Fats are either saturated or unsaturated; know the difference? by Goodhealth

Fats are either saturated or unsaturated; know the difference?

April 17, 2023

It seems that for a long time there has been a bit of a stigma around the word ‘fat’ and that it’s not exactly considered a best friend when it comes to food. While this is true of some fats, there are others that are hugely important to your diet and health (they aren’t called ‘essential’ for nothing!). Without trying to change the world in one health article, we thought it’d be a good idea to break down this complex topic and dispel some of the myths around fats to let you know why it’s so vital you include them in your diet.

Because fatty acids are essential to life on earth, every food we eat will contain fat, even if, in the case of some fruits, the amount is around 0.001%. And every fat in every food will be a combination of saturated, monounsaturated, and polyunsaturated fatty acids, in varying ratios. There is a myriad of short, medium, and long chain fatty acids, within the 3 levels of saturation, e.g., stearic, palmitic, lauric, butyric, linoleic, arachidonic (Omega-6), and docosahexaenoic (DHA – Omega-3), to name but a few! The Omega-6 and 3 fatty acids are considered essential because we cannot make them in our body. Omega 3 has a positive effect on our cardiovascular health, and it also is very good at supporting a healthy immune response.

A saturated fat…

…is so-called because, at a molecular level, the carbon bonds are fully “saturated” with hydrogen atoms. This makes saturated fatty acids generally firm and solid at room temperature, not prone to oxidation, and very stable to cook with. Saturated fats will not “clog your arteries”. The most stable fats are the ruminant (cow, sheep, etc.) fats like tallow, suet, and the fat on red meat. Butter and ghee are also stable, although the milk proteins left in butter can cause the butter to burn when frying. To call animal fats “saturated” is to ignore the monounsaturated and polyunsaturated components of the fat, as a whole. For example, Beef fat is, on average, nearly 50% saturated, but also approximately 45% monounsaturated and 5% polyunsaturated – a perfect ratio for human health.

Contrast that with unsaturated fats,

which are usually liquid at room temperature, prone to oxidation, and very unstable. We know them as fruit oils like olive, avocado, and coconut oil, or seed/vegetable oils like flaxseed oil, soybean, rice bran, and canola, but again, they are not solely unsaturated – they also contain a ratio of saturates to unsaturates. Olive oil is a fruit-derived lipid (fat) and is approximately 73% monounsaturated, 14% saturated, and 11% polyunsaturated. Coconut oil is the most saturated fruit fat, with around 90-92% saturated, 6-8% monounsaturated, and the balance, polyunsaturated.

Just to confuse things, polyunsaturated fats also include the essential fatty acids, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (AA, or AHA). These 3 fatty acids are essential because we cannot make them in our body, and we have to obtain them from our diet. The omega 3s, DHA and EPA, and omega 6, AHA, are only found in animal foods. The plant forms of omega 3, alpha linolenic acid, and omega 6, linoleic acid, are poorly converted to the useable forms in most of us. Algae oils do contain DHA, EPA, and AHA, but they are still in a form that we also need to convert in our body, so are not a completely reliable substitute for animal fats in the diet.

Weird science

For a while now, due to incomplete and inaccurate science undertaken in the middle of last century, the thinking has been that there was a benefit of using unsaturated vegetable oil over saturated fat because it is “better for heart and cardiovascular health”. This was because eating unsaturated oils “lowered cholesterol levels” in the blood. We now know that cholesterol is not the cause of problems, in and of itself. Cholesterol is vital for all animal life and our body makes the bulk of the cholesterol we need.

What makes polyunsaturated oils…

…more dangerous to our heart health is that when they are heated the oil oxidises, producing free radicals, which can damage arteries. They’re called vegetable oils, but they have little to do with vegetables, as such. They are extracted from seeds, and most are industrially processed oils, the processes creating toxic chemicals within the oil. Hydrogenated oil, found in margarines, etc., is altered to behave like a saturated fat – to be solid at room temperature, and is the most dangerous because it becomes a trans-fat. While a small amount of cold-pressed, organic seed oil, is ok, ditch the margarine and stick to butter! Use other animal fats (and some coconut oil) for cooking, and olive oil and whole avocado for salads, mayos, etc.

Another reason vegetable oils should be avoided is because they contain relatively high levels of linoleic acid (LA), an omega-6 fatty acid. Small amounts are present in traditional foods, but with vegetable oils in almost all processed foods, our modern diets are far too high in LA. The issue with excess LA is complicated but the main problems are how easily it oxidises, how it competes with Omega-3s for metabolism, its harmful breakdown products (OXLAMS and aldehydes), and how it hijacks satiety levels through cannabinoid receptor activation in the gut.

Vegetable oils also contain phytosterols, which compete with cholesterol for use in the body. Cholesterol is essential for life and around 80% of Cholesterol is made in the liver. Cholesterol is so important that the brain makes its own.

Fat for fuel

Fats can be utilised as a fuel, just like glucose, but in a different way in our mitochondria (cell powerhouses). A healthy metabolism is not overloaded with energy and able to switch between these 2 fuel sources via the Randle cycle. Glucose is thought to be the main fuel utilised during waking hours and for “explosive”, fast movement, whereas fat is preferentially “burned” during sleep and during endurance type activities, but we swap between them all the time, if healthy. Fat can also be utilised in the form of ketones but that is a topic for another day! The key thing to remember is that if you are not eating ultra-processed foods or much in the way of refined oils and sugar, so that you are keeping your insulin within normal levels, you should be able to switch between fuel sources with ease.

The final skinny on fat

The important thing to remember is that fats are an important part of our diet and should be eaten in whole food form, not in the form of industrially produced oils. Eating natural, animal fats from land and sea animals is not bad and, in fact, could be the very thing that made us human. They contain fat soluble vitamins, A, C, D, and E, and are very stable and contain many little-known, healthy fatty acids like CLA, and odd-chain FAs.

Dietary fat is a much more complex and nuanced topic than most healthcare providers would have you believe. To make things simpler, avoid vegetable oils, especially if they’re hydrogenated, as much as possible. These are the fats you would find in processed and junk “foods”. Deep fried foods should be avoided at all costs due to the toxic nature of the vegetable oils when they are heated. If you can find a takeaway bar that still uses highly stable beef tallow or pork lard (any kind of meat dripping or rendered fat) to fry with, that is a much healthier choice. At the end of the day, don’t fear the natural fat, just the oil!