Australasian Science: Australia's authority on science since 1938

Is Saturated Fat Good or Bad?

By Rosemary Stanton

Populist TV, blogs and publications have portrayed saturated fats as healthy rather than dietary villains, but this is an oversimplification as it’s not valid to judge our complex dietary intake by only one component.

Internet blogs, popular books and some TV chefs are propounding the idea that saturated fat is now “healthy”, asserting that the “experts got it wrong” and we wouldn’t be so fat and sick if we hadn’t shunned saturated fat. Popular papers push the idea with headlines such as “Butter is back,” “Bacon for breakfast” and “Vegetable oils are toxic”.

Those pushing these ideas claim that “studies” have proved them right. When pressed, most quote a review (not a study) by Chowdhury et al. which reported no significant differences for coronary disease with different levels of saturated fat.

Chowdhury and colleagues’ analysis has been widely criticised. It did not examine what those who reported a lower intake of saturated fat had eaten in its place, nor did it report any advantages from saturated fat. Many eminent researchers identified multiple errors and omissions, finding that had all relevant studies been quoted correctly, replacing saturated fats with polyunsaturated fats has clear benefits for heart disease.

These criticisms do not appear to bother those who continue to proclaim that faulty dietary guidelines cause our diet-related health problems. Nor do they seem aware that few people follow dietary advice.

Australia’s dietary guidelines, first released in 1981, did recommend less fat, principally by avoiding lard and dripping, trimming fat from meat and skimming some cream from milk. Later revisions recommended healthier sources of fat, such as nuts, seeds, avocado and liquid oils. All editions have recommended more fruit, vegetables, legumes and wholegrains (especially important for dietary fibre), and less sugar and salt.

Sadly, fruit consumption remains at half the recommended two pieces per day, just 7% of adults consume the recommended minimum amount of vegetables (consumption has fallen 39% since 1995), legumes are largely ignored, and wholegrain breads and other products (never dominant) have slipped further. Foods high in sugar or salt remain high.

There has been no absolute reduction in the quantity of saturated fat consumed in Australia (or the United States), but US studies have shown that the percentage of energy from saturated fat has fallen because consumption of fast foods and junk foods and drinks has increased, and hundreds of fat-reduced versions of processed foods now have some (or all) of the fat replaced with sugar and refined starches. This does not exonerate saturated fat, but does show there is more than one route to a poor diet.

The real problem lies in taking a nutrient-centred approach. Defining a complex food supply by a single nutrient is so gross that it is meaningless. We don’t shop for saturated fat, which comes in a wide variety of different foods. For example, the same amount of saturated fat is found in 35 grams of cheese, 35 grams of white chocolate, a tablespoon of lard, 70 grams of potato crisps, 90 grams of roasted cashews, 145 grams (a modest piece) of rump steak, 50 grams of polyunsaturated margarine or a small custard tart. These foods have little in common, apart from their saturated fat content, and it’s absurd to judge them as “equals”.

When considering a diet’s saturated fat, we need to know its source. As the World Health Organisation recommends, any valid assessment of a diet requires details of the entire dietary pattern.

Coconut oil has added a further fillip to those claiming that saturated fats have been unfairly targeted. There is scant evidence to support consumption of coconut oil, and much of what is quoted refers to studies of medium chain triglycerides, assuming that this is equivalent to lauric acid, the major fatty acid in coconut. As any biochemistry text will confirm, medium chain fatty acids have 8–10 carbon atoms, while lauric acid has 12. Some small studies show that coconut oil will increase high-density lipoprotein cholesterol. However, it also increases the less desirable low-density lipoprotein cholesterol, so it’s hardly the ideal fat.

It all goes to show the importance of understanding your topic!

Rosemary Stanton OAM is a nutritionist and is a Visiting Fellow in the School of Medical Sciences at UNSW.