly, one of the vitamin K 2 variants, MK-4, is more effective at mitigating osteoclast formation and the negative health effects of vitamin D overdose [ , ]. Thus, although MK-4 might have the greatest effect on carboxylation of osteocalcin, both vitamin K 1 and K 2 interact with each other in order to optimize bone health and are essential to the human body.

Further research in athletic populations should focus on the optimal dosage for vitamin D 3 in combination with vitamin K. In summary, an interesting theme has emerged from animal studies that supraphysiological dosages of vitamin D 3 have potential ergogenic effects on the human metabolic system and lead to multiple physiological enhancements.

These dosages could increase aerobic capacity, muscle growth, force and power production, and a decreased recovery time from exercise. These dosages could also improve bone density. However, both deficiency Coaches, medical practitioners, and athletic personnel should recommend their patients and athletes to have their plasma 25 OH D measured, in order to determine if supplementation is needed.

McCollum E, Simmonds N, Becker J, Shipley P. An experimental demonstration of the existence of a vitamin which promotes calcium deposition. J Biol Chem.

Google Scholar. Jones G. Metabolism and biomarkers of vitamin D. Scand J Clin Lab Invest. Wang T-T, Tavera-Mendoza LE, Laperriere D, Libby E, MacLeod NB, Nagai Y, et al. Large-scale in silico and microarray-based identification of direct 1,dihydroxyvitamin D3 target genes. Mol Endocrinol. Smith DT, Broughton KS, Larson-meyer DE.

Vitamin D status and biomarkers of inflammation in runners. Alvarez-Díaz S, Valle N, García JM, Peña C, Freije JMP, Quesada V, et al. Cystatin D is a candidate tumor suppressor gene induced by vitamin D in human colon cancer cells. J Clin Invest. Article PubMed Google Scholar.

Dhesi JK, Jackson SHD, Bearne LM, Moniz C, Hurley MV, Swift CG, et al. Vitamin D supplementation improves neuromuscular function in older people who fall. Age Ageing. Reddy Vanga S, Good M, Howard PA, Vacek JL.

Role of vitamin D in cardiovascular health. Am J Cardiol. Sukumar D, Shapses SA, Schneider SH. Mol Cell Endocrinol. Schoenmakers I, Francis RM, McColl E, Chadwick T, Goldberg GR, Harle C, et al. Vitamin D supplementation in older people VDOP : Study protocol for a randomised controlled intervention trial with monthly oral dosing with 12, IU, 24, IU or 48, IU of vitamin D 3.

Article PubMed Central PubMed Google Scholar. Close GL, Leckey J, Patterson M, Bradley W, Owens DJ, Fraser WD, et al. The effects of vitamin D 3 supplementation on serum total 25[OH]D concentration and physical performance: a randomised dose—response study.

Br J Sports Med. Bendik I, Friedel A, Roos FF, Weber P, Eggersdorfer M. Vitamin D: a critical and essential micronutrient for human health. Front Physiol. Grudet C, Malm J, Westrin A, Brundin L. Suicidal patients are deficient in vitamin D, associated with a pro-inflammatory status in the blood.

Article Google Scholar. Polak MA, Houghton LA, Reeder AI, Harper MJ, Conner TS. Serum hydroxyvitamin D concentrations and depressive symptoms among young adult men and women.

Chei CL, Raman P, Yin Z-X, Shi X-M, Zeng Y, Matchar DB. Vitamin D levels and cognition in elderly adults in China. J Am Geriatr Soc. Holick MF. Vitamin D: its role in cancer prevention and treatment. Prog Biophys Mol Biol.

Article CAS PubMed Google Scholar. Guillot X, Prati C, Wendling D. Vitamin D and spondyloarthritis. Expert Rev Clin Immunol. Welch TR, Bergstrom WH, Tsang RC. Vitamin D-deficient rickets: the reemergence of a once-conquered disease. J Pediatr. Bikle DD. Vitamin D metabolism, mechanism of action, and clinical applications.

Chem Biol. Article PubMed Central CAS PubMed Google Scholar. Ogan D, Pritchett K. Vitamin D and the athlete: risks, recommendations, and benefits.

