Renee McGregor, Registered Sports Nutritionist February 06, 2015

Vitamin D is made in our bodies from sunlight. However, those who live in countries where sunlight might be limited, those who spend little time outdoors; including athletes that do a high volume of their training indoors, those who cover up with high-factor sunscreen and those who are darker-skinned, may actually be at risk of a vitamin D deficiency. A vitamin D deficiency can lead to several health issues such as:

  1. Chronic fatigue
  2. Depression
  3. Increased risk of bone injury
  4. Chronic musculoskeletal pain
  5. Viral respiratory tract infections

There also seems to be strong emerging evidence that supplementing an athlete who has sub-optimal levels of vitamin D with up to 4,000 IU vitamin D3 (the form of vitamin D that is made naturally in the body) has real benefits to performance, particularly in strength, power, reaction time and balance.

Presently there is no universally accepted definition for vitamin D but the following classifications from blood test levels are often cited:

  1. When blood levels are below 50nmol/L – deficiency
  2. When blood levels are below 75nmol/L – insufficient levels
  3. Levels between 75–120nmol/L – ideal range

It is not possible to meet your Vitamin D requirements through food alone but small amounts of vitamin D can be found in the following foods:

  1. Oily fish
  2. Egg yolks
  3. Fortified foods such as milk, margarine, cereals

Vitamin D supplements are readily available but if you are an athlete, always make sure that you buy from a reputable source. The most recent guidelines (Jan 2015) produced by UKAD, the UK anti-doping agency, have introduced higher sanctions for those that fail a drugs test. It is important to note that these new sanctions can be applicable to both athletes and in some cases practitioners or support staff as well. It is essential that any supplement, including vitamins and minerals should be batch tested and preferably independently accredited under the Informed Sport program. Although this does not guarantee that a product is safe completely it does provide athletes with highest level of assurance available. If an athlete can show proof that have only taken products accredited by Informed-Sport, it demonstrates that they have not purposefully gone looking for performance enhancing aids.

Renee McGregor is a registered sports dietician/nutritionist working with a variety of athletes from elite GB/commonwealth Marathon runners, England Netball pathway athletes to junior tennis academy players. Renee is also the author of “Training Food: Get the fuel you need to achieve your goals before, during and after exercise” and contributes to a number of national publications such as trail running, cycling plus and outdoor fitness. She also continues her clinical work in the area of eating disorders and is the lead nutritional advisor to the national eating disorders charity, Anorexia and Bulimia Care.



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