U.S. dietary guidelines have long recommended that people steer clear of whole milk, and for decades, Americans have obeyed. Whole milk sales shrunk. It was banned from school lunch programs. Purchases of low-fat dairy climbed.
“Replace whole milk and full-fat milk products with fat-free or low-fat choices,” says the Dietary Guidelines for Americans, the federal government's influential advice book, citing the role of dairy fat in heart disease.
Scientists who tallied diet and health records for several thousand patients over ten years found, for example, that contrary to the government advice, people who consumed more milk fat had lower incidence of heart disease.
By warning people against full-fat dairy foods, the United States is “losing a huge opportunity for the prevention of disease,” said Marcia Otto, an assistant professor of epidemiology at the University of Texas and the lead author of large studies published in 2012 and 2013, which were funded by government and academic institutions, not the industry. “What we have learned over the last decade is that certain foods that are high in fat seem to be beneficial.”
This year, as the “Dietary Guidelines for Americans” undergoes one of its periodic updates, the federal bureaucrats writing them must confront what may be the most controversial and weighty question in all of nutrition: does the consumption of so-called saturated fats -- the ones characteristic of meat and dairy products -- contribute to heart disease?
It is, without doubt, an important question. Heart disease is the leading cause of mortality in the United States, and the federal government has long blamed saturated fats.
But the idea that spurning saturated fat will, by itself, make people healthier has never been fully proven, and in recent years repeated clinical trials and large-scale observational studies have produced evidence to the contrary.
After all the decades of research, it is possible that the key lesson on fats is two-fold. Cutting saturated fats from diets, and replacing them with carbohydrates, as is often done, likely will not reduce heart disease risk. But cutting saturated fats and replacing them with unsaturated fats -- the type of fats characteristic of fish, nuts and vegetable oils -- might.
This shift in understanding has led to accusations that the Dietary Guidelines harmed those people who for years avoided fats -- as instructed -- and loaded up excessively on the carbohydrates in foods such as breads, cookies and cakes that were marketed as "low fat."
It also has raised questions about the scientific foundations of the government’s diet advice: To what extent did the federal government, and the diet scientists they relied upon, go wrong? When the evidence is incomplete on a dietary question, should the government refrain from making recommendations?
The dietary science has drawn the skepticism of some on Capitol Hill. On Wednesday, a House committee will air concerns regarding the evidence for the guidelines with Agriculture Secretary Tom Vilsack and Health and Human Services Secretary Sylvia Burwell.
Some, including representatives of the American Heart Association, disagree. In their view, the evidence for the dangers of saturated fats arises from these two ideas: Consuming saturated fats raises levels of so-called “bad” cholesterol in the blood, and higher levels of “bad” cholesterol, in turn, raise risks of heart disease.
In support of their position, they point to the trials of statin drugs, which show that the drugs lower “bad” cholesterol levels and lower risks of heart disease.
There is a “mountain of evidence” explaining how consumption of saturated fats raises the risk of heart disease, said Penny Kris-Etherton, a nutrition professor at Penn State University and a former member of the Dietary Guidelines advisory committee.
The case against saturated fats begins
Over the long tortured course of fat research, it certainly seemed at times that there was strong evidence in the case against saturated fats.
The history of the fat warning is usually traced to the work of Ancel Keys, a scientist at the University of Minnesota, whose study of heart disease in the 1950s startled the medical world.
Keys examined fat consumption and rates of heart disease in various countries. In places where people eat lots of fat, he found high levels of heart disease. One of his famous charts, from 1953, showed that in the United States, where close to 40 percent of the diet came from fat, people suffered a disproportionate number of heart disease deaths. People in Japan and Italy, by contrast, consumed less fat and died of heart disease less often.
In 1953, scientist Ancel Keys linked national fat consumption to heart disease.
To Keys, the data offered proof that Americans could improve their health by reducing the fats in their diets.
