The idea of artery-clogging fatty foods gave birth to the low-fat food industry. But the theory was never proven and now medicine admits it got it all wrong-for more than 30 years
It's been like watching a school of fish or a formation of birds suddenly change direction: in just a few months, medicine-followed by its ardent admirers in the mainstream media-has declared that fats aren't the cause of heart disease after all. It's sugar, stupid. It's as though the theory, which launched the multibillion-dollar low-fat food industry, had never been uttered.
It's been hard to pick up a British newspaper of late that hasn't been running regular features and helpful lists for readers about the foods that contain 'hidden' sugars, which the Daily Mail describes as "the new nicotine".
The now discredited theory, first mooted by researcher Ancel Keys in the 1950s, suggested that saturated fats from meat, dairy, eggs and plant sources raise total cholesterol in the blood, so increasing the risk of clogged arteries and heart disease. By the 1980s, the theory had been widely accepted by governments and health agencies, and the food industry was quick to offer low-fat and hydrogenated vegetable oil alternatives. Phrases like 'artery-clogging fats' became a fixture in our everyday talk.
Good business, perhaps, but it was never good science, and hardly any evidence has been produced to demonstrate a connection between saturated fats and heart disease. And, in the last few months, researchers and doctors have woken up to the dreadful truth that the emperor had never been wearing so much as a thong.
One of the first to break rank was Dr James DiNicolantonio from Ithaca College, New York, who says we have been "led down the wrong dietary road for decades". He is now calling for a public health campaign as pervasive and aggressive as the one enjoyed by the low-fats theory, telling the public that medicine got it wrong, and that carbohydrates and sugars are the
Quick on his heels were a team of European researchers from the UK and the Netherlands, who took another look at 76 studies involving nearly 650,000 participants, and concluded that total saturated fatty acids, whether measured in the diet or bloodstream, were "not associated with coronary disease".2
So how did they get it so wrong and for so long? It all began with Ancel Keys and his messianic drive to 'prove' that saturated fats cause heart disease. By the 1950s, coronary heart disease had become a major killer in the West, and Keys, a researcher with the University of Minnesota, noticed that heart disease was far less prevalent in Mediterranean countries.
He was much influenced by one researcher, David Kritchevsky, who had shown that cholesterol fed to rabbits caused atherosclerosis, hardening and clogging of the arteries. Based on flimsy evidence-and no human studies-Kritchevsky claimed later that year that not only do saturated fats cause heart disease, but also that polyunsaturated fats, found in vegetable and corn oils, soybeans, safflower and sunflower seeds, could reduce cholesterol levels.
Keys was convinced by this, and the Mediterranean diet, with its emphasis on fruits, vegetables and seeds, seemed to provide living proof. He confirmed it-or so it seemed-in 1958 when he published the Seven Countries report, which gave wings to the Mediterranean diet. It demonstrated a direct correlation between heart disease and the amount of animal fats in the diets of populations from seven countries, including Finland and Serbia (formerly Yugoslavia).3
But, in fact, Keys had gathered data from 22 countries and ignored the 15 that didn't produce the results he was looking for. Had he included all the data, the fats connection to heart disease would have disappeared, says Danish researcher Dr Uffe Ravnskov.
Keys took up an influential position on the advisory committee of the American Heart Association, and his fats theory gained momentum. By 1984, his theory had been accepted as fact and a new healthy diet had been born-and with it, a new production line of low-fat foods and drinks.
The tragedy is not so much the promotion of the Mediterranean diet-which is, of course, very healthy-but that other theories pointing to the real causes of heart disease were abandoned. Around the time Keys was first putting his theory together, other scientists were beginning to suspect that the rise of hydrogenated vegetable oils, found in 'new' foods like margarine and in biscuits, might be to blame. In other words, there was a possible link to processed foods.
Keys was also challenged by British researcher John Yudkin, who argued that sugar in food 'tracked' the rate of heart disease far better than saturated fat ever did. Sixty years later, medicine finally agrees.
