This week, we'll be reviewing a variety of the health claims about coconuts and coconut oil. Are they wonderfoods or saturated fat bombs? Do they promote good health or harm it? We'll begin the discussion with an article by Dr. James J. Kenney, who debunks a few coconut health claims...
The June 2012 issue of the Nutrition Action Health Letter skewered two of America's more infamous MDs with long histories of promoting nutrition quackery. Both Drs. Mehmet Oz and Joseph Mercola have apparently gone cuckoo for coconuts. They both claim it is a healthy fat that can help slim you down. However, their claim and those of others that coconuts and its oil aids weight loss are based on studies using MCT oil. While the Nutrition Action article was fairly reasonable, it also confused the issue by erroneously implying that research using MCT oil might also apply to whole coconut oil because Nutrition Action claimed coconut oil is 60% MCT. There is no precise definition of which fatty acids are medium-chained. Some say those with 6-12 carbons are medium-chained whereas others include just those with 8 and 10 carbons. However, the more important issue is that only 10 to 15% of the fatty acids are in whole coconut oil. MCT oil is only 99.9% caprylic acid and capric acid. These two unequivocally medium-chain fatty acids have 8 and 10 carbons, respectively. Coconut oil is 45 to 50% lauric acid, which has 12 carbon atoms. Metabolically, lauric acid appears to have more in common with myristic acid (14 carbons), and palmitic acid (16 carbons) than it does with the shorter, medium-chain fatty acids that make MCT oil. Indeed, lauric, myristic, and palmitic acid all markedly raise LDL-cholesterol levels compared to longer chain saturated fatty acids like stearic and behemic acid (with 18 and 20 carbons, respectively). And they raise LDL-cholesterol more than the shorter medium-chain fatty acids as well.
Is Coconut Oil Heart Healthy?
The promoters of coconut oil often cite a study done on two Polynesian islands many years ago. On the Pukapuka Islands coconuts made up 34% of energy intake. On Tokelau Island, the consumption of coconuts accounted for remarkable 63% of total calorie intake. Given that coconut oil is about 90% saturated fat (nearly ¾ coming from lauric, myristic, and palmitic acids), it was perhaps not surprising that the average total cholesterol levels in these populations were elevated. Indeed, total cholesterol was well above 200mg/dl on Tokelau where coconuts made up 63% of energy intake, cholesterol levels averaged 30 to 50mg/dl higher than on Pukapuka. Women age 55-64 had an average total cholesterol level of 245.4mg/dl on Tokelau despite the fact that their intake of cholesterol was much lower than that of Americans – averaging only about 129mg per day. The authors of this study did claim that vascular disease was uncommon on these Polynesian islands despite their high saturated fat intake and total cholesterol levels. However, this dubious claim was based on a single resting electrocardiogram (ECG) and not on incidence of death or on autopsy data, which would have been far more revealing. Assessing cardiovascular health based on a single ECG is now known to be of little value. Indeed, the US Preventative Task Force has recently recommended that American doctors stop using routine ECGs test to screen patients for heart disease. And there are other rational explanations for why these Polynesians might have less CVD than people in more developed countries, even though they consume more saturated fat. These Polynesians consume far less cholesterol and salt than do people in modern societies. They also likely consumed far more fiber, plant sterols, and omega-3 fatty acids (from fish) than most people in modern societies, and we know all of these dietary factors can mitigate the promotion of atherosclerosis by a high saturated fat diet. In addition, there was little tobacco use and stress levels may well have been less too on these remote Pacific islands. So to cite this study of Polynesians as proof coconut oil is heart-healthy is going well beyond what this data actually showed.
A study that compared the impact of either a meal rich in either coconut oil or safflower oil showed a disturbing change in several biomarkers of arterial health. Several hours after the coconut oil meal, endothelial function was impaired significantly more than it was after a meal high in safflower oil. Even worse, the coconut oil meal altered the subject's HDL particles, making them more pro-inflammatory. This study showed that just a few hours after a single coconut oil rich meal, some of the subject’s "good" HDL was turning into pro-atherogenic "bad" HDL. By contrast, the people who adopted a very low-fat, high-fiber diet for a few weeks saw a significant reduction in dysfunctional pro-inflammatory HDL and an increase in "good" HDL, despite a drop in total HDL cholesterol levels. (Fleming RM. The effect of high-,moderate and low-fat diets on weight loss and cardiovascular disease risk factors. Prev Cardiol 2002;5:110-8).
There are also claims that coconut oil helps Alzheimer’s disease patients, but this claim is based on a very modest benefit for a food supplement made from MCT oil and there are no data showing coconut oil consumption benefits Alzheimer’s disease patients.
The Bottom Line
Claims that coconuts and/or their fat is heart healthy or can improve brain function in Alzheimer’s patients are not supported by credible research data. To make such claims while selling people coconut oil claiming it won’t promote atherosclerosis or can improve brain function in people suffering from Alzheimer’s disease is just plain cuckoo.
By James J. Kenney, PhD, FACN
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Stephanie Ronco has been editing for Food and Health Communications since 2011. She graduated from Colorado College magna cum laude with distinction in Comparative Literature. She was elected a member of Phi Beta Kappa in 2008.