"It is now abundantly clear that degenerative heart disease is not an inevitable consequence of aging," he wrote in the 1953 medical journal article.
More evidence was coming. In the '60s, several clinical trials -- from Oslo, Los Angeles, Finland, London and Minnesota -- put his suspicion to the test. Three of the five suggested that he was right.
The Oslo study, for example, studied 412 men who’d previously had a heart attack. Half were given a special diet that was low in saturated fat; the other half was allowed to eat their usual diet, which was richer in saturated and trans fats. The special diet seemed to work: After five years, 64 subjects on the special diet had a relapse of heart disease, while of those eating their regular diet, 90 people did.
Public health authorities, including those in the United States, were soon recommending that people reduce their consumption of saturated fats -- meat, eggs and dairy -- as a means of lowering heart disease risks.
The idea became a part of U.S. official advice in 1977, when the U.S. Dietary Goals, a forerunner of the Dietary Guidelines, embraced the position.
How a hypothesis became dogma
Indeed, the subsequent 40 years of science have proven that, if nothing else, the warning against saturated fats was simplistic.
By itself, cutting saturated fats appears to do little to reduce heart disease. Several evidence reviews -- essentially summing up years of research -- have found no link.
“There is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of coronary heart disease,” said one published in 2010 in the American Journal of Clinical Nutrition.
“Current evidence does not clearly support” guidelines linking saturated fat and heart disease, according to a review of experiments and observational studies published in the Annals of Internal Medicine.
“Saturated fats are not associated” with mortality, heart disease, strokes or type 2 diabetes, a major review in the British Medical Journal reported in July.
The “campaign to reduce fat in the diet has had some pretty disastrous consequences,” Walter Willett, dean of the nutrition department at the Harvard School of Public Health has said. “With more fat-free products than ever, Americans got fatter.”
The case weakens
For the bureaucrats writing the forthcoming Dietary Guidelines, the shifting evidence against saturated fats may be a lesson, experts said: there were weaknesses in each of the three lines of evidence used.
As further scientific review showed, none of the experiments was perfectly designed to assess the danger of saturated fats, and the results in some cases were modest. Moreover, the diets that seemed to show a benefit were not just low in saturated fats, they were also high in unsaturated fats -- the ones common in fish, nuts and vegetable oil.
“We have strong evidence that replacing saturated fats with carbohydrates has no effect on cardiovascular disease,” said Alice Lichtenstein, a Tufts University nutritionist who served this year on the Dietary Guidelines advisory panel.
No more "blanket recommendations"
Even so, the advisory panel has continued to tout the benefits of limiting saturated fat to 10 percent of the diet, and of swapping whole milk for fat-free.
In doing so, the panel is relying on the third piece of the argument against saturated fats, which is that two-step chain of logic: that saturated fats raise the levels of “bad” cholesterol in the blood, and that higher levels of “bad” cholesterol in turn raise the risks of heart disease.
Scientists generally agree on the premises of that argument. The trouble, according to critics, is that connecting the two and drawing the conclusion that saturated fats lead to heart disease is a vast oversimplification, for a handful of reasons.
So what about whole milk?
While nutrition advice is often presented in terms of “macronutrients” -- fats, proteins, carbohydrates -- foods may be more than the sum of their scientific parts.
Milk is a good example.
Repeated research on milk, not funded by the industry but by public institutions, has provided evidence that the fats in milk are, for some reason, different.
The advocates of whole milk allow that it has more calories than its low fat cousins, and for some, that might be reason to avoid it. But the traditional case against whole milk -- based on the risk of heart disease -- has frayed enough now that many argue the Dietary Guidelines should yield to the new findings.
