Updated 17 September 2015

Bring on the butter: saturated fats may not cause heart disease after all

A study published in 'The British Medical Journal' has found that saturated fats like butter are not associated with an increased risk of death, heart disease, stroke, or type 2 diabetes.


A study led by researchers at McMaster University in Hamilton, Ontario on Canada and published in The BMJ on 11 August 2015 has found that saturated fats – for decades blamed for an increase in heart disease – are in fact not associated with an increased risk of death, heart disease, stroke, or type 2 diabetes.

This echoes what sports scientists Professor Tim Noakes proclaimed in a letter to critics in September 2012, where he said: "The theory that blood cholesterol and a high-fat diet are the causes of heart disease will be one of the greatest errors in the history of medicine."

In 2010 he wrote in Challenging Beliefs, a meta-analysis of studies involving 347 747 subjects and published in the American Journal of Clinical Nutrition, that they "found no significant evidence for concluding that dietary saturated fat is associated with an increased risk of coronary heart disease or cardiovascular disease".

Saturated fats come mainly from animal products, such as butter, cows' milk, meat, salmon and egg yolks, and some plant products such as chocolate and palm and coconut oils.

What the study, whose lead author is Russell de Souza, a registered dietitian and assistant professor in the Department of Clinical Epidemiology and Biostatics at the Michael G De Groote School of Medicine, did show was that trans fats are associated with greater risk of death and coronary heart disease (CHD).

Trans fats, more accurately described as trans fatty acids, are found in vegetable oils which have been chemically altered (or partially hydrogenated) to harden into a solid in order for it to become stable, remain solid at room temperature and give food products (such as biscuits, margarine, deep-fried fatty foods, crisps and pre-packaged meals) a longer shelf life.

As trans fats extend the shelf life of food and are an inexpensive processing method, they are found in most pre-packaged baked goods. They are also found in potato and corn chips, margarine, "slap" chips and most fried fast foods.

Read: The Heart and Stroke Foundation's letter to Tim Noakes

Health24’s DietDoc explains:

“Any food that is manufactured from plant oils which have been hydrogenated, can potentially contain trans fats. However the major manufacturers have already improved their manufacturing processes to the extent that their hydrogenated products contain only traces of trans fats and therefore, no longer constitute a problem. Check food labels to monitor the trans fat content of commonly purchased food products.”

Take a look: How popular margarines in SA fare in terms of fatty acid composition

Trans fats are produced industrially

The study confirms previous suggestions that industrially produced trans fats might increase the risk of coronary heart disease and calls for a careful review of dietary guidelines for these nutrients.

Guidelines currently recommend that saturated fats are limited to less than 10%, and trans fats to less than 1% of energy (that's about 2 g of fat) to reduce risk of heart disease and stroke. Half a store-bought doughnut would typically contain more than 2 g trans fats.

Discovery Health says the South African label laws state that trans fats that occur naturally in food products (animal fats) do not have to be declared in the nutrition information label. However, other foods may only be labelled as “virtually trans fatty acid free” if the product contains no more than 0.1g of trans fat per 100g/100ml.

Be aware that if "partially hydrogenated vegetable oil" appears on the list of ingredients, it indicates the presence of trans fats and it is best to avoid the food item.

Researchers at Harvard University in America proved that having just half to one teaspoon more trans fat than usual (one teaspoon instead of half a teaspoon a day) will increase your risk of having a heart attack by 50 per cent.

Their study was done on a group of 33 000 women over six years as part of the extensive Nurses’ Health Study. The worrying part is that people who follow a typical Western diet eat almost twice as much trans fat per day as the women in the study and therefore run an even greater risk of having a heart attack.

A good general guideline: the harder the margarine, the more trans fats it contains.

The percentage of trans fats in various foods according to the American Food and Drug Administration (FDA):

Portion size-product-grams (and %) trans fats (American products and values)

1 teaspoon baked goods 4 g (30%)

1 tablespoon hard margarine 3 g (27%)

1 commercial doughnut 5 g (27%)

3 (30 g) commercial cookies 2 g (6%)

1 slice (80 g) commercial cake 4,5 g (5,6%)

Read: Global phasing out of trans fats?

To sum up, consumption of industrial trans fats was associated with a 34% increase in all cause mortality, and there is a clear link between consumption of trans fats and death caused by heart disease – i.e., they observed an 28% increased risk of death by coronary heart disease, and a 21% increase in the risk of developing coronary heart disease.

Read: Ocean View tries out the high fat Banting lifestyle

The researchers point out that further research is very likely to have an important impact on our understanding of the association of saturated fats with disease.

They conclude that, for now, dietary guidelines should look at replacing foods high in trans fats with fruits and vegetables, unsaturated fats or vegetable oils such as olive and canola oils, nuts and whole grains. 

Read more:

Saturated fat may not cause heart disease after all

Low fat won't shed the kilos

Banting helped me lose 75kg

Image: Margarine, butter or ghee from Shutterstock


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