In our society, we have a tendency to avoid "fat."
We want low-fat milk, low-fat cheese, and low-fat sweets. This often leads to an increase in carbohydrate intake to compensate, which may contribute to increased weight gain. Most of us are familiar with three types of fats: saturated fat, trans-unsaturated fat, and unsaturated fat. There is constant research about the benefits and risks of these dietary fats. It is up to us then to elucidate which fats are healthy and to avoid those that are not.
Saturated fats increase high-density lipoprotein (HDL) cholesterol as well as low-density lipoprotein (LDL) cholesterol. Trans-unsaturated fat, although may occur in some natural foods, mostly come from oils. These fats may decrease HDL cholesterol while increasing LDL cholesterol and triglyceride levels. LDLs are considered the "bad" cholesterol because it can contribute to the build-up of fats in the arteries that may lead to forming plaques in the arteries and interfering with the blood flow. HDLs are considered the "good" cholesterols because it scavenges the LDLs, carrying it to the liver or eliminating it from the body.
As both saturated fats and trans-unsaturated fat increases the "bad" cholesterol, these are considered unhealthy fats.
On the other hand, unsaturated fats are considered healthier, including monounsaturated fatty acids and polyunsaturated fatty acids. Monounsaturated fatty acids, as indicated by the term "mono," are fatty acids with one double bond in the entire fatty acid chain. This is how it is distinguished from the polyunsaturated fatty acids with two or more carbon-carbon double bonds. The two are also different in the functions that they serve in the body. Monounsaturated fatty acids, found in olive oil, avocado, peanut butter, and almond butter, may decrease LDL while keeping HDL high.
In addition, in a 2015 study, humans were given bread with different oils – sunflower oil, high oleic sunflower oil, and virgin olive oil – where the latter two oil groups contained monounsaturated fat, namely the oleic acid. The study found those who consumed the monounsaturated fat reduced their food intake 24-hours later, potentially indicating its role in the feeling of satiety. Polyunsaturated fatty acids include omega-3 (in kiwi, kale, salmon) and omega-6 (in edamame, tahini, avocado). Omega-3s have been shown to "play important roles in the body as components of the phospholipids that form the structures of cell membranes" and omega-6s, specifically the gamma-linolenic acid, have been identified to improve rheumatoid arthritis in some patients. However, there is some talk around how the ratio of Omega-3 and Omega-6 must be optimized with higher Omega-3 than Omega-6.
While it seems agreed upon that unsaturated fatty acids are healthier than saturated or trans-unsaturated fatty acids, it is not entirely clear how much and which unsaturated fatty acids are the best for us.
There are numerous research speculating possible benefits of unsaturated fatty acids in a myriad of aspects of medicine, including inflammation and brain development, but more investigations are necessary to reach a definitive conclusion.