Sato Y, Iwamoto J, Kanoko T, Satoh K. Low-dose vitamin D prevents muscular atrophy and reduces falls and hip fractures in women after stroke: a randomized controlled trial.

Cerebrovasc Dis. Glerup H, Mikkelsen K, Poulsen L, Hass E, Overbeck S, Andersen H, et al. Hypovitaminosis D myopathy without biochemical signs of osteomalacic bone involvement. Calcif Tissue Int. Pfeifer M, Begerow B, Minne H.

Vitamin D and muscle function. Osteoporos Int. Macdougall JD, Hicks AL, Macdonald JR, Mckelvie RS, Green HJ, Smith KM. Muscle performance and enzymatic adaptations to sprint interval training. J Appl Physiol. Farrokhyar F, Tabasinejad R, Dao D, Peterson D, Ayeni O, Hadioonzadeh R, et al.

Prevalence of vitamin D inadequacy in athletes: A systematic-review and meta-analysis. Sport Med. Calvo M, Whiting S. Prevalence of vitamin D insufficiency in Canada and the United States: importance to health status and efficacy of current food fortification and dietary supplement use.

Nutr Rev. Hossein-nezhad A, Holick MF. Vitamin D for health: a global perspective. Mayo Clin Proc. Schlögl M, Holick MF.

Vitamin D and neurocognitive function. Clin Interv Aging. Vitamin D: evolutionary, physiological and health perspectives. Curr Drug Targets. Prosser DE, Jones G.

Enzymes involved in the activation and inactivation of vitamin D. Trends Biochem Sci. Bischoff H, Borchers M, Gudat F, Duermueller U, Theiler R, Stähelin H, et al. In situ detection of 1,dihydroxyvitamin D3 receptor in human skeletal muscle tissue.

Histochem J. Simpson R, Thomas G, Arnold A. Hamilton B. Vitamin d and athletic performance: the potential role of muscle. Asian J Sports Med. PubMed Central PubMed Google Scholar. Stockton KA, Mengersen K, Paratz JD, Kandiah D, Bennell KL.

Effect of vitamin D supplementation on muscle strength: a systematic review and meta-analysis. PubMed Google Scholar. Tomlinson PB, Joseph C, Angioi M. Effects of vitamin D supplementation on upper and lower body muscle strength levels in healthy individuals. A systematic review with meta-analysis.

J Sci Med Sport. Beaudart C, Buckinx F, Rabenda V, Gillain S, Cavalier E, Slomian J, et al. The effects of vitamin D on skeletal muscle strength, muscle mass and muscle power: A systematic review and meta-analysis of randomized controlled trials. J Clin Endocrinol Metab. Von Hurst PR, Beck KL.

Vitamin D and skeletal muscle function in athletes. Curr Opin Clin Nutr Metab Care. Gregory SM, Parker BA, Capizzi JA, Grimaldi AS, Clarkson PM, Moeckel-Cole S, et al. Changes in vitamin D are not associated with changes in cardiorespiratory fitness. Clin Med Res. Mowry DA, Costello MM, Heelan KA.

Association among cardiorespiratory fitness, body fat, and bone marker measurements in healthy young females. J Am Osteopath Assoc. Ardestani A, Parker B, Mathur S, Clarkson P, Pescatello LS, Hoffman HJ, et al.

Relation of vitamin D level to maximal oxygen uptake in adults. Koundourakis NE, Androulakis NE, Malliaraki N, Margioris AN. Fitzgerald J, Peterson B, Warpeha J, Wilson P, Rhodes G, Ingraham S.

Vitamin D status and VO2peak during a skate treadmill graded exercise test in competitive ice hockey players. J Strength Cond Res. Forney L, Earnest CC, Henagan T, Johnson L, Castleberry T, Stewart L.

Vitamin D Status, Body Composition, and Fitness Measures in College-Aged Students. Jastrzębski Z. Effect of vitamin D supplementation on the level of physical fitness and blood parameters of rowers during the 8-week high intensity training.

Facicula Educ Fiz şi Sport. Sugimoto H, Shiro Y. Diversity and substrate specificity in the structures of steroidogenic cytochrome P enzymes. Biol Pharm Bull. Skeletal muscle hypertrophy and structure and function of skeletal muscle fibres in male body builders.

