13 Studies on Coconut Oil and Its Health Effects
Coconut oil has received a lot of attention in recent years, and there’s some evidence that it may help with weight loss, oral hygiene, and more.
Coconut oil is a saturated fat, but unlike many saturated fats, it doesn’t contain cholesterol. It also contains medium-chain triglycerides (MCTs).
Various studies have suggested that MCTs may have health benefits.
This article looks at 13 controlled human trials on coconut oil. This is the best type of study for deciding whether or not a food is beneficial for people.
1. White, MD, et al. (1999). Enhanced postprandial energy expenditure with medium-chain fatty acid feeding is attenuated after 14 d in premenopausal women. American Journal of Clinical Nutrition. DOI: 10.1093/ajcn/69.5.883
Twelve females without overweight followed an MCT diet for 14 days. They consumed butter and coconut oil as their main sources of fat.
For another 14 days, they followed a long-chain-triglyceride (LCT) diet, consuming beef tallow as their main source of fat.
After 7 days, the resting metabolic rate and the calories burned after meals were significantly higher on the MCT diet compared with the LCT diet. After 14 days, the difference between the diets was no longer statistically significant.
2. Papamandjaris AA, et al. (2000). Endogenous fat oxidation during medium chain versus long chain triglyceride feeding in healthy women. International Journal of Obesity. DOI: 10.1038/sj.ijo.0801350
Twelve females without overweight consumed a mixed diet supplemented with either butter and coconut oil (MCT diet) or beef tallow (LCT diet) for 6 days. For 8 days, both groups consumed LCTs, so that the researchers could assess fat burning.
By day 14, the MCT group burned more body fat than the LCT group. Resting metabolic rate was significantly higher on day 7 in the MCT group compared with the LCT group, but the difference was no longer significant by day 14.
3. Papamandjaris AA, et al. (2012). Components of total energy expenditure in healthy young women are not affected after 14 days of feeding with medium-versus long-chain triglycerides. Obesity Research. DOI: 10.1002/j.1550-8528.1999.tb00406.x
Twelve women without overweight consumed a mixed diet supplemented with butter and coconut oil (MCT diet) for 14 days and beef tallow (LCT diet) for a separate 14 days.
Resting metabolic rate was significantly higher on day 7 of the MCT diet, compared with the LCT diet. However, the difference was no longer significant by day 14. Total calorie expenditure was similar for both groups throughout the study.
4. Liau KM, et al. (2011). An open-label pilot study to assess the efficacy and safety of virgin coconut oil in reducing visceral adiposity. International Scholarly Research Notices. DOI: 10.5402/2011/949686
Twenty people with either overweight or obesity consumed 10 mL of virgin coconut oil three times per day before meals for 4 weeks, or a total of 30 mL (2 tablespoons) per day. Otherwise, they followed their usual diets and exercise routines.
After 4 weeks, the males had lost an average of 1.0 inches (2.61 cm) and females an average of 1.2 inches (3.00 cm) from around the waist. The average weight loss was 0.5 pounds (0.23 kg) overall and 1.2 pounds (0.54 kg) in males.
5. Assunção ML, et al. (2009). Effects of dietary coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity. Lipids. DOI: 10.1007/s11745-009-3306-6
Forty females with abdominal obesity took either 10 mL of soybean oil or coconut oil at each meal, three times per day for 12 weeks. This amounted to 30 mL (2 tablespoons) of oil per day.
The researchers also asked them to follow a low-calorie diet and walk 50 minutes daily.
Both groups lost about 2.2 pounds (1 kg). However, the coconut oil group had a 0.55-inch (1.4-cm) decrease in waist circumference, whereas the soybean oil group had a slight increase.
The coconut oil group also had an increase in high-density lipoprotein (HDL) or “good” cholesterol, and a 35% decrease in C-reactive protein (CRP), a marker of inflammation.
Additionally, the soybean oil group had an increase in low-density lipoprotein (LDL) or “bad” cholesterol, a decrease in HDL (good) cholesterol, and a 14% decrease in CRP.
