Coconut oil: is it good for you or bad for you? Some sources say it’s a super nutrient that miraculously reverses Alzheimer’s dementia and has a multitude of other health benefits. Others advise avoiding it because it increases the risk of heart attacks and strokes. How can you make sense of the conflicting advice you find on the Internet? For a long time, coconut oil was demonized as the most harmful source of dietary saturated fat. Now some people are claiming it has great health benefits. Who is right? There’s only one reliable way for a skeptic to decide: a critical examination of the evidence. As David Hume said, “A wise man … proportions his belief to the evidence.” What does the science say?
Science seems to change its mind regularly; the general public finds this frustrating. They often see it as a defect, but it is actually science’s strong point. As new and better evidence emerges, the scientific community reaches more accurate conclusions that approach ever closer to reality. The quest to understand atherosclerosis is a case in point. It has had a convoluted and confusing history.
The best diet to prevent heart attacks
In science’s first gropings towards understanding heart attacks and atherosclerosis, the public was warned to reduce consumption of eggs and other dietary sources of cholesterol. As more evidence accumulated, they were told to worry about total fat consumption rather than dietary cholesterol. Then they were told to avoid saturated fats; then they were advised that trans fats were the real problem; this was widely accepted and even led to legislation to remove trans fats from foods.
As people adopted various versions of a low-fat diet, they tended to increase carbohydrate consumption and total calories and to gain weight, contributing to the obesity epidemic. Now the wisdom of a low-fat diet is being questioned and low-carb diets have become more popular. It’s not surprising that people are confused about what they should be eating.
Professional consensus based on science: avoid coconut oil
In 2017, the American Heart Association put out a presidential advisory recommending replacing saturated fats with polyunsaturated vegetable oil. They pointed out that coconut oil and palm kernel oil both contain the highest amounts of saturated fat, 82%, compared to 39% for lard, 50% for beef tallow, and 63% for butter. These can be replaced by olive oil with 14% saturated fat or safflower oil with 6%. They reviewed the compelling evidence showing that this could reduce the incidence of cardiovascular disease by 30%.
Many other organizations around the world agree with the AHA. The World Health Organization, the United States Department of Health and Human Services, the Food and Nutrition Board, the National Academy of Medicine, the American Dietetic Association, the Dietitians of Canada, the British Dietetic Association, the British Heart Foundation, the National Heart Foundation of Australia, the National Heart Foundation of New Zealand, the Heart and Stroke Foundation of Canada, the World Heart Federation, the Irish Heart Foundation, the British National Health Service, the United States Food and Drug Administration, the European Food Safety Authority, Dietitians of Canada, the British Dietetic Association, the Harvard School of Public Health, the Mayo Clinic, and the European Society of Cardiology also advise that saturated fat consumption, especially coconut oil, should be limited or avoided and replaced with monounsaturated and polyunsaturated fats. Coconut oil contains a high amount of the saturated fat lauric acid, which raises total blood cholesterol levels. Regular use tends to increase calorie intake and promote weight gain.
There are admittedly some dissenting voices to the mainstream position. In 2009, a scientific conference found no clear evidence for an increased risk of cardiovascular disease with dairy food consumption. A 2010 committee report was criticized for citing evidence that was “inconclusive.” A disputed 2010 meta-analysis found no evidence that dietary saturated fat was associated with increased risk of cardiovascular disease. A critique of US dietary guidelines found the effect of dietary manipulations to be insignificant, but 180 scientists called for the critique to be retracted. All things considered, there is a strong consensus among doctors and scientists that saturated fats in the diet contribute to cardiovascular disease.
