A–Z of nutritional supplements: dietarysupplements, sports nutrition foods and ergogenicaids for health and performance: Part 40D E Larson-Meyer,1 L M Burke,2 S J Stear,3 L M Castell4

1Department of Family andConsumer Sciences, Universityof Wyoming, Laramie,Wyoming, USA2Australian Institute of Sport,Canberra, Australia3Performance InfluencersLimited, London, UK4Green Templeton College,University of Oxford,Oxford, UK

Correspondence toL M Castell, Green TempletonCollege, University of Oxford,Oxford OX2 6HG, UK;lindy.castell@gtc.ox.ac.uk

Received 1 November 2012Revised 1 November 2012Accepted 1 November 2012

To cite: Larson-Meyer DE,Burke LM, Stear SJ, et al. BrJ Sports Med 2013, 47,118–120.

INTRODUCTORY REMARKSAs mentioned before, micronutrients, includingvitamin supplements, are widely used in the generalpopulation and by athletes, and have a variety ofclinical applications. Similar to Part 39, we haveagain devoted an entire part of our A–Z series tovitamin supplementation—this time to vitamin D.Vitamin D was first discussed in our A–Z series inan earlier article on calcium and other bone healthnutrients in 20101. In Part 40, the topic of vitaminD has been discussed anew by our current authorin the context of more recent literature.

Vitamin DD E Larson-MeyerIt is well recognised that vitamin D plays an importantrole in calcium regulation and bone health. Emergingevidence, however, also suggests that vitamin D playsimportant roles in immune and inflammatory modu-lation and skeletal muscle function, and therefore hasthe potential to impact upon the health, training andperformance of athletes. This paper provides an over-view of the potential importance of vitamin D andvitamin D supplementation on the health andperformance of athletes, and offers guidelines forappropriate supplementation.

Vitamin D synthesis and sourcesAlthough vitamin D is thought of as a ‘’vitamin’,required amounts can be obtained entirely fromcutaneous synthesis via exposure to ultraviolet-B(UVB) radiation in sunlight.2 Cutaneous synthesisof vitamin D, however, is dependent on factorsincluding time of exposure, season, latitude, cloudcover, smog, skin pigmentation, sunscreen coverageand age. Vitamin D is not synthesised during thewinter at latitudes greater than 35–37° north orsouth because insufficient UVB photons reach theearth’s surface during these months.2 3

Vitamin D is also obtained in the diet fromlimited natural and fortified sources (table 1).Dietary vitamin D includes vitamin D3 (cholecalcif-erol, derived from animal sources) and vitamin D2

(ergocalciferol, derived from UVB exposure offungi and yeast ergosterols).2 Both forms arereadily absorbed (∼50% bioavailable), except inindividuals with malabsorptive disorders.4

Vitamin D status of athletesIt is well recognised that suboptimal vitamin Dstatus (see definitions, box 1) is widespread amongthe general population worldwide. Among athletes,the prevalence of deficiency varies by sport, train-ing location, skin colour and individual lifestyle

habits.7 For example, a high prevalence of vitaminD deficiency has been observed in gymnasts train-ing in East Germany8 and Finland,9 with 37–68%of these athletes having serum 25(OH)D concentra-tions under 10–15 ng/ml (25–37.5 nmol/l), and inMiddle Eastern sportsmen training in Qatar10 ofwhom 91% have serum 25(OH)D concentrationsunder 20 ng/ml (50 nmol/l), resulting in high ratesof deficiency. In contrast, a low prevalence of insuf-ficiency/deficiency and better overall status has beendocumented in college athletes training in a high-altitude region of the USA.11 The proportion ofathletes found to maintain optimal vitamin D statusis observed to be 15– 76% among some outdoor-training populations.11

Although the most probable reason for subopti-mal vitamin D status is limited (or insufficient)UVB exposure, poor vitamin D intake may contrib-ute. Studies7 12 13 have found that athletes do notmeet the recommended dietary allowance (RDA)for vitamin D of most countries (table 1).7 Onestudy found that only 5% of US college athletesconsumed the US RDA of 600 IU of vitamin Dfrom food alone.11

