Antioxidants in Fruits

Fruits, especially berries, are full of antioxidants essential for good health.

Medically Reviewed by Brunilda Nazario, MD on September 11, 2008
7 min read

Berries are the crown jewels of summer, the gems that inspire pies, parfaits, cobblers, ice cream treats, and whipped cream wonders. Best of all, berries deliver super-healthy antioxidants that help fight disease.

In fact, one landmark study shows that just one cup of berries provides all the disease-fighting antioxidants you need in a single day. Of course, dietitians will tell you, "Don't stop there." A healthy diet needs a variety of nutrients from many food sources.

Raspberries, blueberries, strawberries, and blackberries are plentiful in most corners of the U.S. "Berries are available almost year-round now…and even though they may be more expensive some times of the year, they're still much more accessible than they used to be," says Cindy Moore, MS, RD, spokeswoman for the American Dietetic Association and director of nutrition therapy at The Cleveland Clinic.

Berries and other foods figured in a major study published in Journal of Agricultural and Food Chemistry. This research provides a large comprehensive report of antioxidant content in fruits and vegetables. Berries won hands down, in providing the most antioxidant bang for the buck.

Antioxidants are important disease-fighting compounds. Scientists believe they help prevent and repair the stress that comes from oxidation, a natural process that occurs during normal cell function. A small percentage of cells becomes damaged during oxidation and turns into free radicals, which can start a chain reaction to harming more cells and possibly disease. Unchecked free radical activity has been linked to cancer, heart disease, Alzheimer's disease, and Parkinson's disease.

This study assess antioxidant levels in more than 100 foods, including fruits, vegetables, cereals, breads, nuts, and spices.

Cranberries, blueberries, and blackberries ranked highest among the fruits studied. Apples ran a close second, and dried fruits were also leading contenders. Peaches, mangos, and melons, while scoring lower than berries, still contain plenty of antioxidants as well as other nutrients.

However, there's a catch: Even though some fruits and vegetables have a high antioxidant content, the body does not absorb all of it. The concept is called bioavailability, explains researcher Ronald Prior, PhD, a chemist and nutritionist with the USDA's Arkansas Children's Nutrition Center in Little Rock, Ark. He authored the landmark antioxidant study.

"Bioavailability has to do with absorption or metabolism in the gut," Prior explains. "What's absorbed will be impacted by the mechanical structure of different antioxidants in food -- if they're tied up with fiber or if they have sugar molecules attached."

Some foods benefit from a bit of cooking, he says. One of his studies showed that by mildly steaming blueberries, the antioxidant level was enhanced, making more antioxidants available to the body. "We really don't know much about this, especially with fruits," Prior tells WebMD.

That's why variety in your diet is important. You hedge your bets by eating as many antioxidant-rich foods as possible, since researchers don't yet fully understand the complexities involved with bioavailability. It's also why you should shoot for foods that offer the highest antioxidants, such as the top producers like berries, he says.

On the color wheel, the purple-blue-red-orange spectrum is home to the most antioxidant-rich fruits.

Wild blueberries are the winner overall. Just one cup has 13,427 total antioxidants - vitamins A & C, plus flavonoids (a type of antioxidant) like querticin and anthocyanidin. That's about 10 times the USDA's recommendation, in just one cup! Cultivated blueberries have 9,019 per cup and are equally vitamin-rich. Buying tip: Peak season starts in mid-May, so blueberries are less expensive during the summer.

Cranberries are the tart crown jewels of turkey feasts. They're also antioxidant powerhouses (8,983). To get cranberries after the holiday scene has passed, creative cooks sneak dried cranberries into risottos, salads, salsas, and trail mixes.

Blackberries (7,701), raspberries (6,058), strawberries (5,938), black plums (4,873), sweet cherries (4,873), and red grapes (2,016) are also brimming with vitamins A and C and flavonoids like catechin, epicatechin, quercetin, and anthocyanidin. Tossed into a green salad, these berries add extra color, flavor, and texture. They're also very edible by the handful, with morning cereal, mixed into yogurt, spooned over waffles or pancakes, and sprinkled over ice cream.

