Vitamin D: What’s All the Fuss?


Calling all athletes — and coaches, physical therapists, sports trainers, and sports health physicians who work with them! Here’s a review on the essentials of Vitamin D you won’t want to miss.

Most likely by now, you have heard something about the perils of low vitamin D. Without it, we can suffer low bone mass, decreased immune function, and altered physical performance. Any of those (and especially all in combination) can pose serious problems for athletes.

For example, bone fractures and muscle injuries associated with low vitamin D can sideline athletes for an entire season. Frequent colds, flus, and other more serious illnesses from a compromised immune system can lead to days without practice and poor performance. The athlete may not miss a day but still isn’t at the “top of their game” so-to-speak.

In this article, medical staff at the Hospital for Special Surgery in New York City answer the following questions: Who is at risk? Why? And what can be done about it? The biggest known risk factors are limited sun exposure (based on where athletes live), the use of sunscreen, and athletes with dark skin pigmentation.

To elaborate just a bit, these factors limit the skin’s absorption of ultraviolent B (UVB) rays from the sun needed for vitamin D production in the body. Living, practicing and playing indoors (especially in the northern latitudes) is a direct cause of low UVB radiation. But living in a sunny climate may be thwarted by the increased use of sunscreen products. We use these to keep UVB rays from contributing to skin cancer.

Before anything can be done about low vitamin D, it is essential to know what your vitamin D levels are. This can be done with a simple blood test. But that’s where simplicity ends because experts say there is no clearly known optimal level of vitamin D to shoot for. Right now, the various levels are determined by measuring total serum 25-hydroxyvitamin D (25(OH)D3) and defined as:

Deficient: 25(OH)D3 is less than 20 ng/mL
Insufficient: level is 20 to 31 ng/mL
Intoxication: blood levels are higher than 150 ng/mL
Sufficient: at least 30 ng/mL up to 50 ng/mL

Having “sufficient” blood levels of vitamin D means the body can absorb calcium from our diet to keep bones healthy. And sufficient levels prevent the cascade of biologic events that occur in the body when vitamin D drops too low. For athletes, the end-result is protection from stress fractures, bone fractures, and soft tissue injuries of muscles, tendons, and ligaments.

How do we really know athletes are at risk? Maybe they are young enough and healthy enough to be just fine. Well, we do know because blood tests taken in preparation for surgery to treat sports injuries show that more than half of the athletes tested were vitamin D insufficient. One-third of that group wasn’t just vitamin D insufficient — they were in the deficient zone. And maybe that’s why they injured themselves in the first place.

Several individual studies of National Football League players also showed lower levels of vitamin D (if not insufficient levels) among players with muscle injuries. And a study of elite Australian gymnasts came up with the same findings.

How can this problem be addressed? First, prevention should be dealt with through diet and appropriate sunlight exposure and careful use of sunscreen. Vitamin D supplementation through over-the-counter products can be used for some individuals. Others will need prescription strength capsules. All vitamin D supplementation should be done with the guidance of a physician as doses must be adjusted based on blood work.

In summary, although this article is focused on the effects of low Vitamin D on athletes, this is a problem that can (and does) affect people of all ages from young to old. The authors recommend a blood test to determine levels of total serum 25(OH)D3 for high-risk athletes (or others at risk).

Treatment should be applied to those individuals with low (insufficient or deficient) vitamin D. Taking large (supraphysiologic) doses of Vitamin D supplements is NOT recommended as a way to enhance athletic performance. There are an equal number of studies that show higher levels of vitamin D could lead to kidney (and other tissue) damage.