Chances a low-fat diet will help? Slim and none

Chances a low-fat diet will help? Slim and none By Gina Kolata The New York Times THURSDAY, FEBRUARY 9, 2006 NEW YORK The largest study ever to ask whether a low-fat diet reduces the risk of getting cancer or heart disease has found that the diet has no effect. The $415 million federal study involved nearly 49,000 women aged 50 to 79 who were followed for eight years. In the end, those assigned to a low-fat diet had the same rates of breast cancer, colon cancer, heart attacks and strokes as those who ate whatever they pleased, researchers reported Wednesday. "These studies are revolutionary," said Dr. Jules Hirsch, physician in chief emeritus at Rockefeller University in New York City, who has spent a lifetime studying the effects of diets on weight and health. "They should put a stop to this era of thinking that we have all the information we need to change the whole national diet and make everybody healthy." The study, published in the Journal of the American Medical Association on Wednesday, was not just an ordinary study, said Dr. Michael Thun, who directs epidemiological research for the American Cancer Society. It was so large and so expensive, Thun said, that it was "the Rolls-Royce of studies." As such, he added, it is likely to be the final word. "We usually have only one shot at a very large-scale trial on a particular issue," he said. The study was part of the Women's Health Initiative of the National Institutes of Health, the program that showed that hormone therapy after menopause might have more risks than benefits. The results, the study investigators agreed, do not justify recommending low-fat diets to the public to reduce their heart disease and cancer risk. The investigators added that the best dietary advice was to follow federal guidelines for healthy eating - less saturated fats and trans fats, more grains and more fruits and vegetables. Not everyone was convinced. Some, like Dr. Dean Ornish, a longtime promoter of low-fat diets and president of the Preventive Medicine Research Institute in Sausalito, California, said that the women did not reduce their fat to low enough levels or eat enough fruits and vegetables. He also said the study, even at eight years, did not give the diets enough time. Others said that diet could still make a difference, at least with heart disease, if people were to eat the so-called Mediterranean diet, low in saturated fats like butter and high in oils like olive oil. The women in the study reduced all kinds of fat. The diets studied "had an antique patina," said Dr. Peter Libby, a cardiologist and professor at Harvard Medical School. These days, Libby said, most people have moved on from the idea of controlling total fat to the idea that people should eat different kinds of fat. But the Mediterranean diet has not been subjected to a study of this scope, researchers said. Barbara Howard, an epidemiologist at MedStar Research Institute, a nonprofit hospital group, and a principal investigator in the study, said people should realize that diet alone was not enough to stay healthy. "We are not going to reverse any of the chronic diseases in this country by changing the composition of the diet," Howard said. "People are always thinking it's what they ate. They are not looking at how much they ate or that they smoke or that they are sedentary." Except for not smoking, the evidence for advice on what makes a healthy lifestyle is largely indirect, Howard said. Most medical researchers agree, however, that it also makes sense for people to eat well, control their weight and get regular exercise. That is also what the cancer society recommends. Thun, who described the study's results as "completely null over the eight-year follow-up for both cancers and heart disease," said his group had no plans to suggest that low-fat diets were going to protect against cancer. Others cautioned against being too certain that any particular diet would markedly improve health and noted that whether someone developed a chronic disease might not be entirely under their control - genetics also matters. David Freedman, a statistician at the University of California, Berkeley, who is not connected with the study but has written books on the design and analysis of clinical trials, said the results should be taken seriously. In this case, the diet study addressed a tricky problem. For decades, many scientists have said, and many in the public have believed, that what people eat determines how likely they are to get a chronic disease. But that has been hard to prove. Studies of dietary fiber and colon cancer failed to find that fiber was protective, and studies of vitamins thought to protect against cancer didn't show an effect. Gradually, many cancer researchers began questioning large parts of the diet-cancer hypothesis, but it has retained a hold on the public imagination. "Nothing fascinates the American public so much as the notion that what you eat rather than how much you eat affects your health," said Libby. The new study found that women who were randomly assigned to follow a low-fat diet ate significantly less fat over the next eight years. But they had just as much breast and colon cancer and just as much heart disease. The women were not trying to lose weight, and their weights remained fairly steady. But their experiences with the diets allowed researchers to question some popular notions about diet and obesity. There is a common belief that Americans get fat because they eat too many carbohydrates. The idea is that a high-carbohydrate, low-fat diet leads to weight gain, higher insulin and blood glucose levels, and more diabetes, even if the calories are the same as in a higher-fat diet. That did not happen in the study. Others have said the opposite: that low-fat diets enable people to lose weight naturally. But again, that belief was not supported by the data in the study. As for heart disease risk factors, the only one affected was LDL cholesterol, which increases heart disease risk. The levels were slightly higher in women eating the higher-fat diet, but not high enough to make a noticeable difference in their risk of heart disease. Although all the study participants were women, the colon cancer and heart disease results