Explorers once searched for the fountain of youth, and old legends tell of magic potions that keep
people young. The ancient questions—Why do people grow old? How can we live longer?—still
fascinate people, including the
scientists who study aging (gerontologists). But their most important question is this: How can people stay healthy and independent as they grow older?

Recently, researchers have begun to find certain chemicals in our bodies that may someday answer these questions. However, the advertising claims that these products can extend life are very much exaggerated. As a result, some stores and catalogs now sell products that are similar to these chemicals. Here are some of the chemicals being studied and what scientists have learned about them so far.

Antioxidants. These are natural substances that may help prevent disease. Antioxidants fight harmful molecules called oxygen free radicals, which are created by the body as cells go about their normal business of producing energy. Free radicals also come from smoking, radiation, sunlight and other factors in the environment.

Some antioxidants, such as the enzyme SOD (superoxide dismutase), are produced in the body. Others come from food; these include vitamin C, vitamin E and beta carotene, which is related to vitamin A. The body’s antioxidant defense system prevents most free-radical damage, but not all. As people grow older, the damage may build up. According to one theory of aging, this buildup eventually causes cells, tissues and organs to break down.

There is some evidence to support this theory. For instance, the longer an animal lives, the more antioxidants it has in its body. Also, some studies show that antioxidants may help prevent heart disease, some cancers, cataracts and other health problems that are more common as people get older.

Most experts think that the best way to get these vitamins is by eating fruits and vegetables (five helpings a day) rather than by taking vitamin pills. SOD pills have no effect on the body. They are broken up into different substances during digestion. More research is needed before specific recommendations can be made.

DNA and RNA. DNA (deoxyribonucleic acid) is the material that holds the genes in every cell. Every day some DNA is damaged and most of the time it is repaired. But more and more damage occurs with age, and it may be that DNA repair, never 100 percent perfect, falls further and further behind. If so, the damage that does not get repaired and builds up could be one of the reasons that people age.

As a result, pills containing DNA and RNA (ribonucleic acid, which works with DNA in the cells to make proteins) are on the market. But DNA and RNA are like SOD tablets. When they are taken by mouth, they are broken down into other substances and cannot get to cells or do any good.

DHEA. Short for dehydroepiandrosterone, DHEA is a hormone that has turned back some signs of aging in animals. When given to mice, it has boosted the immune system and helped prevent some kinds of cancer.

DHEA travels through the body in the blood in a special form, called DHEA sulfate, which turns into DHEA when it enters a cell. Levels of DHEA sulfate are high in younger people but tend to go down with age.

Substances labeled DHEA are being sold as a way to extend life, although no one knows whether they are effective.

Other Hormones. For more than a decade, the National Institute on Aging (NIA), a component of the federal government’s National Institutes of Health, has supported and conducted studies in which hormones and similar substances are replenished to find out if they may help reduce frailty and improve function in older people. These studies have focused on hormones known to decline as we grow older. (See the sidebar “Antiaging Hormones: Point, Counterpoint” on this page.)

The results from research projects likely will improve our understanding of the pros and cons of hormone supplementation. Until the results of these studies are in, recommendations to use supplemental hormones should be viewed with skepticism. It is not yet known, for instance, how much is too much or too little, and when or whether hormone supplements should be taken at all.

Editor’s Note: This article was excerpted with permission from the National Institute on Aging’s AgePage “Life Extension: Science or Science Fiction?” (www.nia.nih.gov/health/agepages).