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| Some of the healthy fats we eat now. |
There are many paradigm shifts that one goes through as one transitions to a low carb/high fat lifestyle. For me, having fat compose the majority of my diet was one of the biggest. We've been taught that low fat is the healthiest way to eat. But is that true? I asked Steve to write about the truth about fat. Is it friend or foe??
Does fat make you fat and cause heart disease? The answer I’ve come to is in fact: No.It’s really hard to admit you are wrong. But after 30 years of advocating the low fat diet only to see my patients get fatter and sicker, I’ve come to a completely new understanding. The science has been stacking up and quietly overthrowing the “low fat = healthy diet” mantra we have been taught for the past 50+ years. Since 1977 when the US government first took on the role of promoting “healthy eating” recommendations, obesity has climbed from 15% of the population to now over 70% are overweight and almost 40% obese; and diabetes has gone up 900%! How did we come to this?
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| President Dwight Eisenhower |
In the 1950’s heart disease really started to get everyone’s attention especially after President Eisenhower died of a heart attack. Prior to this, heart disease was relatively rare. Now this “new” terror was striking down mostly healthy men in the prime of their lives. It became the AIDS epidemic of its day, and science was called upon to find an answer to this plague.
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| Dr. Ancel Keyes |
Enter Ancel Keyes. Keyes was a first rate researcher from the University of Minnesota and one of the early scientific nutritionists (after whom the “K-Ration” was named in WWII). He came up with the “Diet-Heart Hypothesis” and published his famous (some would say “infamous”) 7-Countries Study that showed that countries with high saturated fat intake had higher levels of heart disease than those with low levels. Ergo, saturated fat causes heart disease.
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| Truth about 7 Countries Study |
Well, not so fast. First of all, observational studies like this cannot prove causation i.e. just because two things rise and fall together does not mean that one causes the other (you need more rigorous randomized controlled trials for that). Second, others noted that other things, like sugar, actually correlated better. Third, Keyes cherry picked his data since he actually had data from 22 countries (not just seven) and chose just those countries that matched his hypothesis most closely. Some countries (e.g. France) that had high levels of fat intake but low rates of heart disease and visa versa he left out. Finally, when you looked at all comers, the higher the fat intake the lower the mortality.
So the controversy began.
The story gets really interesting here with a lot of political shenanigans. The bottom line is that the fat hypothesis won the day and dissenters were silenced. The government in the interest of trying to stem this cardiovascular disease public health menace and “do something” stepped in before all the data were analyzed and declared that the best thing to prevent it was a low fat diet.
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| The old food pyramid based off Keyes findings |
What is the evidence for fat as the cause of heart disease? The most recent Presidential Advisory from the American Heart Association (2017) still advocates a low fat diet as the best way to avoid heart disease. They base their recommendation on 4 key studies (out of thousands that have been done) dating back to the 1950’s and 1960’s which included a grand total of 2,873 cases.[1]These studies each had their own flaws and weaknesses and even then their results were not striking.
Curiously, they don’t mention many key studies that were much larger and much more rigorous including:
· Anti-Coronary Club Study (1966)More people died in the low fat intervention group than the controls.
· Minnesota Coronary Survey (1968)Involved 9000 men. The low fat group had no improvement in cardiovascular disease but did have a higher rate of cancer. It was not published for 16 years and then in an obscure journal and only after the lead investigator who worked at Keye’s university had retired.
· Sydney Diet Heart Study (1966-1973)Substituting linoleic acid (omega-6) in place of saturated fats increased the rates of death from all causes, coronary heart disease, and cardiovascular disease.
· Multiple Risk Factor Intervention Trial (MRFIT)12,000 men with high cholesterol were divided into two groups one who had multiple interventions like a low fat diet and smoking cessation, and one ate and lived as they pleased. When published in 1982, although men in the intervention group were very successful in changing their diets, quitting smoking, and reducing their blood pressure, they died at slightly higher rates than the controls. In a 16 year follow-up study in 1997, the treatment group was found to have higher rates of lung cancer even though 21% of them had quit smoking compared to only 6% of the controls. MRFIT was not alone in finding that the lower the cholesterol the higher the rate of cancer. This is been seen in nearly a dozen sizable studies on humans and has not been explained to date.
· NIH Prospective Diet-Heart Study (1970’s)$250 million dollar trial where men were fed diets high in polyunsaturated fats (which is what the AHA still wants you to do) i.e. artificial vegetable oil compared to a diet high in saturated fat. It was a complete waste of money as too many could not tolerate a diet high in vegetable oils. Your tax dollars at work!
· Framingham Heart Study(1950’s to present)Started in the 1950’s but not published until 1987 because it showed no association between saturated fat and CVD.
· Women’s Health Initiative (WHI)Starting in 1993 following 49,000 postmenopausal women at a cost of $725 million it was the largest trial ever done to date (until PURE). After 10 years of study there was no difference between the low fat intervention group and controls in terms of either cancer or heart disease. After 9 years, the low fat group lost only 1 lb more than the controls. Among women with heart disease at the beginning of the study, their risk of developing cardiovascular complications was 26% higher in the low fat diet group than controls.
· PURE (Prospective Urban Rural Epidemiology - 2018)Finally, the granddaddy of them all. PURE Included 135,335 individuals in 18 countries. Higher intakes of fat were associated with lower total mortality and not with cardiovascular disease mortality or incidence. Also, the higher the saturated fat intake the lower the risk of stroke.
Finally, lest you think Dr. Riggs is off his rocker (again), there are other eminently more qualified experts that are thinking the same way:
· A recent interview with Dr. Ron Kraus (former head of the AHA Nutrition Committee and one of the world’s experts on lipids) sites that he now believes that saturated fats are healthy and not linked to heart disease. (Link to interview below)
· A review of all the studies of the low fat diet by the United Nations Food and Agriculture Organization found that there is “no probable or convincing evidence” that a high level of fat in the diet causes heart disease or cancer.
· In 2013 a Swedish expert advisory group, after spending 2 years and reviewing 16,000 studies concluded that a diet low in fat was an ineffective strategy for tackling either obesity or diabetes.
· “It is increasingly recognized that the low-fat campaign has been based on little scientific evidence and may have caused unintended health consequences.” – Frank Hu nutrition professor at the Harvard School of Public Health 2001.
· Ancel Keyes himself in the 1980’s (when Keyes was in his 80’s) wrote a paper in which he raised concerns that his diet-heart hypothesis was going too far. His paper was making the point that limiting saturated fat did not reduce mortality and he was concerned about this. But no one would publish it.
· The Cochrane Collaboration (2001 and 2006) which does systematic reviews of the literature noted that “Diets whether low fat or cholesterol lowering, had no effect on longevity and no significant effect on cardiovascular events.”
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| Interview with Dr Krauss on Diet Docto |
Bon Appétit!
[1]Finnish/Helsinki Mental Hospital Study (1958), Oslo Heart Study (early 1960's; published 1966), Wadsworth VA Trial (Dayton et.al) (1969), and the British Medical Research Council study on soy bean oil in myocardial infarction (1968).
