coconut

Cracking the Coconut Oil Controversy

Coconut oil is the edible, fragrant, commercially available oil extracted from mature coconuts. Its flavor and rumored health benefits have made it an attractive option for foodies and nutritionists alike. However, unlike olive oil or soybean oil, coconut oil’s reputation is controversial, and it has been implicated as a risk factor for atherosclerosis and cardiovascular disease. But why is that? Vegetable oils are healthy alternatives, no? Why is there so much controversy on coconut oil, and are there any conclusions we can draw?

Fatty Acid Chemistry

To grasp at the coconut oil debate, it is important to first understand a little chemistry about oils. All oil is fat, and coconut oil is no exception. That isn’t bad in and of itself; fats are the storage form of essential fatty acids, which are long, energy-rich chains of carbon atoms with a carboxylic acid group at one end. Fatty acids are highly variable. Their chains are of different lengths (VLCFAs at 22 carbons1, all the way down to formic acid at one carbon2), and they may have one or more double bonds.

At the double bond, things get interesting. Each carbon atom only forms four bonds in most circumstances. Instead of a line of carbons, with each bound to two hydrogen atoms and to the carbon directly preceding and following it, double bonded carbon atoms are bonded twice to one another (–HC=CH– as opposed to –H2C–CH2–). This prevents the chains from saturating with a second hydrogen, but it also introduces a new structural element to the fatty acid, which can now be referred to as an unsaturated fatty acid.

The double bond introduces a kink in the chain’s structure, which bends it out at a ~60˚ angle instead of allowing it to straighten3. The kinks physically prevent large quantities of the chains from assuming stacked, ordered conformations. This prevents unsaturated fats from aggregating in the body, while single-bonded saturated fats have the tendency to form waxy, solid deposits. In general, vegetative food sources are higher in mono- and polyunsaturated fats, while animal food sources are higher in saturated fat. When you think of common animal fats, like butter or lard, you will note that they tend to be solids at room temperature, while vegetable oils tend to be liquid.

Coconut Oil and Cholesterol

Coconut oil is somewhat peculiar among vegetative oils, as it contains a large percentage of saturated fats. To give an idea of where coconut oil stands among other oils, the saturated fat profiles for corn, soybean, olive, and canola oil are 12.9%, 15.7%, 14.0%, and 7.6%, respectively. Coconut stands out at 91.0%4. This is reflective of climate characteristics, in that oils must maintain a certain fluidity within the living cell. In tropical environments, where the coconut palm developed, ambient heat contributes to this fluidity, so palms get away with loading themselves with less energetically costly single-bonded fatty acids. In cooler, more typical climates, plants must increase their unsaturated fat content in order to maintain the same degree of fluidity. This is why coconut oil is a waxy solid at room temperatures, but also why it is prominent as a less healthy option among the other oils.

Fat content of cooking oils
Fat content of common cooking oils

The American Heart Association recommends limiting the amount of saturated fats in your diet to less than seven percent of your total daily calories, as the accumulation of saturated fats is associated with increased LDL (low-density lipoprotein) cholesterol5. Cholesterol exists in the body in two forms, LDL, and HDL (high-density lipoprotein). LDL is the ‘bad’ form that brings fat around the body from the GI tract, and whose presence generally means there is too much fat in the diet, while HDL is the ‘good’ form that scavenges fats from around the body and takes them to the liver to be metabolized. High LDL levels are the most consistent dose-correlated markers of atherosclerosis and cardiovascular disease risks, while high HDL levels are correlated with the clearing of fatty deposits along the blood vessel walls6. At a glance, coconut oil’s high saturated fat would lend itself to an unhealthy LDL effect.

However, there is evidence that the cholesterol shift associated with oil’s intake might not be as simple as that. It is true that coconut oil is high in the fatty acid lauric acid, which, while saturated, has been shown to increase the ratio of HDL to total cholesterol when consumed, which would be a good thing if you were low in HDL7. These elements obscure the status of coconut oil but certain nutrition scientists have organized the information for us.

To evaluate the truth of these ideas, researchers in 2016 conducted a meta analysis of 7 intervention studies comparing coconut oil with less saturated vegetable oils, attempting to gauge how it was that coconut oil played out within a body of real consumers8. They found that the coconut oil resulted in significantly higher total cholesterol in all 7 of the experiments they analyzed, with significantly higher LDL cholesterol in 6 of the studies. However, HDL was significantly higher in the groups consuming coconut oil in 5 of the studies9-15.

This paints coconut oil as a middle ground between butter fat and vegetable fats. While it increases bad LDL, it also increases good HDL. A fourth type of fat, trans fatty acids, are worth mentioning only because coconut oils outperform them in every way. Trans fatty acids, or partially hydrogenated oils, are the product of an artificial chemical process which hydrogenates the fatty acid chain in order to extend the oil’s shelf life. This change brings them closer to saturated fats, and their consumption is associated with a severe increase of LDL levels and decrease of HDL levels, as well as with a slew of other complications, which may result from our bodies’ handling of their ‘unnatural’ structures16. Trans fatty acids and the mass-produced food they tend to appear in should be avoided as consistently as possible.

The Bottom Lines

Is coconut oil healthier to consume than vegetable oils? No, it is distinctly less healthy than other vegetable oils like olive oil, soybean oil, etc. These oils will lower LDL and increase HDL, while coconut oil will increase both. A good rule of thumb is to check the ratio of saturated to unsaturated fat content of your oil in question. Lower is better, and if you have a high LDL level already, steer clear of coconut oil.

