13 Studies on Coconut Oil and Its Health Effects
Coconut oil has received a lot of attention in recent years.
This is because of its potential health benefits, many of which can be attributed to the medium-chain triglycerides (MCTs) it contains.
There are many promising animal, test-tube and observational studies on coconut oil. However, these types of studies can't prove that coconut oil is beneficial in humans.
Interestingly, it has also been studied in several human controlled trials. These studies are much better at determining whether coconut oil is truly healthy for people.
This article looks at 13 controlled human studies on coconut oil.
1. White MD, et al. "Enhanced postprandial energy expenditure with medium-chain fatty acid feeding is attenuated after 14 d in premenopausal women." American Journal of Clinical Nutrition, 1999.
Twelve normal-weight women followed a medium-chain-triglyceride (MCT) diet for 14 days, consuming 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, resting metabolic rate and calories burned after meals were significantly higher on the MCT diet, compared to the LCT diet. After 14 days, the difference between the diets was no longer statistically significant.
2. Papamandjaris AA, et al. "Endogenous fat oxidation during medium chain versus long chain triglyceride feeding in healthy women." International Journal of Obesity, 2000.
Twelve normal-weight women consumed a mixed diet supplemented with either butter and coconut oil (MCT diet) or beef tallow (LCT diet) for 6 days. For 8 days, long-chain fats were given to both groups in order to 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 seven in the MCT group compared to the LCT group, but the difference was no longer significant by day 14.
3. Papamandjaris AA, et al. "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, 1999.
Twelve normal-weight women 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 seven of the MCT diet compared to the LCT diet, but 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. "An open-label pilot study to assess the efficacy and safety of virgin coconut oil in reducing visceral adiposity." International Scholarly Research Notices Pharmacology, 2011.
Twenty overweight or obese people consumed 10 ml of virgin coconut oil three times per day before meals for four weeks, for a total of 30 ml (2 tablespoons) per day. They were instructed to follow their usual diets and exercise routines.
After four weeks, the men had lost an average of 1.0 in (2.61 cm) and women an average of 1.2 in (3.00 cm) from around the waist. Average weight loss was 0.5 lbs (0.23 kg) overall and 1.2 lbs (0.54 kg) in men.
5. Assuncao ML, et al. "Effects of dietary coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity." Lipids, 2009.
Forty women with abdominal obesity were randomized to take 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 coconut oil per day.
They were instructed to follow a low-calorie diet and walk 50 minutes daily.
Both groups lost about 2.2 lbs (1 kg). However, the coconut oil group had a 0.55-in (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 HDL (the good) cholesterol and a 35% decrease in C-reactive protein (CRP), a marker of inflammation.
Additionally, the soybean oil group had an increase in LDL (the bad) cholesterol, a decrease in HDL cholesterol and a 14% decrease in CRP.
6. Sabitha P, et al. "Comparison of lipid profile and antioxidant enzymes among south Indian men consuming coconut oil and sunflower oil." Indian Journal of Clinical Biochemistry, 2009.
Seventy men with type 2 diabetes and 70 healthy men were divided into groups based on their use of coconut oil versus sunflower oil for cooking over a six-year period. Cholesterol, triglycerides and markers of oxidative stress were measured.
There were no significant differences in any values between the coconut oil and sunflower oil groups. The diabetic men had higher markers of oxidative stress and heart disease risk than the non-diabetic men regardless of the type of oil used.
7. Cox C, et al. "Effects of coconut oil, butter and safflower oil on lipids and lipoproteins in persons with moderately elevated cholesterol levels." Journal of Lipid Research, 1995.
Twenty-eight people with high cholesterol followed three diets containing either coconut oil, butter or safflower oil as the main fat source for six weeks each. Lipids and lipoproteins were measured.
Coconut oil and butter increased HDL significantly more than safflower oil in women, but not in men. Butter raised total cholesterol more than coconut oil or safflower oil.
8. Reiser R, et al. "Plasma lipid and lipoprotein response of humans to beef fat, coconut oil and safflower oil." American Journal of Clinical Nutrition, 1985.
Nineteen men 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 five weeks each, alternating with normal eating for five weeks between each test period.
The coconut oil diet raised total, HDL and LDL cholesterol more than the beef fat and safflower oil diets, but raised triglycerides less than the diet containing beef fat.