“There is no scientific basis for current dietary advice regarding dairy,” Benatar said. “Fears [about whole milk] are not supported by evidence. The message that it is okay to have whole fat food, including whole fat milk, is slowly seeping into consciousness. But there is always a lag between evidence and changes in attitude.”
http://www.washingtonpost.com/news/...millions-away-from-whole-milk-was-that-wrong/
“Replace whole milk and full-fat milk products with fat-free or low-fat choices,” says the Dietary Guidelines for Americans, the federal government's influential advice book, citing the role of dairy fat in heart disease.
Scientists who tallied diet and health records for several thousand patients over ten years found, for example, that contrary to the government advice, people who consumed more milk fat had lower incidence of heart disease.
By warning people against full-fat dairy foods, the United States is “losing a huge opportunity for the prevention of disease,” said Marcia Otto, an assistant professor of epidemiology at the University of Texas and the lead author of large studies published in 2012 and 2013, which were funded by government and academic institutions, not the industry. “What we have learned over the last decade is that certain foods that are high in fat seem to be beneficial.”
This year, as the “Dietary Guidelines for Americans” undergoes one of its periodic updates, the federal bureaucrats writing them must confront what may be the most controversial and weighty question in all of nutrition: does the consumption of so-called saturated fats -- the ones characteristic of meat and dairy products -- contribute to heart disease?
It is, without doubt, an important question. Heart disease is the leading cause of mortality in the United States, and the federal government has long blamed saturated fats.
But the idea that spurning saturated fat will, by itself, make people healthier has never been fully proven, and in recent years repeated clinical trials and large-scale observational studies have produced evidence to the contrary.
After all the decades of research, it is possible that the key lesson on fats is two-fold. Cutting saturated fats from diets, and replacing them with carbohydrates, as is often done, likely will not reduce heart disease risk. But cutting saturated fats and replacing them with unsaturated fats -- the type of fats characteristic of fish, nuts and vegetable oils -- might.
This shift in understanding has led to accusations that the Dietary Guidelines harmed those people who for years avoided fats -- as instructed -- and loaded up excessively on the carbohydrates in foods such as breads, cookies and cakes that were marketed as "low fat."
It also has raised questions about the scientific foundations of the government’s diet advice: To what extent did the federal government, and the diet scientists they relied upon, go wrong? When the evidence is incomplete on a dietary question, should the government refrain from making recommendations?
The dietary science has drawn the skepticism of some on Capitol Hill. On Wednesday, a House committee will air concerns regarding the evidence for the guidelines with Agriculture Secretary Tom Vilsack and Health and Human Services Secretary Sylvia Burwell.
Some, including representatives of the American Heart Association, disagree. In their view, the evidence for the dangers of saturated fats arises from these two ideas: Consuming saturated fats raises levels of so-called “bad” cholesterol in the blood, and higher levels of “bad” cholesterol, in turn, raise risks of heart disease.
In support of their position, they point to the trials of statin drugs, which show that the drugs lower “bad” cholesterol levels and lower risks of heart disease.
There is a “mountain of evidence” explaining how consumption of saturated fats raises the risk of heart disease, said Penny Kris-Etherton, a nutrition professor at Penn State University and a former member of the Dietary Guidelines advisory committee.
The case against saturated fats begins
Over the long tortured course of fat research, it certainly seemed at times that there was strong evidence in the case against saturated fats.
The history of the fat warning is usually traced to the work of Ancel Keys, a scientist at the University of Minnesota, whose study of heart disease in the 1950s startled the medical world.
Keys examined fat consumption and rates of heart disease in various countries. In places where people eat lots of fat, he found high levels of heart disease. One of his famous charts, from 1953, showed that in the United States, where close to 40 percent of the diet came from fat, people suffered a disproportionate number of heart disease deaths. People in Japan and Italy, by contrast, consumed less fat and died of heart disease less often.
In 1953, scientist Ancel Keys linked national fat consumption to heart disease.
To Keys, the data offered proof that Americans could improve their health by reducing the fats in their diets.
"It is now abundantly clear that degenerative heart disease is not an inevitable consequence of aging," he wrote in the 1953 medical journal article.