J Physiol. Schoenfeld B. The mechanisms of muscle hypertrophy and their application to resistance training. Does exercise-induced muscle damage play a role in skeletal muscle hypertrophy?

Garcia LA, Ferrini MG, Norris KC, Artaza JN. J Steroid Biochem Mol Biol. Garcia LA, King KK, Ferrini MG, Norris KC, Artaza JN. Stratos I, Li Z, Herlyn P, Rotter R, Behrendt A-K, Mittlmeier T, et al.

Vitamin D increases cellular turnover and functionally restores the skeletal muscle after crush injury in rats. Am J Pathol. Lund D, Cornelison D. Enter the matrix: shape, signal and superhighway. FEBS J. Barker T, Schneider ED, Dixon BM, Henriksen VT, Weaver LK.

Supplemental vitamin D enhances the recovery in peak isometric force shortly after intense exercise. Nutr Metab Lond. Ainbinder A, Boncompagni S, Protasi F, Dirksen RT. Role of mitofusin-2 in mitochondrial localization and calcium uptake in skeletal muscle. Cell Calcium. Todd JJ, Pourshahidi KL, McSorley EM, Madigan SM, Magee PJ.

Vitamin D: Recent advances and implications for athletes. Ceglia L, Niramitmahapanya S, da Silva MM, Rivas DA, Harris SS, Bischoff-Ferrari H, et al.

A randomized study on the effect of vitamin D 3 supplementation on skeletal muscle morphology and vitamin D receptor concentration in older women. Close GL, Russell J, Cobley JN, Owens DJ, Wilson G, Fraser WD, et al. Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK: implications for skeletal muscle function.

J Sports Sci. Mauras N, Hayes V, Welch S, Rini A, Helgeson K, Dokler M, Veldhuis JD, Urban RJ. Wehr E, Pilz S, Boehm B, März W, Obermayer-Pietsch B. Association of vitamin D status with serum androgen levels in men. Clin Endocrinol Oxf. Pilz S, Frisch S, Koertke H, Kuhn J, Dreier J, Obermayer-Pietsch B, et al.

Effect of vitamin D supplementation on testosterone levels in men. Horm Metab Res. Kinuta K, Tanaka H, Moriwake T, Aya K, Kato S, Seino Y. Endocrinology AD, — Blomberg Jensen M, Nielsen JE, Jørgensen A, Rajpert-De Meyts E, Kristensen DM, Jørgensen N, et al. Vitamin D receptor and vitamin D metabolizing enzymes are expressed in the human male reproductive tract.

Hum Reprod. Blomberg Jensen M, Dissing S. Non-genomic effects of vitamin D in human spermatozoa. Herbst KL, Bhasin S. Testosterone action on skeletal muscle. Urban RJ. Growth hormone and testosterone: Anabolic effects on muscle.

Horm Res Pædiatrics. Holick M, MacLaughlin J, Clark M, Holick S, Potts J, Anderson R, et al. Photosynthesis of previtamin D3 in human skin and the physiologic consequences. Am Assoc Adv Sci. Webb AR. Who, what, where and when-influences on cutaneous vitamin D synthesis. Gilchrest B. Sun exposure and vitamin D sufficiency.

Am J Clin Nutr. Lim HW, Gilchrest BA, Cooper KD, Bischoff-Ferrari HA, Rigel DS, Cyr WH, et al. Sunlight, tanning booths, and vitamin D. J Am Acad Dermatol. Wolpowitz D, Gilchrest BA. The vitamin D questions: how much do you need and how should you get it? Sunligth "D"ilemma: Risk of skin cancer or bone disease and muscle weakness.

Lancet —6. Heaney RP. Vitamin D in health and disease. Clin J Am Soc Nephrol. Mithal A, Wahl DA, Bonjour J-P, Burckhardt P, Dawson-Hughes B, Eisman JA, et al.

Global vitamin D status and determinants of hypovitaminosis D. Walker N, Love TD, Baker DF, Healey PB, Haszard J, Edwards AS, et al. Knowledge and attitudes to vitamin D and sun exposure in elite New Zealand athletes: a cross-sectional study.

