Anyone who still believes you can't have too much of a good thing hasn't shopped for vitamins lately. Stop in any drugstore, health-food emporium, or supermarket and you're very likely to be confounded by shelf after shelf of vitamins and minerals: The choices seem endless. Should you pick a multivitamin—and if so, should it be the stress formula? Can the kids take one with iron? Maybe you should add an extra dose of calcium- with or without vitamin C? Is 1,000 milligrams adequate— or too much? And are time-release capsules better than pills?
Or maybe you should just skip the whole thing and prepare perfectly balanced meals instead?
What's a well-meaning consumer to do? Relax. After years of treating supplements as only slightly more necessary than snake oil, mainstream medical experts are finally starting to recognize that vitamins have a value and to offer guidance on what to take.
What caused their double take is a growing body of research suggesting that nutrients- sometimes at levels well above the Recommended Dietary Allowances (RDAs)- may help combat cancer, heart disease, cataracts and birth defects, as well as slow the effects of aging.
The New Respectability
Last February, the prestigious New York Academy of Sciences held a conference for researchers to share their findings on the potential health effects of vitamins. "The fact that it was held at all indicates a major shift in scientific opinion regarding the role of vitamins in disease prevention," says C.E. Butterworth Jr., M.D., professor of nutrition sciences at the University of Alabama at Birmingham.
Scientists at the University of Texas M.D. Anderson Cancer Center research division certainly seem convinced. They've formulated ONDROX, a tablet containing forty-five ingredients shown in animal studies to inhibit cancer, increase longevity, and protect against cardiovascular and immunological disorders. The supplement will be available this month in pharmacies and health-food stores.
"There's provocative and compelling evidence that the most protective level of nutrients may be achieved through supplementation," says Jeffrey Blumberg, Ph.D., associate director of the U.S. Department of Agriculture (USDA) Human Nutrition Research Center of Aging at Tufts University, in Boston.
In light of the latest research, even some longtime skeptics seem to be won over. "I was in front of the band of naysayers," admits Godfrey Oakley, M.D., director of the division of birth defects and developmental disabilities at the Centers for Disease Control, in Atlanta. "But I changed my mind when I saw that folic acid can prevent certain birth defects."
Vitamins with clout
Vitamins, organic substances that are essential for normal metabolism and growth, help regulate protective chemical reactions in the body. Scientists have long known that these compounds prevent deficiency diseases such as scurvy, rickets, beriberi, pellagra and night blindness, which are virtually unknown in the U.S. today because of improved diet and fortified foods. But over the years, a variety of I nutrients have been touted by health authorities and vitamin faddists alike to have quasi-miraculous powers against other ailments. The most popular assertions are that vitamin C quashes colds; vitamin B6 allays the symptoms of PMS; and vitamin E counters infertility in women.
Though studies failed to prove such claims definitively, health-conscious Americans boosted supplements sales to $3 billion in 1990, more than doubling revenues since 1976. And now, it turns out, the boomers' faith in vitamins as vanguards of preventive medicine may be justified.
Consider some recent studies:
The antioxidant compounds Vitamins C and E and beta carotene (a compound, plentiful in dark- green and orange vegetables, that the body can convert into vitamin A) have been shown to provide the most pronounced benefits by counteracting unstable molecule particles called free radicals. These chemicals, which are produced by the body and also formed in the environment, can damage cells and promote heart disease, cancer and other disorders.
Antioxidants may help prevent heart disease–the nation's leading killer–by inhibiting LDL (low-density lipoprotein, or "bad" cholesterol) from oxidizing and forming fatty deposits on artery walls, notes Ishwarlal Jialal, M.D., co-director of the Lipid Clinic at the University of Texas Southwestern Medical Center, in Dallas.
In an ongoing Harvard Medical School study, male doctors with heart conditions who took 50 mg of beta carotene every other day had fewer heart attacks, strokes, and deaths related to heart disease than those who did not. Charles Hennekens, M.D., professor of preventive medicine at Harvard Medical School, found, too, that elderly people who ate vegetables high in beta carotene had a lower risk of dying from heart disease and that women who consumed beta carotene and vitamin E-rich diets (and/or took supplements of these nutrients) had 22 percent fewer cardiovascular problems.
According to Gladys Block, Ph.D., an epidemiologist at the University of California at Berkeley, a summary of more than ninety studies suggests that high vitamin C intake significantly reduces the risk of cancers of the oral cavity, esophagus, stomach and cervix. Other reports show that beta carotene, alone or in combination with vitamins E and C, can reverse the growth of oral leukoplakia, a precancerous condition.
The eyes may also be protected by antioxidant nutrients. People who took 300 mg to 600 mg of vitamin C (that's five to ten times the RDA) and 400 International Units (IU) of vitamin E (forty times the RDA) showed a 50 to 70 percent lower risk of developing cataracts.
Vitamin C alone may increase longevity. By analyzing data on the vitamin C intake of 11,348 adults, James Enstrom, Ph.D., an epidemiologist at the University of California in Los Angeles, found that women getting 50 mg of vitamin C in their diets and taking a vitamin C supplement were 25 percent less likely to die of cardiovascular diseases. These women also lived about one year longer than women who consumed less than 50 mg of vitamin C in their diets. Men taking the higher amounts of the nutrient had a 45 percent lower death rate form cardiovascular disease and lived up to five years longer than men consuming less than 50 mg. Benefits for women may be more limited because they already live about seven more years longer and have less cardiovascular disease than men.
