For over 30 years, official government advice – supported by a large number of scientists – has told us to reduce our consumption of saturated fat and increase our consumption of polyunsaturated fats. For most people that’s meant eating little if any animal fat (because about 45% of the fat from cattle and sheep is saturated) and instead cooking with vegetable oils and eating foods that contain vegetable oils, especially palm, sunflower, soya bean and corn oils.
This has led to big changes in agriculture. Traditional British breeds of pigs, which naturally produced more back fat to keep warm in outdoor conditions, were driven close to extinction by the introduction of a grading system in 1954 which heavily penalised farmers producing traditional breeds by deducting very large amounts from the prices they received based purely on levels of fat.
Iconic British breeds of cattle like Herefords and Beef Shorthorns, ideally suited to grazing systems, declined to very low numbers and were replaced by leaner and larger Continental breeds like Charolais and Simmental, which generally need to be fed on grain before they are ready to be slaughtered. Pigs, once a rich source of lard, prized as a high-quality cooking fat and key ingredient of the best pastry, are sent to slaughter so lean they hardly have any fat on them. The drive to reduce fat level in pigs has been one of the reasons antibiotics have been over used and in the US farmers use Paylean, which contains the hormone-like drug ractopamine, to make their pigs as lean as possible. This is banned in the EU, Russia and China.
But has this shift away from saturated fat been justified?
The dramatic rise of coronary heart disease (CHD) during the 20th century was linked to saturated fat consumption by several government advisory committees in the mid-1980s. In a session on fats at the Oxford Real Farming Conference, SFT policy director Richard Young presented evidence to suggest that the initial decision on saturated fat was flawed, due to a misunderstanding at the time about the difference between the effects of natural saturated fats in the diet and unnatural trans fats which came from the artificial hardening of vegetable oils so they could be used in processed foods. He also pointed to the significant influence of the sugar industry on the committee’s decision; something not known at the time as members of the food advisory committee were not required to declare their financial interests.
A small number of scientists were pointing to sugar instead of fat as the cause of the epidemic of heart attacks which peaked in the 1970s. At this point hardly anyone was considering the issue of trans fats from vegetable oils. However, graphs showing trends in sugar and polyunsaturated fat consumption provide a near perfect correlation with the rise in deaths from heart attacks, whereas there is no correlation at all with trends in the amounts of saturated fat consumed between 1900 and about 1970 (as best these can be established from incomplete data). The sugar industry was a major funder of research into the causes of heart disease, especially the role of saturated fat, and not beyond using its influence to get researchers to modify any research findings it didn’t like.
And while we’ve been led to believe the evidence overwhelmingly implicates saturated fat, the actual picture is much more complex. Some studies are still being published which appear to support the official view. However, many of these are based on food questionnaires, one of the least reliable ways of establishing exactly what people eat. In contrast studies published in the BMJ in 2013 and 2016 retrieved unpublished data from two major long term comparative studies, where thousands of people had randomly been split into two groups in institutional settings. One group was given a normal amount of saturated fat in their diet. The other had reduced saturated fat and increased vegetable oil. The diets continued for many years and the groups were monitored.
The first of these was the Sydney Diet Heart Study, 1966-73, in middle aged men. Those on the low saturated fat diet/increased vegetable oil diets actually had higher all-cause mortality and were more likely to die from CHD. The second of these studies, the Minnesota Coronary Experiment (1968-73), randomly divided, 9,500 men and women aged 20-97 into two groups. Blood cholesterol levels in the group on the higher vegetable oil, lower saturated fat diet were 13.8% lower than in those on a normal saturated fat diet, but this group had a higher, not lower incidence of CHD. The researchers say they don’t know why these key findings were kept quiet at the time, but there were clearly two powerful industries, the sugar industry and the vegetable oils industry, for whom these findings would not have been welcome.
There continues to be confusion about the difference between the artificial trans fats in processed foods and the natural trans fats in milk and red meat. The former (now supposed to kept to no more than 2% of energy intake) have clearly been shown to be harmful. The latter mostly consist of conjugated linoleic acid (CLA) which has very strong anti-cancer properties and is only found in meaningful quantities in products from ruminants.
But how are we now hardening vegetable oils? The main way is through a process called ‘interestification’. This is where chemists break down fats into their molecular components and reassemble them to produce designer fats with specific textures and other qualities. Is this safer than partial hydrogenation? And are vegetable oils really better for us than animal fats? Some people believe not, but only time will tell, as we continue with yet another dietary experiment on the population at large.
In the film below, Richard tries to unravel the truth behind the claims about saturated fats, and takes a deeper look at the damaging impacts these claims have had.
You can view Richard’s powerpoint slides here.
You can watch part 2 of this session, featuring Linseed Farmer Durwin Banks, here.
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