Athletes and performers are familiar with the calming effect of bananas—a result of the fruit's high concentration of tryptophan, a building block of serotonin. But their real benefit comes from potassium, an electrolyte that helps prevent the loss of calcium from the body.
"Bananas also bolster the nervous system, boost immune function, and help the body metabolize protein," says Bass. "One banana packs a day's worth of potassium, and its carbohydrate content speeds recovery after strenuous exercise."
Like bananas, this fuzzy fruit is high in bone-protecting potassium. "They're also rich in vitamin C and lutein, a carotenoid that can help reduce the risk of heart disease," says Bowerman. "I try to eat at least one or two a week after exercising." Freeze them for a refreshing energy kick, but don't peel the skin: It's edible and packed with nutrients.
George H. W. Bush may hate this cruciferous all-star, but one cup of broccoli contains a hearty dose of calcium, as well as manganese, potassium, phosphorus, magnesium, and iron. And that's in addition to its high concentration of vitamins—including A, C, and K—and the phytonutrient sulforaphane, which studies at Johns Hopkins University suggest has powerful anticancer properties.
"One cup a day will do the trick," says Bowerman. Try cauliflower, kale, brussels sprouts, or cabbage for variation, as all possess many of the same nutritional qualities. "Broccoli may also help reduce excess estrogen levels in the body, thanks to its indole 3-carbinol content," says celebrity trainer Gunnar Petersen.
A renowned muscle builder, spinach is also rich in vitamin K, which has been shown to bolster bone-mineral density (thus protecting against osteoporosis) and reduce fracture rates. Spinach is also high in calcium, phosphorus, potassium, zinc, and even selenium, which may help protect the liver and ward off Alzheimer's.
One more reason to add it to your diet: A study in the Journal of Nutrition suggests that the carotenoid neoxanthin in spinach can kill prostate cancer cells, while the beta-carotene fights colon cancer. "Popeye was on to something," says Bowerman. "Eat one cup of cooked spinach, or two cups raw, four times a week."
These scallion-like cousins of garlic and onions are packed with bone-bolstering thiamine, riboflavin, calcium, and potassium. Leeks are also rich in folic acid, a B vitamin that studies have shown to lower levels of the artery-damaging amino acid homocysteine in the blood.
What's more, "Leeks can support sexual functioning and reduce the risk of prostate cancer," says Michael Dansinger, M.D., an assistant professor of medicine and an obesity researcher at Tufts-New England Medical Center, in Boston. "Chop the green part of a medium leek into thin ribbons and add it to soups, sautés, and salads as often as possible."