Vitamin D status and overall healthIncreasing evidence suggests that suboptimal vitaminD status is linked to increased risk for many chronicand autoimmune diseases including hypertension,diabetes, cardiovascular disease, osteoarthritis andcancer,2 and possibly also acute illnesses and injury.7

Poor vitamin D status and/or low dietary intake hasbeen linked to increased risk for stress fracture,13

upper-respiratory tract infection,11 14 elevated con-centrations of systemic inflammatory markers15 inathletes as well as delayed recovery following ortho-paedic surgery.16 Elevated systemic inflammatorymarkers may prove to be important in the develop-ment and progression of over-training syndrome and/or chronic injury. A few studies have found thatvitamin D supplementation and/or UVB exposureimproves these health outcomes. For example, infemale naval recruits an 8-week supplementationregimen of 800 IU vitamin D plus 2000 mg calciumreduced stress fracture incidence by 20% comparedwith placebo treatment.17 In non-athletic postmeno-pausal women, 1 year supplementation with 2000 IUvitamin D (as part of a randomised-control trialfor osteoporosis prevention) nearly abolished thereported incidence of colds and flu compared tocontrol.18 An older German treatment study foundthat UVB irradiation via a central sun lamp for6 weeks resulted in a reduction in chronic pain result-ing from sports injuries.19

118 Larson-Meyer DE, et al. Br J Sports Med 2013;47:118–120. doi:10.1136/bjsports-2012-091951

Nutritional supplement series

group.bmj.com on June 7, 2014 - Published by bjsm.bmj.comDownloaded from

Vitamin D status and athletic performanceMuscle pain and weakness are well-documented but frequentlyforgotten symptoms of severe vitamin D deficiency (table 1)improve with vitamin D repletion.2 Recent evidence fromanimal and in vitro studies are finding that vitamin D is import-ant for calcium handling across the sarcolemma and expressionof proteins involved in muscle contraction.16 Although pub-lished data on vitamin D status or vitamin D supplementationon muscle performance are not yet available in athletes, pro-vocative evidence from the Russian and German literature at theturn of the 20th century suggests that UVB exposure makes apositive impact upon athletic performance.7 These studies,however, did not simultaneously measure markers of vitamin Dstatus (which were not yet understood) and were also not con-ducted using the rigorous scientific standards employed today.Two recent studies involving non-athletic adolescent young

women found a positive correlative association between serum25(OH)D concentration and both aerobic fitness20 and jumpheight, velocity, and power.21 Because the majority of girls haddeficient status, the results imply that performance is impairedby suboptimal vitamin D status. A recent randomised trial foundthat supplementation with either 2000 or 5000 IU daily for3 months tended to improve muscle performance in non-athletic, middle aged men and women.22

Assessment and recommendations for supplementationVitamin D supplementation may benefit the health and per-formance of many athletes but should not be routinely recom-mended without assessment. Serum 25(OH)D concentration,the best indicator of vitamin D status,2 3 5 should first be evalu-ated along with anthropometric measurements (including bodyfat estimation), dietary intake and lifestyle and environmentalfactors that potentially impact status.7 Both body fat and bodysize are important to consider because they are inversely corre-lated with vitamin D status. This is due to either sequestration2 7

or volumetric dilution23 of ingested or cutaneously synthesisedvitamin D by the larger fat mass which increases supplementaldose in larger or fatter athletes.

Following assessment, recommendations for achieving/main-taining optimal vitamin D status can be tailored to the individ-ual athlete’s current serum 25(OH)D concentration, diet,lifestyle habits, belief system, lifestyle habits and, if present, clin-ical symptoms (table 1).7 Habitual exposure to arms, legs andback several times a week for 5 mins (for fair-skinned indivi-duals) to 30 mins (for darker-skinned individuals) at close tosolar noon without sunscreen2 usually leads to sufficient vitaminD synthesis in summer months.

