The fact that trans fats, or partially hydrogenated oils, are bad for us is pretty much a fact that everyone agrees on. But if you’re like me, it’s not enough to simply know that something is unhealthy. You want to know why.
In this post I will answer the question on why are trans fats bad, and I will discuss some facts about them that you may not have heard of before.
I will talk a bit about the chemistry, the mechanism behind the harmful effects and how to avoid them.
Chemistry 101: Trans fatty acids
If you hate chemistry, just skip over to the next section.
Fatty acids are basically long chains of carbon atoms, with hydrogen atoms attached to them. At one end of the molecule is an organic acid group (COOH, not shown on the picture below) which is the reason they are called “fatty acids“. Fat is composed of a glycerol molecule and three fatty acids.
Fatty acids can be either saturated, unsaturated or polyunsaturated, depending on the amount of double bonds. A double bond means that the molecule has two less hydrogen atoms, that is it is not saturated (unsaturated) with hydrogen.
A double bond can be in two forms: cis or trans. A cis double bond means that both hydrogen atoms are on the same side, and a bend develops in the molecule (pic on left). A trans double bond means that the hydrogen atoms are on opposite sides, and there is no bend (pic on right).
Trans fats are created as side effects when attempting to turn unsaturated or polyunsaturated fats into saturated fats. High pressure is used, as well as hydrogen gas and a metal catalyst. A portion of the fatty acids don’t become fully hydrogenated, and instead become trans fatty acids (partially hydrogenated oils).
Saturated fats and partially hydrogenated fats have a higher melting point and a longer shelf life than unsaturated/polyunsaturated fats.
Why are trans fats bad?
The trans fats that we find in processed foods are foreign materials to the body. It does not know what to do with them because it was never exposed to them during evolution.
One consequence of consuming them is raised small and dense LDL (bad) cholesterol levels, as well as lowered HDL (good) levels. According to research studies, they massively increase chances of developing heart disease (1) and they may also cause increased abdominal fat gain, at least in monkeys (2).
They may also increase risks of cancer and Alzheimers disease, but the case for those is not nearly as strong as for heart disease.
I often see trans fats and saturated fats put in the same category. This is completely wrong, since it has never been scientifically proven that saturated fat causes any harm. According to the studies, saturated fat is not bad for you.
What saturated fat does, is raise large, fluffy LDL cholesterol which is completely benign while raising HDL cholesterol which is good.
Trans fat, however, both raises small, dense LDL (very bad) and lowers HDL (also very bad).
Trans fat in meat and dairy
Actually, meat and dairy contain some natural trans fatty acids such as CLA which actually has health benefits and is often sold as a fat burning supplement. This type of trans fat is nothing to worry about, only the factory produced artificial ones.
This basically just follows the theme of real and natural food having health benefits for people, while the industrially generated counterpart being harmful. The way trans fats are built in the factory is truly disgusting, and it’s a wonder why people would ever think these would be suitable for human consumption.