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The widely-believed notion that low-fat diets are good for your health went “poof” this week—although the busting of that myth shouldn’t be news to regular readers of this column.
Low-fat diets didn’t reduce the risk of cardiovascular disease, colorectal cancer or invasive breast cancer, according to three large studies published this week in the Journal of the American Medical Association.
The researchers divided 48,835 women into two groups based on diet-- one group with 19,541 women consumed a low fat diet and the other group with 29,294 women consumed their usual diets—and followed the women for 8.1 years.
The most significant result of the $415 million study is that low-fat diets don’t reduce heart disease risk. As the researchers put it, “Over [an average] of 8.1 years, a dietary intervention that reduced total fat intake and increased intake of vegetables, fruits and grains did not significantly reduce the risk of coronary heart disease, stroke or cardiovascular disease in postmenopausal women and achieved only modest effects on cardiovascular risk factors…”
Low-fat diets didn’t even improve heart health among the population of women who had heart disease at the beginning of the study. In fact, the low-fat diet regimen was associated with a slightly increased risk of heart disease among these women.
Think about that the next time you turn down the scrumptious banana-pecan French toast with a side of sausage in favor of choking down some tasteless low-fat cereal with skim milk.
So how did the low-fat myth come to be so widely accepted by the public in the first place? For the last 30 years we’ve been constantly bombarded with the message that low-fat is healthy—a message first broadcast by government and public health nannies, and then reinforced on a daily basis by the food industry selling low-fat products at high prices and by pharmaceutical companies selling cholesterol-lowering drugs in an effort to turn us into a “Lipitor Nation.” 
But as has been previously pointed out in this column, scientific study has never supported the dietary propaganda thrust upon us during the past three decades.
Politically correct dietary theory, for example, postulates that high-fat diets—particularly diets high in animal and saturated fats—can raise cholesterol levels to unhealthy levels. But in the much-vaunted Framingham Heart Study involving 5,200 men and women who have been extensively studied in over 1,000 published reports since 1948, high cholesterol levels were not associated with increased heart disease risk after age 47.
After age 47, in fact, those whose cholesterol went down had the highest risk of a heart attack. “For each 1 mg/dl drop of cholesterol there was an 11 percent increase in coronary and total mortality,” reported the study's authors.
There are also the data from the ongoing highly-touted Nurses Health Study involving about 90,000 nurses studied since 1976 by Harvard University researchers. A 1997 interim report published in the New England Journal of Medicine reported that total fat intake, animal fat intake, saturated fat intake and cholesterol intake weren’t associated with coronary heart disease.
Then just last a month, a study published in the Jan. 4 Journal of the American Medical Association involving the same group of women in the current study reported that low fat diets were associated with only moderate and temporary weight loss—an average of 4.8 pounds after the first year, after which most of the weight was regained.
None of this is to say that there aren’t some people with certain genetic backgrounds or medical conditions who might benefit from certain physician-prescribed dietary changes, but generally speaking, low-fat diets don’t appear to confer any significant health benefits that are detectable on a population scale.
“Low-fat,” of course, is not the only dietary myth of the last 30 years that has been debunked—low-salt and high-fiber diets have also been exposed as junk science.
A 2005 analysis of 13 previous studies involving 725,000 individuals published in the Dec. 14 Journal of the American Medical Association reported that high fiber diets did not reduce the risk of colon cancer.
Since 1995, 10 studies have examined whether lower sodium diets produce health benefits. Not a single one of those studies showed that lower sodium diets improved health outcomes for the general population.
What are some other dietary myths that may soon go by the wayside? The sugar scare is a prime candidate. Researchers have been trying for years to link sugar consumption with type 2 diabetes, and obesity in adults and children—without success .
Another endangered scare involves so-called “trans fats”—vegetables oils altered to be firm at room temperature. In much the same mindless fashion that we were goaded into abandoning butter in the 1970s for high-trans fat margarines, we are now being pushed to consume only low-trans fat margarines—even though no evidence indicates that trans fats are harmful or that a diet low in trans fats  provides any health benefits.
The unfortunate fact is that, when it comes to diet and health, we’ve been misinformed, ripped off and unnecessarily medicated by junk scientists, behavior-control nannies and unscrupulous marketers in the government, public health community and the food and pharmaceutical industries. And, of course, let’s not forget the media that seldom miss opportunities to pump health scares and scams.