Nutrition News: Antioxidants

Antioxidants

By BARBARA BRENSEKE

Antioxidants, just as the name implies, are substances that combat the process of oxidation. Oxygen is necessary to many body processes, and oxidation is a natural chemical reaction, which takes place both within our bodies and in our environment. Some common oxidative reactions are the rusting of iron and the darkening of foods like potatoes when they are exposed to the oxygen in air. Although the oxidation reactions that take place in our bodies are normal, they can be harmful when they produce free radicals or chemically active molecules that have a charge on them due to an excess or deficient number of electrons. These charged, free radicals are very unstable and they try to scavenge or donate electrons to surrounding tissues, and while doing this, they often damage these tissues. Blood vessel damage that leads to heart disease is believed to be caused by free radical damage. Cancer, some degenerative eye problems, old age, and other inflammatory conditions are also believed to be affected by these unstable byproducts of oxidation. One would assume, therefore, that antioxidants could be very useful in preventing or possibly curing many diseases. And some studies have shown them to be helpful.

Some common antioxidants found in foods are vitamins A, E, and C, the mineral, selenium, and some carotenoids and polyphenols. Carotenoids and polyphenols are part of a group of substances called phytochemicals. Phytochemicals are found in plants and they affect the taste, color, scent, and other characteristics of the plants. There are thousands of phytochemicals in each vegetable, fruit and whole grain. A lot of studies have been done to explore what they specifically do in our bodies, but we have only begun to see the “tip of the iceberg” of this research.

We have a lot yet to learn about phytochemicals, antioxidants and how they benefit us. Although some studies have shown us that they may affect our bodies in a positive way, some research has been a little discouraging. A recent study to examine whether or not beta-carotene, vitamins A, E, and C and selenium would decrease deaths in adults was done. The results showed that taking a combination of these antioxidants would not make a difference. In fact, taking carotene, vitamin A and vitamin E separately may actually increase mortality. Vitamin C alone did not appear to affect the death rate in the studied individuals and selenium tended to decrease it, but more testing needs to be done. Other studies to find out if vitamin E helps slow heart disease have also not been as promising as expected. And, additional research of beta-carotene has shown us that it may not help prevent heart disease or cancer as we once hoped.

This does not mean, however, that we should give up on antioxidants. There have been some promising studies of these substances in addition to the not-so-promising ones. According to some researchers, a combination of vitamins C and E, beta-carotene and zinc may reduce the risk of developing a degenerative eye disease (age-related macular degeneration), which is a leading cause of blindness in our aging population. Also, vitamins E and C may help protect us from developing Alzheimer’s disease. And selenium seems to play a role in preventing prostate cancer in men. It appears, therefore, that there are some benefits to consuming antioxidants.

At this point, however, it is impossible to formulate any meaningful guidelines for how much of the different antioxidants we should eat. We can assume that it is safe to eat foods that contain antioxidants. In fact, a very good way of including more of these health-promoting substances in our diet is to eat the amount of fruits and vegetables recommended by the USDA Dietary Guidelines for Americans. Eating a variety of at least five servings of fruits and vegetables daily may be our best shot at getting these antioxidants in the least risky way. If you choose to take supplements, a safe rule of thumb to follow is to take no more than 1 ½ times the recommended daily value of vitamins and minerals, unless you are taking them for a specific medical reason that you have discussed with your doctor. Also, keep in mind that all health claims are not necessarily true. As we continue to study antioxidants and their possible benefits, we will discover many more uses for them; but, for now, exercise caution. And please stay informed as nutrition experts continue to develop better guidelines for including them in our diets.