Coconut oil, fatty acids and oils (part 2)
© Dr. Michael D. Jacobson, D.O. Do not reproduce this article without permission.
As we discussed in last month's article, if you can hang in there for a little chemistry with me, it will help you understand the difference between saturated and unsaturated fatty acids, their respective health risks and benefits, etc.
- By definition fats are solid at room temperature, while oils are liquid.
- Fats and oils are both made up of “chains” of fatty acids. These are comprised of a “backbone” of carbon atoms, with hydrogen bound to the carbon atoms.
- Each carbon atom is only bound to three other atoms. A single bond between two carbon atoms is represented by C—C.
- If a carbon atom is only bound to three other atoms, it will stabilize itself by forming a double bond, as represented by C=C. For example, oleic acid is a monounsaturated fatty acid (meaning there is one C=C double bond). It is referred to as an Omega-9 fatty acid because the C=C double bond occurs at the ninth carbon in the chain. Olive oil is rich in oleic acid.
- A fatty acid that is said to have no double bonds (i.e. every C—C bond) is said to be saturated.
- A fatty acid that has at least one C=C double bond is said to be unsaturated. If only one single carbon bond is present, the fatty acid is said to be monosaturated. If more than one carbon double bond is present, the fatty acid is said to be polyunsaturated.
- The more double bonds that are present, the more liquid the form the fatty acid takes (i.e. as an oil).
- The longer the chain of fatty acids, particularly when fully saturated, the harder (more solid) it is at room temperature. For example, palmitic acid is a 16-carbon fully saturated fatty acid, and the most common fatty acid found in nature. Stearic acid is two carbons longer, and commonly found in beef tallow. These two fatty acids are solid even at nearly 150 degrees Fahrenheit. Imagine that floating around in your 98.6 degree bloodstream!
- Fatty acids that are 10 carbons long or shorter do not require emulsification (the breakdown of large fat globules into smaller, uniformly distributed particles) by bile acids for digestion. These are called short- (i.e. 4-carbon butyric acid) and medium-chain fatty acids. They’re absorbed directly through the intestinal wall. There is also some evidence that these short-chain fatty acids nourish the intestinal wall.
- Longer-chain fatty acids require more effort to digest and tend to be transported around the bloodstream in clumps called chylomicrons.
- Unsaturated fatty acids—particularly monounsaturated fatty acids such as olive oil and Omega-3 fatty acids (such as those found in cold water fish, like salmon)—have a considerable body of research that support their heart and overall health benefits. However, the double bonds of unsaturated fatty acids—particularly when there are multiple double bonds in oil—make them vulnerable to oxidation from light, heat or oxygen. Oxidation can produce toxic compounds called free radicals. Thus, oils rich in polyunsaturated fatty acids (including common vegetable blends) should probably not be used in high-temperature cooking.
Some research suggests that Omega-6 fatty acids, like those found in certain seeds, may promote inflammation and actually increase the risk of certain conditions like heart disease, asthma, etc.
So how do we evaluate coconut oil? The oil, somewhat contrary to the information cited in the member’s email that appeared in last month’s article, is 92 percent saturated fat (albeit nearly half of that comes from 12-carbon lauric acid, which functions as a long-chain fatty acid). Another 25 percent comes from 14- and 16-carbon saturated fatty acids, known as myristic acid and palmitic acid. Furthermore, the research articles attesting to its health benefits are somewhat conflicting and of poor quality, leaving us without much basis for making authoritative recommendations. However, given the information above, I would still suggest using coconut oil:
- only in moderation
- primarily as a cooking agent and not for nutritional purposes
Omega-3 and Omega-9 fatty acids, or short- and medium-chain fatty acids, have much better research supporting their use for nutritional benefit (as long as they are protected from oxidation).
By the way, except for high-temperature cooking, butter and olive oil are generally my preferences, both because of their taste and because of their fatty acid composition. Butter has only 60 percent saturated fat, 26 percent oleic acid, and is only four percent butyric acid.