By Lionel Tiger
50 years of mainstream nutritional research and hundreds of millions of research dollars have not proved that if you eat a low-fat diet you will live longer.
Certainly your cholesterol levels will be lower. But the link between diet and longevity remains undemonstrated.
The individual steps of what happens in your body when you have cheese or a steak are well known. Your cholesterol levels will elevate. This increases the likelihood that the cholesterol will congeal and attach itself to your arteries and hence clog them-a malady called atherosclerosis. In turn, this will increase the risk of heart disease and heart attacks, which will diminish your expectancy of life.
This is now the utterly accepted medical and nutritional orthodoxy. It has gripped the society, in practice and symbolically, in a form of brain-and-mouth disease.
Countless people are embarked on more or less strict diets in which consumption of a tablespoon of olive oil or pat of butter or hunk of lambchop is the sign not only of a kind of moral depravity but also a reckless disregard for personal survival.
Fat has become an evil weapon.
And people who pursue a monogamous relationship with low-fat carbs and steamed vegetables will regard a date with a steak as equivalent to an act of flamboyant multi-partner adultery.
However, while the individual steps of the effect of fat have been demonstrated, the whole chain of events and their impact has not been. Among people not already at risk for heart disease (like enthusiastic smokers with high blood pressure), according to Taubes and the research of which he is the accountant, the evidence is weak that sharply reduced consumption of saturated fats will increase longevity more than a few weeks, perhaps as much as three months.
As long ago as 1969, the National Heart Institute stated plainly, “It is not known whether dietary manipulation has any effect whatsoever on coronary heart disease.”
In fact, the authors of the report in which this was the conclusive sentence were concerned that, because fat is so important to cell membranes and the brain (which is 70 percent fat), too little fat could be a more serious medical deficit than too much.
There is some evidence that very low cholesterol levels are associated with increased risk for auto accidents and aggressive interaction. Japanese physicians have found that low levels were associated with hemorrhagic stroke, and may counsel their patients to raise their levels.
Since the beginning of the 70s Americans have dropped their consumption of fat to about 34 percent of their calories, down from more than 40 percent beforehand. The incidence of heart disease does not seem to have declined, according to a 10-year study reported in the New England Journal of Medicine in 1998.
Nonetheless, the treatment of heart disease has improved enormously-with more than 5.4 million heart-related procedures compared with 1.2 million in 1979.
This may provide the questionable impression that it is dietary change that is responsible for improved coronary experience.
Furthermore, the replacement of fat-containing foods by carbohydrates may have contributed to an epidemic of obesity and then diabetes among Americans. The term “fat-free” on a product appears to provide permission to consume large portions of it, producing an intake well beyond what seems to be necessary to balance energy consumed and energy used.
Taubes describes how the principal political supporter of the low-fat push in the public arena was Sen. George McGovern, who had himself gone through the severely low-fat Pritikin diet program. McGovern then held two days of committee testimony in 1976 on the subject, and followed up by commissioning a former labor reporter for the Providence Journal, who had no scientific background, to produce the first “Dietary Goals for the United States.”
In 1977 two government agencies took up the fat/death drama, but only one, Agriculture, had public impact when it reiterated the McGovern findings, though ample contrary evidence was available and ignored. The National Academy of Sciences report on the same subject was far less media-worthy, because all it said was that Americans should eat carefully, modestly and less. But it did not emphasize killer fat as the main mealtime Mephistopheles.
The issue became even more complex when the differences became clearer between HDL-good cholesterol-and the bad, LDL.
Some foods increase both at the same time, and some, such as fats like olive oil, stimulate the good flavor of cholesterol.
Little of this is reflected in current government recommendations about what is good to eat. Taubes provides what is in effect an almost hilarious deconstruction of the nutritional effect of a porterhouse steak. After broiling, the meat is about half fat, half protein. Some 51 percent of the fat turns out to be monounsaturated, and 90 percent of that is the kind of benign fat, as in olive oil.
Some 45 percent of the fat is indeed saturated-bad-but one-third of that is stearic acid-neither good or bad. The remaining 4 percent is polyunsaturated-good. In sum, as much as 70 percent of porterhouse fat will improve cholesterol levels compared with an alternative dose of bread, rice, pasta or potatoes.
I’ve argued here before that human beings did not evolve to eat the carbohydrate foods to which peasants had to turn when they could no longer hunt and gather-mainly rice and the grains. A Rutgers graduate student, Matt Sponheimer, published a convincing report in Science several years ago on his analysis of our ancestral teeth, which revealed clear evidence of meat-eaDIAT.
But it is important to be prudent about the material I’ve described here-there will undoubtedly be a major controversy about it, as there should be. I remain very wary of uncritical consumption of high-fat meats such as prime beef, which may indeed in large quantities be difficult for the evolved human system to process (wild game has about 3 percent animal fat, and prime beef closer to 36 percent). And it seems to me that the Atkins-type diets that replace carbohydrates with foods such as bacon double cheeseburgers may be seriously ill-advised.
Nevertheless, humans evolved as omnivores, and we seem well-equipped to eat well-balanced and moderate diets of the foods that were in our environment as we evolved-animals, fish, legumes, fruits, vegetables, nuts, berries and honey when we could get it.
Ample fruits, vegetables and nuts may deliver protective impacts, and are obviously one sign of the current good gastronomic fortune of North Americans-our temperate climate provides us with a good cross-section of an ideal grocery store. And it would be irresponsible to avoid stressing exercise as a factor in healthy nutrition-we were born to run for our dinner.
It appears that people who are committed to low-fat diets almost invariably turn to high-carbohydrate regimes, many components of which provide physiological stimuli to increased hunger. Perhaps a dab of fat will do you, to provide a satisfying experience with food and transform it from battle rations into a calmly sensible aspect of the pursuit of pleasure.
New York Press Volume 14 Issue 18