Vitamin D and Athletic Performance

Vitamin D has been talked about quite a lot in the past several years. Most commonly it comes up when talking about bone health. However, Vitamin D does have many other functions besides bone health, including sports performance. So, let’s break it down:

• Vitamin D is a fat soluble vitamin that is also a hormone.
• There are two main forms of Vitamin D: D2 (ergocalciferol) which is the inactive form and D3 (cholecalciferol) which is the active form.

• People get Vitamin D mainly from exposure to the sun or ultraviolet B (UVB).
• The recommendation for sun exposure is 5 -30 minutes per day between the hours of 10am -3pm. Age, skin tone, location and what season it is may change sun exposure required. Therefore, people that train inside, partake in winter sports and live in northern latitudes might be more lacking in exposure.
• Vitamin D is also found in certain foods including: fatty fish (salmon, sardines, mackerel, etc.), dairy products and fortified foods and beverages. However, it’s fairly difficult to reach the recommended daily allowance (RDA) with food alone (the RDA is 400-800 IU/day).

• Vitamin D has been shown to play a role in prevention of: cancer, heart disease, autoimmune disease, infection, diabetes and bone disease (including fractures and stress fractures).
• In addition, Vitamin D plays a role in muscle strength, muscle mass, muscle function, balance control, endurance, speed, reaction time and inflammation.
 • Interestingly enough, more than 77% of Americans are Vitamin D deficient which probably includes athletes.
 • Deficiency may cause muscle injuries, stress fractures and respiratory infections. Therefore, it is very important to check what our Vitamin D levels are.

 • Vitamin D is tested by taking a blood sample of 25(OH)D.
 • Deficiency is defined as < 20 ng/dL of 25(OH)D, insufficient is 20.1-29.9 ng/dL and sufficient is > 30 ng/dL. However, it seems that the optimal level for athletes is higher at 40- 50 ng/dL. There is no apparent benefit of having levels higher than 50 ng/dL.
 • Supplementation of Vitamin D is recommended in case of deficiency. To know exactly how much, consult with your physician and registered dietitian.

 So, since summer is just around the corner, make sure you play outside and get at least 10-15 minutes of sun exposure during the peak hours with no sun screen to get some good quality Vitamin D. And don’t forget to apply sun screen, if you are going to be outside for a long time. In addition, make sure you eat high sources of Vitamin D including fish, dairy products and fortified foods and beverages. You can get your Vitamin D level tested and consult with a professional for further guidance.

Written by: Noaa Bujanover - MS, RD, CSP, LD/N, CSCS