The Truth About Saturated Fats


Saturated fats are not that bad for your health. The truth about saturated fats is highlighted by the fact that national guidelines have quietly ditched firm limits for saturated fat from the previous ‘no more than 10% total calories eaten’, or ‘no more than 30g of saturated fat a day for men and no more than 20g of saturated fat a day for women’, to milder suggestions such as ‘cut back on all fats and replace some saturated fat with unsaturated fat’.

In other words, national guidelines got it wrong, although few are willing to admit it. The old guidelines that urged us to stop eating saturated fat and, instead, major on carbohydrates has fuelled a widespread epidemic of obesity and type 2 diabetes. In place of saturated fat, the real demon is sugar.




Saturated fats are healthy

The most natural and nutritious foods available, such as meat, salmon, eggs, milk, cheese, nuts, seeds, olives, avocado, coconuts and prawns have been labelled with red traffic lights because of their saturated fat content. I’ve always been on the side of butter in the butter-versus-margarine debate, and not just because it tastes so good. I’ve yet to find any convincing, robust evidence that butter is bad for me – in moderation, of course.

Yet saturated fats have endured decades of demonisation for their supposed effect on cholesterol levels, even though one-third of saturated fats have no cholesterol-raising activity, and that includes the most common saturated fat, stearic acid, found in dairy products, meat and cocoa butter.

Stearic acid consists of a chain of 18 carbon atoms and only saturated fats with 12, 14 or 16 carbon atoms have any effect on blood cholesterol levels. Even then, their effect depends on your genes. If you’ve inherited ‘good’ genes (thanks mum and dad) you naturally reduce the amount of cholesterol produced in your liver when there’s already plenty in your circulation. As a result, the link between dietary intakes of saturated fat, cholesterol levels and risk of cardiovascular disease is tenuous to say the least. While some early studies showed high intakes of saturated fat increased the risk of heart disease and strokes, other more rigorous studies do not.

A study published in the British Medical Journal, no less, has now confirmed that saturated fats are not associated with an increased risk of heart disease, stroke, type 2 diabetes or – wait for it – death from any medical cause!

Saturated fats are not harmful for health

Data from 12 studies, involving over 339,000 people followed for over 25 years in countries as diverse as Japan, Sweden, China, Canada, Australia, UK and Greece were included in the large analysis. The results showed that people with the highest saturated fat intake had the same risk of death during the study follow-up periods as those with the lowest intake.

To be exact, those eating the most saturated fat were 1% less likely to die, but this small reduction was not statistically significant. No statistically significant differences were found for rates of total or fatal heart attacks, ischaemic stroke or type 2 diabetes between those eating the most saturated fat and those eating the least. That last sentence is so important, please read it again.

That doesn’t mean that slathering an extra butter pat on your artisan-crafted bread isn’t harmful, of course. Like all types of fat, it has a high calorie content and excess is linked with obesity. It does mean you no longer need to feel guilty about enjoying a sensible amount of flavoursome, unsalted, golden Guernsey butter in place of an insipid, synthetic, oil-based spread.

What the study did find was a positive link between all-cause mortality, total and fatal coronary heart disease with trans fats – the very type of fat that was prevalent in the original margarines and spreads touted as healthier than butter!

Another large analysis of 76 studies, involving over 659,000 people, found no significant risks between saturated fat intake and coronary heart disease but did find a 16% increased risk for those eating the most trans fatty acids. The researchers concluded that ‘Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated




What’s the difference between saturated, polyunsaturated and trans fatty acids?

A fatty acid is described as saturated if all the available carbon atom bonds in its backbone are joined to hydrogen atoms, so it only has ‘single’ chemical bonds and no ‘double’ bonds.

A fatty acid that contains one or more double bonds is known as an unsaturated fat – there’s still space to add hydrogen atoms in an industrial process known as hydrogenation.

An unsaturated fatty acid with only one double bond is described as mono-unsaturated. Those with two or more double bonds are referred to as polyunsaturated.

Most polyunsaturated fatty acids are oils are room temperature.