J Int Soc Sports Nutr. Matsuoka LY, Wortsman J, Hollis BW. Use of topical sunscreen for the evaluation of regional synthesis of vitamin D3. Tripkovic L, Lambert H, Hart K, Smith CP, Bucca G, Penson S, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum hydroxyvitamin D status: a systematic review and meta-analysis.

Holick M. Vitamin D deficiency. N Engl J Med. Houghton L,A, Vieth R. The case against ergocalciferol vitamin D2 as a vitamin supplement. CAS PubMed Google Scholar.

Logan VF, Gray AR, Peddie MC, Harper MJ, Houghton LA. Long-term vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum hydroxyvitamin D status over the winter months. Br J Nutr. Harris SS, Dawson-Hughes B. Plasma vitamin D and 25OHD responses of young and old men to supplementation with vitamin D3.

J Am Coll Nutr. Post JL, Ilich Ernst JZ. Controversies in vitamin D recommendations and its possible roles in nonskeletal health issues. J Nutr Food Sci. Ross AC, Taylor CL. Yaktine AL. Calcium Vitamin D: Valle HB Del; Endocrine S. Evalutation, treatment, and prevention of vitamin D deficiency: An endocrine society clinical practice guideline.

Vieth R. Why the optimal requirement for Vitamin D3 is probably much higher than what is officially recommended for adults. Cannell J, Hollis B. Use of vitamin D in clinical practice.

Altern Med Rev. Assessing vitamin D status. Vitamin D supplementation, hydroxyvitamin D concentrations, and safety. Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes B. Estimation of optimal serum concentrations of hydroxyvitamin D for multiple health outcomes.

Pramyothin P, Holick MF. Vitamin D supplementation: guidelines and evidence for subclinical deficiency. Curr Opin Gastroenterol. Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline.

Hollis BW. Circulating hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for establishing a new effective dietary intake recommendation for vitamin D.

J Nutr. Engelman CD. Vitamin D recommendations: the saga continues. Barger-Lux MJ, Heaney RP, Dowell S, Chen TC, Holick MF. International original article vitamin D and its major metabolites : Serum levels after graded oral dosing in healthy men.

Lappe J, Cullen D, Haynatzki G, Recker R, Ahlf R, Thompson K. Calcium and vitamin d supplementation decreases incidence of stress fractures in female navy recruits. J Bone Miner Res. Dawson-Hughes B, Heaney RP, Holick MF, Lips P, Meunier PJ, Vieth R. Estimates of optimal vitamin D status.

Heaney RP, Davies KM, Chen TC, Holick MF, Janet Barger-Lux M. Human serum hydroxycholecalciferol response to extended oral dosing with cholecalciferol.

Galan F, Ribas J, Sanchez-Martinez PM, Calero T, Sanchez AB, Munoz A. Serum hydroxyvitamin D in early autumn to ensure vitamin D sufficiency in mid-winter in professional football players.

Clin Nutr ; 31 : — Cashman KD, Fitzgerald AP, Kiely M, Seamans KM. A systematic review and meta-regression analysis of the vitamin D intake-serum hydroxyvitamin D relationship to inform European recommendations.

Cashman KD, Hill TR, Lucey AJ, Taylor N, Seamans KM, Muldowney S et al. Estimation of the dietary requirement for vitamin D in healthy adults. Am J Clin Nutr ; 88 : — Melamed ML, Michos ED, Post W, Astor B. Arch Internal Med ; : — Durup D, Jorgensen HL, Christensen J, Schwarz P, Heegaard AM, Lind B.

A reverse J-shaped association of all-cause mortality with serum hydroxyvitamin D in general practice: the CopD study. J Clin Endocrinol Metab ; 97 : — Vieth R. Vitamin D supplementation, hydroxyvitamin D concentrations, and safety. Am J Clin Nutr ; 69 : — EFSA Panel on Dietetic Products NaAN..

Scientific opinion on the tolerable upper intake level of vitamin D. EFSA J ; 10 : — Google Scholar. MacLaughlin J, Holick MF. Aging decreases the capacity of human skin to produce vitamin D3.

