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Another driving force in the U.S. is the new "demographic imperative." With a rapidly aging population, America has moved its medical focus from treating acute illness to caring for chronic maladies like heart disease and cancer -- a shift that has sent health-care costs skyward. "There's a growing appreciation of the need to find the most economical way to treat and prevent chronic disease," notes Dr. Charles Butterworth Jr. of the University of Alabama. "Food and vitamins are not that expensive." Calculates Tufts' Blumberg: "We could save billions of dollars if we could delay the onset of - chronic diseases by as little as 10 years."
Overriding all else, however, is the impact of scientific studies. Beginning in the 1970s, population surveys worldwide started to uncover a consistent link between diet and health. A diet rich in fruits and vegetables, for instance, became associated with a lowered incidence of cancer and heart disease. Researchers then turned to examining the data nutrient by nutrient, looking at minerals as well as vitamins, to see which are tied most closely with specific ailments. Low vitamin C intake appears to be associated with a higher risk of cancer, low levels of folic acid with a greater chance of birth defects, and high calcium consumption with a decreased danger of osteoporosis.
Intrigued by such clues, the National Institutes of Health, universities and other research organizations began funding laboratory and clinical investigations. By the late '80s, research exploring vitamins' potential in protecting against disease was on its way to respectability. Though the evidence is still preliminary, scientists are excited about several nutrients.
One vitamin attracting attention is folic acid, also known as folate, which was first isolated from spinach. This B vitamin appears to guard against two of the most common and devastating neurological defects afflicting newborns in the U.S.: spina bifida, in which there is incomplete closure of the spine, and anencephaly, in which the brain fails to develop fully. British researchers found that when women who had already given birth to a malformed child received folic acid supplements during a subsequent pregnancy, the chances of a second tragic birth fell sharply.
Another enticing finding reported last January established a link between folic acid and prevention of cervical cancer. According to a study at the University of Alabama's medical school, women who have been exposed to a virus that causes this cancer are five times as likely to develop precancerous lesions if they have low blood levels of folic acid. The discovery may help explain why cervical cancer is more common among the poor. Indigent women usually eat few vegetables and fruits, which are prime sources of folate. Says Butterworth, head of the research team: "It looks like many cases of cervical dysplasia ((a precancerous condition)) could be prevented with a healthy diet."
Vitamin K, long known to promote blood clotting, appears to help bones retain calcium. Rapid calcium loss is a major plague among postmenopausal women, giving rise to the fragile-bones syndrome called osteoporosis. A recent Dutch study of 1,500 women ages 45 to 80 found that calcium loss (as measured in urine samples) could be halved with daily supplements of vitamin K.