Sports Health.2012 Nov; 4(6): 496–501.

Sports Health Benefits of Vitamin D

Franklin D. Shuler, MD, PhD,^*† Matthew K. Wingate, MD,^† G. Hunter Moore, BS,^‡ and Charles Giangarra, MD^†

Abstract

Vitamin D is a necessary nutrient that must be obtained from the diet when sufficient quantities cannot be synthesized. Vitamin D₃ is primarily produced following incidental skin exposure to ultraviolet B irradiation, with very little derived from dietary sources (Figure 1).⁴⁰ Cutaneous production can be absent or dramatically reduced due to skin coloration and sunblock use.²^,⁴⁰ Melanin in the skin of Africans or African Americans blocks nearly 99% of vitamin D production, with similar decreases in cutaneous synthesis achieved following application of SPF 15 sunblock.²^,⁴⁰ Indoor activities, pollution, time of day, increasing age, latitude, and seasonal changes all affect cutaneous vitamin D production.⁴⁰ As mentioned, very little vitamin D is obtained from dietary sources, including D₂ (ergocalciferol, plant) and D₃ (cholecalciferol, human) forms. Of note, vitamin D₃ is more potent than D₂ and should be used for supplementation.³^,⁶⁸ Unfortunately, the average American diet supplies very little of the 4000 to 5000 IU of vitamin D₃ used per day, even diets with significant amounts of wild-caught fatty fish.¹⁸^,³⁶^,⁴⁰^,⁵⁴ The accepted definition of vitamin D sufficiency is 25-hydroxyvitamin D₃, (25(OH)D) above 30 ng/mL.²¹^,³³^,⁴³^,⁴⁴ Based on this definition, vitamin D deficiency affects all age groups and demographics. Fifty to seventy percent of children and adolescents are vitamin D deficient.²¹^,⁴⁶ Over 75% of whites and 90% of African Americans and Latinos are vitamin D deficient, with increasing age increasing the likelihood of deficiency.¹⁰^,²⁷^,⁷⁶ In addition, deficiency rates have doubled from 1994 to 2004 with multiple factors responsible, including sun avoidance, sunblock use, and increasing obesity rates causing sequestration of this fat-soluble vitamin.²⁷^,⁵¹^,⁷⁵ Vitamin D deficiency is associated with numerous health effects, with the musculoskeletal system affected by both genomic and nongenomic mechanisms.