I recently took a Vitamin D guidelines for athletes class from Enette Larson-Meyer PhD, RD, CSSD, FACSM highlighting the importance of Vitamin D for athletes. We automatically assume, as outdoor athletes we don’t have to be concerned with our Vitamin D status, but that is not the case. Recently one of my athletes living and training in sunny Las Vegas tested deficient for Vitamin D.

Vitamin D deficiency is widespread in athletes. Increasing your serum Vitamin D may make you faster and will most likely make you healthier. There are two ways to do this (1) Safe sun exposure and (2) Supplementation.

Vitamin D is of particular interest to athletes in training. Vitamin D impacts skeletal muscle protein synthesis, inflammation, recovery, immune system health and bone density maintenance.

What test? It is important for athletes to assess their Vitamin D status. You want to ask for the test that measures the circulating form of vitamin D. This is referred to as serum 25[OH]D, or serum 25-hydroxyvitamin D.

Athletes should maintain at least a serum 25-hydroxyvitamin D concentration >30 ng/mL and >40 ng/mL may be preferable. US RDA guideline of >20ng/ml is not enough for athletes in training and racing.

Serum Vitamin D can be increased in three ways:

1. Diet
2. Supplementation
3. Synthesized by the skin following safe sun exposure

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Diet:

Top dietary sources are cod liver oil, wild salmon, sun-dried shitake mushrooms, canned sardines, farmed salmon.

Supplementation:

The recommended level for Vitamin D maintenance is 2,000 Vitamin D IU/day. It is cheap too, NOW Foods Vitamin D-3, 2,000 IU/day costs two dollars per month. Consider supplementing unless you have any health condition that predisposes you to high calcium in the blood (hypercalcemia), hyperparathyroidism, granulomatous disease, sarcoidosis, Lyme disease, lymphoma, kidney disease or are taking the diuretic known as hydrochlorothiazide (HCTZ), a “water pill” drug used to treat high blood pressure and fluid retention caused by a range of conditions, including heart disease.

Sunshine:

The average healthy body can naturally synthesize about 10,000–15,000 IU of vitamin D3 in the skin within just minutes of sun exposure, without ill effect. We have natural checks and balances that shut off vitamin D build-up once we get enough. The half-life of 25(OH)D is 15 days so safe sun exposure once every 3-4 days is adequate.

Safe sun exposure recommendations are to expose arms, legs and back for 5-30 minutes at close to solar noon twice weekly without sunscreen. Never stay in the sun unprotected long enough to get burned.

You might not be getting enough sunshine to synthesize your own Vitamin D if you:

• Train indoors or outdoors in clouded or polluted environments
• Live at latitudes greater than 35 degrees north between mid-Oct and mid-February.
• Wear sunscreen or protective clothing regularly.
• Have dark or very light pigmented skin.
• Have Excess body fat.
• Have a malabsorption disorder, take certain medications and have specific genetics.

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Quirky Tip

Showering and bathing habits may impact Vitamin D status! This is a quirky piece of information I find amusing but makes sense; showering, swimming or hot tubbing immediately after sun exposure may promote the loss of the newly synthesized vitamin D due to sloughing off of the top layer of skin. The recommendation is to postpone bathing for 3 hours post sunshine exposure. Or in other words, stay stinky after your ride for a few hours! This should make your inner 10-year-old happy 😉

Treatment for deficiency

Athletes deficient in serum 25-hydroxyvitamin D should use a combination of light (artificial UVB or sunshine), diet  and supplementation (D3 cholecalciferol) to increase their status to ideal.

Safe sun exposure recommendations are to expose arms, legs and back for 5-30 minutes at close to solar noon twice weekly without sunscreen. Never stay in the sun unprotected long enough to get burned.

Supplementation recommendation is  50,000 IU/week (1250 μg/week; vitamin D2 or D3) for at least 8 weeks to achieve a serum concentration of 25(OH)D >30to 32 ng/mL followed by maintenance therapy of 1500-2000 IU/day

Biological Functions of Vitamin D

Vitamin D modulates the expression of over 1,000 genes and is important in bone health, skeletal muscle function, inflammation and immunity.

Immunity: Studies show soldiers and athletes with higher serum Vit D are less likely to develop respiratory illnesses.

Inflammation: Vitamin D up-regulates production of anti-inflammatory cytokines. NFL players with low Vitamin D serum levels were more likely to sustain muscle injuries.

Skeletal muscle function: Vitamin D is involved in protein synthesis

Recovery and Rehab:  Vitamin D is important for recovery. Stroke patients supplemented with 1000 IU vitamin D/day improved muscle strength and increased the relative number and size of their type II muscle fibers.

Bone density: Vitamin D enhances calcium absorption in the intestine and promotes resorption in the kidneys. Vitamin D status has been correlated with bone mineral density.

Here are the Conclusions and Implications Enette Larson-Meyer closed her seminar with.

• Low vitamin D status linked to increased risk for low bone density, stress fracture, acute illness, injury and sub-optimal muscle performance.
• Important to have vitamin D status tested and treat vitamin D insufficiency and deficiency.
• While a serum 25(OH)D concentration of at least 30 ng/mL should be maintained, concentration of at least higher than 40 ng/mL may be preferable.
• 25(OH)D concentration may be maintained by safe sun exposure or vitamin D supplementation (1200-1500 IU/day).
• Vitamin D supplementation, however, is needed in Winter for all athletes living at > 35 N (or S)
• Athletes with history of frequent illness, bone and joint injury, muscle pain or over-training may benefit from assessment of vitamin D status.

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By Lynda Wallenfels Google+