Health Articles

Coconut Oil Reduces Risk of Diabetes

So why are anti-fat proponents pointing at this study as proof against the use of coconut oil?

Good news for those who are diabetic or overweight—a new study demonstrates that a diet rich in coconut oil protects against insulin resistance (an impaired ability of cells to respond to insulin) and excess body fat accumulation. The bad news is that anti-fat proponents are pointing to this study as proof that coconut oil is harmful and may cause liver disease.

Dr. Nigel Turner and colleagues from Sydney’s Garvan Institute of Medical Research compared fat metabolism and insulin resistance in two groups of mice, one fed coconut oil (rich in medium chain fatty acids) and the other fed fats (consisting of long chain fatty acids) typical to those which are eaten in the Western world. The diets contained a total 45-60 percent fat. The mice receiving the coconut oil showed better insulin sensitivity and had less fat accumulation. Their findings are published in the international journal Diabetes.

The beneficial effects of the coconut oil used in the study were attributed to the medium chain fatty acids. The results showed that medium chain fatty acids improve insulin action and can help prevent insulin resistance. Insulin resistance is the underlying cause of type 2 diabetes.

The study also provided evidence that obesity, which is a strong risk factor for diabetes, may also be lessened by the use of coconut oil. Rather than be stored into fat cells, medium chain fatty acids are used to produce energy. “The medium chain fatty acids, like those found in coconut oil, are interesting to us because they behave very differently to the fats normally found in our diets,” said Dr. Turner. “Unlike the long chain fatty acids contained in animal fats, medium chain fatty acids are small enough to enter mitochondria—the cells’ energy burning powerhouses—directly, where they can then be converted to energy.” This process not only reduces the amount of fat packed away into storage as body fat, but improves insulin sensitivity.

This study offers strong support justifying the use of coconut oil as part of a healthy diet. However, while this study praises coconut oil on one hand, it criticizes it on the other. Despite showing an improvement in insulin sensitivity and reduced body fat accumulation, the coconut oil fed mice developed fatty deposits and insulin resistance in the liver. “Unfortunately,” Turner cautions, “the downside to eating medium chain fatty acids is that they can lead to fat buildup in the liver, an important fact to be taken into consideration by anyone considering using them as a weight loss therapy.”

Once this study became public, news stories began popping up everywhere. The stories highlighted the positive effects of coconut oil on insulin and body fat, but also cautioned against its use due to the risk of developing a fatty liver.

Coconut oil critics are quick to point out that excess fat buildup can lead to liver failure. No matter what benefits the oil might otherwise have, if it causes serious harm to the liver it is not good. Some people who were eating coconut oil are now having second thoughts.

This study appears to contradict itself. It seems strange that coconut oil would improve insulin sensitivity and reduce fat accumulation throughout the body, yet cause insulin resistance and excessive fat accumulation within the liver. Other studies, in addition to this one, have shown that medium chain fatty acids reduce body fat. Some have also shown that they lower fat deposits in the liver, 2-5 which is contrary to the findings in this study. Other studies have shown that medium chain fatty acids protect the liver when subjected to toxins that cause fatty liver.6-7 If all these other studies show that medium chain fatty acids protect the liver from fat buildup, why would this study show that they cause it? Something obviously doesn’t add up.

When the livers of the coconut oil fed mice in this study were examined, the researchers discovered that 95 percent of the fats in the liver were long chain fatty acids, not medium chain. Where did these long chain fatty acids come from?

Medium and short chain fatty acids comprise about 64 percent of coconut oil. The remainder consists of long chain fatty acids, some of which are unsaturated. Here is where the problem lies. Although there is no mention of it in the news articles or even in the abstract of the study, the type of coconut oil the researchers used was not ordinary coconut oil. If you read the entire article, buried in the technical procedures of the article the authors state that they used hydrogenated coconut oil. Now it all makes sense.

