Doctors, dietitians and other experts advise people to eat a wide variety of fruits, vegetables, whole grains and legumes. (LINDA DAVIDSON/THE WASHINGTON POST)

Grocery shelves are full of products with labels bragging that they contain antioxidants and implying that you’re just a few bites (and a few bucks) away from better health. But it’s not that simple. More is not necessarily better when it comes to antioxidants. And research has found that how you consume them can make a big difference in your health. To help distinguish the myths from the truth, here’s a close look at the latest on antioxidants.

MYTH: Antioxidants are all vitamins.

TRUTH: There are thousands of antioxidants, but relatively few of them are vitamins. Some are minerals and others are enzymes, which are protein molecules that facilitate chemical reactions necessary for cells to function properly.

What antioxidants have in common is their ability to block the action of free radicals, those unstable chemical fragments that can wreak havoc on healthy components in your body’s cells. This damage can cause cells to grow and reproduce abnormally, part of a dangerous chain reaction. In time, that process is thought to play a role in chronic conditions including cancer, cardiovascular disease, Alzheimer’s, Parkinson’s and eye diseases such as cataracts and age-related macular degeneration.

Your body produces free radicals during exercise and when converting food into energy. And your body generates antioxidants to help stabilize them. Other factors — cigarette smoking, alcohol consumption and exposure to sunlight and such environmental contaminants as pesticides — trigger the production of more free radicals, which can potentially overwhelm your body’s natural defenses. Antioxidants in foods, especially fruits, vegetables and whole grains, can come to the rescue.

MYTH: All antioxidants are created equal.

TRUTH: Different antioxidants fight different free radicals, and they work well together. For example, Vitamin C recycles Vitamin E. Once a molecule of Vitamin E neutralizes a free radical, Vitamin C converts that molecule of E back to its antioxidant form, allowing it to combat more free radicals.

The synergistic effect among thousands of antioxidants is a major reason doctors, dietitians and other experts advise people to eat a wide variety of fruits, vegetables, whole grains and legumes. Even though scientists have yet to pinpoint all the ways those compounds protect against disease, many observational studies suggest that people who consume a greater amount of antioxidant-rich foods have a lower risk of certain diseases than people who don’t.

MYTH: Be sure to eat pomegranates, berries and other “super fruits.”

TRUTH: All fruits are “super.” Each type of fruit or vegetable has a unique combination of healthful compounds, including antioxidants. By eating only those billed as “super,” you shortchange your health by skipping those combinations of nutrients in other produce.

MYTH: You should amp up your intake with supplements.

TRUTH: Focus on food instead. Overall, clinical trials that have examined the disease-fighting capability of specific antioxidant nutrients in supplement form haven’t shown very promising results.

Talk with your physician about supplement use, because some studies have suggested that some can cause harm. Selenium supplements of 200 micrograms a day have been linked to a higher incidence of recurrence of non-melanoma skin cancers in people who previously suffered such a cancer.

MYTH: If some antioxidants are good, more are better.

TRUTH: Too much can be problematic, so beware of multi- and single-antioxidant capsules labeled “megadoses,” which contain more than the recommended daily values for antioxidants. Some evidence suggests that when taken in megadoses, antioxidants can become pro-oxidants, which increase the production of free radicals, especially in people who drink alcohol or smoke.

It’s much less likely that you’ll consume too many antioxidants from food. But eating one type of fruit or vegetable in excessive amounts can result in some odd, if harmless, effects. For example, consuming extremely large amounts of carrots or other vegetables rich in beta-carotene can result in orange-tinted skin.

MYTH: Packaged food with labels that promise antioxidant benefits will boost your health.

TRUTH: Antioxidant claims on packaged food don’t always mean a health benefit. Some food manufacturers add an antioxidant, such as Vitamin C or E, and then label the product as containing antioxidants, presumably in hopes of boosting sales.

Kellogg’s FiberPlus Antioxidants Dark Chocolate Almond bars, for example, have 20 percent of the daily value of Vitamin E and zinc. But they also contain seven grams of sugar and five grams of fat. You can avoid processed food and eat an ounce of dry-roasted almonds, which provides more Vitamin E, and three ounces of lean beef, which has more zinc.

Copyright 2013. Consumers Union of United States Inc.