Cohen and Deutsch may be a step ahead of their colleagues, but their stories reflect a fundamental shift in the way the medical world views vitamins. “Until quite recently, it was taught that everyone in this country gets enough vitamins through their diet and that taking supplements just creates expensive urine,” says Dr. Walter Willett, a Harvard epidemiologist studying diet, supplements and chronic diseases. “I think we have proof that this isn’t true. I think the scientific community has realized this is a very important area for research.”
That’s an understatement. A growing body of evidence suggests that while the old daily allowances are fine for warding off acute deficiencies, higher intakes may help combat everything from bone loss to cancer. Just two weeks ago, Willett and his colleagues grabbed the world’s attention with two new studies suggesting that vitamin E can help prevent heart disease, the nation’s leading killer. The researchers followed more than 120,000 men and women for up to eight years and found that those taking daily supplements of at least 100 units reduced their risk of heart disease by about 40 percent. Other recent studies have shown that B vitamins can prevent birth defects. And some scientists now believe that vitamin D could become a vital tool for preventing breast cancer.
Major research organizations are launching efforts to tap vitamins’ full potential. Many of the brightest prospects will take years to confirm, but consumers aren’t waiting idly. A NEWSWEEK Poll shows that seven in 10 Americans use vitamin supplements at least occasionally, and 15 percent of daily users say they have started in the past year. As the market for vitamins and other food supplements explodes, health officials worry that consumers are more vulnerable than ever to phony health claims (page 52). But if even half of today’s promising leads pan out, they could change our whole approach to nutrition. “There’s very solid data to suggest that nutrients can promote optimal health and prevent chronic disease,” says Dr. Jeffrey Blumberg of Tufts University’s Center for the Study of Human Nutrition and Aging. “This is a new paradigm.”
Vitamins are simply chemicals that our bodies use in tiny amounts to build, maintain and repair tissues. The first ones were identified in the early part of this century, after researchers found that eating certain foods protected people from diseases like rickets, pellagra and beriberi, which had once been deemed infectious. The acute-deficiency diseases were largely eradicated during the 1930s, as chemists learned to synthesize various vitamins and food manufacturers started adding them to milk, flour and rice. By 1941, the National Academy of Science’s Food and Nutrition Board was publishing recommended daily allowances (RDAs) for most of the 13 vitamins.
The RDAs are periodically updated, but they still reflect the old thinking, and they’ve begun to show their age. In the case of folic acid, many experts consider the RDAs woefully obsolete. Folic acid, a B vitamin found in yeast, liver and leafy green vegetables, aids in various metabolic processes, including the synthesis of DNA. When a shortage of folic acid interferes with that process, the body may produce aberrant cells. The official guidelines recommend a daily intake of 180 to 200 micrograms to prevent anemia, but recent research suggests that women of childbearing age need higher doses to help prevent certain birth defects. Studies have suggested that women need 400 to 800 micrograms a day during the first six weeks of pregnancy to ensure proper development of a fetus’s neural tube, the tissue that becomes the brain and spinal cord. Lower intakes have been linked to neural-tube defects such as anencephaly (which causes death just hours after delivery) and spina bifida (which can cause everything from paralysis to lifelong bowel and bladder problems). The Food and Nutrition Board does provide a separate RDA of 400 micrograms for women who are pregnant. The trouble is, most women don’t even learn they’re pregnant until the critical six weeks have passed. Despite the RDA, the U.S. Public Health Service now advises all women of childbearing age to take 400 micrograms daily.
Pregnancy isn’t the only reason women may need extra folic acid. Last year, researchers at the University of Alabama found that among women infected with HPV-16, a virus implicated in cervical cancer, those with the highest levels of folic acid in their blood were the least likely to exhibit precancerous lesions. In an earlier study, the same team showed that when heavy smokers took 1,000 micrograms of folic acid along with B12 supplements every day, they were less likely than untreated smokers to develop precancerous lung lesions. Since folic acid is usually safe at high levels, some experts now advise smokers to increase their intake, at least until they manage to quit.
Vitamin D, which largely eradicated rickets 50 years ago, is another old nutrient that’s gaining new respect. Though it’s found in some foods (mainly fish oils and fortified milk), our bodies manufacture it when exposed to sunlight and use it to ferry calcium from food into the blood and bones. People who drink a quart of milk a day get plenty of vitamin D (the RDAs are 400 units for children, 200 for grown-ups), but many adults fall short. The deficiencies may contribute to osteoporosis, the bone decay that disables millions of elderly people.
Frank and Cedric Garland, both epidemiologists at the University of California, San Diego, are leading a growing group of scientists who suspect that a lack of vitamin D also fosters breast, colon and prostate cancer. Virtually unknown at the equator, all three cancers become more and more prevalent at higher latitudes. It’s clear from lab studies that vitamin D can retard the growth of cancer cells in test tubes and in animals. The Garlands have amassed voluminous evidence that colon-cancer rates vary according to people’s sun exposure, the amount of vitamin D in their diets and the amount of vitamin D in their blood. They’ve recently shown that the same principle applies to breast cancer, a disease that more widely publicized risk factors such as fat intake have done little to explain. Other researchers have found that prostate cancer, an equally mysterious affliction, follows the same pattern. Clinical trials won’t start to yield results for another decade or so. But if the Garlands are right, the battle against breast cancer may ultimately be won not with lasers or designer genes but with a little vitamin D added to ice cream, cottage cheese and yogurt.