When unsaturated fats are hydrogenated, they become more saturated. In the process, artificial saturated fats known as trans fatty acids are created. These fats are not like natural saturated fats and cause a multitude of health problems, among which is insulin resistance and fatty liver. Hydrogenated oils have long been known to cause fatty liver.8-9 It doesn’t matter if it is hydrogenated soybean, corn, or coconut oil. All hydrogenated oils cause fat buildup in the liver. It is the long chain trans fatty acids in the hydrogenated coconut oil that clogged the liver of these mice. Keep in mind, that the researchers were feeding the animals very large amounts of fat—45-60 percent of daily calories. So they were receiving a lot of harmful trans fatty acids in the experimental diet.

This is a good example of a study producing negative results because the researchers used hydrogenated coconut oil. The authors of the study seemed to ignore the fact that hydrogenated coconut oil could produce a different outcome from natural coconut oil.

It is very interesting that despite the fact that the coconut oil the researchers used was hydrogenated, the undamaged medium chain fatty acids in the coconut oil were still powerful enough to overcome the negative effects of the trans fatty acids and were still able to reduce body fat and preserve insulin sensitivity throughout the body. However, they apparently were not able to completely block the damage the trans fatty acids did to the liver.

Many researchers do not yet recognize or understand the difference between natural saturated fats and artificially produced saturated trans fatty acids. For this reason, hydrogenated coconut oil is often used in studies. Usually somewhere in the study the authors make mention they used hydrogenated oil. In many of the older studies, however, this fact is not mentioned.  So you must be careful about studies that report negative effects of coconut oil. Like the one here, you may need to read the entire article in order to discover this fact. Most people don’t bother to track down the study and read it in detail. They prefer to rely on a reporter’s interpretation, which probably came from a news release and not the actual study. Important facts, like using hydrogenated oils, are not often revealed in news releases unless they were an important aspect of the study. This is one of the ways the “myths” about the so-called harmful effects of coconut oil are started and perpetuated.

Since many news articles were written and circulated on the Internet about this study, no doubt the fatty liver issue will be broadcast loudly by anti-coconut proponents claiming more “proof” of the dangers of consuming coconut oil or saturated fat. You need not be troubled if you run across such reports because you now have the facts.

References

1. Turner, N., et al. Enhancement of muscle mitochondrial oxidative capacity and alterations in insulin action are lipid species dependent: potent tissue-specific effects of medium chain fatty acids. Diabetes 2009;58:2547-2554.
2. Lieber, C.S., et al Beneficial effects versus toxicity of medium-chain triacylglycerols in rats with NASH. J Hepatol 2008;48:318-326.
3. Baldermann, H., et al Changes of hepatic morphology during parenteralnutrition with lipid emulsions containing LCT or MCT/LCT quantified by ultrasound. JPEN J Parenter Enteral Nutr 1991;15:601-603.
4. Nosaka, N., et al Effects of dietary medium-chain triacylglycerols on serum lipoproteins and biochemical parameters in healthy men. Biosci Biotechnol Biochem 2002;66:1713-1718.
5. Romestaing, C., et al. Long term highly saturated fat diet does not induce NASH in Wistar rats. Nutr Metab 2007;4:4.
6. Mak, K.M., et al. Adipose differentiation-related protein is a reliable lipid droplet marker in alcoholic fatty liver of rats. Alcohol Clin Exp Res 2008;32:683-689.
7. Lieber, C.S., et al. Difference in hepatic metabolism of long- and medium-chain fatty acids: the role of fatty acid chain length in the production of the alcoholic fatty liver. J Clin Invest 1967;46:1451-1460.
8. Degrace, P., et al. Association of liver steatosis with lipid oversecretion land hypotriglyceridaemia in C57BL/6j mice fed trans-10, cis-12-linoleic acid. FEBS Lett 2003:546:335-339.
9. Tetri, L.H. Severe NAFLD sith hepatic necroinflammatory changes in mice fed trans fat and a high-fructose corn syrup equivalent. Am J Physiol Gastrointest Liver Physiol 2008;295;G987-995.