Individuals with limited sun exposure require supplementationwith at least 1500–2000 IU/day vitamin D to keep 25(OH)Dconcentrations in the sufficient24 but not necessarily the optimalrange. Higher supplemental doses may be required in those withlittle sun exposure, regular sunscreen use, dark-pigmented skinand/or excess adiposity. Athletes who live or train at latitudesabove/below 35–37° north or south should supplement with atleast 600 IU/day during winter, rainy or cloudy seasons even ifthey maintain adequate stores during sunnier seasons. Regularconsumption of vitamin D-fortified foods is not likely to result insufficient status in the absence of UVB exposure.25

Although specific guidelines for supplemental vitamin D arenot yet established, a rule-of-thumb is to increase supplementalvitamin D by 1000 IU over 3–4 months for every 10 ng/ml eleva-tion in 25(OH)D desired.25 Thus, a ‘normal-weight’ athlete witha serum 25(OH)D concentration of 20 ng/ml would requirean additional 2000 IU daily to increase stores to 40 ng/ml in3–4 months. Higher doses than estimated, using thisrule-of-thumb, may be needed to improve status in some athletes,particularly when adipose stores are high or the starting serum25(OH)D concentration extremely low. Genetic differences alsoinfluence response to supplementation.26 Supplemental vitaminD can be taken either daily or as a larger bimonthly or monthlydose (ie, 50 000 IU/month ∼ 1667 IU/day).

To replenish stores more rapidly, athletes with deficient statusmay benefit from short-term, high-dose ‘loading’ regimens underthe supervision of a physician. Examples of high-dose regimensinclude 50 000 IU/week for 8–16 weeks or 10 000 IU/day forseveral weeks.2 25 While supplementation with either D3 and D2

are effective at doses of 1000 IU/day,27 D3 is recommended forhigher supplemental doses (50 000 IU) due to its greater potencyat raising and maintaining serum 25(OH)D concentrations.28

Athletes—who often believe more is better—should be cautioned

BOX 1 Reference values for serum 25 (OH)D

▸ Deficient: <20 ng/ml (50 nmol/l)▸ Insufficiency: <30 to 32 ng/ml (75–80 nmol/l)▸ Sufficient: ≥30 to 32 ng/ml (75–80 nmol/l)▸ Optimal: 40–70 ng/ml (100–175nmol/l)▸ Toxicity: >150 ng/ml (375 nmol/l)▸ Plus hypercalcaemiaNote: Definitive thresholds for vitamin D status have not beenscientifically established. The cut-off for deficiency is theapproximate concentration at which parathyroid hormonerises abruptly and the cut-off for insufficiency is theconcentration where parathyroid hormone plateaus andcalcium absorption is maximised.3 5 Some researchers arguethat the distinction between deficiency and insufficiency isnot useful or necessary but rather that maintenance ofoptimal stores, associated with preventable disease, shouldbe achieved.6

Table 1 Vitamin D: recommended dietary allowance, dietarysources, and signs and symptoms of deficiency and toxicity

Recommended DietaryAllowance(Adults*)

Australia & New Zealand: 200 IUNordic Countries: 300 IUUK: Exposure via sunlight, 400 IU for adults†USA and Canada: 600 IUWHO: 200 IU

Dietary Sources Fatty-fish (salmon, mackerel, sardines, tuna);irradiated mushrooms; fortified-milk; egg yolk; somebrands/types of margarine, yogurt, soy milk, fruitjuice and ready-to-eat cereal; egg yolks

Signs and Symptoms ofDeficiency

Elevated parathyroid concentration, decreased bonedensity; bone pain; increased bone fracture risk;muscle weakness and discomfort; atrophy of type IIfibers, abnormal growth in children(Note: Many symptoms of deficiency mimic those offibromyalgia and chronic fatigue syndrome.)

Signs and Symptoms ofToxicity

Elevated serum calcium; fatigue; constipation; backpain; forgetfulness; nausea; vomiting. Complicationsof prolonged elevated serum calcium include softtissue calcification, hypertension, and abnormalheart rhythm.

*Adult requirements generally include adults 18 or 19 years and older; requirementsare higher in most countries in adults older than 65–70 years.†These amounts are under review worldwide.

