Dr. Greenland echoed that assessment, stating that “the marketing of coconut oil is confusing. It’s trying to sell it as a healthy fat, but those who know its composition don’t think that at all.”
These and other experts part company with advertisers and advocates for coconut oil based on its chemical makeup and the well-established biological activity of different kinds of fatty acids.
“Fat can’t circulate by itself,” Dr. Greenland said, explaining that long-chain fatty acids like those prominent in beef tallow are absorbed into the bloodstream by fat-carrying particles called chylomicrons that deliver the fat to tissues throughout the body. Chylomicrons keep LDL cholesterol in circulation, giving it ample opportunity to get stuck in arteries. Fats that are mainly medium-chain fatty acids, on the other hand, are more water-soluble; they can be absorbed into the bloodstream without the assistance of chylomicrons and transported directly to the liver, where they are used for energy.
Although lauric acid is usually referred to as a medium-chain fatty acid, Dr. Sacks said, this label is really arbitrary. “Classifying lauric acid as a medium-chain fatty acid is a misnomer,” he wrote. “Rather than the number of carbon atoms in a fat,” he said, “what counts is how the fat is metabolized in the body. Lauric acid behaves like a long-chain fatty acid,” the kind that promotes atherosclerosis. In addition, coconut oil has two other long-chain fatty acids — myristic and palmitic — and all three have an artery-damaging effect on cholesterol levels in the blood.
One claim made for coconut oil is undisputed: It can raise blood levels of HDL cholesterol, which has long been thought to protect against heart disease. However, a clear-cut health benefit of HDL cholesterol has yet to be demonstrated in people. As Dr. Sacks reported, “Genetic studies and HDL-raising drugs have not so far supported a causal relationship between HDL cholesterol and cardiovascular disease. HDL is composed of a huge array of subparticles that may have adverse or beneficial actions. It is unknown which, if any, foods or nutrients that raise HDL cholesterol do so in a way that reduces atherosclerosis and coronary events.”
Ditto, said Dr. Greenland. “Efforts to raise HDL have not led to beneficial clinical improvements.”
Proponents are also fond of citing the fact that a number of Indigenous populations — including Polynesians, Melanesians, Sri Lankans and Indians — consume rather large amounts of coconut products without suffering high rates of cardiovascular disease. However, most of these people have traditionally eaten coconut flesh or squeezed coconut cream as part of a diet that is low in processed foods and rich in fruits and vegetables, with fish as the main source of protein. They are also far more active physically than typical Westerners.
But even that is now changing, a New Zealand research team reported, with the “imports of unhealthy foods such as corned beef, fast food and processed ingredients, leading to huge increases in obesity and poor health.”