Looking at the studies behind the diet antagonist

“When looking at the average American diet, overall percentage of calories from fat has actually decreased and continues in a downward trend yet heart disease is still one of the leading  causes of death for North Americans.

It was Ancel Keys who first proposed the low-fat dogma in the 1950s. His Seven Countries Study examined the association between increased serum cholesterol and coronary heart disease (CHD) as well as proposing the idea that a diet low in animal fat protected against heart disease and one high in animal fat would lead to heart disease. As a result of this study, the American Heart Association informed the general public that a diet including butter, lard, eggs and beef would lead to CHD, and the government would then recommend adopting a low fat diet. Since then, many hundreds of medical papers have been published in relation to the Seven Countries Study and it is generally accepted by health care professionals as ‘very useful’.

The issue here is that Keys had collected data from 22 countries, but only chose to analyze data from seven of those countries. A decision that has resulted in much criticism in more recent years. Figure 1. presents the data from all 22 countries, comparing intake of fat calories to mortality from heart disease. When all the data is analyzed, the correlation doesn’t exist. Numerous studies have shown otherwise throughout the years, yet Keys has received far more publicity than the alternate views. The National Institute of Health spent several hundred million dollars trying to show a connection between fat intake and heart disease, and despite their attempts, they have failed. Five major studies during this time failed to show such a link, though a sixth concluded that if a cholesterol lowering drug could prevent heart attacks than a low-fat and low-cholesterol diet should do the same. Thus the low-fat dogma continues to this day.

In 2009, a meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease followed 347,747 subjects where 11,006 developed CHD or suffered a stroke. Intake of saturated fat was not found to be associated with an increased risk of CHD, stroke or CVD. In 2009, Mente et al. published a systematic review of a randomized clinical trial and showed an increased consumption of marine omega-3 fatty acids and also showed that Mediterranean diet patterns were associated with a significantly lower risk of CHD. Higher intake of polyunsaturated or total fats were not significantly associated with CHD and the link between saturated fats and CHD received a Bradford Hill score of two out of four signifying weak evidence of a causal relationship.

Another study done in 2009 by the Cochrane Collaboration published a meta-analysis of clinical trials that either reduced or modified dietary fat for preventing cardiovascular disease. While twenty-seven studies met the criteria, no significant effect on total or cardiovascular mortality was found between the intervention and control groups. In 2006, the Women’s Health Initiative conducted a study of 48,835 women over eight years, and there was no significant difference between intervention and control.

In 1989, the Diet and Reinfarction trial studied 2,033 men over two years, and there were no significant differences in ischaemic heart disease between intervention and control. In the same year, the Minnesota Coronary Survey surveyed 4,393 men and 4,664 women in a double-blind experiment over a four year period and reported no significant reduction in cardiovascular events or total deaths from the treatment diet.

In 1972, the Finnish Mental Hospital conducted a study over 12 years and saw a decrease in coronary heart disease death in men (5.7 deaths/1000 persons vs. 13 deaths/1000 person in the control), but found a non-significant decrease in CHD in women. In 1969, the Los Angeles Veteran’s Trial did an eight-year study of 846 subjects and found a non-significant difference in primary endpoints (sudden cardiac death or myocardial infarction). In 1968, the Oslo Heart Study of 412 men over five years saw a slight decrease in CHD with intervention, but many other dietary interventions accompanied the low saturated fat diet and when stratified by age the results were only significant in subjects younger than 60. Examples of similar studies are endless.

When looking at the average American diet, overall percentage of calories from fat (especially saturated fat) has actually decreased and continues in a downward trend. Yet in spite of this, obesity and type II diabetes continue to skyrocket and heart disease is still one of the leading  causes of death for North Americans. Even many of today’s experts will say that low-fat is blown out of proportion, and that fats such as virgin coconut oil (known for its health benefits as well as increasing good cholesterol and lowering bad cholesterol) is 92 per cent saturated fat.

It is unfortunate that “low-fat” is still promoted since fats from animals and vegetable sources provide us with a concentrated source of energy and building blocks for cell membranes and hormones. In addition, fat as part of a meal slows down absorption which provides us with satiety so we can go longer without feeling hungry. Fat also plays an important role as a carrier for many fat-soluble vitamins such as A, D, E and K. Dietary fat is also needed for mineral absorption and a host of other processes. If that isn’t convincing enough, mother’s milk also provides a higher proportion of cholesterol than almost any other food and it contains over 50% of our calories from fat (much of it being saturated). Both cholesterol and saturated fat are absolutely essential for growth of babies and children, especially in the development of the brain. In addition, we must ask ourselves why, if fat is so bad, does our body store excess energy as saturated body fat? In fact, when we burn body fat for energy through exercise or diet we are literally consuming large amounts of saturated fat. All fat goes through the same processes in your body in order to be converted to energy, therefore saturated fat through diet is no different than fat stored in our bodies. If saturated fat did clog our arteries, than losing weight would put us at greater risk of heart disease, and we know this simply is not true. So even from an evolutionary perspective it is difficult to rationalize why fat, especially saturated, is ‘bad’ for us.

Why again is it that conventional wisdom tells us to reduce out fat intake, particularly saturated fats from animal sources?

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