A great many parts of our bodies rely on fat to perform their essential functions, and I’d like to review some of them here. The better you understand fats, their functions, and their structures, the less susceptible you will be to the advertising that influences consumers to purchase products made with industrially-modified fats. Today we’re talking about fat. For purposes of this essay, consider the terms “fat” and “oil” to be interchangeable.
Firstly, our brains are made primarily from fat; and our nerves are insulated by fat. Fat is critical for properly functioning nerves, and its absence or destruction typically results in devastating illness.
When Nature was working out how to keep the water component of our bodies from leaking onto the floor whenever we stood up, fat was the solution. Nature chose fats to make cell membranes. Our cell membranes are composed of fat, which makes sense when you think about it. Cell membranes serve as envelopes that keep their watery worlds inside. This is an essential job, so it isn’t a stretch to say that fats are essential to life. After all, since we are made mostly from water, and oil and water do not mix, oil keeps water inside, where it belongs, and prevents it from moving outside, where it does not.
When we need to keep the acid in our stomachs from being neutralized by the basic bicarbonate in our intestines, fat is used to separate them once and for all. Fats are an ideal way to keep apart all kinds of watery solutions.
Fats carry the fat-soluble vitamins (which is all of them, excepting Vitamin C and the B vitamins, which are water-soluble). So if you eat a diet that is deficient in fat, there is also a chance that you may be deficient in one or more fat-soluble vitamins.
I also want to talk about the difference between fats and fatty acids, the building blocks of fats. At a molecular level, fats consist of a backbone with three tails, just like the letter E. The backbone is a sugar-like compound called a glycerol. The tails are fatty acids. A fatty acid is a chain of carbon molecules.
The term fat describes a source. A fat might derive from an avocado, like avocado oil, or a peanut, like peanut oil. It might be liquid at room temperature but solid in the refrigerator, like olive oil. Or it might be solid at room temperature, but turn liquid when you heat it, like butter. Their physical characteristics depend on the kinds of fatty acids of which the fat is composed.
Strictly speaking, a fat is not accurately described as mono- or polyunsaturated. That’s because all fats are made up of combinations of fatty acids. Fatty acids themselves can be monounsaturated, polyunsaturated, or saturated; and most fats contain a mixture of these. In fact, even olive oil, which is typically considered “monounsaturated,” actually contains all three kinds of fatty acids, with 33% monounsaturated fatty acids, 16% saturated fatty acids, and the remainder a mix of various fatty acids. The fat molecules in cocoa butter are composed of approximately 33% monounsaturated and 67% saturated fatty acids. Almond oil is composed of approximately 10% monounsaturated, 30% saturated and 60% polyunsaturated fatty acids. Chicken fat is composed of approximately 42% monounsaturated, 21% polyunsaturated and 35% saturated fatty acids. There is a significant amount of variability among crops and species, which explains why the list of fatty acid components does not always add up to 100%.
Because each fatty acid in a fat molecule is different, it would be more accurate to describe each fatty acid than to group the entire fat in one word. Describing a fat as having a particular property is actually misleading. It would be more accurate to describe oils as they truly are, as mixes of their constituent fatty acids. This might be like describing triplets by their individual characteristics [“He likes dinosaurs, she is taking gymnastics, and he’s already in a size 8 shoe.”] than in one statement [“They’re almost 5.”]. You’d be much more likely to get some helpful information.
Some chains of fatty acids are very short, just a few carbon atoms long, whereas others are long, more than 20 carbons long. Sometimes a fat molecule consists of two identical fatty acids and one different one; sometimes all three are different from one another. Only rarely are all three fatty acids in a fat molecule identical; it is usually composed of a variety of fatty acids. This is why describing a fat as “monounsaturated” or “saturated” is misleading.
Next time: More on monounsaturated, polyunsaturated, and saturated fatty acids, as well as omega-3’s and 6’s.