Corn is technically a grain and not a vegetable—the seed of a type of grass, like wheat. It therefore counts toward the recommended three daily servings of whole grains. The corn we eat is “sweet corn” (white, yellow or bi-colored), which has become even sweeter since scientists began breeding varieties with more sugar. Some “supersweet” corn also stays sweet longer. Baby corn (available canned) is sweet corn that’s been harvested early, and can be eaten cob and all.
Corn is a high-carbohydrate food with lots of fiber, some protein, B vitamins (e.g., thiamin and folate), a little vitamin C and a handful of minerals. Treating corn with lime (as in tortillas) makes certain amino acids and niacin more available to the body. Yellow corn contains some beta carotene and is rich in lutein and zeaxanthin—which may help keep eyes healthy and possibly protect against cataracts and age-related macular degeneration. Corn contains more calories than most veggies: 175 in a cup.
For the best fresh corn, purchase in season (usually mid-to-late summer). Check that the corn has been kept cool. The sugar in corn gets converted to starch more quickly at warm temperatures. Feel through the husk to see if the kernels are tightly packed and plump. Refrigerate corn when you get home, and cook it as soon as possible. Unless it’s a supersweet variety, there may be a noticeable decline in sweetness in just a day or two.
Boil, grill or microwave corn. Don’t add salt to the boiling water, because salt toughens the kernels. As an alternative to butter, rub with wedges of lemon or lime. Instead of salt, sprinkle with cayenne, dill or other spices and herbs. You can also add corn kernels to rice and bean dishes, soups, salads, even pancakes. Frozen and canned are just as nutritious as fresh—just watch out for extra sodium and high-fat sauces.
Popcorn is a special variety of “field corn” that contains a small amount of water inside a thick-walled casing; when heated, steam builds up until the kernel explodes. It’s a healthy high-fiber snack when air-popped with no added butter. Look for packaged microwave popcorn that is low in sodium and contains no trans fats. Be aware: movie-theater popcorn often contains these unhealthy fats.
Field corn is also processed into corn syrup, cornstarch and corn oil (as well as ethanol fuel, plastics and other nonfood products). Corn oil is rich in unsaturated fats and sterols, both of which can help lower blood cholesterol.