More evidence was coming. In the '60s, several clinical trials -- from Oslo, Los Angeles, Finland, London and Minnesota -- put his suspicion to the test. Three of the five suggested that he was right.
The Oslo study, for example, studied 412 men who’d previously had a heart attack. Half were given a special diet that was low in saturated fat; the other half was allowed to eat their usual diet, which was richer in saturated and trans fats. The special diet seemed to work: After five years, 64 subjects on the special diet had a relapse of heart disease, while of those eating their regular diet, 90 people did.
Public health authorities, including those in the United States, were soon recommending that people reduce their consumption of saturated fats -- meat, eggs and dairy -- as a means of lowering heart disease risks.
The idea became a part of U.S. official advice in 1977, when the U.S. Dietary Goals, a forerunner of the Dietary Guidelines, embraced the position.
How a hypothesis became dogma
Indeed, the subsequent 40 years of science have proven that, if nothing else, the warning against saturated fats was simplistic.
By itself, cutting saturated fats appears to do little to reduce heart disease. Several evidence reviews -- essentially summing up years of research -- have found no link.
“There is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of coronary heart disease,” said one published in 2010 in the American Journal of Clinical Nutrition.
“Current evidence does not clearly support” guidelines linking saturated fat and heart disease, according to a review of experiments and observational studies published in the Annals of Internal Medicine.
“Saturated fats are not associated” with mortality, heart disease, strokes or type 2 diabetes, a major review in the British Medical Journal reported in July.
The “campaign to reduce fat in the diet has had some pretty disastrous consequences,” Walter Willett, dean of the nutrition department at the Harvard School of Public Health has said. “With more fat-free products than ever, Americans got fatter.”
The case weakens
For the bureaucrats writing the forthcoming Dietary Guidelines, the shifting evidence against saturated fats may be a lesson, experts said: there were weaknesses in each of the three lines of evidence used.
As further scientific review showed, none of the experiments was perfectly designed to assess the danger of saturated fats, and the results in some cases were modest. Moreover, the diets that seemed to show a benefit were not just low in saturated fats, they were also high in unsaturated fats -- the ones common in fish, nuts and vegetable oil.
“We have strong evidence that replacing saturated fats with carbohydrates has no effect on cardiovascular disease,” said Alice Lichtenstein, a Tufts University nutritionist who served this year on the Dietary Guidelines advisory panel.
No more "blanket recommendations"
Even so, the advisory panel has continued to tout the benefits of limiting saturated fat to 10 percent of the diet, and of swapping whole milk for fat-free.
In doing so, the panel is relying on the third piece of the argument against saturated fats, which is that two-step chain of logic: that saturated fats raise the levels of “bad” cholesterol in the blood, and that higher levels of “bad” cholesterol in turn raise the risks of heart disease.
Scientists generally agree on the premises of that argument. The trouble, according to critics, is that connecting the two and drawing the conclusion that saturated fats lead to heart disease is a vast oversimplification, for a handful of reasons.
So what about whole milk?
While nutrition advice is often presented in terms of “macronutrients” -- fats, proteins, carbohydrates -- foods may be more than the sum of their scientific parts.
Milk is a good example.
Repeated research on milk, not funded by the industry but by public institutions, has provided evidence that the fats in milk are, for some reason, different.
The advocates of whole milk allow that it has more calories than its low fat cousins, and for some, that might be reason to avoid it. But the traditional case against whole milk -- based on the risk of heart disease -- has frayed enough now that many argue the Dietary Guidelines should yield to the new findings.
“There is no scientific basis for current dietary advice regarding dairy,” Benatar said. “Fears [about whole milk] are not supported by evidence. The message that it is okay to have whole fat food, including whole fat milk, is slowly seeping into consciousness. But there is always a lag between evidence and changes in attitude.”
http://www.washingtonpost.com/news/...millions-away-from-whole-milk-was-that-wrong/
