essential nutrients

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Potassium is a vital mineral for the function of all cells, tissues and organs in the human body—i.e., life as we know it. "We also know that potassium is important for controlling blood pressure, and there's a lot of evidence that it reduces your risk of stroke," says Walter C. Willett, MD, chair of the nutrition department at the Harvard School for Public Health. And, as many athletes are aware, it can help prevent muscle cramps and post-workout soreness.

You need: 4,700 mg a day

You get: National survey data shows over 90 percent of Americans don't get the recommended daily allowance, says Willett, who is also the author of Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating.

Good sources: Eat a variety of fruits and vegetables that have higher levels, like broccoli, cantaloupe, winter squash, sweet potatoes and, yes, bananas (these foods should be eaten raw, steamed or baked but not boiled, since boiling depletes potassium.)
As a reminder, always consult your doctor for medical advice and treatment before starting any program.