J Clin Invest ; 76 : — Hulshof MO KFAM, van Rossum CTM, Buurma-Rethans EJM, Brants HAM, Drijvers JJMM et al. Resultaten van de Voedselconsumptiepeiling Zeist Download references. Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.

NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands. You can also search for this author in PubMed Google Scholar. Correspondence to L C P G M de Groot.

EMP Backx, M Tieland, M Mensink, LJ van Loon and CPMG de Groot have no conflicts of interest. AK Kies is a researcher with DSM Food Specialties. Reprints and permissions.

Backx, E. et al. The impact of 1-year vitamin D supplementation on vitamin D status in athletes: a dose—response study. Eur J Clin Nutr 70 , — Download citation. Received : 06 October Revised : 23 May Accepted : 24 June Published : 27 July Issue Date : September Anyone you share the following link with will be able to read this content:.

Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Reproductive Biology and Endocrinology Journal of the International Society of Sports Nutrition Skip to main content Thank you for visiting nature.

nature european journal of clinical nutrition original article article. Subjects Biomarkers Calcium and vitamin D. Conclusions: Vitamin D deficiency is highly prevalent in athletes.

Access through your institution. Buy or subscribe. Change institution. Learn more. Figure 1. Figure 2. References Ross AC, Manson JE, Abrams SA, Aloia JF, Brannon PM, Clinton SK et al. Article CAS Google Scholar Allison RJ, Close GL, Farooq A, Riding NR, Salah O, Hamilton B et al.

Article Google Scholar Close GL, Leckey J, Patterson M, Bradley W, Owens DJ, Fraser WD et al. Article Google Scholar Ducher G, Kukuljan S, Hill B, Garnham AP, Nowson CA, Kimlin MG et al. PubMed Google Scholar Mowe M, Haug E, Bohmer T. Article CAS Google Scholar Salles J, Chanet A, Giraudet C, Patrac V, Pierre P, Jourdan M et al.

Article CAS Google Scholar Close GL, Russell J, Cobley JN, Owens DJ, Wilson G, Gregson W et al. Article CAS Google Scholar Barker T, Schneider ED, Dixon BM, Henriksen VT, Weaver LK. Article Google Scholar Wyon MA, Koutedakis Y, Wolman R, Nevill AM, Allen N. Article Google Scholar Holick MF. Article Google Scholar Wyon MA, Wolman R, Nevill AM, Cloak R, Metsios GS, Gould D et al.

Article Google Scholar Dubnov-Raz G, Livne N, Raz R, Cohen AH, Constantini NW. Article CAS Google Scholar Gezondheidsraad Evaluation of Dietary Reference Values for Vitamin D. Article Google Scholar Cashman KD, Wallace JM, Horigan G, Hill TR, Barnes MS, Lucey AJ et al.

Article CAS Google Scholar Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ. Article CAS Google Scholar Halliday TM, Peterson NJ, Thomas JJ, Kleppinger K, Hollis BW, Larson-Meyer DE.

Article CAS Google Scholar Clark M, Reed DB, Crouse SF, Armstrong RB. Article CAS Google Scholar Brouwer-Brolsma EM, Vaes AM, van der Zwaluw NL, van Wijngaarden JP, Swart KM, Ham AC et al. Article CAS Google Scholar Blum M, Dolnikowski G, Seyoum E, Harris SS, Booth SL, Peterson J et al.

Article CAS Google Scholar Holick MF, Matsuoka LY, Wortsman J. Article CAS Google Scholar Mavroeidi A, O'Neill F, Lee PA, Darling AL, Fraser WD, Berry JL et al. Article CAS Google Scholar Dawson-Hughes B, Harris SS, Palermo NJ, Ceglia L, Rasmussen H. Article CAS Google Scholar Siebelink E, Geelen A, de Vries JH.

Article CAS Google Scholar Faul F, Erdfelder E, Lang AG, Buchner AG. Article Google Scholar Cashman KD, Seamans KM, Lucey AJ, Stocklin E, Weber P, Kiely M et al. Article CAS Google Scholar Farrokhyar F, Tabasinejad R, Dao D, Peterson D, Ayeni OR, Hadioonzadeh R et al.

