While Americans ate 28 percent more fresh fruit in 2000 than in the 1970s, current U.S. Department of Agriculture (USDA) figures show that we could be doing better. Less than 40 percent of American adults and only 26 percent of children over the age of 1 eat the recommended two to five servings of fruit a day. And there are plenty of reasons why we should try to do better. Simply put, fruits are among the most nutritious foods on the planet. They contain virtually no fat, and they're loaded with fiber, vitamins, minerals, and health-protecting antioxidants. They also give you the satisfying sweetness of sugar without the empty calories of most other sweets. And fruit may even help you lose weight. USDA researchers recently found that people who eat more fruit tend to have a lower body mass index (a measure of your weight relative to your height) and lower overall weight.

So what fruits should you choose when organic isn't available? A number of fruits tend to be low in pesticide residues and have little negative impact on the environment. Coincidentally, they also tend to be higher in valuable nutrients than other varieties. Here's the rundown on which conventionally grown fruits you can choose with confidence.

Tropical Fruits
Whenever you need healthy fruit fast, reach for bananas, plantains, pineapples, mangoes, papayas, or kiwifruits. Compared with other types of fruit, tropical fruits are sprayed less and have lower pesticide concentrations. They're also some of the most nutritious fruits available to us. One banana supplies nearly 400 milligrams of potassium. Research shows that eating bananas a few times a week can help to lower your lifetime risk of high blood pressure, heart attack, and stroke. Bananas are also a good source of other electrolytes, which help to replace and regulate fluids lost during exercise. After your next workout, replenish yourself with a banana and some water instead of a bottle of sports drink. (Ditto when the kids come in from a full day of play.)

If you find bananas labeled "Rainforest Alliance Certified" in your market, grab 'em. While not strictly organic, these bananas are grown using environmentally responsible practices you can feel good about.

Kiwis make another highly nutritious and low-pesticide choice. In fact, kiwis contain more nutrients per calorie than any other fruit. Two kiwis supply more potassium than a banana, as much fiber as grapefruit, and twice as much vitamin C as an orange. These little powerhouses are also high in glutamate and arginine, two amino acids that have been shown to help your body secrete growth hormones that reduce the effects of aging. Plus, a kiwi packs easily and has a refreshingly tart-sweet citrus-like flavor that kids tend to like.

Can't find kiwis? Try mangoes instead. Mangoes are low in chemical residues yet high in vitamin C, fiber, and beta-carotene. One mango provides 6 grams of fiber. That's more than what you'll get in a cup of cooked oat bran.

If kiwis, mangoes, or papayas are too hard to find in your area, try pineapple -- another tropical fruit that's usually lower-pesticide than many other fruits. Fresh pineapple contains bromelain, an enzyme that aids digestion by breaking down proteins. (That's one reason why pineapples go so well with pork -- bromelain acts as a natural meat tenderizer.) And pineapples are high in immunity-boosting vitamin C. One cup of pineapple chunks supplies 40 percent of your daily vitamin C needs, while 8 ounces of pineapple juice supplies 100 percent. For an even bigger shot of vitamin C, look for fresh "golden" pineapple imported from Costa Rica. It's sweeter and juicier, and it has more than four times the vitamin C of regular pineapple.

Melons
Most melons are low in pesticide residues and high in important nutrients. Both honeydew melons and cantaloupe provide high amounts of potassium and vitamin C and a fair amount of fiber. Cantaloupe also contains beta-carotene, which can help protect against cancer. Some imported cantaloupe has been linked to outbreaks of salmonella poisoning, but it's such a healthy fruit, there's no reason to avoid it. To help reduce any salmonella risk, scrub the rind of cantaloupe under running water like you would a potato. A quick scrub before cutting into cantaloupe helps to eliminate any bacteria on the rind that could be carried to the fruit via the knife.

For the lowest pesticide residue among melons, sink your teeth into a stab of juicy watermelon. One of summer's supreme eating pleasures, watermelon also makes terrific soup.

Grapefruit and Other Citrus Fruits
Grapefruit carries a fairly low pesticide risk and ranks high in nutritional benefits. Grapefruit provides several powerful antioxidants that have been shown to help relieve cold symptoms, prevent cancer, and heal bruises. The fruit's high pectin content also supplies plenty of fiber, which can help lower cholesterol and reduce risk of heart disease. While these may sound like age-related diseases, new research shows that health-boosting fruits such as grapefruit may help kids, too, to ward off cancer and heart disease in the long run. Give your kids a healthy head start by getting them in the habit of eating low-pesticide citrus like grapefruit, tangerines, and mandarin oranges.

Among citrus fruits, navel oranges are slightly higher in residues, but most of the pesticides are concentrated in the peel. If you're eating the fruit only, conventionally grown versions are reasonably safe. But if you plan to use the peel of oranges (or lemons or limes), the best bet for reducing pesticide exposure is to buy organic. As for orange juice, tests by the Consumers Union show that pesticide risks in conventional orange juice are fairly low.

Blueberries
You won't find a healthier berry than a blueberry. While most commercial berries are extremely high in insecticide residues, blueberries are among the lowest of any fruit. Plus, these little treasures are low in calories and high in vitamin C, potassium, and fiber. They're also the number one source of antioxidants in the produce aisle. The compounds in blueberries can help prevent heart disease, urinary tract infections, and certain forms of cancer, as well as improve vision from a disease called macular degeneration. Recent studies even show that blueberries can play a role in boosting your memory and slowing the aging process. When they're in season (July to September), keep blueberries in the fridge for tossing into cereal, whipping into fruit shakes, or making pies, crisps, and cobblers. Freeze them to enjoy during the rest of the year. Or try dried blueberries, which taste great in muffins and other quick breads. Blueberries pair well with poultry, too.

California Grapes
Most U.S.-grown grapes come from California and test low in pesticide residues. Look for them in markets from May to December. The other four months of the year, however, choose organic grapes to help protect your health. Imported grapes (usually shipped in from Chile) are available in U.S. markets year-round, but USDA data shows that 88 percent of imported grapes have high pesticide residues. Whenever you reach for an organic or low-pesticide grape, you'll also reap some important health benefits. Grapes provide a fair amount of vitamin C and potassium and some boron, a mineral that can help strengthen your bones. Grapes also contain the natural plant chemical ellagic acid, which has been shown to help prevent cancer in laboratory studies by breaking down hydrocarbons, the cancer-causing substances in cigarette smoke and exhaust fumes.

Grapes are a natural for snacking and in fruit salads, but try them other ways, too. If you're concerned your fresh grapes may go bad before you get to eat them, toss them into a freezer bag and freeze them. On a hot day, pop a few frozen grapes into your mouth for a refreshing snack. Or add fresh grapes to sauces. And there's more good news about grape juice. Most bottled and canned grape juices carry a low pesticide risk, according to tests conducted by Consumers Union. Purple grape juice also provides some of the same heart-protecting flavonoids found in red wine. These compounds help to lower blood cholesterol by preventing it from sticking to artery walls.

Plums
Many stone fruits (like peaches) are heavily sprayed with synthetic chemicals to ward off insects. But plums rank among the lowest of all fruits for insecticide residues. Known as a good source of vitamin A and potassium, plums -- especially dried plums (also known as prunes) -- may even have properties that can stop the growth of the bacteria that cause food poisoning, according to new research. Scientists at Kansas State University mixed a small amount of plum extract with raw meat and found that it suppressed the growth of 90 percent of harmful bacteria such as Salmonella and E. coli 0157:H7. The research is still preliminary, but until we find out more, it certainly doesn't hurt to pair plums with meat.