Vitamin D and Athletes

What is Vitamin D? Here is some background information: 

• Fat soluble vitamin meaning that the body stores excess amounts for later use opposed to water soluble vitamins which get flushed out through the system
• Functionally it acts as a hormone with a similar structure as steroid hormones 
• Known to be important for optimal muscle function as well as playing an important role in bone growth and repair, cell functioning, neuromuscular immune functioning and the management of inflammation. 
• It is produced in the body when your skin is exposed to sunlight 
• Not “just a vitamin”, but rather the only known substrate producing multiple effects related to functions in the body. 
• Important to ensure adequate intake of calcium and vitamin D together to ensure bone health 
• Vitamin D is needed for absorption of calcium

Why is it important to athletes specifically? 

• Vitamin D has been shown to improve athletic performance (International Medicine & Science in Sports & Exercise, 2009) 
• A related finding noted that peak athletic performance occurs during summer sun exposure when your body produces the most Vitamin D 
• Been shown to increase the size and percentage of “fast twitch” muscle fibers playing a huge role in generating quick bursts of speed and power
• Supplementing vitamin D in athletes with sub-optimal levels may have beneficial effects on athletic performance in particular strength, power, reaction time and balance (AIS) 
• A deficiency can lead to several health issues including increased risk of bone injuries, chronic musculoskeletal pain and viral respiratory tract infections 
• Deficient athletes tend to have a higher incidence of stress fractures according to the Cleveland Clinic

References 
1) Australian Institute of Sport (AIS) – “Fuelling your success – Vitamin D” 
2) Institute of Medicine, 2010 
3) Medicine & Science in Sports & Exercise: Athletic Performance & Vitamin D (John Cannell, 2009) May 2009 - Volume 41 - Issue 5 - pp 1102-1110 
4) International Journal of Sport Nutrition & Exercise Metabolism; “Should We be Concerned About the Vitamin D Status of Athletes?” K.S. Willis et al.; 2008 5) Cleveland Clinic –“ Vitamin D deficiency Hazardous to Athletes’ Health & Performance”

Guest Blogger: Liz Wray, USD Dietetic Intern