"For decades, we have been told the avoid fats in our diet at all costs. We were told to consume a low fat diet and to replace fats with healthy whole grains and carbohydrates. We were told to avoid the consumption of animal product because saturated fats were the cause of heart disease. Like the good citizens we are, we listened to what our government advised, and now the average American consumes 152 pounds of sugar and 146 pounds of flour per year. Almost 20 percent of our daily calories come from sugar-sweetened beverages like soda, sports drinks, sweetened coffees and teas, and juice. In a dramatic study in the journal Circulation, researchers attributed 184,000 deaths each year to the effects of drinking these sugary concoctions. These drinks have been proven to cause obesity, heart disease, type 2 diabetes, and cancer." - Dr. Mark Hyman, Eat Fat, Get Thin
In the course of this article (Part 1), I will highlight:
1. Why fats, and particularly saturated fat, became the ugly step child our diets
2. Why the science and the logic behind avoiding fats is fundamentally flawed
Next week's article (Part 2) will be about:
3. What the best science available actually says about saturated fats
Why We Hate Fat, an Intimate History
As a quick primer, saturated fat is the type of fat found in butter, lard, coconut oil, full fat milk, cheese, eggs, and red meat. We have been told that we should be categorically avoiding these foods to maintain a healthy heart and prevent heart attacks. As Americans, we have faithfully followed these recommendations, thus causing a boom in sales of "fat-free" foods. However, instead of preventing heart disease, the avoidance of saturated fat has, in fact, accelerated the heart disease epidemic we are experiencing today.
The theory that fat, and specifically saturated fat, is the cause of heart disease all started because of two main findings. First was that rabbits (which are obviously very different from humans) developed atherosclerosis (fatty deposits in the arteries) when they were fed cholesterol in a laboratory setting. Normally, dietary cholesterol is completely absent from their vegetable diet. Moreover, researchers found that cholesterol is a primary component of atherosclerotic plaques, so it was assumed to be one of the main culprits in the development of coronary disease. Second, countries that seemed to consume more saturated fat and the most fat generally (for example, Finland and the United States compared to Japan and Greece) had more heart disease. Since saturated fat raised blood levels of cholesterol, it was assumed that saturated fat caused heart disease.
This idea, spawned in 1953, was the brainchild of a very outspoken, passionate scientist from the University of Minnesota named Ancel Keys, who was determined to make saturated fat the scapegoat for the growing concern of heart disease in the United States. Many questioned Keys’ scientific conclusions, but he was vigorous in criticizing anyone who challenged him. He was a dominant, persuasive, and charismatic man who convinced the world of his hypothesis.
Dr. Ancel Keys presented the "Six Countries Study" which displayed a graph that seemed to clearly show the link between saturated fat and death. This graph is displayed below in Figure 1. This presentation almost single handedly launched us on a crusade to falsely accuse fats, particularly saturated fats of wrongdoing.
However, There are several fatal flaws with this study that completely invalidates it. First of all, this was a epidemiological study, otherwise known as observational studies. Observational studies have several issues with them, outlined in detail in this article. An observational study is one that draws inferences about the effect of an exposure or intervention on subjects where the researcher or investigator has no control over the subject. They are just looking at populations of people and making guesses about the effects of a diet or lifestyle variable. Because of this, observational studies are simply meant help generate hypotheses and NOT directly inform dietary guidelines. Moreover, at best, observational studies can show correlation, but not causation. To provide a simple example, after I wake up, the sun always seems to rise. There is a correlation between the time that I wake and up and the sun rising. However, my waking up does not cause the sun to rise. Likewise, the data used to formulate this graph could possibly demonstrate a correlation between fats in the diet and death, but could certainly not prove that the former causes the latter. However, this observational data was improperly utilized to incriminate dietary fats. At the very best, this data might have been used to peak the interest of the scientific community to encourage further study through a proper causation study, otherwise known as a Randomized Controlled Trial (RCT).
What exactly was Key's hypothesis? Blood cholesterol was associated with (but not proven to be a factor in) increased risk of heart disease. At the time, it was known that saturated fat in the diet increased levels of cholesterol in the blood. So the enemy was assumed to be saturated fat. To illustrate the weakness of this logic, let's look at an example- if A is associated with (but not proven to cause) B and B is associated with (but not proven to cause) C, then A must be the cause C. That is like saying the sun rise is associated with my waking up (because it occurs around the same time) and traffic on the road starts after the sun rises, therefore my waking must be the cause of all traffic on the road.
Nutritional epidemiology is basically the board game equivalent of a Ouija board—whatever you want it to say, it will say. – Dr. Peter Attia
Moreover, Dr. Ancel Keys cherry picked the data to conveniently match his hypothesis. At the time, the Food and Agriculture Organization of the United Nations had data available regarding heart disease, death rates, and fat consumption in twenty-two countries. Dr. Keys picked the data from 6 of those countries, completely ignoring data from the other16. When data from all 22 countries were taken into consideration, which was done a mere four years after the presentation of the "6 countries study," there was absolutely zero correlation between fat in the diet and heart disease.
Dr. Keys followed up his "6 Countries study" with the famous "7 Countries Study" in which he planned to follow in detail some 12,700 middle-aged men in mostly rural populations in Italy, Greece, Yugoslavia, Finland, the Netherlands, Japan, and the United States. Keys was facing significant criticism for cherry picking the countries, but yet again picked areas that were most likely to confirm his hypothesis rather than contradict it.