Yet Keys won the argument, though no one was ever able to provide proof. For 11 years, researchers from the US Surgeon General's office worked on what was supposed to be the definitive report on fats and heart disease. It was abandoned because they couldn't find any evidence. As oversight committee member Bill Harlan said afterwards: "The report was initiated with a preconceived opinion of the conclusions."
This failure of proof has been repeated by other researchers down the years. One review of seven clinical studies and 16 observational studies, involving hundreds of thousands of people, failed to establish an association,4 nor could Dutch researcher Robert Hoenselaar uncover any data to support the current dietary advice.5
The European researchers mentioned above also couldn't prove the other part of Keys' theory-that polyunsaturated fats reverse cholesterol levels.
In fact, researchers are discovering the very opposite of Keys' central thesis: fats are good for us, they now say. Stearic acid, a saturated fat found in chocolate and beef, helps keep our heart healthy, according to several studies. One that concentrated on the benefits of dark chocolate in young people found that it reduced blood pressure and the risk of cardiovascular disease.6
If sugar is the culprit, how is it causing heart disease? Some researchers are beginning to abandon the whole cholesterol theory of heart disease. LDL-the 'bad' cholesterol-may indeed be clogging up our arteries, but it's doing so as a natural healing response. It appears to be repairing damage to the artery wall caused by inflammation, and inflammation is a response to stress which, in physiological terms, can be due to sugar-laden processed foods.
The alpha of omega
If inflammation is a key factor in heart disease, then balancing your omega-3/omega-6 intake becomes vital. Essentially, the omega-3s are anti-inflammatory and the omega-6s are inflammatory. Omega-3 is found in fatty fish like salmon and tuna, and in fish oils and walnuts, while omega-6 is found in poultry, eggs, avocados and nuts.
Although our body needs both, the balance is usually way off, especially with the typical Western diet. A healthy ratio is said to be 4:1 (with omega-6 being the first number), whereas the typical Western diet is more like 16:1 and sometimes even higher.
Cholesterol-lowering statin drugs never seem to be out of the news.
First, one study claimed to have discovered the drugs had no side-effects whatsoever, although the researchers later said this was rather overstating their findings;1 then the British Medical Journal was forced to moderate an article claiming that side-effects may affect up to 20 per cent of users.
Medical researcher Prof Sir Rory Collins says the article had overestimated side-effects by 20 times, and asked for it to be retracted.
As ever, the truth seems to lie somewhere between the two. Plenty of studies have demonstrated that statins do come with side-effects.
Aside from the common reaction of muscle weakness, one found the drug doubles the risk of breast cancer,2 while also increasing the risk of cataracts, especially among people with lower LDL-cholesterol levels.3
Cardiologist Stephen Sinatra agrees that statins can be a life-saver among people with very high cholesterol levels and established coronary artery disease, but he does not accept that it's a drug for everyone over the age of 50, as many of the drug's advocates recommend. "We must treat the patient thoughtfully and choose statin drugs carefully, and with extreme diligence to avoid unnecessary side effects," he says.4
BMJ Open Heart, 2014; 1: e000032
Ann Intern Med, 2014; 160: 398-406
Keys A. Seven Countries: A Multivariate Analysis of Death and Coronary Heart Disease. Cambridge, MA/London: Harvard University Press, 1980
Am J Clin Nutr, 2010; 91: 502-9
Nutrition, 2012; 28: 118-23
Cardio Vasc Syst, 2014; 2: 3
the alpha of omega References
Simopoulos AP, De Meester F, eds. World Review of Nutrition and Dietetics, vol 100. Basel: Karger Publishing, 2009
statin controversies References
Eur J Prev Cardiol, 2014; 21: 464-74
Cancer Epidemiol Biomarkers Prev, 2013; 22: 1529-37
JAMA Ophthalmol, 2013; 131: 1427-34
J Am Coll Nutr, 2014; 33: 79-88