- The many health claims made for coconut oil online and in popular books have either not been verified by scientific research, or have been disproven.
- Coconut oil consumption does not assist with weight loss.
- Several risk factors for cardiovascular disease are raised by coconut oil, and populations eating more of it have a higher risk of heart disease.
- There is absolutely no evidence that coconut oil prevents or reverses Alzheimer’s disease; it is more likely to contribute to it given its effects on cardiovascular risk factors.
Unless you’ve been living under a rock for the last few years, you’ll know that coconut oil is being heavily promoted online and in popular books, as a ‘health food’. Self-styled health gurus wax lyrical about its content of medium chain triglycerides (a fat that doesn’t make you fat), antimicrobial properties, stability when heated, and of course, the very appealing notion that Polynesian people eat lots of the stuff and don’t get heart disease. In the last couple of years, it’s even been claimed that coconut oil prevents or cures Alzheimer’s disease.
So let’s look at how the scientific facts compare with the marketing fantasies.
First of all, by the broadly-accepted definition of nutritiousness of food – nutrient content per kilojoule/calorie – there is absolutely no way that coconut oil can qualify as a health food. It contains absolutely no protein, carbohydrate, fibre, vitamins A, C or E, folate or other B vitamins, magnesium, calcium, manganese, phosphorus, iron, selenium, zinc or omega 3 fats. Zip, zero and zilch of the key nutrients needed for the human body to function optimally.
The only nutrient that it boasts is fat, and most of that fat is saturated fat – 92% in fact, which makes it the most heavily saturated fat found in nature (see table below).
Contrary to the claims you may have read on many blogs, saturated fat has been definitively proven to
- Raise total and LDL cholesterol levels;
- Increase the risk of cardiovascular disease and death from cardiovascular causes; and
- Cause insulin resistance (which leads to metabolic syndrome and type 2 diabetes).
Coconut oil promoters claim that it is unlike other saturated fats (such as butter or lard) because it contains medium chain triglycerides (MCTs). One of those much-vaunted MCTs, lauric acid, has antimicrobial properties, which gets the coconut oil advocates very excited.
I say, so what? How many people get sick from microbial illnesses, compared to the number that are sick from overweight and its associated conditions: diabetes, heart disease and common cancers such as breast, prostate and bowel? We are surrounded by, covered in and contain uncountable numbers of microbes, and this inevitable condition of human life doesn’t make most of us sick, most of the time.
But where the coco crowd really goes nuts is over the claim that coconut oil helps you lose weight because of its MCTs. MCTs are absorbed and metabolised somewhat differently from other fats. Most fats are absorbed through lacteals (lymphatic capillaries in the small intestine) and dumped into the bloodstream, from which it’s a short trip into your butt, thighs or muffin top.
On the other hand, MCTs are transported directly from the intestinal tract to the liver, where they’re likely to be directly burned off as fuel. They also raise the metabolic rate slightly. These properties of MCTs fuel the marketing hype that coconut oil consumption aids in weight loss.
The first flaw in this argument is that MCTs make up only about 45-50% of the overall fat content in coconut oil, and are frequently removed from coconut oil sold for human consumption anyway, because they are used in the cosmetics industry.
The second flaw – and it’s a humdinger – is that only one published study, a master’s thesis from Brazil, has tested the hypothesis that coconut oil causes weight loss, and the results were less than spectacular.
40 poor, mostly illiterate women with abdominal obesity were recruited for this study. 20 of them were given daily supplements of 30 ml of soyabean oil, and the other 20 were given 30 ml of coconut oil per day. All participants attended sessions with a nutritionist over the 12-week duration of the study, in which they were counselled to
- Reduce their overall calorie intake
- Increase their consumption of fruits and vegetables,
- Reduce intake of animal fats and refined carbohydrates,
- Drink adequate water, and
- Reduce alcohol intake and cigarette smoking.
In addition, they were given sessions with a personal trainer 4 times per week, consisting of stretching exercises followed by 50 minutes of walking.
At the end of 12 weeks, despite all these significant diet and lifestyle changes, the women in the soyabean oil group lost, on average, 1 kg while those in the coconut oil group lost – drum-roll please – 1.1 kg. Whooppee! I’ll bet you want to rush straight out to the health food store and buy a big tub of coconut oil so you can get results as impressive as that!