9. Muller H, et al. "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, 2003.
Twenty-five women consumed three diets: a high-fat, coconut oil based diet; a low-fat, coconut oil based diet; and a diet based on highly unsaturated fatty acids (HUFA).
They consumed each for 20–22 days, alternating with one week of their normal diet between each test diet period.
The high-fat, coconut oil based diet group had greater increases in HDL and LDL cholesterol than the other groups.
The low-fat, coconut oil based diet group showed an increase in the LDL to HDL ratio, while the other groups showed a decrease.
10. Muller H, et al. "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, 2003.
Eleven women consumed three different diets: a high-fat, coconut oil based diet; a low-fat, coconut oil based diet; and a diet with mostly highly unsaturated fatty acids.
They followed each diet for 20–22 days. Then they alternated with 1 week of a normal diet between the test periods.
Women who consumed the high-fat, coconut oil based diet had the largest reductions in markers of inflammation after meals, as well as fasting markers of heart disease risk, especially when compared to the HUFA group.
11. Kaushik M, et al. "The effect of coconut oil pulling on Streptococcus mutans count in saliva in comparison with chlorhexidine mouthwash." Journal of Contemporary Dental Practice, 2016.
Sixty people were randomized to rinse their mouths with coconut oil for 10 minutes, chlorhexidine mouthwash for one minute or distilled water for one minute. Plaque-forming bacteria in their mouths were measured before and after treatment.
Both the coconut oil and chlorhexidine were found to significantly reduce the amount of plaque-forming bacteria in saliva.
12. Peedikayil FC, et al. "Effect of coconut oil in plaque related gingivitis — A preliminary report." Niger Medical Journal, 2015.
Sixty teenagers aged 16–18 years with gingivitis (gum inflammation) did oil pulling with coconut oil for 30 days. Inflammation and plaque markers were measured after seven, 15 and 30 days.
Markers of plaque and gingivitis were significantly decreased by day seven and continued to decrease for the duration of the study.
However, there was no control group in this study, so it cannot be concluded that the benefits were caused by coconut oil.
13. Law KS, et al. "The effects of virgin coconut oil (VCO) as supplementation on quality of life (QOL) among breast cancer patients." Lipids Health Disease Journal, 2014.
Sixty women with advanced breast cancer undergoing chemotherapy participated in this study. They were randomized to receive either 20 ml of virgin coconut oil daily or no treatment.
Women 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.
All five studies examining changes in fat loss or metabolism found some benefit with coconut oil, compared to other oils or control groups. However, the effects were usually modest.
Here are a few facts to consider:
- Coconut oil increased metabolism during at least one time point in each study where it was measured (1, 2, 3).
- In one study, subjects in the coconut oil group experienced decreases in body fat and waist circumference without intentionally reducing calories (4).
- A study comparing calorie-restricted diets found decreased abdominal fat only in the group who took coconut oil (5).
There are also several studies that have looked at fat loss and metabolic changes in response to MCT oil, which makes up about 65% of coconut oil.
Here is a detailed article about the effects of coconut oil on weight and belly fat.
Five studies looked at the effects of different fats on cholesterol and triglycerides. Here are a few points about the findings:
- Coconut oil increased HDL cholesterol more than unsaturated fat did and at least as much as butter (5, 13, 14, 15).
- Coconut oil was found to raise total and LDL cholesterol more than safflower oil and beef fat, but less than soybean oil and butter (5, 13, 14).
- Triglycerides didn't change much in response to coconut oil versus other oils in diets 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 (5, 16).
The practice of oil pulling with coconut oil was found to reduce the bacteria responsible for plaque. In addition, it significantly improved gingivitis in teenagers.
Quality of Life in Breast Cancer
The addition of a small amount of coconut oil to the diets of women undergoing chemotherapy for breast cancer resulted in significantly better quality of life scores.
Coconut oil seems to help overweight people lose abdominal fat. It also appears to increase metabolic rate, at least temporarily.
However, since each tablespoon of coconut oil provides 130 calories, this increase in metabolism can easily be offset if large amounts are consumed.
Although coconut oil seems to raise LDL cholesterol more than some other fats, its most consistent effect is an increase in HDL cholesterol.
It's also important to remember that responses to dietary fats can vary a lot from person to person.
That being said, coconut oil is generally a healthy and natural food. Including it in your diet may improve your health, weight and quality of life.