Article Google Scholar Constantini NW, Arieli R, Chodick G, Dubnov-Raz G. Article Google Scholar Hamilton B, Grantham J, Racinais S, Chalabi H.

Article Google Scholar Bescos Garcia R, Rodriguez Guisado FA. CAS PubMed Google Scholar Galan F, Ribas J, Sanchez-Martinez PM, Calero T, Sanchez AB, Munoz A. Article CAS Google Scholar Cashman KD, Fitzgerald AP, Kiely M, Seamans KM.

Article CAS Google Scholar Cashman KD, Hill TR, Lucey AJ, Taylor N, Seamans KM, Muldowney S et al. Article CAS Google Scholar Melamed ML, Michos ED, Post W, Astor B. Article Google Scholar Durup D, Jorgensen HL, Christensen J, Schwarz P, Heegaard AM, Lind B.

Article CAS Google Scholar Vieth R. Article CAS Google Scholar EFSA Panel on Dietetic Products NaAN.. Google Scholar MacLaughlin J, Holick MF. Article CAS Google Scholar Hulshof MO KFAM, van Rossum CTM, Buurma-Rethans EJM, Brants HAM, Drijvers JJMM et al.

Acknowledgements We thank all the students and Lucy Okma for assisting during the tests. View author publications. Rights and permissions Reprints and permissions. About this article. Cite this article Backx, E.

Copy to clipboard. This article is cited by Evolution of Vitamin D Status and Vitamin D Receptor Gene Expression Among Professional Handball Athletes During a Competitive Period. About the journal Journal Information Open Access Fees and Funding About the Editors Contact For Advertisers Subscribe.

Search Search articles by subject, keyword or author.

The distance from the equator, season, time of day, cloud cover, pollution, sunblock, skin pigment and age all dictate whether Vitamin D is available from the sun. Vitamin D can only be synthesised if UVB radiation from the sun is absorbed through the skin in adequate amounts.

This means that if you avoid the sun between 10am and 3pm, wear sunblock or cover most of your skin when outside, you may actually be Vitamin D deficient — even in the summer.

During the winter months the angle of the sun prevents UVB radiation from reaching latitudes greater than 35—37 degrees that includes us in the UK. Therefore Vitamin D cannot be synthesised from the sun in these areas during the winter months.

The table below shows some of the studies that have found different groups of athletes to be deficient. Of note are the Israeli athletes whom you would have thought would get plenty of sunshine! It is important to get your head around the fact that researchers distinguish between three levels of Vitamin D in the blood.

It is also only at these higher levels that vitamin D is stored in muscle and fat for future use. The recommended daily Vitamin D intake according to most experts to maintain optimal Vitamins D status, is at least IU per day.

However, more is required if you start with suboptimal levels. IU stands for international units and for Vitamin D 1 IU equals 0.

With these massive differences in recommendations one wonders if it is possible to overdose on Vitamin D? Apparently the amount of Vitamin D produced from 15 min of unprotected sun exposure is 10, to 20, IU, in a light-skinned individual, which makes most experts believe toxicity to be a rare and unlikely event.

There has, however, been increasing reports of people who has suffered from overdoses and national guidelines currently advise that you should not take more than IU per day. The sun is the most plentiful source of Vitamin D but certain foods also contain significant levels salmon, fatty fish, egg yolks and fortified milk, cereal and orange juice.

The one produced by BetterYou has been shown to be more effective at boosting your Vitamin D levels than tablets. I found it at Holland and Barrett and it tastes quite nice. It comes in and IU. It is also worth noting that Vitamin D3 appears to be the best supplement to take.

There is mounting evidence that taking Vitamin D2 can actually decrease the amount of active Vitamin D in your blood.

Vitamin D deficiency can have an influence on athletic performance and injury. If you work indoors, wear sunscreen, avoid the sun between 10am and 3pm or live above 35 degrees latitude you are very likely to have sub-optimal levels of Vitamin D.

Need more help with your injury? Maryke Louw is a chartered physiotherapist with more than 15 years' experience and a Masters Degree in Sports Injury Management. Follow her on LinkedIn , ResearchGate. Allison RJ, Close GL, Farooq A, et al. Severely vitamin D-deficient athletes present smaller hearts than sufficient athletes.