should also apply to men, said Dr. Jacques Rossouw, the project officer for the Women's Health Initiative. NEW YORK The largest study ever to ask whether a low-fat diet reduces the risk of getting cancer or heart disease has found that the diet has no effect. The $415 million federal study involved nearly 49,000 women aged 50 to 79 who were followed for eight years. In the end, those assigned to a low-fat diet had the same rates of breast cancer, colon cancer, heart attacks and strokes as those who ate whatever they pleased, researchers reported Wednesday. "These studies are revolutionary," said Dr. Jules Hirsch, physician in chief emeritus at Rockefeller University in New York City, who has spent a lifetime studying the effects of diets on weight and health. "They should put a stop to this era of thinking that we have all the information we need to change the whole national diet and make everybody healthy." The study, published in the Journal of the American Medical Association on Wednesday, was not just an ordinary study, said Dr. Michael Thun, who directs epidemiological research for the American Cancer Society. It was so large and so expensive, Thun said, that it was "the Rolls-Royce of studies." As such, he added, it is likely to be the final word. "We usually have only one shot at a very large-scale trial on a particular issue," he said. The study was part of the Women's Health Initiative of the National Institutes of Health, the program that showed that hormone therapy after menopause might have more risks than benefits. The results, the study investigators agreed, do not justify recommending low-fat diets to the public to reduce their heart disease and cancer risk. The investigators added that the best dietary advice was to follow federal guidelines for healthy eating - less saturated fats and trans fats, more grains and more fruits and vegetables. Not everyone was convinced. Some, like Dr. Dean Ornish, a longtime promoter of low-fat diets and president of the Preventive Medicine Research Institute in Sausalito, California, said that the women did not reduce their fat to low enough levels or eat enough fruits and vegetables. He also said the study, even at eight years, did not give the diets enough time. Others said that diet could still make a difference, at least with heart disease, if people were to eat the so-called Mediterranean diet, low in saturated fats like butter and high in oils like olive oil. The women in the study reduced all kinds of fat. The diets studied "had an antique patina," said Dr. Peter Libby, a cardiologist and professor at Harvard Medical School. These days, Libby said, most people have moved on from the idea of controlling total fat to the idea that people should eat different kinds of fat. But the Mediterranean diet has not been subjected to a study of this scope, researchers said. Barbara Howard, an epidemiologist at MedStar Research Institute, a nonprofit hospital group, and a principal investigator in the study, said people should realize that diet alone was not enough to stay healthy. "We are not going to reverse any of the chronic diseases in this country by changing the composition of the diet," Howard said. "People are always thinking it's what they ate. They are not looking at how much they ate or that they smoke or that they are sedentary." Except for not smoking, the evidence for advice on what makes a healthy lifestyle is largely indirect, Howard said. Most medical researchers agree, however, that it also makes sense for people to eat well, control their weight and get regular exercise. That is also what the cancer society recommends. Thun, who described the study's results as "completely null over the eight-year follow-up for both cancers and heart disease," said his group had no plans to suggest that low-fat diets were going to protect against cancer. Others cautioned against being too certain that any particular diet would markedly improve health and noted that whether someone developed a chronic disease might not be entirely under their control - genetics also matters. David Freedman, a statistician at the University of California, Berkeley, who is not connected with the study but has written books on the design and analysis of clinical trials, said the results should be taken seriously. In this case, the diet study addressed a tricky problem. For decades, many scientists have said, and many in the public have believed, that what people eat determines how likely they are to get a chronic disease. But that has been hard to prove. Studies of dietary fiber and colon cancer failed to find that fiber was protective, and studies of vitamins thought to protect against cancer didn't show an effect. Gradually, many cancer researchers began questioning large parts of the diet-cancer hypothesis, but it has retained a hold on the public imagination. "Nothing fascinates the American public so much as the notion that what you eat rather than how much you eat affects your health," said Libby. The new study found that women who were randomly assigned to follow a low-fat diet ate significantly less fat over the next eight years. But they had just as much breast and colon cancer and just as much heart disease. The women were not trying to lose weight, and their weights remained fairly steady. But their experiences with the diets allowed researchers to question some popular notions about diet and obesity. There is a common belief that Americans get fat because they eat too many carbohydrates. The idea is that a high-carbohydrate, low-fat diet leads to weight gain, higher insulin and blood glucose levels, and more diabetes, even if the calories are the same as in a higher-fat diet. That did not happen in the study. Others have said the opposite: that low-fat diets enable people to lose weight naturally. But again, that belief was not supported by the data in the study. As for heart disease risk factors, the only one affected was LDL cholesterol, which increases heart disease risk. The levels were slightly higher in women eating the higher-fat diet, but not high enough to make a noticeable difference in their risk of heart disease. Although all the study participants were women, the colon cancer and heart disease results should also apply to men, said Dr. Jacques Rossouw, the