Posted July 17, 2019

Circulating on health blogs and twitter posts are claims that coconut oil is the new secret to longevity, cardiovascular health, luminous skin, and enhanced memory. Claims that coconut oil could be considered a dietary antidote to the onset of Alzheimer’s disease compelled us to weigh in with what has and has not been shown to be the impact on brain health when incorporating coconut oil in the diet.

Coconut oil has hit the mainstream as a replacement for olive oil. Even the extraction process of the oil itself conjures up images of island vacations and coconut palm trees. Despite this alluring imagery, there is only limited evidence evaluating the health effects of coconut oil and no support for the use of coconut oil for prevention or treatment of Alzheimer’s disease.

Let’s begin by examining where coconut oil gained its reputation as a disease-fighting elixir. There are two main types of coconut oil, copra oil and virgin coconut oil, which have similar fatty acid profiles. Fatty acids are important components of lipids – fat-soluble components of living cells. In general, a fatty acid consists of a straight chain of carbon atoms with hydrogen atoms along the length of the chain that ends in a carboxyl group that makes it an acid. From a metabolic standpoint, the length and character of a fatty acid determine how useful its function in the body. For example, certain fatty acids contain vitamin E and dietary bioactive compounds like polyphenols. Polyphenols are typically found in basil, ginger, cumin, cinnamon, coffee, red wine, leafy greens, flaxseed, apricots, and olive oil to name only a handful of foods containing this antioxidant. Many of the health benefits associated with polyphenols may be related to their role as an antioxidant. Antioxidants (sometimes called “free-radical scavengers”) can slow the damage to cells caused by free radicals and other unstable molecules that the body produces as a reaction to environmental pressures.

The Food and Agriculture Organization of the United Nations estimated that approximately 3 million tons of coconut oil are produced each year. This is a lot of saturated fatty acids being consumed worldwide. Eating foods that contain saturated fats raises the level of cholesterol in your blood. High levels of LDL cholesterol in the blood can increase the risk of heart disease and stroke. The American Heart Association recommends aiming for a dietary breakdown that achieves 5% of calories from saturated fat. If you need about ~2,000 calories per day, that means no more than 120 of them should come from saturated fat. That’s about 13 grams per day. From a chemical standpoint, saturated fats are simply fat molecules that have no double bonds between carbon molecules because they are saturated with hydrogen molecules. This chemical composition makes saturated fats a solid at room temperature – which is one of the reasons coconut oil is so popular. It is easy to transport and store due to its solid composition at room temperature. There is evidence that replacing saturated fats with unsaturated fats is associated with reduced blood levels of total cholesterol and low-density lipoprotein cholesterol (LDL). This simple switch away from coconut oil to an unsaturated oil could reduce the risk of cardiovascular disease.

For more information on types of fat and unsaturated fats to incorporate in your diet instead of coconut oil, please see this article from the Nutrition Source at the Harvard T.H. Chan School of Public Health:

Scientists are learning more and more about how saturated fats like coconut oil are digested. After the fat is consumed, it is digested and absorbed through the intestinal wall. An enzyme known as lipase acts on fat emulsified by bile acids in the small intestine. Long-chain fatty acids combine with proteins to form molecules called lipoproteins. These lipoproteins circulate in the bloodstream after entering through the lymphatic system. As they circulate, they deliver fatty acids to the tissues and contribute to the accumulation of body fat. During this process, fats can accumulate on artery walls and if introduced in excess can increase the risk of cardiovascular and metabolic disorders. The length of the fatty acid determines whether or not it is more likely to be metabolized by the liver or circulated in the bloodstream.

As an important note, fatty acids cannot pass the blood-brain-barrier, but the product they are broken down into, ketone bodies, can serve as an alternative fuel source for the brain. The brain favors glucose as its energy source, but in times of starvation or glucose deficiency, it will use ketone bodies. The alleged link between coconut oil and Alzheimer’s prevention came from a hypothesis about the metabolism of fatty acids generating alternative energy sources for the brain. A fact that is supported is the observation that fatty acid metabolism is initiated in mitochondria – the energy powerhouses of the cell. Medium-chain fatty acids can enter the mitochondria and be converted into two components referred to as ketone bodies — acetoacetate and beta-hydroxybutyrate for biochemistry connoisseurs. These two ketone bodies are metabolized by the liver to produce carbon dioxide, water, and you guessed it, energy. This fast-metabolic conversion of medium-chain fatty acids means that the energy generated is used for fuel rather than being deposited as fat.

Several studies indicate that “ketogenic diets” that incorporate very low carbohydrate levels, substantial amounts of protein, and high fat levels can have deleterious effects on cardiovascular function. There is no getting around the fact that coconut oil has large amounts of saturated fat and should be consumed only in moderation (less than 5-10% of dietary caloric intake should come from saturated fat.) While coconut oil does contain antioxidants like phenols, there are far more effective sources for getting a dose of antioxidants.

There are no clinical or observational studies that have specifically assessed the effects of coconut oil on the incidence of Alzheimer’s disease. The handful of basic science papers that have examined the effects of coconut oil have looked at the effect of medium-chain fatty acids on biomarkers associated with Alzheimer’s disease. Far greater research has been documented demonstrating a link between high levels of saturated fats and cardiovascular risk. Increased plasma cholesterol and high blood pressure are considered risk factors for Alzheimer’s. While any changes to the diet should be discussed with an individual’s primary care physician, the current scientific literature suggests that no human studies have assessed the potential preventative or therapeutic effects of coconut oil intake on Alzheimer’s disease.