In a former life, when I was an Air Force doctor, one of my duties was to give “Healthy Heart” briefings with a script furnished by Air Force experts. It covered the scientific consensus of the time (the early 80s) about diet. It recommended a low fat diet, restricted cholesterol and saturated fat, and demonized tropical oils like palm oil and coconut oil. (Trans fats weren’t yet on the agenda.)
Times have changed. Today we are more lenient about cholesterol in the diet, less concerned about total fat and saturated fat, and more concerned about trans fats. While many major health organizations still discourage its use, coconut oil has not only been rehabilitated in the public mind, but all kinds of health benefits are being claimed for it.
The fats in coconut oil
Coconut oil is high in saturated fats; it contains more saturated fatty acids than any other non-hydrogenated oil. It is stable and has a long shelf life. It is used in movie theaters to pop popcorn and in South Asian cuisine for dishes like curries. A hydrogenated version of coconut oil is an ingredient in non-dairy creamers. Much of the research done on coconut oil studied hydrogenated or partially hydrogenated forms. According to an article in The New York Times:
Partial hydrogenation creates dreaded trans fats. It also destroys many of the good essential fatty acids, antioxidants and other positive components present in virgin coconut oil. And while it’s true that most of the fats in virgin coconut oil are saturated, opinions are changing on whether saturated fats are the arterial villains they were made out to be. “I think we in the nutrition field are beginning to say that saturated fats are not so bad, and the evidence that said they were is not so strong,” Dr. Brenna said.
Coconut oil contains lauric acid, which raises both HDL and LDL cholesterol levels. This may improve the cholesterol profile, although there are concerns that it may promote atherosclerosis by other means. Virgin coconut oil contains medium-chain triglycerides, which are not as risky as some other saturated fats.
Any number of health claims have been made for lauric acid. According to proponents, it’s a wonder substance with possible antibacterial, antimicrobial, antiviral properties that could also, in theory, combat HIV, clear up acne and speed up your metabolism. Researchers are skeptical:
“There are a lot of claims that coconut oil may have health benefits, but there is no concrete scientific data yet to support this,” said Dr. Daniel Hwang, a research molecular biologist specializing in lauric acid at the Western Human Nutrition Research Center at the University of California, Davis.
The hype comes from unreliable sources. Joe Mercola says it is the smartest choice for cooking, is good for your heart, contains the kind of fat found in mothers’ milk, enhances immunity, and helps with weight loss by stimulating metabolism. And of course he sells it. Dr. Oz says it is a heart healthy food that helps resist viruses, bacteria, yeast, fungi, and candida; boosts thyroid function; improves blood sugar control and reduces the need for insulin; increases energy and endurance; increases digestion and improves absorption of vitamins; lowers cholesterol; helps control weight; has anti-aging effects; is good for skin and hair; and is quite safe to take in reasonable amounts. The Wellness Mama website lists 101 uses for coconut oil, including treating sunburns, athlete’s foot, Alzheimer’s disease, nasal allergies, arthritis, insomnia, autism, heartburn, hemorrhoids, depression, acne, cellulite, mosquito bites, and lice.
The Wellness Mama website provides a link to a reference for Alzheimer’s disease but it is only a case study showing that the writer’s husband improved and was able to draw a more accurate picture of a clock after adding coconut oil to his diet. Natural News says coconut oil can prevent and reverse Alzheimer’s. Naturopath Bruce Fife has several books touting the benefits of coconut oil and coconut water. One title claims you can “Stop Alzheimer’s Now!”
A clinical query search for “Alzheimer’s coconut oil” on PubMed yielded no results. Snopes has evaluated the claims for coconut oil and agrees that “there are no peer-reviewed articles addressing research on coconut oil as a treatment for Alzheimer’s disease.” Even the Alzheimer’s Association says: “A few people have reported that coconut oil helped the person with Alzheimer’s, but there’s never been any clinical testing of coconut oil for Alzheimer’s, and there’s no scientific evidence that it helps.”
The liquid inside a coconut is being promoted as a sports drink and as a miracle food. They claim it is so compatible with the human body that it can be infused directly into the bloodstream (indeed, it is likely sterile and there are reports of its use as an intravenous fluid substitute in emergencies when medical saline was unavailable). As with coconut oil, there are a few suggestive studies in animals and test tubes, but no credible evidence for clinical benefits in humans.
Conclusion: Neither demon nor angel
Coconut oil is probably not as bad as once thought, but it’s no “miracle” food either. It is probably safe to use it in reasonable amounts to replace other oils in the diet, and doing so may have a favorable effect on lipid profiles; but it’s not clear whether that will actually reduce the risk of cardiovascular events. There is no justification for adding it to the diet on top of the usual consumption of other fats. There is no credible evidence to support any of the many health benefits claimed for using it as a supplement.
This article was originally published in the Science-Based Medicine blog.