Imagine a diet genie appearing in your kitchen and declaring that, henceforth, you would consume only full-fat milk, butter and cream, and eat standard cuts of meat. No more semi-skimmed milk, margarine, lean cuts and low-fat anything for you. Would you think this a death sentence, that you'd been condemned to die from a heart attack as your arteries clogged up with 'bad' cholesterol?
If so, you haven't been keeping up. There's always been a small group of scientists who have doubted that fats in our diet have anything to do with levels of cholesterol in the blood, and a recent review has discovered that low-fat health advice from government agencies was based on no scientific evidence whatsoever.
Worse, many low-fat foods-such as cereals, yoghurts, snacks and ready meals-contain very high quantities of sugar, which medicine is now quietly accepting is the real culprit behind the epidemic of heart disease. One review discovered that one low-fat meal contains almost six times the amount of sugar found in its full-fat equivalent, while fat-free drinking yoghurt has almost as much sugar as a Mars bar.
Many of these processed foods also contain the kind of fat that's bad for the heart and our general health: trans fat. Trans fats are found in many ready meals and fast foods, and are the result of a manufacturing process that uses shortening, or partially hydrogenated vegetable oil.
These fats are so dangerous that America's health regulator, the Food and Drug Administration (FDA), has instructed food manufacturers to remove them from all products within three years. "This action is expected to reduce coronary heart disease and prevent thousands of fatal heart attacks every year," said the FDA's acting commissioner Stephen Ostroff.
Low-fat foods and drinks are big business, however. In the UK, they generate around lb8 billion from sales every year, while they represent 99 per cent of sales growth in the entire food sector in the US. Driven by the demand of consumers who have bought the message that fats are bad for the heart, sales are expected to continue to grow by an average of 5.7 per cent until 2017.
"What is good for public health is also good for business. Companies that don't pay attention to this message are leaving money on the table," said food researcher Hank Cardello.
If sugar and trans fats are the real culprits, how did saturated fats, found in fatty meats, full-fat dairy products and butter, get the blame? The idea that saturated fats raise cholesterol levels had been kicking around for the better part of the 20th century, but was given legitimacy by scientists like Ancel Keys, a biology professor at Minnesota University.
Tasked with the job of tackling the inexorable increase in cases of coronary heart disease (CHD), the US Senate Select Committee on Nutrition and Human Needs decreed in 1977 that saturated fats should constitute no more than 10 per cent of our total energy intake. Six years later, the UK followed suit and issued its own public-health warning about saturated fats. The mighty food industry tipped its hat and watched the money roll in.
Yet, in an analysis of the data available to the two public health agencies at the time, Zoe Harcombe, from the University of the West of Scotland, has discovered that the recommendations were based on flimsy evidence at best.
There were six 'good science' trials available at the time. In all, 1,227 men were put on one of several 'healthy heart' diets, such as low-fat, soybean oil and corn oil regimes, and their health was compared with that of 1,240 controls, who didn't adopt any special diets.
There were exactly 370 deaths in both groups, and the numbers of those who died of CHD was roughly similar in the two groups. But the diets had done one thing: they had dramatically reduced cholesterol levels-yet not one life was saved from heart disease.
Harcombe's review is but the latest assault on the fats-cholesterol theory. Not only was there no evidence to support the public-health advice in the first place, but government scientists couldn't find any proof afterwards either. Eleven years after the US Senate's Select Committee's recommendations against dietary fat were published, the US Surgeon General's office set about preparing a definitive report on fats and heart disease. Eleven years later, in 1999, they abandoned the project, unable to find any evidence.
Researchers from Brown University in Providence, Rhode Island, had no better luck in 2011. They tracked the lives of 1,815 men and women who had suffered a heart attack for 10 years, and compared them with a case-matched group of healthy people. Both groups ate similar amounts of dairy products, with some in the healthy group eating up to 593 g of dairy per day-yet no one in either group suffered either a first or a subsequent heart attack.
Leading cardiologist Aseem Malhotra, from Croydon University Hospital, London, is not surprised. In an article for The British Medical Journal, he said it's time "to bust the myth" of the role of saturated fat in heart disease. Not only have studies failed to uncover any significant association between saturated fats and cardiovascular risk, but also the very opposite has been found: fats help to protect the heart and arteries, says Malhotra.
TIME it's a-changin'
TIME magazine is famed for the people it features on its cover. In 1961, pride of place went to biologist Ancel Keys, who led the landmark Seven Countries Study, which appeared to establish a relationship between the fats we ate and heart disease.
But in 2014, TIME's cover carried an image of a roll of butter and the words: "Eat butter. Scientists labelled
fat the enemy. Why they were wrong."
In the accompanying feature, the magazine admitted that the war on fat had been wrong all along and that the science supporting the theory had been "junk". As the article also reported: "Keys chose the countries most likely to confirm his hypothesis, while excluding nations like France-where the diet is rich in fat but heart disease is rare-that might have challenged it."
The boys pay a visit
When the US Senate Select Committee on Nutrition and Human Needs issued its report in 1977, Dr Mary Enig, then a graduate student at the University of Maryland, thought there was something very odd about it.
Essentially, they were exhorting the American public to eat less saturated fat, but it was something they'd been doing since the turn of the 20th century. In fact, people were consuming far more vegetable oils, or trans fats.
Animal-fat consumption by the average American had declined from 104 g/day in 1907 to 97 g/day in 1972, whereas the consumption of vegetable fat-the deadly trans fats-had increased from 21 g/day to almost 60 g/day over the same period, she revealed in a study. Yet, despite eating supposedly less of the 'dangerous' saturated fats, the rate of heart disease in general, and heart attacks in particular, continued to climb.
But there were powerful groups that wanted to see the fats-cholesterol theory promulgated as fact, as Enig discovered soon after her paper was published.
In early 1979, as she recounted later, she had a visit from S.F. Reipma of the National Association of Margarine Manufacturers.
"Reipma was visibly annoyed. He explained that both his association and the Institute for Shortening and Edible Oils kept careful watch to prevent articles like mine from appearing in the literature. The paper should never have been published, he said. 'We left the barn door open, and the horse got out,' he told me."
Weeks later, Reipma returned, this time with Thomas Applewhite from Kraft Foods, Ronald Simpson of Central Soya, and an unnamed representative for Lever Brothers, angrily brandishing press cuttings of articles that had reported on her findings.
There are saturated fats and saturated fats. In fact, there are more than a dozen of them, but we mainly consume just three types: stearic, palmitic and lauric acids.
They represent 95 per cent of the fats found in animal meats, and 70 per cent of what's in butter and whole milk.
And it's little wonder that scientists couldn't find much evidence to support the theory that they cause heart disease-because these fats are good for us.
Stearic acid, also found in cocoa, is converted into a monounsaturated fat called 'oleic acid' once it reaches the liver. Oleic acid is the main ingredient in olive oil, one of the mainstays of the very healthy Mediterranean diet.
Palmitic and lauric acids are considered the bad boys because they supposedly raise your blood cholesterol levels (even though the biological mechanism remains a mystery).
But what is almost never mentioned is that they also boost levels of the so-called 'good' cholesterol, the high-density lipoprotein (HDL) cholesterol, to higher levels than they do of the 'bad' low-density lipoprotein (LDL) kind.
This means that any harmful effects they supposedly have on your arteries are more than compensated for by their beneficial effects.