Larson-Meyer DE, et al. Br J Sports Med 2013;47:118–120. doi:10.1136/bjsports-2012-091951 119

Nutritional supplement series

group.bmj.com on June 7, 2014 - Published by bjsm.bmj.comDownloaded from

that daily supplementation with more than 10 000 IU could leadto toxicity (see table 1).

CONCLUSIONVitamin D plays an important role in a vast array of physiologicalfunctions that could negatively impact the health and performanceof athletes. Research suggests that certain athletes are at risk forsuboptimal vitamin D status, which may increase risk for stress frac-tures, acute illness, elevated inflammatory markers and impairedrecovery following orthopaedic injury. Given these findings,regular vitamin D supplementation may be beneficial for some, butnot all, athletes to help optimise health and athletic performance.

CONCLUDING COMMENTSIt is interesting to note that Vitamin D deficiency can producesome symptoms similar to those in chronic fatigue syndrome andfibromyalgia. There is still debate about the distinction betweendeficiency and insufficiency of Vitamin D. On the other hand, asdiscussed in this comprehensive article, taking high doses ofVitamin D supplementation exemplifies the situation in supple-mentation where more is not necessarily better (see table 1). It issuggested that supplementation with Vitamin D should be care-fully monitored, due to risk of toxicity if allowed to accumulateunchecked. While D3 is recommended for higher doses, it comesfrom sheep's wool lanolin and thus is not suitable for vegan ath-letes. There is good evidence in the literature that Vitamin D, inmoderate doses, may be helpful to some athletes. However, weconsider that it is again appropriate to remind athletes that theyshould seek the advice of a qualified sports nutritionist beforeembarking upon any course of nutritional supplements.

Competing interests None.

Provenance and peer review Commissioned; not externally peer reviewed.

REFERENCES1 Houtkooper L, Manore M. Calcium and bone health. Br J Sports Med 2010;44:389–91.2 Holick MF. Vitamin D deficiency. N Engl J Med 2007;357:266–81.3 Hollis BW. Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency:

implications for establishing a new effective dietary intake recommendation forvitamin D. J Nutr 2005;135:317–22.

4 Basu TK, Donaldson D. Intestinal absorption in health and disease: micronutrients.Best Pract Res Clin Gastroenterol 2003;17:957–79.

5 Zittermann A. Vitamin D in preventive medicine: are we ignoring the evidence? Br JNutr 2003;89:552–72.

6 Heaney RP. Assessing vitamin D status. Curr Opin Clin Nutr Metab Care 2011;14:440–4.7 Larson-Meyer DE, Willis KS. Vitamin D and athletes. Curr Sports Med Rep

2010;9:220–6.

8 Bannert N, Starke I, Mohnike K, et al. (Parameters of mineralmetabolism in children and adolescents in athletic training). Kinderarztl Prax1991;59:153–6.

9 Lehtonen-Veromaa M, Mottonen T, Irjala K, et al. Vitamin D intake is low andhypovitaminosis D common in healthy 9- to 15-year-old Finnish girls. Eur J ClinNutr 1999;53:746–51.

10 Hamilton B, Grantham J, Racinais S, et al. Vitamin D deficiency is endemic inMiddle Eastern sportsmen. Public Health Nutr 2010;15:1–7.

11 Halliday T, Peterson N, Thomas J, et al. Vitamin D status relative to diet, lifestyle,injury and illness in college athletes. Med Sci Sports Exerc 2011;42:335–43.

12 Helle C, Bjerkan K. Vitamin D status blant norske toppidrettsutøvere-OG Faktorer AVBetydning for vitamin D-status. Idrettsmedisinsk Høstkongress 2011:38

13 Sonneville KR, Gordon CM, Kocher MS, et al. Vitamin D, calcium, and dairy intakesand stress fractures among female adolescents. Arch Pediatr Adolesc Med.Published Online First: 5 Mar 2012 doi:10.1001/archpediatrics.2012.5.

14 Laaksi I, Ruohola JP, Tuohimaa P, et al. An association of serum vitamin Dconcentrations &lt; 40 nmol/L with acute respiratory tract infection in young Finnishmen. Am J Clin Nutr 2007;86:714–17.