European journal of preventive cardiology ;22 4 Bermon S, Castell LM, Calder PC, et al. Consensus statement immunonutrition and exercise. Chiang C-m, Ismaeel A, Griffis RB, et al. Effects of vitamin D supplementation on muscle strength in athletes: a systematic review.

Close GL, Russell J, Cobley JN, et al. Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK: implications for skeletal muscle function. Journal of sports sciences ;31 4 Malczewska-Lenczowska J, Sitkowski D, Surała O, et al.

The Association between Iron and Vitamin D Status in Female Elite Athletes. Nutrients ;10 2 Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete.

International journal of sport nutrition and exercise metabolism ;28 2 Ogan D, Pritchett K. Vitamin D and the athlete: risks, recommendations, and benefits. Nutrients ;5 6 Owens DJ, Allison R, Close GL. Vitamin D and the athlete: current perspectives and new challenges.

Sports Med Veach M. Pre-Season Vitamin D and Iron Levels as a Predictor of Musculoskeletal Injury in Division I Athletes. University of Arkansas, LCL sprain? Eight LCL exercises to regain your former strength. How often should you change your running shoes?

Close GL, Leckey J, Patterson M, Bradley W, Owens DJ, Fraser WD et al. The effects of vitamin D 3 supplementation on serum total 25[OH]D concentration and physical performance: a randomised dose—response study. Br J Sports Med ; 47 : — Ducher G, Kukuljan S, Hill B, Garnham AP, Nowson CA, Kimlin MG et al.

Vitamin D status and musculoskeletal health in adolescent male ballet dancers a pilot study. J Dance Med Sci ; 15 : 99— PubMed Google Scholar. Mowe M, Haug E, Bohmer T. Low serum calcidiol concentration in older adults with reduced muscular function.

J Am Geriatr Soc ; 47 : — Salles J, Chanet A, Giraudet C, Patrac V, Pierre P, Jourdan M et al. Mol Nutr Food Res ; 57 : — Close GL, Russell J, Cobley JN, Owens DJ, Wilson G, Gregson W et al. Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK: implications for skeletal muscle function.

J Sports Sci ; 31 : — Barker T, Schneider ED, Dixon BM, Henriksen VT, Weaver LK. Supplemental vitamin D enhances the recovery in peak isometric force shortly after intense exercise.

Nutr Metab ; 10 : Wyon MA, Koutedakis Y, Wolman R, Nevill AM, Allen N. The influence of winter vitamin D supplementation on muscle function and injury occurrence in elite ballet dancers: a controlled study. J Sci Med Sport ; 17 : 8— Holick MF.

Vitamin D status: measurement, interpretation, and clinical application. Ann Epidemiol ; 19 : 73— Wyon MA, Wolman R, Nevill AM, Cloak R, Metsios GS, Gould D et al. Acute effects of vitamin D3 Supplementation on muscle strength in Judoka athletes: a randomized placebo-controlled, double-blind trial.

Clin J Sport Med ; 26 : — Dubnov-Raz G, Livne N, Raz R, Cohen AH, Constantini NW. Vitamin D Supplementation and Physical Performance in Adolescent Swimmers.

Int J Sport Nutr Exerc Metab ; 25 : — Gezondheidsraad Evaluation of Dietary Reference Values for Vitamin D.

The Hague Health Council of the Netherlands: Hague, Gallagher JC, Sai A, Templin T 2nd, Smith L. Dose response to vitamin D supplementation in postmenopausal women: a randomized trial.

Ann Intern Med ; : — Cashman KD, Wallace JM, Horigan G, Hill TR, Barnes MS, Lucey AJ et al. Am J Clin Nutr ; 89 : — Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ. Human serum hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr ; 77 : — Halliday TM, Peterson NJ, Thomas JJ, Kleppinger K, Hollis BW, Larson-Meyer DE.

Vitamin D status relative to diet, lifestyle, injury, and illness in college athletes. Med Sci Sports Exerc ; 43 : — Clark M, Reed DB, Crouse SF, Armstrong RB. Pre- and post-season dietary intake, body composition, and performance indices of NCAA division I female soccer players.