All-American apples are also vitamin- and antioxidant-rich treats. The classic Red Delicious (5,900), Granny Smith (5,381), Gala (3,903), and many other varieties are available nearly year-round. Applesauce, juice, and jellies are also tasty apple sources, but beware of added sugar (check the label). Here's a tip: Mix some chopped apple into a tuna salad for a sandwich.

Finally, orange-colored fruits are good sources of antioxidants as well. One naval orange has 2,540; the juice has about half that. Bite into a luscious ripe mango, and you'll get 1,653. A peach has 1,826, tangerines, 1,361, and pineapple, 1,229.

Dried versions of these fruits are smaller, but they still have plenty of antioxidants. For instance, just half a cup of these dried fruits packs quite a punch: prunes (7,291), dates (3,467), figs (2,537), and raisins (2,490). Some people prefer the taste or texture of certain dried fruits over fresh ones. Dried cranberries are a prime example; they tend to be much less tart than the fresh variety.

When buying dried fruit, check the label for added sugar and portion size. "One thing people don't realize is that portion size for dried fruit is fairly small, usually a quarter of a cup," Moore tells WebMD. "So it's very easy to overeat dried fruit, getting a lot more calories than you need. For people struggling with weight control, that can be too much of a good thing. If you eat the fruits in their natural form, they are very low in calories, very nutritious, full of fiber, vitamins, minerals, and many, many antioxidants. The whole fruit helps keep you in line calorie-wise."

Also, frozen fruits are a good way to go, adds Moore. "Make sure you buy the ones without added sugar. Frozen berries are especially good for a smoothie, where texture and appearance doesn't matter. Also, they're good over ice cream or cake, when you're dishing and serving them fairly soon out of the bag. If you wait too long after they've thawed, they're going to get fairly soggy."

More than 300 studies cite plentiful antioxidants in red wine, grape juice, grape seed, and grape skin extracts. Red wine is loaded with flavonoids like anthocyanidins and catechins. Studies show that when animals are given grape products (the study did not specify which products) the artery-clogging process slows down. The same thing seems to happen with humans, Prior says.

This is at the heart of what's known as the French paradox, a theory that emerged in the 1990s. French people have lower rates of heart attacks despite the rich cuisine they eat because they drink moderate amounts of red wine with their meals.

Many of the same flavonoids are found in black and green tea as well as dark chocolate, but the bulk of research has been on grape flavonoids. Researchers say that flavonoids may help promote heart health by preventing blood clots (which can trigger a heart attack or stroke), prevent cholesterol from damaging blood vessel walls, improve the health of arteries (making them expand and contract more easily), and stimulating the production of nitric oxide, which may prevent hardening of the arteries (atherosclerosis).

Another antioxidant called reservatrol, found in red grapes, raspberries, and mulberries, seems to affect age-regulated genes, allowing cells to live longer and offsetting the risk of cancer, heart disease, and Alzheimer's disease.

According to the American Heart Association, drinking a moderate amount of wine -- one or two glasses daily for men, no more than one for women -- lowers heart disease and may be safe. However, it cautions that this recommendation should be tailored for an individual's risks for heart disease and the potential benefits (as well as risks) of drinking.

Grape juice has similar antioxidant powers, researchers say. One study showed that drinking a tall glass of grape juice daily lowered LDL (also called "bad") cholesterol significantly. It also improved the blood flow in artery walls. Another point: You can drink all you want and drive home safely.

"A number of studies show that Concord grapes and grape juice have a higher concentration of antioxidants than ordinary table grapes," says Prior.

Just don't make the mistake of downing too much grape juice - or wine - in a day's time, says Moore. "Like dried fruit, these are very concentrated calories. Be careful, because those calories add up. It's better to eat more grapes."