For other chronic diseases, plain old fruits and vegetables may be the secret to prevention. The big stars of the vitamin craze are the so-called antioxidants: vitamins C and E, and beta carotene, a form of vitamin A with its own special properties. Since 1988 the U.S. market for beta carotene supplements has soared from $7 million to $82 million a year, while vitamin E sales have jumped from $260 million to $338 million. The reason can be summed up in two words: free radicals. These molecules, which crop up in our bodies with every breath we take, are implicated in some 60 age-related afflictions, including cancer and heart disease. Unlike a stable molecule, in which every atom is ringed by pairs of electrons, a free radical carries an unmatched electron with a strong impulse to mate. By snatching an electron from a neighbor, it can set off a chain reaction that wreaks widespread havoc on cells, eating away at their membranes and damaging their genetic material (diagram).
The body has elaborate strategies for controlling this corrosive process, known as oxidation, but the safeguards aren’t foolproof. Countless stresses, from smoking to aging, can accelerate oxidative damage. That’s where the antioxidant vitamins come in. Biochemists have long suspected that vitamin E, vitamin C and beta carotene can neutralize free radicals by binding their lonely electrons. The first hints that antioxidant vitamins might help prevent cancer came from surveys in the 1970s showing that incidence is lowest in populations where people consume the most fruits and vegetables. In a review published last year, Dr. Gladys Block of the University of California, Berkeley, tallied the results of 20 studies that monitored the incidence of mouth, throat and stomach cancers in relation to vitamin C intake. In 18 of those 20 studies, low intake emerged as a clear risk factor: on average, people consuming the least vitamin C were stricken at twice the rate of those consuming the most.
Regina Ziegler, an epidemiologist at the National Cancer Institute, uncovered similar trends when she analyzed more than 20 studies that tracked cancers of the lung and other tissues in relation to beta carotene intake. Virtually all the studies linked high levels of the nutrient to low rates of lung cancer. The studies showed similar but less dramatic patterns for cancers of the mouth, throat, stomach, bladder and rectum. It’s possible, of course, that something other than vitamin intake accounts for the variations these studies have documented. To prove cause and effect, scientists have put people on measured doses of particular vitamins and recorded the long-term effects. At least 12 such “chemoprevention” studies are underway. Health authorities have calculated that if antioxidants really explain all the variations seen in the population studies, simply getting people to consume more of them could reduce U.S. cancer mortality by a third.
Heart experts are notoriously skeptical of vitamin claims, but they, too, are embracing the antioxidant revolution-and with good reason. A decade of laboratory research has shown that oxidation is what makes cholesterol so harmful to coronary arteries (NEWSWEEK, May 31), and there’s growing evidence that antioxidants can help block the phenomenon.
Only a handful of human studies have been published, but most have pointed in the same direction as the recent vitamin E findings at Harvard. Last year, after analyzing results from a decadelong federal health survey, researchers at UCLA reported that low vitamin C intake was a strong predictor of death from heart disease and other causes. During the study, men who consumed in the neighborhood of 300 milligrams daily (five times the RDA) suffered 40 percent fewer deaths than those consuming less than 50 milligrams. Meanwhile, researchers at Harvard have found preliminary evidence that 50-milligram beta carotene supplements, taken every other day, can halve the risk of heart attack among men with histories of cardiovascular disease. Such findings are doubly encouraging because the antioxidants are so safe. Excessive vitamin C may cause diarrhea, but the body expels what it can’t use, so overdose isn’t a danger. Vitamin E and beta carotene can accumulate in our fat stores, but neither is known to cause any side effect more serious than a stomachache or a reversible yellowing of the skin.
As any doctor will tell you, the real secrets to good health are exercising, giving up cigarettes and substituting carrots for candy bars. Those measures alone could work much of the magic that millions of Americans now seek in vitamin pills. But there may be excellent reasons to take supplements as well. If today’s hopes are realized, mere vitamins may have the power to cut some common birth defects by half, protect the elderly from bone loss and hip fractures, and dramatically reduce the incidence of heart disease and cancer. Best of all, this medical revolution won’t require a new generation of weaponry. Your corner drugstore is already armed to the teeth.
Scientists believe that compounds like vitamin E, known as antioxidants, may help thwart many common diseases by taming harmful molecules known as free radicals.
A normal oxygen atom has four pairs of electrons. The body’s natural metabolism can rob the atom of an electron. It is now a free radical, which tries to replace the lost electron by raiding other molecules.
When the free radical takes an electron from a molecule in a cell wall, a new free radical is created and a chain reaction begins.
The chain of electron theft erodes the cell membrane, leading to disintegration of the cell and opening the door to cancer and other ills.
Because of their molecular structures, antioxidants can give up electrons to free radicals without becoming harmful, heading off the dangerous chain reaction.(J. SCHNEIDMAN/K. HAMILTON)
