Nutrition for Runners

Why you should eat your leafy greens.

Power Packed

Greens have what a runner's body needs. They are packed with oodles of vitamins, minerals, fiber and phytochemicals for good health, disease prevention and top performance.

Here's a look at what most leafy green vegetables have to offer in a 1-cup serving (raw) or 1/2-cup serving (cooked).

I admit I use the term "leafy green vegetables" as if these weed-like veggies make regular appearances on your dinner plate. They probably don't. Most of us wouldn't be able to pick one out of a produce lineup, let alone know what to do with it. That's too bad, since greens are incredibly nutritious. After a training partner recently asked me how a bunch of gritty-looking leaves (they were collard greens) could possibly be edible, I knew it was time to tackle the topic.

So here's a primer on 19 leafy greens. First I'll summarize their nutrient highlights. Then I'll describe the characteristics and include tips on selection, storage and how each can be used.

Carotenes

They're a mouthful to say-beta carotene, lutein, lycopene, and zeaxanthin. But antioxidant carotenes ward off many age-related diseases, including macular degeneration, which has caused blindness in two million people in the United States. In one study, individuals who ate two servings a week of spinach or collard greens had half the risk of this eye disease than nongreens eaters. A serving of greens typically contains about 2 to 20 milligrams of carotenes (suggested intake is 5 milligrams).

Fiber

Most greens provide about 2 to 5 grams of fiber per serving, with a good mix of cholesterol-lowering soluble fiber and digestion-aiding insoluble fiber. Water-soluble fiber also helps reduce appetite. Toss up a mixed green salad topped with garbanzo and kidney beans (also good sources of soluble fiber) for an evening meal that should keep late-night hunger away.

Folic Acid

Famed for its role in preventing certain birth defects, this B vitamin also helps ward off heart disease by working with enzymes that dispose of homocysteine, a harmful blood chemical that irritates artery walls. Most greens have between 10 to 25 percent of your folic-acid needs per serving.

Phytochemicals

In addition to carotenes, greens also supply an array of other cancer-fighting phytochemicals. These nonvitamin/nonmineral substances found in all plants are believed to help protect leaves from UV sunlight, parasites and other invaders. When we eat the leaves, phytochemicals work by boosting enzymes that fight cancer cells or cancer-causing agents, research shows. Watercress, for example, contains the family of phytochemicals called isothiocyanates that inhibit carcinogens you get from tobacco smoke. Eat a variety of greens to get the full benefit of several different types of phytochemicals.

Magnesium

This mineral plays a vital role in energy metabolism during exercise. Poor magnesium intake may make the heart work harder, resulting in more physiological stress during exercise, according to recent research from the Department of Agriculture's Human Nutrition Research Center in Grand Forks, N.Dak. Women who consumed a marginal magnesium diet (two-thirds of the 280-milligram requirement) for several months showed signs of greater energy use and more stress during an exercise test than when they were eating a diet with adequate magnesium.

Most of us eke by with marginal magnesium levels, which is all the more reason to make leafy greens a daily staple. A serving of greens supplies about 10 to 30 percent of the Daily Value for this mineral. Magnesium hides in the leaf's green chlorophyll molecule. The greener the foliage, the higher the magnesium content.

Iron

A standard serving of leafy greens supplies 10 to 15 percent of daily iron needs, a mineral that is notably low in many runners' diets (particularly in female vegetarians). The body absorbs iron poorly from some greens, such as spinach, because these greens also contain a substance called oxalate that binds iron and makes it unavailable for use. Adding acidic foods such as tomatoes or citrus fruits will help your body break the iron down into a more absorbable form.

Potassium and calcium

Greens are decent sources of these minerals, both of which fight high blood pressure. One serving provides about 10 to 20 percent of the Daily Value for calcium and 5 to 10 percent for potassium. These minerals can be lost when you boil greens, so microwave or steam them.

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