With all the talk about saturated fat and monounsaturated fat, polyunsaturated fat and trans fat, it’s easy to get confused about how they fit into the big picture and, more importantly, what it means for the food choices you make. I’d like to give you another strategy for figuring out what to eat. Instead of FAT, I am going to talk about FATTY ACIDS. First, some definitions.
If fat is a sentence, then fatty acids are words. If fat is a word, then fatty acids are letters. If fat is the universe, then fatty acids are galaxies. If fat is a solar system, fatty acids are planets and moons. If fat is a pyramid, fatty acids are bricks.
If foods are words, then I want to focus on the letters. Today, I want to talk not about olives and avocados, not olive oil and avocado oil, but rather about the o’s and the e’s with which they are spelled. This conversation is not about lard or chicken fat. It’s about the fatty acids of which they are composed.
Every molecule of fat consists of three fatty acids, each of which is attached at one end to a glycerol molecule. Think of glycerol as the backbone of the molecule. Each fatty acid consists of a chain of carbon molecules, and each one is completely independent from the other two. Sometimes two or, occasionally, even all three of the fatty acids are identical, but usually they are all different. Fatty acids can be long (20 carbon molecules or more in length) or short (just a few carbon molecules long). Because each fatty acid performs a different job, it’s good to eat a variety of fats.
Length is not the only way in which fatty acids vary one from another. There is also the matter of saturation. Saturation refers to how thoroughly a carbon chain is packed with hydrogen molecules. If each and every one of the available bonding spaces on every single carbon in a fatty acid contains a molecule of hydrogen, we say that fatty acid is saturated. If one single space is still available for one additional hydrogen molecule, that fatty acid is monounsaturated. Mono- comes from the Greek word for one. Finally, if more than one space is available, that molecule is called polyunsaturated. Poly- means many. It is entirely possible that a fat molecule might consist of one monounsaturated fatty acid, one polyunsaturated fatty acid, and one saturated fatty acid. Each of these contributes different characteristics to the fat (or oil).
Along the way, we have gotten the impression that the more saturated fatty acids in a fat, the more likely it is to cause disease, and that, conversely, the more polyunsaturated the less likely. I would like to suggest that there’s more to this, and that we do not yet have the whole picture.
Let’s start with saturated fatty acids. One of the fats in our diet with the highest percentage of saturated fatty acids is cocoa butter. Cocoa butter is the primary fat in dark chocolate. We have good data and extensive research on the beneficial health effects of eating dark chocolate. What does that tell me? That we don’t have the whole story.
What about monounsaturated fatty acids? The most commonly mentioned fat in the category of monounsaturated fatty acids is olive oil, with approximately three-fourths, or 75%, of its fatty acids being monounsaturated. The rest of its constituent fatty acids are divided between saturated and polyunsaturated fatty acids. Avocado oil (70%) and almond oil (65%) are also are high in monounsaturated fatty acids. Additional fats with significant amounts of monounsaturated fatty acids include sesame oil (40%), lard (45%), peanut oil (45%), tahini (50%), chicken fat (~50%) and goose fat (52%).
I know that this is confusing. If lard, chicken fat, and goose fat are high in monounsaturated fatty acids, then why are they not included in the same category as olive oil? Are they okay to eat or not? Again, I do not believe that we have the whole story. In the meantime, I would suggest that it is no longer necessary to scrape off every last bit of fat and skin from chicken breasts before you cook them. Enjoy your dinner.
Finally some thoughts on polyunsaturated fatty acids. Corn oil (60%) and tub margarine (~50%) are examples of two items with a high proportion of polyunsaturated fatty acids. Sunflower oil is even higher at ~70%. Unfortunately, not all polyunsaturated fatty acids are equal.
If you have read or heard about omega-3s and omega-6s, this is the class of fatty acids to which they belong. Whereas omega-3 fatty acids appear to have a significant anti-inflammatory effect, omega-6s are pro-inflammatory. This does not mean that they are bad for you; pro-inflammatory mediators are essential for fighting off foreign invaders and reducing collateral damage. But your body functions best with an even balance of omega-6s and omega-3s. And because the ultra processed industry is built on omega-6’s, whose greater chemical stability slows the onset of rancidity, consumers whose diets consist primarily of ultraprocessed items end up taking in exceedingly large amounts of omega-6s. This tips the metabolic balance heavily in the direction of inflammation, and away from the anti-inflammatory effects of omega-3 fatty acids.
Even the most beautiful building in the world, if built with substandard materials, is at greater risk of collapse. The same is true for nutrients: the most appetizing-looking food will not nourish you if it is made with poor-quality fats.
Flaxseeds and edamame are also very high in polyunsaturated fatty acids. That’s good, right? In the case of flaxseeds, edamame, and sunflower seeds, yes. Definitely. Eat away! But in the case of cottonseed, corn, and sunflower oil, there’s more here than meets the eye.
An important meta-analysis of multiple research studies on fatty acid intake and polyunsaturated fat supplementation did not support the currently accepted guidelines promoting 1) increased consumption of polyunsaturated fatty acids and 2) reduced consumption of saturated fatty acids. The researchers concluded that further research is necessary, especially in healthy individuals. But they went on to say that until we understand better, people should stick to the current guidelines on fat consumption. Even though they just showed that those guidelines are not consistent with the observed outcomes? In view of their conclusions, I cannot support this recommendation.
My recommendation would be to continue to do your best to eat whole foods. Well-raised dairy, eggs, poultry, fish, and meats; tons of vegetables, beans, fruit, nuts and seeds; whole grains only (to the extent you are able), and of course olive oil, peanut butter, avocado oil, and dark chocolate. And, as best you can, avoid anything that was invented in the 20th century.