6. Sabitha P, et al. (2009). Comparison of lipid profile and antioxidant enzymes among south Indian men consuming coconut oil and sunflower oil. DOI: 10.1007/s12291-009-0013-2
This study involved 70 males with type 2 diabetes and 70 males without diabetes. Researchers divided the participants into groups based on their use of coconut oil versus sunflower oil for cooking over a 6-year period.
The researchers measured cholesterol, triglycerides, and markers of oxidative stress.
There were no significant differences in any values between the coconut oil and sunflower oil groups. Those with diabetes had higher markers of oxidative stress and heart disease risk than those without diabetes, regardless of oil type.
7. Cox C, et al. (1995). Effects of coconut oil, butter and safflower oil on lipids and lipoproteins in persons with moderately elevated cholesterol levels.Journal of Lipid Research. https://www.jlr.org/content/36/8/1787.long
Twenty-eight people with high cholesterol followed three diets containing coconut oil, butter, or safflower oil as the main fat source for 6 weeks each. The researchers measured their lipid and lipoprotein levels.
Coconut oil and butter increased HDL significantly more than safflower oil in females, but not in males. Butter raised total cholesterol more than coconut oil or safflower oil.
8. Reiser R, et al. (1985). Plasma lipid and lipoprotein response of humans to beef fat, coconut oil and safflower oil. American Journal of Clinical Nutrition. DOI: 10.1093/ajcn/42.2.190
Nineteen males with normal cholesterol levels consumed lunch and dinner containing three different fats for three sequential trial periods.
They consumed coconut oil, safflower oil, and beef fat for 5 weeks each, alternating with their usual diet for 5 weeks between each test period.
Those who followed the coconut oil diet had higher levels of total, HDL (good), and LDL (bad) cholesterol than those who consumed the beef fat and safflower oil diets. However, their triglyceride levels rose less than those who consumed beef fat.
9. Müller H, et al. (2003). The Serum LDL/HDL Cholesterol Ratio Is Influenced More Favorably by Exchanging Saturated with Unsaturated Fat Than by Reducing Saturated Fat in the Diet of Women. Journal of Nutrition. DOI: 10.1093/jn/133.1.78
Twenty-five females consumed three diets:
- a high fat, coconut oil-based diet
- a low fat, coconut oil diet
- a diet based on highly unsaturated fatty acids (HUFA)
They consumed each for 20–22 days, alternating with 1 week of their normal diet between each test diet period.
In the high fat, coconut oil-based diet group, HDL (good) and LDL (bad) cholesterol levels rose more than in the other groups.
In the low fat, coconut oil-based diet group, LDL (bad) cholesterol levels rose more, compared with HDL (good) levels. In the other groups, LDL (bad) cholesterol fell in comparison with HDL (good).
10. Müller H, et al. (2003). A diet rich in coconut oil reduces diurnal postprandial variations in circulating tissue plasminogen activator antigen and fasting lipoprotein (a) compared with a diet rich in unsaturated fat in women. Journal of Nutrition. DOI: 10.1093/jn/133.11.3422
Eleven females consumed three different diets:
- a high fat, coconut oil-based diet
- a low fat, coconut oil-based diet
- a diet with mostly highly unsaturated fatty acids.
They followed each diet for 20–22 days. Then they alternated with 1 week of their usual diet between the test periods.
Females who consumed the high fat, coconut oil-based diet had the largest reductions in markers of inflammation after meals. Their fasting markers of heart disease risk also fell more, especially compared with the HUFA group.
11. Kaushik M, et al. (2016). The effect of coconut oil pulling on Streptococcus mutans count in saliva in comparison with chlorhexidine mouthwash. Journal of Contemporary Dental Practice. DOI: 10.5005/jp-journals-10024-1800
Sixty people rinsed their mouths with one of the following:
- coconut oil for 10 minutes
- chlorhexidine mouthwash for 1 minute
- distilled water for 1 minute
Scientists measured levels of plaque-forming bacteria in their mouths before and after treatment.