In this study, researchers measured body weight, blood pressure, and cholesterol levels in addition to surveying the men about diet and smoking habits. For a small subset of these men, samples of the food they ate over the course of a week were collected and sent to labs for chemical analysis. How small of a sample? If you read Keys’s study design very closely, you find that, of the 12,770 participants, the food samples were collected and analyzed for only 499 of them, or just 3.9 percent. Moreover, in a stunning oversight, Keys took dietary samples in the Greek cities of Crete and Corfu during the 48 day fasting period of lent, in which Greek Orthodox abstain from all foods of animal origin, including fish, cheese, eggs, and butter! So, the diet samples taken during the time of the study did not adequately represent the normal diet of the population studied. Despite the significant flaws in the study, the data collected was used to inform decades of nutritional recommendations around the world!
Despite the the fact that observational studies cannot be used to determine cause and effect, Key's studies initiated a cascade effect that eventually led to the nation wide demonization of fats in diet, which was ultimately codified in the 1977 Dietary Goals for the United States. These goals famously recommended that Americans should limit fat to 30 percent of calories while increasing carbohydrate consumption to 60 percent of calories.
Moreover, In 1999, when the Seven Countries study’s lead Italian researcher, Alessandro Menotti, went back twenty-five years later and looked at data from the study’s 12,770 subjects, he noticed an interesting fact: the category of foods that best correlated with coronary mortality was sweets. By “sweets,” he meant sugar products and pastries, which had a correlation coefficient with coronary mortality of 0.821 (a perfect correlation is 1.0). By contrast, “animal food” (butter, meat, eggs, margarine, lard, milk, and cheese) had a correlation coefficient of 0.798, and this number likely would have been lower had Menotti excluded margarine.
However, Keys wasn't looking to find the true culprit in our diet that causes heart disease. He was only looking to confirm his hypothesis that saturated fat is the one to blame for heart disease. In, fact, in 1984, when Keys went back to reanalyze the data and looked at the effect of saturated fat on all causes of death, rather than just heart disease as he originally did in the 1950s, he found that people eating diets low in saturated fat had just as high a risk of dying as their fat-gorging counterparts. The longevity of those who lived the longest amongst those who were studied showed no correlation with saturated fat in their diet, nor the cholesterol levels in their blood. He published these findings in the Journal of Preventative Medicine, but by this time his earlier work was so entrenched in our society that food industries had already mobilized to create fat free (and high carb) foods and the original Seven Country Study was referenced nearly one million times i medical literature.
In addition to the two studies conducted by Ancel Keys, the Anti-Coronary Club trial, the VA Hospital study, the Finnish Mental Hospital study, and the Oslo experiment are the clinical trials most frequently cited in support of the low saturated fat and low cholesterol diet hypothesis, also known as the diet-heart hypothesis.
A deeper look into the results of these studies uncovers some pretty damning evidence against the low fat, high carbohydrate diets. The Oslo Study (1968): A study of 412 men, aged 30-64 years found eating a diet low in saturated fats and high in polyunsaturated fats had no influence on rates of sudden death. The participants were told to substitute meat and eggs for fish, shellfish, and "whale beef," all rich sources of omega-3 fats. The study participants were also told to cut out trans fats and limit refined grains and sugar. All these things reduce the risk of heart disease. This study never proved that vegetable oils and reduced saturated fat were beneficial. They only showed that eating more omega-3 fats and eating less trans fats and refined grains are protective. Yet, this didn't stop proponents of Key's hypothesis from trumpeting this study as basis for recommending a low fat diet for the entire country.
The VA hospital study, A study of 850 elderly men that lasted for six years is widely used to support the diet-heart hypothesis. No significant difference was found in rates of sudden death or heart attack among men eating a mostly animal-foods diet and those eating a high-vegetable oil diet. However, more non-cardiac deaths, including from cancer, were seen in the vegetable oil group. 31 of the men in the cholesterol lowering diet died of cancer compared to only seventeen in the control group who maintained their normal diet.
In the Anti-Coronary Club Trial, participants in the low fat group, which replaced animal fats with vegetable oils, experienced decreases in the heart disease risk factors of cholesterol, weight, and blood pressure. However, these changes translated into adverse results for the intervention group. 26 members of the low fat group had died during the trial, compared with only six of the men in the group who consumed a higher fat diet.
The Finnish Mental Hospital study seemed to reduce heart disease deaths by half when inmates a mental hospital were put on a cholesterol lowering diet. The men on the diet also lived longer, though the women did not. However, a look into the methodology used in the study reveals that the study was non-randomized and poorly controlled. Despite this fact, this study was heralded as definitive proof for banishing saturated fats from our diets. However, if lower death rates in the Finnish Mental Hospital study were considered compelling evidence that the diet worked, why weren't the higher death rates in the Anti-Coronary Club Trial considered evidence that it did not?
Perhaps the most damning evidence against the diet-heart hypothesis was the Minnesota Coronary Survey, the largest ever clinical trial of its kind and thus belongs in the same category along with the four studies listed above. Shockingly, the evidence from this trial was buried, having gone unpublished for 16 years because the results did not what turn out the way that the experts had hoped. The study split over 9000 men and women into two groups, feeding one a diet low in saturated fat and dietary cholesterol and high in polyunsaturated fat. The other group continued their normal diet. The average subject at the diet for a little more than a year. Average cholesterol levels dropped by 15 percent. Overall, the cholesterol-lowering diet was associated with an increased rate of heart disease with 269 in the diet group dying during the trail versus 206 people consuming the normal fare. The diet low in saturated fat had failed to show any advantage at all. When asked why the evidence had gone unpublished for 16 years, the lead researcher responded, "we were just disappointed in the way it came out." The study had been selectively ignored because it inconveniently failed to support the hypothesis they were hoping to prove.
What is the verdict on Saturated Fats? We will see that in next week's article.
Dr. Ram, Pharm.D.
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