Efficacy of high dose vitamin D supplements for elite athletes
Owens DJ, Tang CY, Bradley WJ, Sparks A, Fraser WD, Morton JP, and Close GL. Med Sci Sports Exerc. 2016. [Epub Ahead of Print].
Take Home Message: A Blanket high dose vitamin D supplement plan results in elevated levels of vitamin D metabolites after the supplementation is completed. This could result in lower than normal levels of vitamin D, which is the opposite effect of the intended supplementation.
Vitamin D is a necessary nutrient in all individuals, especially the physically active population, and has been shown to be influential in muscle development and repair among other benefits. Many athletes consume large supplemental doses of vitamin D for these reasons; however, the long-term effects of this are not well understood. Therefore, Owens and colleagues completed a repeated measures study with 42 elite male athletes to identify the responses of the body to both a moderate and high dose of supplemental vitamin D. None of the athletes reported currently taking a vitamin D supplement, using tanning beds, or were injured. Athletes were randomized into one of two groups. The moderate consumption group received 35,000 international units (IU) of vitamin D3 per week, and the high consumption group received 70,000 IU per week. These doses are the most prominently prescribed doses for elite athletes. All included athletes continued the supplementation plan for 12 weeks during which time they had minimal exposure to sunlight. Quantities of vitamin D metabolites, which break down vitamin D, were measured via blood samples taken at baseline, 6, 12, and 18 weeks from the start of supplementation. Overall, serum levels of vitamin D3 for both groups increased significantly during the supplementation period. Metabolite levels were also elevated during the supplementation period; however, upon cessation of supplementation, the levels of metabolites in the moderate treatment group returned to baseline, while levels in the high supplementation group had elevated levels of vitamin D3 metabolites.
The authors’ results are important for clinicians as elevated levels of metabolites after the cessation of supplementation indicate that metabolites continue to metabolize vitamin D3 at an elevated rate despite intake levels returning to normal. If levels of D3 metabolites are elevated while D3 intake levels are stable this could result in the opposite effect of the intended supplementation such as bone pain, muscle weakness, and elevated blood pressure. These results suggest that clinicians may not wish to suggest blanket vitamin D3 supplementation programs, but rather, may wish to consult with a physician for more individualize treatment. Future research should further investigate how high-dose supplementation of vitamin D3 impacts long-term metabolite levels for a longer follow-up period as well as how these metabolite levels compare to more individualized treatment. Patient-reported outcome measures may also be useful in assessing how patients subjectively feel during the treatment period, which may also be useful to the development of clinical best practices. Until more research can be completed, clinicians who wish to supplement athletes with vitamin D3 should be cautious in their recommendations, and should consult with a registered dietitian and or a physician prior.
Questions for Discussion: Have you prescribed large-dose vitamin D supplement programs for your athletes? If so, what other collaboration did you have prior to and during supplementation?
Written by: Kyle Harris
Reviewed by: Jane McDevitt
National Athletic Trainers’ Association Position Statement: Evaluation of Dietary Supplements for Performance NutritionOwens DJ, Tang JC, Bradley WJ, Sparks SA, Fraser WD, Morton JP, & Close GL (2016). Efficacy of High Dose Vitamin D Supplements for Elite Athletes. Medicine and science in sports and exercise PMID: 27741217