Folic acid - Scientists at the University of Alabama at Birmingham have found that folic acid (foliate) may help block dysplasia, an early stage of cervical cancer. "Even mild folic-acid deficiency, a condition that has no detectable symptoms, appears to promote dysplasia," says Butterworth.
Women in seven countries who took daily doses of 4 mg (twenty times the RDA) of folic acid prior to becoming pregnant and on through the twelfth week of pregnancy reduced by 72 percent the risk of having a baby with neural tube defects.
Vitamin E has shown an ability to brace the immune system, an edge that may guard against infectious diseases. A majority of healthy people over age sixty who took 800 IU (eighty times the RDA) of vitamin E daily for a month had significant increases in immune responsiveness. Vitamin B6 Similarly, the immune systems of older people deficient in vitamin B6 were normalized with supplementation at levels above the RDA. Vitamin K A Dutch study showed that vitamin K given to postmenopausal women inhibited the loss of calcium in the urine, which may be linked to loss of bone mass and osteoporosis.
The health bounty of food
Experts agree that it's best to get nutrients from a varied, balanced diet because food contains protein, fatty acids, carbohydrates and fiber, as well as vitamins and minerals. Food also includes some nutrients not yet in pills; earlier this year, for instance, researchers from John Hopkins isolated an ingredient in broccoli, called sulforaphane, that protects cells against cancer-causing molecules.
However, even the most steadfast food-is-best ally admits that very few of us eat the proper diet. According to a 1990 analysis of government data by the National Cancer Institute (NCO, only 9 percent of those people surveyed had eaten the recommended two servings of fruit plus three servings of vegetables in the previous twenty-four hours. "The proportion of the population meeting these guidelines is shockingly small," says Blossom Patterson, the study's lead investigator.
A USDA survey shows that the average intake for women ages nineteen to fifty for iron, zinc, magnesium, phosphorus, calcium and vitamins B6 and E was below the RDA. In many cases, people know what they're missing nutritionally but don't seem willing to change: The American Dietetic Association found that 25 percent of respondents to a recent poll said they do not eat a healthier diet because keeping track of their food would take too much time. And although 79 percent considered nutrition important, 38 percent didn't eat better because they were unwilling to give up favorite foods.
So for all these people and for those whose nutritional needs may be greater than average, including vegetarians, pregnant and lactating women, senior citizens, crash dieters, smokers or people with chronic illnesses, a basic multi- vitamin/mineral formula containing about 100 percent of the U.S. Recommended Daily Allowances (U.S. RDA) is a good idea. Women who are not getting adequate calcium should also consider taking a calcium/vitamin D supplement. "Vitamin D is essential because it promotes the absorption of calcium," Blumberg says,.
So-called stress vitamins - basically, higher- potency preparations - hint that, somehow, mental anxiety can be treated with a special vitamin. While that is not true, these vitamins are safe for people who want higher dosages.
Proceed with caution
But vitamins aren't miracle pills; for one thing, they can't counteract a lifetime of bad habits, cautions Blumberg. "There's no doubt that a diverse diet, low in fat and high in fiber, vitamins and minerals, is absolutely critical."
And although some pro-vitamin gurus advocate popping megadoses (loosely defined as between ten and one thousand times the U.S. RDA, depending on the nutrient), that can cause adverse side effects, Blumherg warns. Vitamins C and E and beta carotene seem to be safe at supplementary intakes of up to five or ten times the RDA; but very high doses of vitamin C can cause diarrhea and stomach irritation, and too much beta carotene can give the skin a yellow tinge (as can overindulging in carrot juice).
Other vitamins and minerals can actually be toxic: 500 mg to 1,000 mg of vitamin B6 may cause tingling and numbness of the limbs (almost always reversible); too much of vitamin D or A—the kind that is already formed, not beta carotene, which turns into vitamin A in the body—can harm the liver; and selenium and copper can be harmful in extra large doses as well.
According to Blumberg, however, you really have to work at it to overdose. "Unwanted side effects from vitamins do not occur from a single dose. A person would have to take daily megadoses for about six months. Most adverse reactions are from intravenous injections given by doctors."
While research on specific nutrients proceeds, here's how you and your family can take safe advantage of vitamin pourer:
Evaluate and improve your diet. Are you eating two to four servings of fruits and three to five servings of vegetables daily? Do you include six to eleven helpings of whole grains and cereals? Have you cut back on fat, sugar and salt?
Assess your health status to determine whether you have greater than average nutritional requirements and need supplemental vitamins and minerals.
Unless your doctor advises against it, take a multivitamin/mineral that contains about 100 percent of the U.S. RDA levels. Says Patricia Hausman, M.S., L.N., former staff nutritionist at the Center for Science in the Public Interest, "It will support the nutrients you get through eating and minimize the ill effects from days when its difficult to control what you eat. It's far riskier for the majority of people not to take one every day than to take it."
Ladies Home Journal,Aug. 92