project officer for the Women's Health Initiative. NEW YORK The largest study ever to ask whether a low-fat diet reduces the risk of getting cancer or heart disease has found that the diet has no effect. The $415 million federal study involved nearly 49,000 women aged 50 to 79 who were followed for eight years. In the end, those assigned to a low-fat diet had the same rates of breast cancer, colon cancer, heart attacks and strokes as those who ate whatever they pleased, researchers reported Wednesday. "These studies are revolutionary," said Dr. Jules Hirsch, physician in chief emeritus at Rockefeller University in New York City, who has spent a lifetime studying the effects of diets on weight and health. "They should put a stop to this era of thinking that we have all the information we need to change the whole national diet and make everybody healthy." The study, published in the Journal of the American Medical Association on Wednesday, was not just an ordinary study, said Dr. Michael Thun, who directs epidemiological research for the American Cancer Society. It was so large and so expensive, Thun said, that it was "the Rolls-Royce of studies." As such, he added, it is likely to be the final word. "We usually have only one shot at a very large-scale trial on a particular issue," he said. The study was part of the Women's Health Initiative of the National Institutes of Health, the program that showed that hormone therapy after menopause might have more risks than benefits. The results, the study investigators agreed, do not justify recommending low-fat diets to the public to reduce their heart disease and cancer risk. The investigators added that the best dietary advice was to follow federal guidelines for healthy eating - less saturated fats and trans fats, more grains and more fruits and vegetables. Not everyone was convinced. Some, like Dr. Dean Ornish, a longtime promoter of low-fat diets and president of the Preventive Medicine Research Institute in Sausalito, California, said that the women did not reduce their fat to low enough levels or eat enough fruits and vegetables. He also said the study, even at eight years, did not give the diets enough time. Others said that diet could still make a difference, at least with heart disease, if people were to eat the so-called Mediterranean diet, low in saturated fats like butter and high in oils like olive oil. The women in the study reduced all kinds of fat. The diets studied "had an antique patina," said Dr. Peter Libby, a cardiologist and professor at Harvard Medical School. These days, Libby said, most people have moved on from the idea of controlling total fat to the idea that people should eat different kinds of fat. But the Mediterranean diet has not been subjected to a study of this scope, researchers said. Barbara Howard, an epidemiologist at MedStar Research Institute, a nonprofit hospital group, and a principal investigator in the study, said people should realize that diet alone was not enough to stay healthy. "We are not going to reverse any of the chronic diseases in this country by changing the composition of the diet," Howard said. "People are always thinking it's what they ate. They are not looking at how much they ate or that they smoke or that they are sedentary." Except for not smoking, the evidence for advice on what makes a healthy lifestyle is largely indirect, Howard said. Most medical researchers agree, however, that it also makes sense for people to eat well, control their weight and get regular exercise. That is also what the cancer society recommends. Thun, who described the study's results as "completely null over the eight-year follow-up for both cancers and heart disease," said his group had no plans to suggest that low-fat diets were going to protect against cancer. Others cautioned against being too certain that any particular diet would markedly improve health and noted that whether someone developed a chronic disease might not be entirely under their control - genetics also matters. David Freedman, a statistician at the University of California, Berkeley, who is not connected with the study but has written books on the design and analysis of clinical trials, said the results should be taken seriously. In this case, the diet study addressed a tricky problem. For decades, many scientists have said, and many in the public have believed, that what people eat determines how likely they are to get a chronic disease. But that has been hard to prove. Studies of dietary fiber and colon cancer failed to find that fiber was protective, and studies of vitamins thought to protect against cancer didn't show an effect. Gradually, many cancer researchers began questioning large parts of the diet-cancer hypothesis, but it has retained a hold on the public imagination. "Nothing fascinates the American public so much as the notion that what you eat rather than how much you eat affects your health," said Libby. The new study found that women who were randomly assigned to follow a low-fat diet ate significantly less fat over the next eight years. But they had just as much breast and colon cancer and just as much heart disease. The women were not trying to lose weight, and their weights remained fairly steady. But their experiences with the diets allowed researchers to question some popular notions about diet and obesity. There is a common belief that Americans get fat because they eat too many carbohydrates. The idea is that a high-carbohydrate, low-fat diet leads to weight gain, higher insulin and blood glucose levels, and more diabetes, even if the calories are the same as in a higher-fat diet. That did not happen in the study. Others have said the opposite: that low-fat diets enable people to lose weight naturally. But again, that belief was not supported by the data in the study. As for heart disease risk factors, the only one affected was LDL cholesterol, which increases heart disease risk. The levels were slightly higher in women eating the higher-fat diet, but not high enough to make a noticeable difference in their risk of heart disease. Although all the study participants were women, the colon cancer and heart disease results should also apply to men, said Dr. Jacques Rossouw, the project officer for the Women's Health Initiative.