What are saturated fats & where to find them
Fats can be categorised into 3 distinct groups, poly-unsaturated fats, mono-unsaturated fats, and saturated fats. They differ from the amount of unsaturated chemical bonds they contain, with saturated fats contaminating no double bonds at all. There are a number of types of saturated fats, and these only vary from the length of the molecule. The double bonds (or lack of) heavily influence their structure and properties of the fat; saturated fats are very straight with no bends, whereas the mono-unsaturated and poly-unsaturated fats have bends and kinks in their structure. Saturated fats typically have the following properties which allow you to identify them and their sources:
- Solid at room temperature (shorter saturated fats may be liquid on a warm day – think coconut oil)
- Very heat stable (making them ideal to cook with)
- Most abundant in animal fats (with some exceptions)
With this in mind it is unsurprising to know that beef/ lamb fat are some of the highest sources of saturated fats, as are butter, cream, eggs and any foods which are sourced from animals. There are a few exceptions to this rule though, with coconuts and avocados also containing large amounts of saturated fats too. You may already start to see flaws in the health messages we hear about saturated fats in the media. How can coconut oil and avocados be good for you when saturated fats are bad for you?
Early research into saturated fats
Post world war 2 saw a rise in cardiovascular disease in the Western world, and no one knew what the cause was. A man called Ancel Keys did have a hypothesis based on the limited evidence available at the time though – the rise in cardiovascular disease was due to high consumption of animal fats, which are high in saturated fats. He presented this idea to the World Health Organisation (WHO) in 1955, and then went out to conduct the infamous 7 country study to prove his hypothesis. Now, for anyone who has done a science subject beyond high school, alarm bells should be ringing at this point, and even for those who didn’t, you may notice the fatal fault with what has just happened. Ancel Keys went out to prove his hypothesis. You should never go out to prove your hypothesis, but rather you should go to investigate a relationship. For example, in the case of fats and cardiovascular disease, you should investigate the relationship between fats and cardiovascular disease whereas a bad researcher will investigate how fats cause cardiovascular disease. Ancel Keys had already decided that fats were the cause of cardiovascular disease, and so selected data to prove his hypothesis. If you think you know the answer before you investigate, it is very easy to find that answer – this gives bias results. This bias is shown by the fact that Ancel Keys cherry picked data from 7 countries which ‘proved’ his hypothesis and ignored data from 14 other countries. In addition to this, there are other serious flaws with this study, such as the assumption that the total amount of cholesterol in the blood increases the risk of cardiovascular disease, and sugar consumption was not recorded. Most, if not all, modern scientists, nutritionists, doctors, researchers etc don’t accept this study as valid (although the message has not yet reached everyone).
However, when Ancel Keys conclusions wer published saying that saturated fats were the cause of cardiovascular disease, the media jump on his conclusions, and ignored all the critics who said that the research was flawed and more research was needed. Why? Well, what sells newspapers more, a headline saying that no still knows the cause, or a headline identifying the cause of heart disease.
Since the 1950’s, research methods have come on in leaps and bounds, so current finding are much less likely to suffer from the same bias and the 7 country study. Looking at data collected in 1998 (which includes many more countries than Ancel Keys did) we can see that there is in fact no correlation between % of energy from saturated fats and heart disease (graph right, click to enlarge).
When scrolling through scientific journal databases we see much the same story from recent studies. In 2011 an analysis of 33 data sets from prospective epidemiological studies found that there was ‘no meaningful relationship between intake of saturated fatty acids (SFAs) and the risk of coronary heart disease (CHD)’1.
A more recent study published in the Atherosclerosis Journal stated that ‘consumption of animal products, per se, is not necessarily associated with increased CVD risk’ and ‘the total matrix of a food is more important than just its fatty acid content in predicting the effect of a food on CVD risk, and a healthy diet should be the cornerstone of CVD prevention2.
Likewise, randomized controlled trials that replaced saturated fat with vegetable oils did not provide convincing evidence for a benefit in preventing CHD. It is increasingly realized that other risk factors such as hypertension, insulin resistance, diabetes, obesity, the metabolic syndrome, lack of physical activity, and elevated serum homocysteine levels are also important1.
The evidence is mounting that there is actually no relationship between cardiovascular disease and saturated fat consumption. Now that it’s ascertained that saturated fats don’t pose a risk to your heart health, lets have a look at what they do in the body.
Role of saturated fats in the body
Increase cholesterol levels – Saturated fats have been shown to increase circulating LDL (bad cholesterol) and HDL (good cholesterol). As already mentioned, this neither is not an indicator of cardiovascular disease, and has neither a positive or negative effect on cardiovascular disease.
Provide energy – Most fats are a great source of energy, and contain approximately 9kcals per gram which is over double the energy that you will get from 1g of carbohydrates or protein. Shorter saturated fats (such as those in coconut oil) can be converted to energy easier than longer saturated fats, and so are a great source of quick energy. Many people prefer fats in general as a source of energy, as they do not impact on insulin levels like carbohydrates do.
Gene expression – All the food you eat will affect gene expression, and saturated fats are no different. Aside from metabolic gene expression, saturated fat can increase (or more accurately, normalise) many hormones in the body, including testosterone in men.
Nerve/ cell structure – The membrane of all our cells (from our immune cells to red blood cells) is made up of a mixture of fats including saturated fats. In addition to this, saturated fats from an important part of nerve cells called the myelin sheath which facilitates rapid nerve transmissions.
Vitamin transport – Of the 13 essential vitamins, 4 of them are fat soluble (vitamin A, D, E and K), which means that they must be transported throughout the body in fats. Saturated fats are one of the types of fat able to facilitate this.
Anti-inflammatory/ anti-bacterial – Some saturated fats, such as lauric acid and capric acid have demonstrated powerful anti-bacterial and anti-inflammatory properties. Lauric acid seems to be the more potent of the two, and both of these fats can be found in coconut oil.
Saturated fats have been portrayed as damaging to the cardiovascular system as a result of poor science and the medias need to publish shocking headlines. In reality saturated fats do not seem to have any impact of cardiovascular health (good or bad), but is a valuable nutrients for the body, both as an energy source and maintaining a healthy body.
1. P.W. Parodi. (2011). Nutrition and Health | Nutritional and Health-Promoting Properties of Dairy Products: Fatty Acids of Milk and Cardiovascular Disease. Encyclopedia of Dairy Sciences (Second Edition), 1023-1033.
2. George Michas, Renata Micha, Antonis Zampelas. (2014). Dietary fats and cardiovascular disease: Putting together the pieces of a complicated puzzle. Atherosclerosis. 234 (2), 320-328.