Vitamin D Deficiencies in Cyclists

It is automatically assumed that as outdoor athletes, most cyclists don't need to be concerned with low levels of vitamin D. This couldn't be further from the truth.

Recently one of the athletes I coach who lives and trains in sunny Las Vegas tested deficient for vitamin D. But how could this be? Cyclists are outside in the sun more often than most, but this alone doesn't make you immune to low levels of vitamin D. In fact, vitamin D deficiency is widespread among athletes in general.

For cyclists in training, vitamin D impacts skeletal muscle protein synthesis, inflammation, recovery, immune system health and bone-density maintenance. In order to determine whether or not you need to supplement with vitamin D, you'll need to have a blood test that measures the circulating form of vitamin D. This is referred to as serum 25 (or serum 25-hydroxyvitamin D).

More: Are You Getting Enough Vitamin D?

For athletes training and racing, the U.S. RDA guideline suggests a serum between 25- to 30-hydroxyvitamin D concentration. Fortunately, if you're one of the many cyclists low in vitamin D serum levels, there are ways to boost production that will make you healthier and help you improve your performance on the bike.

Ways to Increase Serum Vitamin D

In order to receive the amount of vitamin D that your body needs to function properly, you should get your requirements through a combination of:

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

More: What is Vitamin D?

Diet

To increase serum levels through your diet, the following are foods highest in vitamin D:

• Cod liver oil
• Wild salmon
• Sun-dried shitake mushrooms
• Canned sardines
• Farmed salmon

More: Protecting Against Bone-Density Loss

Supplementation

The recommended level for vitamin D maintenance is 2,000 vitamin D IU per day. The good news is that this supplement is relatively inexpensive and can be purchased for less than two dollars per month (Now Foods Vitamins is one option).

Consider supplementing unless you a health condition that predisposes you to one of the following conditions:

• Hypercalcemia (high calcium in the blood)
• Hyperparathyroidism
• Granulomatous disease
• Sarcoidosis
• Lyme disease
• Lymphoma
• Kidney disease or are taking the diuretic known as hydrochlorothiazide (HCTZ), a "water pill" used to treat high blood pressure and fluid retention caused by a range of conditions, including heart disease.

More: 6 Bone-Strengthening Exercises for Cyclists

Sunshine

The average healthy body synthesizes 10,000 to 15,000 IU of vitamin D3 in the skin within minutes of sun exposure without ill effect. We have a natural system of checks and balances within the body that shut off vitamin D buildup once we get enough. The half-life of 25 (OH) D is 15 days. This means that sun exposure once every 3 to 4 days is adequate.

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

Since most cyclists are in the sun for much longer periods of time than this, the following list may be one of the causes for a vitamin D deficiency:

• Train indoors or outdoors in a clouded or polluted environment.
• Live at latitudes greater than 35 degrees north between the middle of October and the middle of February.
• Wear sunscreen or protective clothing regularly.
• Have dark or very light pigmented skin.
• Have excess body fat.
• Have a malabsorption disorder.
• Are genetically predisposed.

More: Why Cyclists Should Wear Sunglasses

Other Factors

Showering and bathing habits also impact Vitamin D levels. This is a quirky piece of information, but it does make sense: showering, swimming or getting in a hot tub immediately after sun exposure may promote the loss of the newly synthesized vitamin D due to sloughing off of the top layer of skin. This is a likely cause of for many cyclists who are deficient in vitamin D despite plenty of sun exposure.

The recommendation is to postpone bathing for three hours post sun exposure. If this is not an option, you may want to begin use of supplements or dietary changes to meet your needs.

Conclusion

Vitamin D plays a crucial role in our everyday health. For cyclists, it is important not to neglect our vitamin D requirements. More stress is placed on the body during training, and a deficiency could affect immune system health and performance on the bike. Here's a summary of what you should keep in mind as an athlete:

• Low vitamin D can increase the risk for low bone density, stress fractures, acute illness, injury and suboptimal muscle performance.
• It's important to have your vitamin D tested for deficiencies before it becomes problematic.
• While a serum level of 25 to 30 is needed, a concentration of over 40 is preferable.
• A serum level of 25 can be maintained by safe sun exposure or supplementation.
• Supplementation is needed for all athletes during the winter if you live at latitudes greater than 35-degrees north.
• Athletes with a history of frequent illness, bone and joint injury, muscle pain or overtraining may benefit from a vitamin D assessment.
• The best way to stay healthy and give your body the amount of vitamin D needed to function properly is through a combination of safe sun exposure, diet and supplementation.

More: What I Learned When I Got Skin Cancer