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Eating right to prevent heart disease may seem complicated and confusing, but it's a breeze compared with trying to design an anticancer diet. Cardiovascular disease is relatively simple; it's the result of normal bodily processes taken to the extreme. Cancer, by contrast, involves changes in the programming of DNA within the nuclei of individual cells. Beyond that, heart disease is an illness that affects a single organ system, while cancer is dozens of different diseases that target body parts as radically different as the brain, breast and bone.
That being the case, it's no surprise that the relationship between diet and cancer is still largely a matter of educated guesswork—and in many cases, the guesses have turned out to be wrong. Take the much publicized link between high-fat diets and breast cancer, for example. Women, who live in Western countries, where high-fat diets are the norm, tend to have high breast-cancer rates. Even more telling: women of Japanese ancestry who live in the U. S. get the disease six times more often than their grandmothers and great-grandmothers in Japan. Yet a huge recent study of 90 000 women has refuted the breast cancer-fat link.
A similar process of educated-guess-and-error led people to load up on the nutritional supplement beta carotene (a natural red substance found in carrots and other vegetables) in the early 1990s. Scientists noted that those who eat lots of fruits and vegetables tend to get less cancer and speculated that carotenoids—the same antioxidant substances that seem to protect against heart disease—were responsible. In particular, they focused on beta carotene, the most abundant and common carotenoid, as the most likely to prevent cancer.
Yet a series of targeted studies in Finland and the U. S. showed that beta carotene supplements don't ward off cancer at all. "It looks like taking this substance in high doses is not the right thing to do," says a Harvard's researcher.
Health experts are not ready to list the foods that will keep cancer at bay, but some broad outlines of an anti-cancer diet are taking shape. Beta carotene might not be the key. But fruits and vegetables seem to help. So along with giving up tobacco and limiting alcohol consumption, the best way to prevent a broad range of cancers, given the current state of medical knowledge, is to eat more fruits and vegetables. That sort of diet will help you stay trim and prevent heart disease anyway—so if, against all odds, it turns out to have no effect on cancer, it certainly can't hurt.
26. We may conclude from the first paragraph that
[A] heart disease is mainly caused by abnormal eating habits.
[B] cancer is far more difficult to prevent than heart disease.
[C] changing the programming of DNA may help treat cancer.
[D] designing an anticancer diet is as easy as a breeze.
27. Observations and studies of women living in the U. S. prove that
[A] American women are in better health than women of Japanese ancestry.
[B] there is a clear relationship between high-fat diets and breast cancer.
[C] Japanese women have not yet fully adapted to Western eating norm.
[D] there is nothing conclusive in terms of the breast cancer-fat link.
28. We can learn from the selection that beta carotene supplements
[A] are ineffective in preventing heart disease.
[B] may not be effective in preventing cancer.
[C] are the most important nutrients we need.
[D] should normally be taken in low doses.
29. According to health experts, eating more vegetables and fruits
[A] will definitely do us no harm whatsoever.
[B] is the most effective anti-cancer diet.
[C] provides us with enough beta carotene.
[D] can protect us against the harms caused by drinking.
30. Which of the following questions does the selection best answer?
[A] Can food protect us against cancer?
[B] Should we believe in educated guesswork?
[C] Is beta carotene good for our health?
[D] Are Japanese women more likely to get breast cancer?
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