Vitamin D and Athletes

Even Swimmers In a Training Program May Need Vitamin D

By Erin Kelley, MS, RD

Since the 1920s, vitamin D was thought to only be necessary for preventing rickets (a bone disease), but recently has become widely popular. In the last few years, scientists and health professionals got a wake-up call when learning that this long-forgotten vitamin had so many beneficial effects on health—ranging from cancer to diabetes to fighting the flu. Even the government officially raised its recommended daily intake levels in 2010, due to the attention and scientific support.

Roughly 75% of Americans have insufficient or deficient vitamin D levels. This is due in part to our modern lifestyle of wearing clothes, being indoors, and wearing sunblock. Athletes typically do not meet the required dietary intakes. Here’s a look at how vitamin D may affect athletes:

Vitamin D improves athletic performance

Vitamin D is produced in the body when exposed to UVB rays from the sun. Studies done decades ago in both Russia and Germany suggest that use of sunlamps (lamps which give off UVB rays, thereby producing vitamin D in the body) improved muscle strength in world-class athletes. In one of the studies, one group of sprinters was exposed to the sunlamps; the other group was not. Both underwent the same training for the 100-meter dash. Those without the sunlamps had low sprint times. The runners exposed to sunlamps actually improved their sprint time by 7.4 percent!
Another study testing vertical jumping ability done in 2009 showed that adolescent athletes with the lowest levels of vitamin D weren’t able to jump as high as those with higher blood levels. Finally, observational studies show athlete’s peak performance is in late summer, when they’ve had enough time to store vitamin D from the sun. Performance (measured by maximal oxygen uptake) tended to decline as the winter grew near—even though training remained the same.

Vitamin D improves muscle strength and recovery

Vitamin D helps muscle fibers to develop and grow normally, and it affects the size and number of fast-twitch muscle fibers. Research shows muscle strength improves when those who are deficient in vitamin D attain normal vitamin D levels.

What’s more, low vitamin D levels are associated with higher inflammation and inflammatory disease risk. Inflammation is a normal part of exercise and training—and as a result, compounds in the body called “cytokines” are produced. Vitamin D reduces cytokine production, thereby allowing the body to recover quicker between heavy training.

Vitamin D improves bone health

Vitamin D promotes calcium absorption and maintains bone mineral density—in other words, it keeps bones strong. Strong bones mean less risk for developing stress fractures, which can sideline athletes. This is especially important for swimmers who may not get as much impact-exercise as say, runners do.

Vitamin D improves immune health

A study published in the Archives of Internal Medicine in 2009 looked at nearly 19,000 Americans and found that those with the lowest levels of vitamin D in their blood were more likely to suffer from the cold/flu virus.

Optimizing your performance

Peak athletic performance is estimated to occur when vitamin D levels in the blood are between >32-50 ng/mL. Food sources include fish (4 oz. canned salmon or tuna provides roughly 600 IU vitamin D), fortified milk and other fortified foods. A word of caution: taking more than 5,000 IU per day may worsen athletic performance. Besides, the Institute of Medicine’s upper limit is set at 4,000 IU per day. Getting a blood test done at the doctor’s office is the only way to know what your vitamin D level is.

If your swimming training program is indoors and you use sunscreen for times that you’re outside, it may be a good idea to get your vitamin D level checked.

Did you know?

  • Sunscreen with SPF 8 or higher completely blocks UVB rays, which prevents vitamin D production in the body
  • It is nearly impossible to get too much vitamin D from the sun, since vitamin D production in the body stops when the body senses it has enough
  • Individuals with dark skin have a lower ability to produce vitamin D from the sun
  • Fish is one of the few food sources of vitamin D. Dietary supplements are a convenient way to obtain the nutrient
  • Vitamin D3 is more bioavailable than vitamin D2. If using supplements, look for the D3 form
  • The RDA for vitamin D is 600 IU for most adults and children over age 1

Erin Kelley, MS, RD is a registered dietitian and member of the Academy of Nutrition and Dietetics.

4 Responses to Vitamin D and Athletes

  1. Goran Olson

    The by far most efficient and the only natural source of vitamin D is UVB rays (297 nm wavelength is the peak for vitamin D creation).
    We can get UVB rays from the sun (but only when it is higher than 50 degrees above the horizon and when there are no clouds) and from the lamps in a tanning bed.30 minutes of sunshine, when the conditions are right, gives between 10,000-15,000 IU (depending on your skin-type).10 minutes in a tanning bed with low-pressure lamps and a UVB percentage of 6-8% (according to the definition in North-America) gives you the same amount (shorter time because you expose more skin).Taking into account that we do not want the aging UVA -rays (that always comes with the UVB and that makes your skin darker), tanning beds seems to be a better alternative than sunlight. It is definitely more controllable.
    It is therefore no surprise that athletes are using tanning beds as an essential part of their training.

    Manchester United and Liverpool FC, are, for example two soccer teams in the UK that regularly put their players in tanning beds for better performance.

    They use special UV-lamps that are high in UVB and low in UVA.

    Here is and article about just that … 

  2. Henry Lahore

    Vitamin D has been helping athletes a lot since the 1930’s.
    Especially for those with indoor sports
    There is an overview of vitamin D and sports, which has the following summary:
    – Faster reaction time- Far fewer colds/flues during the winter- Less sore/tired after a workout- Fewer micro-cracks and broken bones- Bones which do break heal much more quickly- Increased VO2 and exercise endurance Feb 2011 

  3. Nlmachinist

      Two additional benefits of Viamin D.

    1. Stimulation of the pineal gland  which mediates melatonin production important especially when athletes change time zones
    2. Lite therapy -UV Lamps- which also stimulates Vitamin D production has the added benefit of being a tremendous therapy for mood disorders particularly SAD- seasonal affective disorder. Researcg documents that for many people lite therapy is far more affective than most psychiatric medication.

  4. Jimmy007UK

    What about the risk of skin cancer?


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