Those who used either coconut oil or chlorhexidine saw significant reductions in the number of plaque-forming bacteria in saliva.
12. Peedikayil FC, et al. (2015). Effect of coconut oil in plaque related gingivitis — a preliminary report. Niger Medical Journal. DOI: 10.4103/0300-1652.153406
Sixty teenagers ages 16 to18 with gingivitis (gum inflammation) did oil pulling with coconut oil for 30 days. Oil pulling involves using coconut oil as a mouthwash.
Researchers measured inflammation and plaque markers after 7, 15, and 30 days.
Markers of plaque and gingivitis fell significantly by day 7 and continued to decrease during the study.
However, there was no control group, so it’s not certain that coconut oil was responsible for these benefits.
13. Law KS, et al. (2014). The effects of virgin coconut oil (VCO) as supplementation on quality of life (QOL) among breast cancer patients. Lipids in Health and Disease. DOI: 10.1186/1476-511X-13-139
This study involved 60 females who were undergoing chemotherapy for advanced breast cancer. They received either 20 mL of virgin coconut oil daily or no treatment.
Those in the coconut oil group had better scores for quality of life, fatigue, sleep, loss of appetite, sexual function, and body image than those in the control group.
Effects on weight loss and metabolism
All five studies that looked at changes in fat loss or metabolism found that coconut oil had some benefit, compared with other oils or control groups.
However, many of the studies were small, and the effects were usually modest.
- Coconut oil increased metabolism during at least one time point in each study where it was measured.
- In one study, people in the coconut oil group saw decreases in body fat and waist circumference without intentionally reducing calories.
- A study comparing calorie-restricted diets found that abdominal fat fell only in the group who took coconut oil.
Several other studies have looked at fat loss and metabolic changes in response to MCT oil, which makes up about 65% of coconut oil.
Each of these suggested that MCT oil could increase metabolism, reduce appetite and calorie intake, and promote fat loss.
However, not all researchers are convinced. Some studies haven’t detected any weight loss benefits, and the evidence is inconsistent overall.
Here’s a detailed article about the effects of coconut oil on weight and belly fat.
Effects on cholesterol, triglycerides, and inflammation
Five studies looked at the effects of different fats on cholesterol and triglycerides. Here are some of the findings:
- Coconut oil increased HDL (good) cholesterol more than unsaturated fat did and at least as much as butter.
- Coconut oil raised total and LDL (bad) cholesterol more than safflower oil and beef fat, but less than soybean oil and butter.
- Triglycerides didn’t change much in response to coconut oil compared with other dietary oils with similar fat content.
- Markers of inflammation and oxidative stress decreased more in people who consumed coconut oil compared to people who consumed other oils.
Unfortunately, the studies didn’t look at ApoB or the LDL particle count. These are more accurate markers for heart disease risk than the standard LDL (bad) cholesterol measurement.
Other health benefits of coconut oil
The practice of oil pulling with coconut oil may reduce the bacteria responsible for plaque. In addition, it significantly improved gingivitis in the study involving teenagers.
Quality of life with breast cancer
Adding a small amount of coconut oil to the diet while undergoing chemotherapy for breast cancer may improve a person’s quality of life at this time.
The bottom line
Coconut oil may help people lose abdominal fat and temporarily increase their metabolic rate.
However, each tablespoon of coconut oil provides 130 calories. The extra calorie intake might outweigh the benefits to the metabolic rate.
Responses to dietary fats can vary widely between individuals. For many, consuming too much of any type of fat can lead to weight gain and related health problems.
The body needs some fat, but it’s important to choose the right one and to consume any fat in moderation.
Overall, current Dietary Guidelines for Americans recommend consuming a diet that’s low in saturated fat. Saturated fat should represent fewer than 10% of calories a day, according to the guidelines.
That said, coconut oil may be a healthy choice that could benefit your overall health, weight, and quality of life.
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