The Athlete's Vitamin If you think you’re getting enough Vitamin D, think again.

When it comes to supplement recommendations for my pro athlete clients, I don’t have a one-size-fits-all approach. Which supplements you need, and in what amounts, can vary based on factors including your sex, age, diet, training regime, injury status, overall health and family history. That said, there are a few crucial nutrients I find myself recommending to nearly everyone, and vitamin D is currently at the top of the list. Even with a stellar diet, it’s difficult to obtain an adequate amount of this powerhouse through food alone, and a bevvy of research indicates that getting enough may be crucial for gaining a completive edge. Here are four key benefits, and how to ensure that you’re meeting your body’s needs.

Immune Support
In addition to performance and injury prevention, immunity is one of my top priorities when working with athletes. Back-to-back games, a grueling travel schedule and stress each take their toll, but vitamin D can bolster your defenses. Research indicates that a deficiency of vitamin D weakens the immune system, and ups the risk of mild respiratory infections. And in a recent University of Eastern Finland study, subjects with the lowest blood vitamin D levels had a two and a half times greater risk of contracting pneumonia than those with high levels.

Muscle Efficiency
For the first time, new science shows that there is a direct link between vitamin D and muscle function, which may explain the fatigue commonly experienced by those with poor vitamin D status. Researchers from Newcastle University discovered that vitamin D impacts the functioning of mitochondria, the “power stations” within each of our cells that generate energy. Muscle cells in particular need a large amount of energy to support movement, and scientists found that vitamin D plays a vital role in sustained energy production. Using non-invasive magnetic resonance scans to evaluate human subjects, researchers learned that 10-12 weeks of vitamin D supplementation slashed the amount of time cells need to replenish energy after muscle contractions. In others words, vitamin D improves mitochondrial efficiency and reduces fatigue.

Muscle Power
We’ve known for some time that an inadequacy of vitamin D is associated with muscle weakening, but until recently little was known about how vitamin D impacted muscle power and force. In a UK study, scientists assessed just that in 99 girls, between the ages of 12 and 14. After taking blood samples to gauge the teens' vitamin D status, researchers used an instrument to measure muscle power, force, velocity and height during a series of jumping activities. The results: Girls with adequate blood vitamin D levels performed significantly better than those with deficiencies.

Injury Prevention
Sports Medicine doctors at the Hospital for Special Surgery in New York City studied 89 football players from one NFL team, including assessments of vitamin D levels, as part of pre-season evaluations. Only 16 of the players had blood vitamin D levels within the recommended limits, and poor vitamin D status closely correlated with injury data. There were 45 players categorized as insufficient, and another 27 fell into the deficient range. Among 16 players who had suffered muscle injuries, the mean vitamin D level was 19.9, which is in the deficient range (30 – 74 is considered normal).

How to Get Enough
Vitamin D’s nickname is the “sunshine vitamin,” because exposure to the sun’s ultraviolet (UV) rays triggers its production in the body. But where you live, the time of year and day, cloud cover, smog, sunscreen, and clothing all affect UV exposure and vitamin D production, so you can’t rely on the sun as your sole source. In fact, one recent study found that 51% of sun-drenched Hawaiians, who spend 20-30 hours per week outdoors, still had low vitamin D levels. Unfortunately, there are few foods that are naturally rich in vitamin D, primarily salmon, tuna, whole eggs (the vitamin D is found in the yolk), and mushrooms, foods you’re unlikely to eat daily or eat enough of to fill your needs. That means a supplement is likely in order. To know for sure and establish the proper dose, have your blood vitamin D level checked. Depending on your status, a daily dose of 400 International Units (IUs), or even up to 2,000 may be needed, but more isn’t necessarily better. Four thousand IUs is generally the maximum recommended intake, and vitamin D toxicity can trigger unwanted side effects, including heart arrhythmias, loss of appetite, and high blood calcium, which may lead to heart, blood vessel and kidney damage. Striking the right balance is the key to reaping the rewards.    


Cynthia Sass, author of S.A.S.S. Yourself Slim: Conquer Cravings, Drop Pounds and Lose Inches, is a nutritionist, Board Certified as a Specialist in Sports Dietetics. She is the nutrition consultant to the New York Rangers and Tampa Bay Rays and works with professional and competitive athletes in numerous sports. She can be reached via