A beginner’s guide to cholesterol


Remember the 80’s? First IBM PC was made, bright cheap noisy clothes were the norm (at least in the West) and the Cold War ended. Ah, and the anti-cholesterol craze was in full motion. Wonder what happened to that? Here’s a beginner’s guide to cholesterol!

What even is cholesterol?

According to the U.S. Government, it is a waxy fat-like substance and our bodies use it for all sorts of things, like making vitamin D, hormones and cell membranes.

Therefore, it is very important and we need it. Luckily our body produces it, but we can also take it from animal foods, especially egg yolks. One medium sized egg can contain ~60% of recommended daily intake.

Yet why all the fear? Mostly because cholesterol has been linked to many common heart and vascular diseases. But the story is not that simple.


Lipoproteins are substances containing both lipids (fats) and proteins. Cholesterol doesn’t mix well with water so it needs a packaging, like Low-Density Lipoproteins (LDL) or High-Density Lipoproteins (HDL), to travel through your blood.

HDL, sometimes called “good cholesterol”, is used to carry excess cholesterol to the liver where it is broken down and eliminated.

LDL, also called “bad cholesterol”, serves to disperse cholesterol in your body, where, if it is too much, leads to build-up of plaque in your arteries.

What we eat and what we do influence a lot the amount of HDL and LDL in our blood. For example:

  • Smoking rises LDL and lowers HDL
  • Exercising lowers LDL and raises HDL
  • Being overweight favours heart and arterial diseases.

Since cholesterol level variation in blood is not something with immediate and visible effect, the U.S. Government recommends having a check-up every 5 years if you are under 65 and every 2 years if you are over.

Good cholesterol levels are:

  • Under 200 mg/dL for total (including HDL, LDL and other)
  • Under 100 mg/dL for LDL
  • Over 60 mg/dL for HDL

Let’s talk a bit about fats.

Oils, Butter and Lard

 I for one love avocado. Guac is the best spreadable there is (fight me) and, thanks to its oils, it carries well any extra flavour you may add, for example garlic or chili. I am sure that it became such a popular fruit thanks to its “good fat” and the marketing around it. But how can a fat be good? Or bad?

Lipids can be separated in 2 groups: saturated, like butter, coconut oil and lard, which are solid at room temperature, and unsaturated, like fish oil, olive oil and sunflower oil, which are liquid at room temperature

Unsaturated fats have some carbon-carbon double bonds. Maybe you remember from chemistry about “cis” and “trans” bonds. When you hear “trans fat” it actually means “unsaturated lipid with at least one trans bond” which I am sure you will agree it doesn’t roll off your tongue as easily.

Trans fats are a bit rare in nature. You can find it in cows, sheep and goats because the bacteria that breaks down grass in their stomach makes them as a by-product. But most of the trans fats that humans consume are artificially made. At high temperature part of the cis bonds from oils can become trans, something that happens a lot in the production of margarine or fried fast-food.

So which is good? Which is bad?

According to this free Stanford course:

  • Unsaturated cis fats are the best. They lower LDL level and raise HDL.
  • Saturated fats are so and so: they raise LDL and don’t significantly affect HDL
  • Trans fats are the worst: they rise LDL and lower HDL

WHO recommends that less than 30% of our total daily energy intake comes from fats, of which less than a third should be saturated. Also, no trans fats!

It is worth mentioning that natural trans fats are not considered dangerous and some studies found that some of them can be even healthy (so you don’t have to give up on butter).

Although the heart and arterial diseases mentioned here usually manifest later in life, I say it is worth preserving your body even as a zoomer so you have a better chance at a healthy old age. All you need to do is to eat better. Knowing all this information about cholesterol, you have a slightly better understanding about why avocado is amazing, and margarine should be thrown in the bin.


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