15 Willis KS, Smith DT, Broughton KS, et al. Vitamin D status and biomarkers ofinflammation in runners. Open Access J Sports Med 2012;3:35–42.

16 Barker T, Martins TB, Hill HR, et al. Low Vitamin D impairs strength recovery afteranterior cruciate ligament surgery. JEBCAM 2011;16:201–9.

17 Lappe J, Cullen D, Haynatzki G, et al. Calcium and vitamin D supplementationdecreases incidence of stress fractures in female navy recruits. J Bone Miner Res2008;23:741–9.

18 Aloia JF, Li-Ng M. Re: epidemic influenza and vitamin D. Epidemiol Infect2007;135:1095–6; author reply 1097-8.

19 Spellerberg AE. Increase of athletic effectiveness by systematic ultraviolet irradiation.Strahlentherapie 1952;88:567–70.

20 Foo LH, Zhang Q, Zhu K, et al. Relationship between vitamin D status, bodycomposition and physical exercise of adolescent girls in Beijing. Osteoporos Int2009;20:417–25.

21 Ward KA, Das G, Berry JL, et al. Vitamin D status and muscle function inpost-menarchal adolescent girls. J Clin Endocrinol Metab 2009;94:559–63.

22 Diamond T, Wong YK, Golombick T. Effect of oral cholecalciferol 2,000 versus5,000 IU on serum vitamin D, PTH, bone and muscle strength in patients withvitamin D deficiency. Osteoporos Int. Published Online First: 16 Mar 2012.doi:10.1007/s00198-012-1944-7.

23 Drincic AT, Armas LA, Van Diest EE, et al. Volumetric dilution, rather thansequestration best explains the low vitamin D status of obesity. Obesity (SilverSpring) 2012;20:1444–8.

24 Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, andprevention of vitamin D deficiency: an Endocrine Society Clinical Practice Guideline.J Clin Endocrinol Metab 2011;96:1911–30.

25 Cannell JJ, Hollis BW. Use of vitamin D in clinical practice. Altern Med Rev.2008;13:6–20.

26 Fu L, Yun F, Oczak M, et al. Common genetic variants of the vitamin D bindingprotein (DBP) predict differences in response of serum 25-hydroxyvitamin D (25(OH)D) to vitamin D supplementation. Clin Biochem 2009;42:1174–7.

27 Holick MF, Biancuzzo RM, Chen TC, et al. Vitamin D2 is as effective as vitamin D3in maintaining circulating concentrations of 25-hydroxyvitamin D. J Clin EndocrinolMetab 2008;93:677–81.

28 Heaney RP, Recker RR, Grote J, et al. Vitamin D(3) is more potent than vitamin D(2)in humans. J Clin Endocrinol Metab 2011;96:E447–52.

120 Larson-Meyer DE, et al. Br J Sports Med 2013;47:118–120. doi:10.1136/bjsports-2012-091951

Nutritional supplement series

group.bmj.com on June 7, 2014 - Published by bjsm.bmj.comDownloaded from

doi: 10.1136/bjsports-2012-091951 2013 47: 118-120Br J Sports Med

 D E Larson-Meyer, L M Burke, S J Stear, et al. Part 40ergogenic aids for health and performance:supplements, sports nutrition foods and

Z of nutritional supplements: dietary−A

http://bjsm.bmj.com/content/47/2/118.full.htmlUpdated information and services can be found at:

These include:

References http://bjsm.bmj.com/content/47/2/118.full.html#ref-list-1

This article cites 25 articles, 3 of which can be accessed free at:

serviceEmail alerting

the box at the top right corner of the online article.Receive free email alerts when new articles cite this article. Sign up in

CollectionsTopic

(37 articles)Gymnastics   � Articles on similar topics can be found in the following collections

Notes

http://group.bmj.com/group/rights-licensing/permissionsTo request permissions go to:

http://journals.bmj.com/cgi/reprintformTo order reprints go to:

http://group.bmj.com/subscribe/To subscribe to BMJ go to:

group.bmj.com on June 7, 2014 - Published by bjsm.bmj.comDownloaded from