Int J Sport Nutr Exerc Metab ; 13 : — Brouwer-Brolsma EM, Vaes AM, van der Zwaluw NL, van Wijngaarden JP, Swart KM, Ham AC et al. Relative importance of summer sun exposure, vitamin D intake, and genes to vitamin D status in Dutch older adults: The B-PROOF study.

J Steroid Biochem Mol Biol , e-pub ahead of print 11 August doi Fitzgerald JS, Peterson BJ, Wilson PB, Rhodes GS, Ingraham SJ. Vitamin D status is associated with adiposity in male ice hockey players. Med Sci Sports Exerc ; 47 : — Blum M, Dolnikowski G, Seyoum E, Harris SS, Booth SL, Peterson J et al.

Vitamin D 3 in fat tissue. Endocrine ; 33 : 90— Holick MF, Matsuoka LY, Wortsman J. Age, vitamin D, and solar ultraviolet. Lancet ; 2 : — Mavroeidi A, O'Neill F, Lee PA, Darling AL, Fraser WD, Berry JL et al. Seasonal hydroxyvitamin D changes in British postmenopausal women at 57 degrees N and 51 degrees N: a longitudinal study.

J Steroid Biochem Mol Biol ; : — Dawson-Hughes B, Harris SS, Palermo NJ, Ceglia L, Rasmussen H. Meal conditions affect the absorption of supplemental vitamin D3 but not the plasma hydroxyvitamin D response to supplementation.

J Miner Res ; 28 : — Siebelink E, Geelen A, de Vries JH. Self-reported energy intake by FFQ compared with actual energy intake to maintain body weight in adults.

Br J Nutr ; : — Faul F, Erdfelder E, Lang AG, Buchner AG. Behav Res Methods ; 39 : — Cashman KD, Seamans KM, Lucey AJ, Stocklin E, Weber P, Kiely M et al. Relative effectiveness of oral hydroxyvitamin D3 and vitamin D3 in raising wintertime serum hydroxyvitamin D in older adults.

Am J Clin Nutr ; 95 : — Farrokhyar F, Tabasinejad R, Dao D, Peterson D, Ayeni OR, Hadioonzadeh R et al. Prevalence of Vitamin D inadequacy in athletes: a systematic-review and meta-analysis. Sports Med ; 45 : — Constantini NW, Arieli R, Chodick G, Dubnov-Raz G. High prevalence of vitamin D insufficiency in athletes and dancers.

Clin J Sport Med ; 20 : — Hamilton B, Grantham J, Racinais S, Chalabi H. Vitamin D deficiency is endemic in Middle Eastern sportsmen. Public Health Nutr ; 13 : — Bescos Garcia R, Rodriguez Guisado FA. Low levels of vitamin D in professional basketball players after wintertime: relationship with dietary intake of vitamin D and calcium.

Nutr Hosp ; 26 : — CAS PubMed Google Scholar. Galan F, Ribas J, Sanchez-Martinez PM, Calero T, Sanchez AB, Munoz A. Serum hydroxyvitamin D in early autumn to ensure vitamin D sufficiency in mid-winter in professional football players. Clin Nutr ; 31 : — Cashman KD, Fitzgerald AP, Kiely M, Seamans KM.

A systematic review and meta-regression analysis of the vitamin D intake-serum hydroxyvitamin D relationship to inform European recommendations. Cashman KD, Hill TR, Lucey AJ, Taylor N, Seamans KM, Muldowney S et al. Estimation of the dietary requirement for vitamin D in healthy adults.

Am J Clin Nutr ; 88 : — Melamed ML, Michos ED, Post W, Astor B. Arch Internal Med ; : — Durup D, Jorgensen HL, Christensen J, Schwarz P, Heegaard AM, Lind B. A reverse J-shaped association of all-cause mortality with serum hydroxyvitamin D in general practice: the CopD study. J Clin Endocrinol Metab ; 97 : — Vieth R.

Vitamin D supplementation, hydroxyvitamin D concentrations, and safety. Am J Clin Nutr ; 69 : — EFSA Panel on Dietetic Products NaAN..

Scientific opinion on the tolerable upper intake level of vitamin D. EFSA J ; 10 : — Google Scholar.