Good News Adds Up in Heart Study
A healthful diet, moderate physical exercise, no smoking and limited alcohol consumption can lower women’s risk of heart disease by up to 83% and stroke by 75%, Boston researchers report today.
Although each of these lifestyle guidelines has been known to be effective in reducing risk of heart disease individually, researchers say they were surprised by the enormous benefits of collective lifestyle modifications. This amount of risk reduction is rarely if ever achievable through diet, exercise, medication or any other single lifestyle modification alone, study leaders said.
The results from the continuing Nurses’ Health Study, reported in today’s New England Journal of Medicine, provide the strongest evidence yet that relatively simple changes in lifestyle can lead to dramatic reductions in deaths from heart attack--the leading killer of both women and men. One of every two women’s deaths in the U.S. is the result of cardiovascular disease.
That these are risk factors is “old news,” said Dr. Meir Stampfer, of the Harvard School of Public Health, the study’s lead author. “The new part is putting it all together and quantifying the benefits. Over 80% of these heart attacks could be prevented. . . . Taken together with medical intervention, you could very drastically reduce the burden of heart disease in this country.”
Researchers say there is every reason to believe that the results would also apply to men. “We’re not asking people to run marathons. . . . Everyone could achieve these goals,” said Dr. Walter Willett, chairman of Nutrition at Harvard School of Public Health and a co-author of the study.
Women with the lowest risk were nonsmokers who exercised at least 30 minutes per day, were not overweight (having a body mass index of 25 or less), and who consumed an average of half an alcoholic beverage per day. They were also in the top 40% of the group in terms of healthful diet.
Such diets are high in cereal fiber, fish and folic acid found in citrus fruits and leafy green vegetables--and low in trans-fatty acids found in many margarines and commercially fried foods and foods that raise blood glucose levels such as white bread, potatoes and pasta. Healthful diets also have a high ratio of polyunsaturated to saturated fats.
The American Heart Assn. estimates that 1.1 million Americans will have heart attacks this year and that more than 40% of those attacks will result in death. Although men on average suffer heart attacks about 10 years earlier than women, cardiovascular disease--which also includes strokes--has claimed the lives of more women each year since 1984.
Because women generally believe breast cancer to be a bigger threat to their health, “many women have delayed intervention and treatment of heart disease, so it’s really important to dispel that myth,” said Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women’s Hospital in Boston, where the study is based.
The Nurses’ Health Study began in 1976, when 121,700 women ages 30 through 55 first provided detailed answers to a questionnaire. The study covers 11 states, including California, and is the longest women’s health study ever initiated.
Stampfer and his colleagues have followed 84,129 female registered nurses for 14 years in the heart disease portion of the study. They chose women who were initially free of cardiovascular disease, cancer and diabetes and followed them by questionnaire every two years.
During the course of the heart disease study, 296 of the women died from cardiovascular disease and 832 had nonfatal heart attacks.
The study found cigarette smoking to be the most important individual risk factor. Women who smoke 15 or more cigarettes a day were more than five times as likely to suffer heart attacks as women who never smoked.
The researchers said that, of the risk factors, diet is probably the least understood by the public. “People [think] that ‘fat is bad’ and ‘low-fat’ is healthy,” said Stampfer. “ It’s not that simple.”
For example, Stampfer said, bagels raise blood glucose levels, making them a questionable choice for a health food even though they are low in fat.
According to Willett, some types of fat are far worse than others and unsaturated fats, such as those found in vegetable oils, can actually prove to be healthful.
The study is important, experts said, because it focused on behaviors that women can modify themselves. Although recent advances in drugs to treat hypertension and cholesterol levels have proved beneficial, these interventions require prescriptions, may be costly and may have unwanted side effects. In contrast, the behavior changes recommended by the researchers are inexpensive, have no side effects, and may also reduce the risk of other diseases, including cancer and diabetes.
If all study participants had been following the lowest-risk pattern of behaviors, more than 80% of all heart attacks among the group might have been prevented, according to the study.
Unexpectedly, only 3% of the study population fell into the lowest-risk group. This surprised researchers who say that the nurses in the study are likely to be healthier on average than the population as a whole. Dr. Ronald Krauss, head of molecular medicine at Lawrence Berkeley National Laboratory, commented, “It tells us that we really have a ways to go to promote” lifestyle changes.
Krauss said the biggest weakness in the study is that it does not account for medical treatment of high blood pressure and high cholesterol levels. Since nurses are more likely to be receiving treatment for these conditions, risk reduction attributable to lifestyle alone may be overestimated, he said.
However, Krauss and the study researchers see the benefit of lifestyle factors as complementary to medical treatment. “It’s a good message. We are coming more into an understanding that global risk factors are the most important issue, not any single component,” Krauss said.
Manson said that education on the benefits of good nutrition and exercise should be a high priority in public health and part of patient-physician encounters: “Heredity is not destiny when it comes to risk of heart disease and this study clearly illustrates the benefits of lifestyle modification. It is important that people understand that heart disease is largely preventable.”
