In the wake of the American Heart Association’s warning about the saturated fat content of coconut oil, some experts have weighed in and found the health organization’s study wanting.
It’s cherry picking, and it’s how a lawyer builds an argument but not how a scientist works to establish reliable knowledge.
The AHA released a Presidential Advisory stating coconut oil contained more saturated fat than butter and beef fat. It also recommended saturated fat intake should be limited in order to avoid raising “bad” cholesterol levels and prevent clogged arteries and heart-related conditions.
Critics question the AHA’s methodology in finding these conclusions.
Fabian Dayrit, president of the Integrated Chemists of the Philippines, published an article stating there are “experimental errors and biases” in the study on which the AHA based its recommendations. “Defective experiments have led to defective guidelines,” he said.
“To decrease saturated fat effectively means an increase in unsaturated fat in the diet. The actual result has been an increase in omega-6 fats and a high omega-6 to omega-3 fat ratio. This unhealthy ratio has been linked to heart disease, the very disease that the AHA wants to target, as well as cancer and inflammatory diseases.”
Dayrit, who is also chairman of Asian and Pacific Coconut Community’s Scientific Advisory Committee for Health, said the warnings against saturated fats were based on studies by Ancel Keys in the 1950s.
“The Keys hypothesis, generally known as the saturated fat-cholesterol-heart disease hypothesis, states that saturated fats raise serum cholesterol which in turn increases the risk for heart disease,” he said.
He added that Keys used hydrogenated coconut oil in one of his studies.
“The use of hydrogenated fats in this feeding study casts doubt on the validity of the conclusions of this work regarding the effects of coconut oil,” Dayrit said. “It was already known in the 1920s that hydrogenation of vegetable oils produced trans fats. In 1957, the same year when both Keys papers came out, it was reported that trans fats were deposited in various human tissues, such as adipose tissues, liver, aortic tissue, and atheroma of those who died of atherosclerosis. In a 1961 paper on hydrogenated fats, Keys himself noted that hydrogenated oils raised serum cholesterol and triglycerides. Therefore, the increase in serum cholesterol that Keys observed may have been due to the trans fats in margarine and hydrogenated coconut oil and this would make his conclusions invalid.”
Gary Taubes, an award-winning science writer, took the AHA to task over its apparently selective use of source material.
“It’s cherry picking, and it’s how a lawyer builds an argument but not how a scientist works to establish reliable knowledge, which is the goal of the enterprise,” he wrote in an opinion piece.
Taubes, who has authored books such as Good Calories, Bad Calories, Why We Get Fat and The Case Against Sugar, charges the AHA with disregarding studies that don’t support its stance against the use of saturated fats.
“The AHA concludes that only four clinical trials have ever been done with sufficiently reliable methodology to allow them to assess the value of replacing saturated fatty acids with polyunsaturated fatty acids and concludes that this replacement will reduce heart attacks by 30 percent,” he said. “These four trials are the ones that are left after the AHA experts have systematically picked through the others and found reasons to reject all that didn’t find such a large positive effect, including a significant number that happened to suggest the opposite.”
Taubes adds the AHA ignores results from some of the biggest studies ever conducted, including the Minnesota Coronary Survey, the Sydney Heart Study and the Women’s Health Initiative.
“Whether consciously or unconsciously, they assume that what they think is true surely is, and then they methodically eliminate the negative and accentuate the positive until they can make the case that they are surely, clearly and unequivocally right.”
Anthony Pearson, a cardiologist at St. Lukes of Chesterfield hospital in St. Louis, argued in a post on his blog that the AHA’s recommendations are flawed because not all fatty acids are created equal.
“The kinds of saturated fats in coconut oil differs markedly from both dairy saturated fatty acids and beef saturated fatty acids. Some saturated fatty acids may have beneficial effects on blood lipids, weight, and cardiovascular health,” he said. “The types of unsaturated fatty acids in vegetable oils differ markedly and may have differential effects on cardiovascular health.”
He added: “Although containing lots of saturated fat, the saturated fatty acids in coconut oil are drastically different from other dietary sources of saturated fatty acids The medium-chain fatty acids like lauric acid, which make up the coconut, are absorbed and metabolized differently from long-chain fatty acids found in animal fat,” Pearson wrote.