For decades, medical researchers have been intrigued by the white, waxy substance called cholesterol that is found in the bodies of all animals. Because of its suspected link to heart disease in humans, cholesterol has become one of the major health concerns of the 1980s. As a result, books with such titles as The Enlightened Eater and The 8-Week Cholesterol Cure line the shelves in bookstores, and growing numbers of men and women are changing their diets to avoid increasing the amount of cholesterol in their bodies. But, despite growing public concern, researchers are divided over what effect dietary changes have on the levels of cholesterol in the body. As well, a heated debate is raging about whether doctors should encourage screening to test for potentially dangerous cholesterol levels.
Still, most medical researchers say that there is a strong link between cholesterol and heart disease. Studies have shown that the risks are higher for men, especially those with other risk factors, which include obesity, smoking, excessive use of alcohol, a family history of
heart disease, high blood pressure or diabetes. At the same time, doctors and researchers disagree on how strong the efforts should be to reduce the amount of cholesterol in the blood.
Screening: Last year, the federal National Heart, Lung and Blood Institute in Bethesda, Md., firmly supported screening to detect potentially dangerous cholesterol levels in adults. But last summer, the British Medical Association took just the opposite position, recommending that family doctors should not be encouraged to rely on cholesterol tests, because other factors such as diet, lifestyle and genetics can also provide early warning signs of heart disease. And in March, 1988, at the Canadian Consensus Conference on Cholesterol in Ottawa, doctors recommended that screening become part of periodic health examinations for everyone. But Canadian Medical Association officials have taken a different stand. Said spokesman Douglas Geekie: “The CMA rejects total-population mass-screening. This is not indicated or cost-effective.”
The fatty substance at the centre of the debate is both produced by the human body and
absorbed into it through the consumption of fats and oils. Most cholesterol is manufactured in the body and found in all cells, especially those in the brain and spinal cord. Some cholesterol is needed by the body because it is used in the production of hormones and acts as a protective covering around nerves. But when there are excessive amounts, and when other fats are present, they can gradually build up as deposits in the arteries and impede the flow of blood. When the arteries become too narrow to permit normal blood circulation, the risk of heart attack or stroke “ increases.
2 Calories: To a large exz tent, the amount of cholesteric ol in the blood can be elevatie ed—or lowered—by the type § of fat that is eaten. The total 5 amount of cholesterol in an individual’s body is influenced by the cholesterol in the food he eats. The rest is produced mainly by the liver, primarily from saturated fats in the diet. Nutritionists say that many Canadians eat far too much fat—and, as a result, produce too much cholesterol. Indeed, fatty foods account for about 40 per cent of the calories that Canadians consume, and nutritionists say that figure is about 10 per cent higher than it should be. Said Dr. Howard Seiden, an assistant professor at the University of Toronto family and community medicine department: “If you go to a restaurant, you should have a fouror six-ounce steak. But show me a restaurant that has one, except on a children’s menu. There is too much high-fat, high-protein food available.”
Still, some fats are less dangerous than others. Mono-unsaturated fats (found in olive and rapeseed oils, peanuts and avocados) and polyunsaturated fats (found in corn, sunflower and most other vegetable oils) help to keep cholesterol levels lower. But saturated fats— which come from such things as meat, milk and butter—tend to increase cholesterol. Many medical authorities in Canada and the United States say that a level of below 200 milligrams of cholesterol per decilitre—or about one-fifth of a pint—of blood is unlikely to cause health problems as a result of cholesterol. But with a cholesterol level above 240 milligrams, an individual is at a high risk of having heart problems. As a result, doctors may encourage changes in eating habits as well as treatment with drugs to reduce the risk.
Surgery: But some say that treatment is unlikely to improve the chances of avoiding a heart attack. In a controversial book entitled Heart Failure, published last month, Washington, D.C.-based writer Thomas J. Moore— who wrote an award-winning series on heart bypass surgery for Knight-Ridder newspapers in 1986—claims that experiments to lower the
amount of cholesterol in the body have been disappointing and have done nothing to extend life. After surveying a number of cholesterol studies carried out in the United States, Moore concludes that there was little or no difference between those patients who had been treated for high cholesterol and those who had not. Citing a study which showed that over a llhyear period drugs consistently lowered cholesterol levels in 2,000 men with elevated counts, Moore concludes that, despite the reduction, the chances of the patients suffering a nonfatal heart attack was reduced by only a tiny percentage.
