Coconut oil may alter metabolism and cause obesity, mouse study finds

Evan Walker
Evan Walker TheMediTary.Com |
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Is coconut oil healthy? A mouse study finds it may contribute to obesity. Vera Lair/Stocksy
  • Though many consider coconut oil healthy, a new study suggests otherwise.
  • The study finds that coconut oil disrupted mice’s ability to use leptin and insulin, two critical hormones, with insulin resistance being a primary characteristic of type 2 diabetes.
  • Nutritionists recommend unsaturated or polyunsaturated oils instead of saturated oils like coconut oil.

Low doses of coconut oil added to the diet of mice for eight weeks led to alterations in their metabolism that contributed to the development of obesity and related co-morbidities, according to a new study.

The coconut oil disturbed the mice’s ability to properly use leptin and insulin, two hormones important for regulating energy expenditure, hunger, and how the body handles fats and sugars.

The findings support the hypothesis that a diet high in saturated fatty acids can lead to leptin resistance. At the same time as leptin resistance is developing, the body’s fat storage tissue, known as white adipose tissue, also becomes less responsive to leptin.

The study builds upon previous research in which the authors observed that coconut oil produced a central and peripheral inflammatory response, weight gain, a higher percentage of fat, reduced energy expenditure, and anxious behavior in mice, suggesting a systemic imbalance.

The 60 mice in the current study were divided into three groups receiving a liquid supplement. One group, the control group, received water, one received 100 microliters of commercial extra-virgin coconut oil, and one received 300 microliters of the same.

The daily coconut oil doses were calorically similar to what would equal about 13 grams of saturated fat or 5% of the saturated fat calories for a healthy human adult. At the end of the experiments, the mice were anesthetized and decapitated for hypothalamic study.

The study was published in the Journal of Functional Foods.

The relevance of the study’s findings to humans is not completely clear. Asked about this, Kirkpatrick said, “Impossible to say with certainty, however, studies find that mice and humans share similar genetics, so it’s a great first start.”

Wallace listed some of the factors that may give pause. He cited biological differences, dose differences, mice’s tightly controlled experimental environments that lack the variables found in a human study, genetic uniformity, rodents’ simpler systems, rodent interspecies differences, and ethical concerns.

“Because of these factors,” said Dr. Wallace, “while rodent studies can provide invaluable insights and guide further research, they are usually considered preliminary. They can highlight potential areas of concern or benefit that deserve further study in humans.”

In a systematic review cited by Dr. Wallace, only 37% of animal studies were replicated in humans, and 20% of them showed contradictory results.

He added that “any findings usually need to be validated through rigorous, controlled human trials before definitive conclusions can be made.”

“When referencing dietary oils,” said Kirkpatrick, “the most beneficial studies are often found in extra virgin olive oil as well as avocado oils, sesame, flaxseed, walnut, etc., suggesting that consumers should focus on using these oils more than oils containing saturated or trans fats.”

She added, “the most prevalent studies in humans show benefits to blood sugar management, fat storage, lower inflammation etc. when consuming dietary fats that are monounsaturated and polyunsaturated (similar to a Mediterranean pattern).” In addition, Kirkpatrick noted that data shows the benefit of replacing saturated fats with unsaturated fats.

Among common dietary fat sources, coconut oil has the highest percentage of saturated fats

Runners-up include butter, palm oil, palm kernel oil, and cocoa butter. Though popular in kitchens, shortening consists of hydrogenated vegetable oils, said Dr. Wallace, and is designed to be high in saturated fats.

“I’m not a huge fan of coconut oil personally,” said Dr. Wallace, “But only because it has been marketed and hyped-up as a health food, when it’s worse than butter, lard, and other animal-derived fats.”

He is, on the other hand, a fan of canola oil, which has one of the lowest amounts of saturated fats.

The American Heart Association’s scientific advisory statement agrees on the greater health value of unsaturated fats, noting that coconut oil has been seen to increase LDL (“bad cholesterol”) levels.

For people with an existing heart condition or who are at risk of one, the organization suggests consuming no more than 6% of a day’s calories from saturated fat. That’s equal to roughly 13 grams based on a 2,000-calorie diet, and just one tablespoon of coconut oil comes close to that limit.

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