Advocates of the coconut-oil-for-weight-loss theory must be out of their minds. Clients who follow my dietary advice – a wholefoods, plant-based diet with no added fats and oils – typically lose that amount of weight, or more, every week until they’re close to their ideal weight. Even worse, the coconut oil-eating women’s total cholesterol, LDL, triglyceride and insulin levels all went up, indicating a higher risk of developing metabolic syndrome, type 2 diabetes and cardiovascular disease.
The study’s authors made much of the fact that the waist circumference of the women in the coconut oil reduced, unlike those in the soyabean oil group. How big a reduction? All of 1.4 cm – again, after 12 weeks of regular exercise and a reduced-calorie diet! (See table below). Are you serious?????? Again, I see my clients losing that much off their waist circumference after a week or so of healthy eating. It seems more likely to me that the 270 extra calories from coconut oil that the women were consuming each day hindered weight loss than that it helped.
What about Alzheimer’s? As yet, there has not been a single published study on the use of coconut oil to treat this dreaded disease, although the fact that coconut oil raises LDL cholesterol, triglycerides and other risk markers for cardiovascular disease should sound a warning bell, since Alzheimer’s and cardiovascular share common risk factors and researchers now believe that these conditions are causally related.
Even isolated MCT oil doesn’t improve cognitive function in Alzheimer’s disease, as the following chart shows; early gains in cognitive function in Alzheimer’s sufferers taking the MCT product (red line) were lost by the end of the study.
The claim that coconut oil is heart-healthy is a sick joke. When given to healthy human volunteers in a study conducted by Australian researchers, coconut oil dramatically decreased endothelial function and impaired the antioxidant capacity of HDL for at least 6 hours after consumption.
What that means is that if you eat coconut oil, your blood will be more prone to clotting, there will be accelerated formation of plaque inside your arteries and your arteries will be unable to dilate (open up to allow more blood flow to the tissues they supply) for at least 6 hours. Do that often enough, and you’ll make yourself an excellent candidate for a heart attack or stroke.
The claim that populations eating coconut oil are healthy and don’t get heart disease doesn’t hold water either. A study comparing food consumption patterns and heart disease rates in Singapore and Hong Kong (where the majority of both populations is ethnic Chinese), found that the death rate from heart disease in 1993-1995 was 2.98 times higher in Singaporean men, and 3.14 times higher in Singaporean women, than in Hong Kong men and women respectively. Singaporeans were found to have higher serum total cholesterol and LDL (‘bad’) cholesterol, but lower HDL (‘good’) cholesterol than those living in Hong Kong.
After analysing the dietary patterns in both territories, the researchers concluded that
“higher consumption of coconut and palm oil, mainly containing saturated fat, in Singapore”
was one of the primary explanations for the dramatic difference in heart disease deaths. Coconut oil raises total and LDL (‘bad’) cholesterol, which no doubt contributes to the increased risk of heart disease observed.
Finally, claiming that the Polynesians ate lots of coconut oil and had a low incidence of heart attacks is just plain naïve. All the other characteristics of the traditional Polynesian diet and lifestyle were heart-protective:
- Their traditional diet (now, sadly, largely abandoned) was characterised by a high intake of fibre, plant sterols, antioxidants and omega 3 fats; and an extremely low sodium (salt) intake;
- They had a very high activity level; and
- Rates of overweight and obesity were very low – certainly not the case in Polynesia now!
Since the remainder of their diet was low in calories and fat, the addition of total fat and saturated fat from coconut wasn’t a deal-breaker in relation to the overall healthfulness of their diet.
But if you think that sedentary, overweight Westerners with a low plant food intake can reap benefits from adding coconut oil to their diet, you’re living in cloud cuckoo land. If you’re slim, active, have no major cardiac risk factors, and eat a diet high in unrefined plant food, you can get away with having some coconut oil now and then – but don’t overdo it. If you are overweight, sedentary and have high cholesterol, high blood pressure, high C-reactive protein, a high waist to hip ratio, impaired glucose tolerance or diabetes, don’t even think about it.