Is coconut oil healthier to consume than butter? Yes, it is distinctly healthier than butter and other animal fats. Animal fats will increase LDL and decrease HDL. Coconut oil may increase LDL, but that will be cast in a much more positive light with the increase of HDL that accompanies its uptake. If your HDL level is low, coconut oil can be helpful in raising it, but care should be taken that LDL levels do not similarly increase.

Is coconut oil healthier to consume than trans fatty acids? Very much so, yes. Partially hydrogenated oils are the worst type of fat a person can put into their body. Their effects on cholesterol profiles are shocking, and they have been implicated in a variety of metabolic disorders, from coronary heart disease to diabetes to liver dysfunction17-19. Any other type of oil is preferable to consuming hydrogenated oils.

As with everything else (excluding trans fats, perhaps), moderation is key, and being aware of your cholesterol profile is a helpful guide to which oils would ameliorate or exacerbate your risk of disease. With that awareness, coconut oil can be a valuable and delicious ingredient in your food, and not something to apprehend.

Figures

Figure 1: Photograph of a cross section of a typical left main coronary artery with an advanced atherosclerotic plaque (as associated w/ a high LDL profile), and a corresponding contour trace; Glagov, 1987

Figure 2: Differences in serum total cholesterol, HDL and LDL, and triglyceride concentrations when 9% of energy of trans-fatty acids in the diet was replaced with high-lauric acid saturated fatty acids; de Roos, 2001

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Citations

1. Rezanka T. Very-long-chain fatty acids from the animal and plant kingdoms. Progress in Lipid Research. 1989; 28(3): 147-187

2. Brody T. Nutritional Biochemistry (2nd ed.). Academic Press. 1999. p. 320.

3. Casimir C, Akoh DB. Min. Food Lipids: chemistry, nutrition, and biotechnology. New York: M. Dekker. 2002; p. 1–2.

4. Nutrient database, Release 24. United States Department of Agriculture.

5. Know Your Fats. American Heart Association. 2014

6. Glagov S, Weisenberg E, Zarins CK, Stankunavicius R, Kolettis GJ. Compensatory Enlargement of Human Atherosclerotic Coronary Arteries. N. Engl. J. Med. 1987; 316 (22): 1371–1375.

7. Temme EH, Mensink RP, Hornstra G. Comparison of the effects of diets enriched in lauric, palmitic, or oleic acids on serum lipids and lipoproteins in healthy women and men. Am J Clin Nutr. 1996; 63(6): 897-903

8. Eyres L, Eyres MF, Chisholm A, Brown RC. Coconut oil consumption and cardiovascular risk factors in humans. Nutr Rev. 2016; 74(4): 267-280.

9. Cox C, Mann J, Sutherland W, et al. Effects of coconut oil, butter, and safflower oil on lipids and lipoproteins in persons with moderately elevated cholesterol levels. J Lipid Res. 1995; 36: 1787–1795.

10. Cox C, Sutherland W, Mann J, et al. Effects of dietary coconut oil, butter and safflower oil on plasma lipids, lipoproteins and lathosterol levels. Eur J Clin Nutr. 1998; 52: 650–654.

11. Fisher EA, Blum CB, Zannis VI, et al. Independent effects of dietary saturated fat and cholesterol on plasma lipids, lipoproteins, and apolipoprotein E. J Lipid Res. 1983; 24: 1039–1048.

12. Mendis S, Kumarasunderam R. The effect of daily consumption of coconut fat and soya-bean fat on plasma lipids and lipoproteins of young normolipidaemic men. Br J Nutr. 1990; 63: 547–552.

13. Ng TK, Hassan K, Lim JB, et al. Nonhypercholesterolemic effects of a palm-oil diet in Malaysian volunteers. Am J Clin Nutr. 1991; 53(4 suppl): 1015S–1020S.

14. Reiser R, Probstfield JL, Silvers A, et al. Plasma lipid and lipoprotein response of humans to beef fat, coconut oil and safflower oil. Am J Clin Nutr. 1985; 42: 190–197. Nutrition Reviews VR Vol. 74(4): 267–280

15. Voon PT, Ng TK, Lee VK, et al. Diets high in palmitic acid (16:0), lauric and myristic acids (12:0 þ 14:0), or oleic acid (18:1) do not alter postprandial or fasting plasma homocysteine and inflammatory markers in healthy Malaysian adults. Am J Clin Nutr. 2011; 94: 1451–1457

16. de Roos NM, Schouten EG, Katan MB. Consumption of a Solid Fat Rich in Lauric Acid Results in a More Favorable Serum Lipid Profile in Healthy Men and Women than Consumption of a Solid Fat Rich in trans-Fatty Acids. J. Nutr. 2001; 131: 2 242-245

17. Zaloga GP, Harvey KA, Stillwell W, Siddiqui R. Trans Fatty Acids and Coronary Heart Disease. Nutrition in Clinical Practice. 2006; 21 (5): 505–512.

18. Hu FB, van Dam RM, Liu S. Diet and risk of Type II diabetes: the role of types of fat and carbohydrate. Diabetologia. 2001; 44(7): 805–817

19. Mahfouz M. Effect of dietary trans fatty acids on the delta 5, delta 6 and delta 9 desaturases of rat liver microsomes in vivo. Acta biologica et medica germanica. 1981; 40(12): 1699–1705

by Paris Thatos