Unsupported health claims
Meanwhile, all sorts of health claims are being made for coconut oil. Marketing hype has triumphed over scientific evidence. 72% of the general public believe coconut oil is a health food. Coconut oil (or its main component, medium chain triglycerides or MCTs) is used internally and externally. It is swallowed and is applied to the skin and hair. It is used for oil pulling (said to promote oral hygiene). It is alleged to reverse Alzheimer’s disease, improve heart health, raise good HDL cholesterol, reduce bad LDL cholesterol, improve diabetes, treat epilepsy, re-grow damaged hair, heal many skin diseases, provide peak performance energy, kill candida fungus, remove stress on the pancreas, increase metabolic rate, support healthy functioning of the thyroid and endocrine system, kill many bacteria and viruses, strengthen hair, promote weight loss, reduce abdominal obesity, kill lice, speed wound healing, slow aging, improve bone strength and dental health, promote nutrient absorption, prevent wrinkles, repair the skin barrier, and even improve dandruff. It is used in aromatherapy and many hair and skin care products. It is said to reduce stress, improve asthma, and prevent liver disease. The problem is, there is little or no evidence from human studies to support the multitude of claims. That doesn’t mean they are not true; but in the absence of good evidence, it seems rather unlikely. How could a single treatment produce all the broad spectrum of diverse health benefits that are claimed? When treatments are claimed to cure everything it usually means they cure nothing.
WebMD has a handy list of the health claims[i] for MCTs showing that they are “possibly effective” for only a few very limited uses, “possibly ineffective” for weight loss and exercise performance, and there is “insufficient evidence” for Alzheimer’s and several other indications. They also list side effects and warn against use during pregnancy and breast-feeding or in patients with diabetes or liver disease. Pretty ironic when you consider coconut oil is being advocated to treat diabetes and liver disease!
Space doesn’t permit addressing all the published evidence for all the claims, so let’s just examine the evidence for three prominent claims: oil pulling, heart disease, and Alzheimer’s.
Oil pulling is an ancient Ayurvedic practice that has been resurrected as a health fad. A tablespoonful of coconut oil (or sometimes sesame oil or olive oil) is swished around in the mouth for 15-20 minutes up to three times a day. It should not be swallowed and should be spit out into a trash can rather than into a sink or toilet, which could result in clogging. It supposedly “pulls” bacteria from the mouth. Small studies have shown a decrease in mouth bacteria and reduced plaque. One study showed 10 minutes of oil pulling reduced bacteria as much as using chlorhexidine mouthwash for one minute.[ii] Using chlorhexidine would save both time and money. A website that promotes oil pulling admits that “the research is relatively limited.”[iii]
There are extravagant claims that coconut oil or MCTs can reverse Alzheimer’s disease. Wouldn’t that be great? The experts all say that treatments for Alzheimer’s can only slow the progression of the disease; no treatment can cure it or reverse the signs and symptoms. If coconut oil is effective, wouldn’t that make for big headlines? Why isn’t it common knowledge, and why aren’t the experts prescribing it? They aren’t, because they know the evidence is preliminary, skimpy, and not trustworthy. There are a few small pilot studies that suggest a benefit, but the claims are mainly based on unverified sensational anecdotal reports from family members, and there is no good evidence that those patients actually had Alzheimer’s disease in the first place rather than some other, reversible condition.
While the consensus of mainstream science is that saturated fats increase the risk of heart attacks, some proponents claim it prevents them. A typical coconut oil enthusiast, heart surgeon Steven Gundry, was impressed by a story about PukaPuka Island. He wanted to know how an entire island of people can eat a diet loaded with saturated fats and still be healthy, energetic, and thin. He investigated and found that they are cuckoo for coconut. They cook coconut and eat it raw, drink coconut milk, and fry foods in coconut oil. Coconuts are high in saturated fats, but he says they are “good” saturated fats, medium-chain triglycerides (MCTs) that are a superfood that is only burned for energy and never stored as fat. He says they are converted into ketones that provide more energy, mental sharpness, less brain fog, a slimmer physique, and more self-confidence. He says the benefits are due to caprylic acid, and he has developed a caprylic acid supplement fortified with two additional ingredients that “pack a bioflavonoid punch:” grape seed extract and red- and blackcurrant extract. Yes, he is selling supplements, which is often a bad sign. He did no controlled studies to test his product’s effects. He is also selling books that are short on science and long on hype. His claims have been debunked and labeled pseudoscientific by other cardiologists.
In short, the evidence that coconut oil is a health hazard is stronger than the evidence that it is a health food. Remember “the dose makes the poison” and “moderation in all things.” If you like the taste, I don’t see any reason a moderate amount of coconut oil couldn’t be part of a healthy diet.
This article was originally published as a SkepDoc column in Skeptic magazine.