Other researchers have reached similar conclusions.
Dr. John Frank, an associate professor of preventive medicine and biostatistics at the University of Toronto, is one of the four authors of a report to a joint task force of the Ontario ministry of health and the Ontario Medical Association in April that recommended that only people with high-risk factors in their background should have their cholesterol levels tested. Said Frank: “We think it’s certainly inefficient, and it may not be ethical, to screen everybody.” If everybody were screened, said Frank, “the result would be that 25 per cent of the adult population would be under medical treatment for the rest of their lives. And none of the treatments have been shown to add to life expectancy.” At an annual cost of between $600 and $1,200 per person for drugs to reduce high cholesterol levels, Frank said that the expense would be prohibitive—and the benefits uncertain.
But Dr. Alick Little, director of the lipid research clinic program at Toronto’s St. Michael’s Hospital, said that when accurate screening techniques are used and the results are reported to the patient and the family doctor, cholesterol testing is beneficial. As for the expense, Little added: “It’s not my problem. It’s not your problem. Because it’s expensive does not mean you should not advise the public what’s good for them.”
Intake: In the United States, health officials have generally taken a similar position. Four years ago, U.S. health authorities unveiled the National Cholesterol Education Program, which later proposed that everyone over 20 be screened for cholesterol. As well, then-U.S. Surgeon General C. Everett Koop last summer presented a comprehensive 712-page nutrition and health report that included general recommendations for reducing fats, cholesterol and alcohol in the diet. At the time, Koop said that “of greatest concern is our excessive intake of dietary fat and its relationship to risk for
chronic diseases such as coronary heart disease, some types of cancers, diabetes, high blood pressure, strokes and obesity.”
Disease: Still, when the British Medical Association rejected the adoption of acrossthe-board cholesterol screening, the decision reflected concerns that family doctors would rely too heavily on the tests and ignore other risk factors. An association spokesman said studies have shown that high cholesterol levels may not lead to heart disease, while people with low levels may develop heart problems. As a result, “testing everyone would run the
risk of unnecessarily worrying some people while giving others a false sense of security.”
According to many doctors, cholesterol screening tests are not always accurate. In his recent book, Getting to the Heart of Cholesterol, Seiden noted that a U.S. study of 5,000 laboratories showed that almost half produced screening results more than five per cent off the real cholesterol level. Of those, he added, 16 per cent were inaccurate by 10 per cent and eight per cent were 15 per cent off the mark. And that inaccuracy, many experts say, could lead doctors to mistakenly prescribe drugs to people with acceptable cholesterol levels.
Despite that, other researchers support screening because of studies that show a clear correlation between high cholesterol levels and heart disease. In a study carried out at the Honolulu Heart Program, Japanese men living in Japan were compared with those who had moved to Hawaii and California. The study showed that as the Japanese immigrants switched to American-style eating habits and increased their consumption of saturated fats,
their levels of blood cholesterol rose—along with the incidence of coronary disease. As well, Dr. John LaRosa, a researcher at George Washington University Hospital in Washington, D.C., and chairman of the diet committee of the American Heart Association, noted that the study showed diet played a key role. Indeed, the average Japanese man’s cholesterol level is 160, compared with about 210 in an American man. “Genetics isn’t an issue at all here,” said LaRosa. “The idea that diet has no effect on cholesterol levels is absolute nonsense.”
Debate: Many food manufacturers have begun to respond to public concerns about diet. One result has been the popularity of cereals, breads and even snack foods made with oat bran, which many experts say helps to lower cholesterol levels. Other products are advertised as containing no cholesterol. But much of that kind of advertising, warned Seiden, is misleading, because cholesterol is only found in animal products. “People are selling margarine that’s ‘cholesterol-free,’ ” said Seiden. “Well, of course it is. There’s no cholesterol to be found in the plant world.”
Meanwhile, the debate about whether or not lower cholesterol levels result in fewer heart attacks is clearly far from over. Still, despite their differences in opinion about the diet’s relation to heart disease, researchers all agree that maintaining a balanced diet, low in saturated fats, is one of the best ways to stay healthy.
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