The secret to lasting youth may not lie in a pill or potion, but in produce! Carrots, spinach, and broccoli among other vegetables contain compounds known as antioxidants, which research suggests may be powerful weapons in the war against the effects of aging. "I think the evidence is very compelling, although not definitive, that as you increase your intake of certain antioxidants, you do increase the benefits," says Dr. Jeffrey Blumberg, chief of the Antioxidant Research Lab at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.
Antioxidants and Free Radicals in the Body
As the body uses oxygen, byproducts called free radicalsoxygen molecules that are missing electronsare formed. These free radicals steal electrons from healthy cells, causing damage to these cells. This cell damage is thought to be cumulative, and scientists theorize that this may lead to aging and disease. Everything from cancer and heart disease to wrinkles and cataracts may be attributed to the action of free radicals. Environmental factors such as exposure to radiation and tobacco smoke may also increase the number of free radicals in the body.
Antioxidants are compounds that work to deactivate free radicals, thus preventing cell damage. The three best-known antioxidants are vitamins E and C and beta carotene, but there are many others, including selenium, lutein, and lycopene.
Research Shows Mixed Results
Positive findings
A study involving 30,000 participants in China demonstrated that over the course of five years, those participants who received a daily supplement containing vitamin E, selenium, and beta carotene had a 13% lower rate of cancer than those study participants who received a placebo (or sugar pill). In the United States, a study of 1,795 nurses who had a history of heart problems showed that those nurses who consumed larger amounts of vitamins C and E and beta carotene showed the greatest cardiac improvement and reduced their chances of further heart damage.
A study reported in the May 20, 1993 issue of The New England Journal of Medicine reported a significant decrease in the incidence of coronary artery disease in men and women who consumed 100 international units (IU) of vitamin E daily. The current recommended intake for vitamin E is 15 mg per day (22.5 IUs).
Although it's tempting to take these kinds of results to heart, some critics have argued that studies like these have not ruled out other reasons for the study subjects' improvements, such as increased exercise or other dietary changes. In other words, maybe the effect is entirely unrelated to the supplement.
Inconclusive findings
In January 2000, The New England Journal of Medicine reported the results of a 4 1?2-year study of more than 9500 men and women aged 55 and older with risk factors for heart disease. Half of the participants were given 400 international units of vitamin E from natural sources, while other participants received a placebo, or sugar pill. Over the length of the study, there was no significant difference in the number of cardiac events or cardiac deaths in either group.
Why do these results contradict the results from other studies? The researchers themselves note that perhaps the study wasn't long enough to demonstrate any effect. They also suggest that perhaps the findings were influenced by the fact that they used vitamin E supplementation alone, without any other antioxidants. It may be that vitamin E requires other factors to have a beneficial effect.
Too much of a good thing?
Some studies have suggested that for certain people, over-consumption of antioxidants can be harmful. Studies of beta-carotene in humans were stopped in 1994, after results suggested that people at risk for cancer were at even greater risk after taking high doses of synthetic beta-carotene.
It's important to remember that the antioxidants were provided as dietary supplements, not foods. Some scientific data suggests that the antioxidant effect may be enhanced when the antioxidants come from food—and in particular from fruits and vegetables—because of other compounds in the fruits and vegetables not available in a purified supplement.
Benefits of Dietary Changes Are Clear
Dr. Blumberg cautions that research is ongoing. He cites new studies of the benefits of lesser-known antioxidants such as lycopene, which may reduce prostate cancer risk, and lutein, which is strongly associated with a decrease in age-related macular degeneration and prostate cancer. Studies of high-risk groups, such as the nurses with heart disease, suggest the greatest benefit from increased consumption of antioxidants is realized by those at the greatest risk of disease.
Though the jury is still out on the role of antioxidants as disease and age fighters, consuming more antioxidant-rich fruits and vegetables has well-documented benefits in improving health, aside from their antioxidant contents.
· Antioxidant
· Recommended Amount*
· Good Food Sources
· Vitamin C
· Women: 75 mg Men: 90 mg
· Smokers: extra 35 mg
· Citrus fruits, cruciferous vegetables such as broccoli, cauliflower, and cabbage
· Vitamin E
· 15 mg
· Fortified cereals, vegetable oils, nuts, spinach and kale, mangoes, and wheat germ
· Selenium
· 55 micrograms (mcg)
· Onions, garlic, mushrooms, wheat germ, and rice bran
· Vitamin A
· Women: 700 RAE** Men: 900 REA
· As retinol: Eggs, liver, vitamin A-fortified milk
As beta-carotene: Yellow-orange or dark-green leafy vegetables and fruits, such as kale, beet greens, spinach, carrots, sweet potatoes, pumpkin, papaya, apricots, parsley, and basil
* Recommended amounts are given as dietary reference intakes (DRIs), which replace recommended dietary allowances (RDAs); these are the government's recommendations for good health.
** REA = retinol equivalents; a measurement of vitamin A that includes the two major forms of vitamin A found in foods: retinol and beta-carotene. There is no separate DRI set for beta-carotene.
Are Supplements Necessary?
The problem for many people lies in consuming enough of these foods to receive any kind of benefit. "Few people meet the recommended intakes for all nutrients," Dr.Blumberg says. "And people eat less as they grow older. As their appetite decreases, they don't change how they eat, they just eat less." Instead of adding more fruits and vegetables to their diets, many older people eat smaller portions of the same kinds of foods they've eaten for years, which are often high in fats, starches, and sugars.
Smokers, heavy drinkers, people with impaired immune systems, and those on calorie-restricted diets may also have difficulty getting the nutrients they need from food alone. For these people in particular, supplements may be the only way for them to fulfill their nutrient needs. In addition, vitamin E is found in a limited number of foods, making it difficult to get enough of it in the average diet. While consuming more vegetables and fruits is still the best way to get essential nutrients, a good multivitamin can fill in any nutrient gaps.
The American Heart Association and the American Cancer Society do not endorse antioxidant supplements for the general population, but they do recommend a diet with plenty of antioxidant-rich fresh fruits, vegetables, and whole grains. Please also discuss any antioxidant use with yout doctor before you begin it.
RESOURCES:
National Institute on Aging http://www.nih.gov/nia/
National Cancer Institute http://www.nci.nih.gov/
American Heart Assiciation http://www.americanheart.org
Nutrition
