The idea that saturated fat is bad is beginning to be questioned as more and more research is being published showing it to be no worse than unsaturated fat.
So why do people still believe saturated fat needs to be limited?
Nina Teicholz, an investigative journalist, has spent years looking back through history to uncover why saturated fat was given such a bad name in the first place and how serious mistakes have endured to the current day.
Nina explains that the bad name that sat fat has carried, for half a century now, dates back to a ground-breaking, but flawed, research study. The Seven Countries Study was the first multi-country epidemiological study. The first study to gather data in a number of countries to look for patterns of behaviour that affect health.
heart attacks felling men in their prime
The study came at a time when heart disease was becoming a significant problem in America as apparently healthy men were dying in middle-age of heart disease.
This was a relatively new phenomenon as at the start of the 20th Century, very few people fell victim of heart disease.
The author of the Seven Countries Study was Ancel Keys, who was working at Oxford University before he started work on his world-changing study.
He’d been informed by an Italian doctor, Dr Bergami, that, in Italy, heart disease wasn’t a problem. Keen to find out more, Keys started to study the diet and lives of people in Italy.
These findings set in motion Keys’ notion that diet and cholesterol were key factors in heart disease. Keys presented his findings and conclusions at a congress in Amsterdam in 1952.
In 1955, USA’s President, Dwight D. Eisenhower, suffered a heart attack just two years after being elected. Heart disease had penetrated to the very top of America.
The next year, with funding from the US Public Health Service, Ancel Keys started the long process of collecting data for the seven countries of Finland, Greece, Italy, Japa, Netherlands, USA and Yugoslavia.
Fighting against fat
Whilst the study was underway, Keys also spent time on other projects, including a book he wrote with his wife Margaret, entitled ‘Eat Well and Stay Well’ that was published in 1959.
The book soon became a best seller and laid out the clear message that saturated fat leads to high cholesterol which leads to heart disease. This was his ‘diet heart hypothesis’.
It was a simple answer to the serious problem of heart disease that America was facing at the time.
In 1961, the American Heart Association put the diet heart hypothesis at the centre of their first dietary guidelines. The guidelines stated that American diets should be low in saturated fat to protect against heart disease. In the same year, Keys appeared on the cover of Time magazine.
Two more books from Mr and Mrs Keys, who were now living in Italy, were published in 1967 and 1975. The books focused on the Mediterranean diet as the healthy model of eating for Americans to follow.
Heart disease continued to dominate as the leading cause of death in the USA and the government was keen to implement action to tackle the problem. They were “willing to cut corners with the science” as Nina puts it.
Before the Seven Countries Study was published in 1978, the government was using the idea that fat, and in particular saturated fat, was the cause of heart disease to guide their dietary policy.
In 1977, the first set of dietary goals were published, which included a target to have 55-60 per cent of calories coming from carbohydrate and to ensure a maximum of 30 per cent of calories came from fat.
The first ever ‘Dietary Guidelines for Americans’ brochure appeared in 1980 which provided food choice guidance for people in seven steps.
The UK would follow suit and, in 1983, adopted similar guidelines with a recommendation to eat a low-fat and higher carb diet.
Whilst Keys became a star of the health industry, he and his colleagues held a lot of power over the way in which research was funded.
Researchers struggled to get funding if their views differed from that of Keys and, as Nina points out, if you weren’t on the cholesterol bandwago, essentially “you couldn’t be a scientist”.
The dietary goals and guidelines were questioned by many scientists but by 1986 the critics had been completely shut out and silenced.
The Seven Countries Study was ground-breaking in its scope and vision. However, as with any first try at something, it had its weak points.
One key problem was that Keys had designed his study partly to gather new insights but also to present his cholesterol theory as being true.
So, he picked specific areas of countries to study that were of interest to him but also those that would support his hypothesis.
One of the areas chosen was the Greek island of Crete, which he visited three times, spending a week gathering data each time.
Keys knew that the people of Crete had very high life expectancy and followed a typical Mediterranean diet. Crete would therefore be a key area to support his hypothesis and it became his star set of data.
In researching the study, Nina noted that a lot of the data had been fudged.
Complicating the matter of data collection was the fact that one of the weeks in which Keys visited Crete was during Lent. The people of Crete were Christian Orthodox and this meant that, during Lent, the island’s population were observing Lent by not eating any meat or dairy.
Whilst Keys noted that this fact had little effect on the outcome, researchers that have retrospectively reviewed the data note that Lent would have made an enormous difference on the data gathered.
As Nina notes, this was just one of many errors that appeared throughout the study.
An uncomfortable truth
The decision to lower saturated fat intake and increase carbohydrate did see a drop in rates of heart disease falling but Nina states that when studies were carried to out to pitch a cholesterol-lowering diet against a standard American diet, no overall change in death rates was observed.
The LA Veteran’s Study of 1969, published by the American Heart Associatio, showed that whilst a low-saturated fat, cholesterol-lowering diet reduced incidence of heart disease, rates of cancer and other causes of death went up.
Another study which showed similar effects was the Minnesota Coronary Experiment. This study, also from the 1960s, was never published because the results had shown that people with the lowest cholesterol levels were actually twice as likely to die as those with the highest cholesterol.
The US National Institutes of Health had a series of expert panels which considered the problem but didn’t know how to resolve it so, the problem was allowed to persist unresolved.
Ancel Key’s legacy is one that has helped to reduce heart disease from its height in the 1950s to 1970s but in its wake, we have seen increases in cancer and diabetes rates.
If there are messages to take from this, perhaps it’s that:
- We should ensure researchers are given the chance to question and check whether guidelines are working.
- We should not attempt to set dietary recommendations in stone when the research behind those recommendations are built on sand.