Edited by Kate Findley, The Great Courses Daily
You may have heard that fats found in nuts and avocado are good for you, while fats in meat and dairy lead to heart disease. According to Dr. Ormsbee, though, it’s not as clear-cut as this.
Saturated and Unsaturated Fats
Saturated and unsaturated fats, which comprise the two categories of fatty acids, vary by the length of their carbon-to-carbon chain and the number of hydrogen atoms that surround the carbon chain. That’s the definition of saturated or unsaturated—they’re either saturated with hydrogens or not.
When fatty acids are joined together, they form a triglyceride. A triglyceride, as the prefix tri tells us, are lipids with three fatty acids that are attached to a glycerol backbone. Triglycerides are the major storage form of fat in the body and the major form of fat in your diet.
On a food label, you will often see saturated and unsaturated fats highlighted. You may also see monounsaturated, polyunsaturated, and trans fats listed.
Saturated fats are saturated with hydrogens and have no double bonds in the carbon chain. These fats, which include animal fats in meat, butter, and coconut oil, are usually solid at room temperature.
Are Animal Fats Bad?
When saturated fats are the predominant source of fat in the diet, or eaten in excess, they are associated with increased blood levels of total cholesterol. High cholesterol levels have been correlated in some research to increased risk of heart disease.
However, not everyone agrees on this. In fact, new research no longer supports the idea that high cholesterol causes heart disease, although correlational data does exist.
Some research also shows that excessive intake of saturated fat, without balancing it by also eating unsaturated fat, is correlated to other serious conditions like Alzheimer’s disease, certain cancers, diabetes, and cardiovascular disease. Again, though, new research questions the common recommendation that we need to lower our saturated fat intake from our diets.
Some experts now suggest that high saturated fat in combination with high intake of sugar and other processed carbohydrates may be the real problem for our health and body composition. In fact, saturated fat may be less of a problem than originally thought, so long as carbohydrate intake is not excessive and balanced fat intake is in place. A balance of fat intake occurs when unsaturated fats are also in your diet.
Types of Unsaturated Fats
Unsaturated fats contain one or more double bonds along the carbon chain, meaning that, unlike saturated fat, they are not completely saturated with hydrogen molecules. There are two types of unsaturated fats, which are called mono and polyunsaturated fats.
Monounsaturated fats have only one unsaturated bond—these are called a double bond—while polyunsaturated fats have more than one unsaturated double bond. An easy way to identify an unsaturated fat is that it is typically liquid at room temperature.
However, if unsaturated fats are chilled or refrigerated, they will solidify. Examples of monounsaturated fat include olive oil, canola oil, peanut oil, and sesame oil. You will also find monounsaturated fats in foods like avocados, peanut butter, and even nuts and seeds.
The polyunsaturated fats are also known as essential fatty acids, meaning that they are essential to eat because our bodies cannot make them naturally. Many foods have a mix of fat types, but some examples of polyunsaturated fats include soybean oil, canola oil, flax, tofu, soybeans, and fatty fish like salmon.
Polyunsaturated fats include both omega-6 and omega-3 fatty acids. These essential fatty acids are needed for immune function, vision, and cell membrane integrity among other things.
Dr. Michael Ormsbee is an Associate Professor in the Department of Nutrition, Food, and Exercise Sciences and Interim Director of the Institute of Sports Sciences and Medicine in the College of Human Sciences at Florida State University. He received his M.S. in Exercise Physiology from South Dakota State University and his Ph.D. in Bioenergetics from East Carolina University.