As a sports nutritionist who works with professional and competitive athletes, including tennis players, I’m always on the lookout for tips and tricks that give my clients an edge. An in my 10-plus years of practice, not a week goes by that we don’t learn more about how particular foods and nutrients help the body operate like a well-oiled machine. Each one of your body’s 100 trillion cells relies solely on what you eat and drink to fuel your performance and help you recover. And while sports nutrition isn’t an exact science, there are plenty of tried and true techniques every tennis player should know.

The 20 Things You Need to Know About Nutrition

11. Relying on the Sun for Vitamin D May Be a Mistake

Vitamin D’s nickname is the “sunshine vitamin” because exposure to the sun’s ultraviolet rays triggers its production in the body. But recent research found that Hawaiians who spend more than 20 hours a week in the sun, including half of the time without sunscreen, still had low vitamin D levels. And a study published in the <em>Journal of Clinical Endocrinology and Metabolism</em> found that nearly 60 percent of Americans have too little Vitamin D in their blood and nearly a quarter had serious deficiencies. Not getting enough has been linked to autoimmune disorders, certain cancers, increased body fat and decreased muscle strength. In healthy, young Californians, researchers found an inverse relationship between blood Vitamin D levels and muscle fat. Ask your doctor to test your blood vitamin D level to determine if you need a supplement.

More:

**1. Your Diet Impacts Your Brain Function

2. The Right Breakfast Fights Hunger All Day  
3. Food Can Fight Pain  
4. Don't Run on Empty  
5. Sleep Matters ... A Lot  
6. Omega-3s Are Beyond Essential  
7. Milk Does More Than Double Duty  
8. Don't Get Fooled by the Afterburn Myth  
9. Organic Food is Worth the Extra Money  
10. Alcohol May Weaken Muscle  
11. Relying on the Sun for Vitamin D May Be a Mistake  
12. Spices are a Secret Weapon  
13. Chocolate is a Key Superfood  
14. Buyer Beware When it Comes to Supplements  
15. A Little Vitamin C Makes a Big Difference  
16. Variety Trumps Quantity for Fruits & Veggies  
17. Drinking Water May Help You Lose Weight  
18. Bacteria Are Critical to Your Health  
19. Calcium Isn't Just for Strong Bones  
20. Let an Expert Personalize Your Plan<strong>**</strong>

Originally published in the January/February 2012 issue of TENNIS.