Updated: Feb 2, 2019
To review major points from previous articles (here and here), Americans have been advised to categorically avoid foods high in saturated fats, such as cheese, red meat, full fat milk, coconut oil, etc. based on the theory that saturated fats increase cholesterol in the blood stream. Because cholesterol had been isolated from plaques that constrict blood flow in major arteries of the heart, it was believed then that saturated fat should be eliminated from our diets. This theory is known as the diet-heart hypothesis.
There have been several studies executed in attempt to prove this theory correct. However, as we saw last week, when analyzed collectively, the data indicate that there is NO connection between reducing saturated fat in the diet and saving lives. In this weeks article, I will demonstrate that, in fact, avoiding saturated fats not only provides zero benefit, but it can also causes harm and actually increases the risk of dying.
Simple analysis of available data demonstrate that reduction of saturated fat in the diet leads to an increased risk of all-cause mortality. When analyzing deaths from JUST cardiovascular causes (heart attack, stroke, etc.), some studies may have shown marginal benefits, if at all; However, looking at deaths from all causes, and not restricting to just cardiovascular deaths, the studies show potential harm from reducing saturated fat in the diet. This fact didn't stop proponents of the diet-heart hypothesis from parading the data as support for their cause, despite the potential harms of recommending a diet low in saturated fat.
The first, and most highly publicized trial looking at the effects of reducing saturated fat in the diet was the Anti-Coronary Club Trial, launching in the late 1950's. The study put 1100 middle aged men in a "prudent diet" which reduced saturated fat from beef, lamb, and pork and replacing it with one ounce of daily vegetable oil. The results, published in 1966 reported that the diet protected against heart disease, claiming that the prudent diet had only one third the heart disease of the controls.
However, just nine months later, the investigators published a second, lesser known article, which revealed that 26 members of the club and died during the trial, compared to only six from the control group, who had not been on the prudent diet. Eight members of the club died of heart attack, but zero members of the control group died from heart attack.
So if eight members of the reduced saturated "prudent diet" club versus zero in the control group, then why did the researchers report a one third reduction of heart disease? The researchers defined heart disease as improvements in heart-disease risk factors, such as cholesterol, weight, and blood pressure. However, improvement in these risk factors did not translate to saving lives, and in fact, led to an increase in death from all causes.
The above narrative of the Anti Coronary Club Trial exemplifies the issue with the dietary fat hypothesis as the mortality problem continued to plague future trials.
A study of 850 Veterans replaced saturated fats in butter, milk, ice cream, and cheese with corn, soybean, safflower, and cottonseed oil. The control group was served their normal diet in which fat quantity and type hadn't changed. The first group saw cholesterol drop 13 percent lower than controls and only 66 died from heart disease versus 96 in the control group on the placebo diet.
These initial results seemed promising until we look at deaths from all causes and not just cardiovascular deaths. Worryingly, 31 participants in the cholesterol lowering diet died of cancer, compared to only seventeen in the controls. Overall, the cholesterol lowering diet failed to increase longevity as the risk of death was effectively equal after comparing results between the two groups.
Also, the study was riddled with issues that would skew the results in favor of the intervention group. Namely, the rate of heavy smoking was twice as high in the placebo group. Moreover, the results were skewed as only half the patients in the intervention group actually completed the trial since many patients got well enough to be discharged from the hospital, causing them to drop out from the trial by default.
Despite these issues, because researches were focused on the role of saturated fat in the diet, the endpoint that the medical community chose to focus on was whether or not the intervention of the trial had appeared to reduce the risk of heart attacks alone.
The Minnesota Coronary Survey - As mentioned in last week's article, this trial included 9000 men and women and yielded results so devastating for the diet-heart hypothesis that the investigators hid the data for 16 years because researchers were "disappointed in the way it came out." Overall, researchers were unable to find any differences between the low saturated diet group and the control group for cardiovascular deaths, though heart attacks surprisingly increased in women. Cancer was also higher in the diet group, which had 269 deaths overall versus 206 deaths in the control group.
Framingham Study- Men with the lowest levels of cholesterol, below 190 mg/dl were more than three times as likely to get colon cancer as men with cholesterol greater than 220. They were nearly twice as likely to get cancer than those with cholesterol over 280.
Multiple Risk Factor Intervention Trial (MRFIT) - Investigators sampled cholesterol levels of 362,000 middle aged American men. After doing so, they took the 12,000 men with the highest levels of cholesterol and putting them on a low fat, low-cholesterol diet. The men were followed for 7 years at a cost of $115 million. The results showed higher deaths among those men who had been counseled to eat a low fat diet and to quit smoking. In 1997, the 16 year follow up to this study showed that the treatment group had higher rates of lung cancer even though 21% of them had successfully quit smoking versus 6% in the control group.
Other Research: In 1974, the principle investigators of six on-gong population studies reported in The Lancet found that men who had developed colon cancer had surprisingly low cholesterol levels. Swiss Red Cross researchers reached the same result two years earlier, citing polyunsaturated fats in the form of vegetable oils as the possible culprit. In 1978, Hungarian, British, and Czech researchers reported similar findings from a clinical trial studying 16,000 people. By 1980, the link between cholesterol lowering diets and cancer of all types was appearing in study after study.
Despite the mounting evidence over the last several decades indicating the downsides of avoiding saturated fats in the diet, major medical associations continue to recommend decreasing saturated fat in the diet as a 'heart healthy diet.'
Last week, we saw that there is no correlation between the reduction of saturated fat in the diet and saving lives. This week, we looked at the risks of avoiding saturated fat in the diet. Next week, we will analyze the health benefits of adding saturated fat to your diet. Stay tuned!
Dr. Ram, Pharm.D.
Get next week’s Big Ideas directly in your mailbox by signing up here.