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Trans, Unsaturated, and Saturated Fats - What do they mean?

Updated: Mar 2, 2021

By: Silvia DiPaola, Contributing Writer

On any common food label, you may see the words “no trans fat,” “high in unsaturated fats” and “low in saturated fats.” What exactly do these terms mean? The difference lies in the chemical structures in each that give them their distinct properties.

Let’s begin with saturated fats. All fats are a part of the biological macromolecules group called lipids. Lipids are hydrophobic, meaning they tend to repel water, and they are made of a molecule called glycerol attached to a number of hydrocarbon chains (also known as fatty acid chains). Saturated fats are made up of one glycerol and three fatty acid chains linked together by a covalent bond. The hydrocarbon chains in saturated fats are made up of hydrogen and carbon linked by single bonds. These single bonds cause rigidity in the structure of saturated fats, allowing them to remain solid at room temperature. Examples include butter and lard. Saturated fats get their name from the fact that the hydrocarbon chain is “saturated” with two to three hydrogens per carbon molecule on each chain.

Unsaturated fats also have one glycerol molecule with three fatty acid/ hydrocarbon chains attached. However, one of these chains has a cis double bond between two carbons instead of a single bond. This causes a “kink” in the structure of the fatty acid that prevents it from remaining rigid. Thus, unsaturated fats are liquid at room temperature. On each double-bonded carbon on the chain, there is one less hydrogen molecule attached, which is why the chain is said to be unsaturated. Examples of unsaturated fats include avocados and nuts. The phrase “hydrogenated vegetable oils” on food labels means that unsaturated fats have been synthetically converted to saturated fats by adding hydrogen, allowing them to solidify at room temperature. This process also produces unsaturated fats with trans double bonds, known as trans fats. It seems that trans fats can contribute to coronary heart disease, so efforts have been made by the FDA to reduce the amounts of trans fats in the local food supply.

Now that we know the chemical differences between each type of fat, we can delve into which is the healthiest to consume. The word “fats” may have a negative connotation, but our bodies require them to perform their basic metabolic processes. Trans fats are automatically the unhealthiest type of fat to consume. It has no benefits and it is correlated with heart disease and atherosclerosis. It is best to avoid consuming any trans fats at all. Common sources of trans fats include packaged/processed goods, stick margarine, and fried foods. There is some debate about whether saturated fats are good or bad for you; recent studies have shown that there is not much correlation between saturated fats and high cholesterol/heart disease, but scientists in the past thought it did increase your risk of heart disease. It is likely safe to consume but in moderation. It is not the healthiest fat you can eat. Sources include cured meats, packed goods, and cakes. Unsaturated fats are undoubtedly the healthiest for your body. These fats can actually help lower your LDL (Low-Density Lipoprotein, your “bad” cholesterol) levels and raise your HDL (High-Density Lipoprotein, your “good” cholesterol) levels, reduce your risk of heart disease and improve your overall heart health. Salmon, nuts, and avocados are excellent sources of unsaturated fats.

By eating salmon instead of steak and replacing your canola spray oil with olive oil, you can easily trade out unhealthy fats for healthier ones. Red meat may be correlated with cancer risks, so it is best to have it in moderation regardless. Instead of eating processed snacks, try having nuts.

Hopefully, you are better aware of the nutritional value of the different types of fats. Fats are necessary for your body, they are not something to be feared!

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Hilary Hong
Hilary Hong
Jan 26, 2021

Will definitely be making changes in my diet now.

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