Health Benefits of Coconut Oil: Fact or Fiction?

Posted: November 11, 2015 in Diet and Nutrition
Tags: , , , , , , ,

NOTE: This is a repost of my latest article written for the Huffiness Institute at Texas A&M University, which you can find at this link.

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Recently, coconut oil has exploded in popularity: it is added to coffee, used in cooking, and even consumed by the spoonful. This begs the question of what exactly makes coconut such a “miracle food”? A number of organizations advise against the consumption of coconut oil because of its high saturated fat (SF) content, including the U.S. Food and Drug Administration, Academy of Nutrition and Dietetics, and American Heart Association.  Indeed, coconut oil is approximately 90% SF (14), which has generally been shown to increase total, LDL, and HDL cholesterol. However, fatty acids vary in their number of carbons, yielding different categories of chain length that affect fat metabolism.  Coconut oil is mainly composed of medium chain fatty acids (MCFA), which may give it unique properties that differentiate it from other SF.

Lauric acid is a 12-carbon MCFA that makes up 50% of coconut oil. Studies have shown that lauric acid may have a lesser effect on total and LDL cholesterol compared to other SF (4), and any increase in total cholesterol is attributed to increased HDL cholesterol (5, 9). Lauric acid is not degraded in the intestines, but is transported directly to the liver where it easily diffuses into mitochondria to be converted into acetyl-CoA and ketone bodies for energy (2, 5). Lauric acid is the most highly oxidized fatty acid, therefore contributing least to fat accumulation (5). Additionally, it has been shown to exhibit antibiotic and antiviral properties that may positively impact immune function (5, 11).

Animal studies have shown that virgin coconut oil supplementation in rats decreases total and LDL cholesterol, blood triglycerides, and abdominal fat while increasing HDL cholesterol (11, 15). Surveys of Pacific Islanders who obtain 50-80% of their energy from coconut sources have lower rates of cardiovascular disease (13), and such coconut-based diets show reduced markers of heart attack risks (9). During a weight-loss intervention in women, exercise with coconut oil supplementation increased HDL while decreasing both LDL:HDL and waist circumference (1); another study showed an increase in HDL with coconut oil supplementation in women but not in men (4).

Fewer studies have looked at the effect of coconut oil on exercise performance. An animal model showed that mice fed MCFAs significantly increased their swimming endurance, with increased markers of fat oxidation and ketone body utilization (6). A case study on elite endurance cyclists who were fed high SF diets containing coconut oil showed greater endurance capacity compared to a polyunsaturated diet (8).

While little research is available on the effects of coconut oil ingestion on exercise performance, the high concentrations of MCFAs (specifically lauric acid) exhibit potential for application to athletes. These fatty acids are available for “quick” energy while contributing least to fat accumulation, which could positively impact performance. Additionally, the general population may benefit from increased HDL cholesterol, lower LDL:HDL, and decreased abdominal obesity by consuming coconut oil in place of other SF. All of these properties together suggest that perhaps the “coconut craze” may have some truth to it after all.

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References:

1. Assuncao M.L., H.S. Ferreira, A.F. dos Santos, C.R. Cabral Jr, T.M.M.T. Florencio. Effects of dietary coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity. Lipids. 44(7):593-601. 2009.

2. Bach and Babayan. Medium-chain triglycerides: an update. American Journal of Clinical Nutrition. 36:950-962. 1982.

3. Chempro: http://www.chempro.in/fattyacid.htm (accessed 7/1/2015)

4. Cox, C., J. Mann, A. Chisholm, M. Skeaff. Effects of coconut oil, butter, and safflower oil on lipids and lipoproteins in persons with moderately elevated cholesterol levels. Journal of Lipid Research. 36(8):1787-1795. 1995.

5. Dayrit, F.M. The properties of lauric acid and their significance in coconut oil. Journal of the American Oil Chemists Society. 92(1):1-15. 2015.

6. Fushiki, T., K. Matsumoto, K. Inoue K, T. Kawada. Swimming endurance capacity of mice is increased by chronic consumption of medium-chain triglycerides. Journal of Nutrition. 125:531-539. 1995.

7. Lukaski, H.C., W.W. Bolonchuk, L.M. Klevay, J.R. Mahalko, D.B. Milne, H.H. Sandstead. Influence of type and amount of dietary lipid on  plasma concentrations in endurance athletes. American Journal of Clinical Nutrition. 39:35-44. 1984.

8. Lukaski, H.C., W.W. Bolonchuk, L.M. Klevay, J.R. Mahalko, D.B. Milne, H.H. Sandstead. Interactions among dietary fat, mineral status, and performance of endurance athletes: a case study. International Journal of Sport Nutrition and Exercise Metabolism. 11:186-198. 2001.

9. Mensink, R.P., P.L. Zock, A.D.M. Kester, M.B. Katan. Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials. American Journal of Clinical Nutrition. 77(5):1146-1155. 2003.

10. Muller, H., A.S. Lindman, A. Blomfeldt, I. Seljeflot, J.I. Pedersen. A diet rich in coconut oil reduces diurnal postprandial variations in circulating tissue plasminogen activator antigen and fasting liproprotein (a) compared with a diet rich in unsaturated fat in women. Journal of Nutrition. 133(11):3422-3427. 2003.

11. Nevin, K.G., T. Rajamohan. Beneficial effects of virgin coconut oil on lipid parameters and in vitro LDL oxidation. Clinical Biochemistry. 37(9):830-835. 2004.

12. Nevin, K.G., T. Rajamohan. Virgin coconut oil supplemented diet increases the antioxidant status in rats. Food Chemistry. 99(2):260-266. 2006.

13. Prior, I.A., F. Davidson, C.E. Salmond, Z. Czochanska. Cholesterol, coconuts, and diet on Polynesian atolls: a natural experiment: the Pukapuka and Tokelau island studies. American Journal of Clinical Nutrition. 34(8):1552-1561. 1981.

14. USDA: http://ndb.nal.usda.gov/ndb/foods/show/636?fgcd=&manu=&lfacet=&format=&count=&max=35&offset=&sort=&qlookup=Coconut+Oil (accessed 7/1/2015)

15. Zulet, M.A., A. Barber, H. Garcin, P. Higueret, J.A. Martinez. Alterations in carbohydrate and lipid metabolism induced by a diet rich in coconut oil and cholesterol in a rat model. Journal of the American College of Nutrition. 18(1):36-42. 1999.

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