They are converted into semi-solid margarines and spreads by incorporating extra hydrogen atoms into their chemical structure to convert some double bonds to single bonds.

Some of these artificially produced, partially hydrogenated fats are twisted around on themselves to form rigid molecules that are more like saturated fats than flexible unsaturated fatty acids. These artificially twisted molecules are known as trans-fatty acids and are harmful to health.

Trans fats increase the rigidity of cell membranes and are have harmful effects on the liver to raise blood levels of ‘bad’ LDL-cholesterol, lower production of ‘good’ HDL cholesterol and increase inflammation.

As well as being linked with heart disease, a high intake of trans fats are also associated with the development of certain cancers, especially those of the breast and prostate gland. Trans fats are also associated with poor glucose tolerance, obesity and type 2 diabetes, which may account for the link with all-cause mortality in the recent study.

What’s the bottom line?

Margarines and low-fat spreads have largely been reformulated to reduce their trans-fat content. Always check labels and select foods with the lowest or no content of trans fats or partially hydrogenated polyunsaturated fats.

The latest UK healthy eating guidelines no longer restrict saturated fat intake as there is no robust evidence to do so. Instead, they suggest selecting unsaturated oils and spreads to eat in small amounts.

If your cholesterol level is raised, aim for a wholefood diet, select lean cuts of meat, have more fish and vegetarian days, use olive or rapeseed oil for cooking, and olive, avocado or nut oils in dressings. This should ensure your doctor remains happy for you to enjoy a sensible intake of butter, rather than a bland spread, if you wish. I know which I prefer – what about you?

Image credits: sandid/pixabay; david_masters/flickr; aj_cann/flickr;



About DrSarahBrewer

Dr Sarah Brewer MSc (Nutr Med), MA (Cantab), MB, BChir, RNutr, MBANT qualified from Cambridge University with degrees in Natural Sciences, Medicine and Surgery. After working in general practice, she gained a Master's degree in Nutritional Medicine from the University of Surrey. Sarah is a licensed Medical Doctor, a Registered Nutritionist, a Registered Nutritional Therapist and the award winning author of over 60 popular self-help books. Sarah's other websites are www.MyLowerBloodPressure.com and www.ExpertHealthReviews.com.


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9 thoughts on “The Truth About Saturated Fats

  • themindfulgap

    Dr Michael Moseley just did his all-fat, no sugar tour here, and now cardiologist Dr Aseem Malhotra is joining with our anti-stat Dr Maryanne Demasi for a ‘Bring back the fat’ speaking tour. I think the penny dropped for me when I found a study showing dairy fats boosted palmitoleate in fatty tissue etc – T2D protective by boosting insulin’s effect (especially so in males).

    It was a study funded by the Dairy Corp. Ahahhh, best to remain skeptical of anything until med research improves governance.

    • DrSarahBrewer Post author

      The phrase everything in moderation comes to mind! Fat was demonised for well-meaning reasons, but replacing them with processed carbs has helped fuel the current obesity, type 2 diabetes and fatty liver epidemics.

    • DrSarahBrewer Post author

      Exactly – carbs trigger insulin secretion and insulin is a powerful fat-storing hormone. ALthough Atkins was too low carb for most HCPs to accept, low Gi now seems to be mainstream.

  • Jackie

    Thanks, Dr. Sarah! My family went through the whole gamut of medical theory of butter vs. margarine. First, back in the 1970’s, dad’s doctor said use margarine. So we did for years. Then came an about face, and butter was okay. Then when I got married, my husband’s doctor was recommending Smart Balance or some such. Then I started following the First Place 4 Health program, and eliminated processed and manufactured foods, so went back to butter! Nice to know it was a good decision! Thanks.

    • DrSarahBrewer Post author

      And if you use butter from Guernsey cows you get even greater benefits as the golden colour and rich flavour is due to the high content of carotenoid pigments – they are less able to convert it on to vitamin A than some other breeds. 🙂

      • Jackie

        Ah, Dr. Sarah! If only I could. But I fear the cost of sending butter from Guernsey to the USA would be prohibitive! You see, I live in New Jersey, not isle of. Not too many Guernsey cows here. 🙂