I’ve just finished reading an extended article from Thursday’s Guardian. It describes how guidelines on low-fat diets arose and explains how they have been rigorously defended to the exclusion of other theories – to the detriment of health, science and some careers.
I was struck by the parallels with global warming, and pertinent quotes are pasted below.
I am sure I don’t need to spell out the analogous climate tales; the highlighting in bold below is mine. The article is well worth reading in full.
In 1972, a British scientist sounded the alarm that sugar – and not fat – was the greatest danger to our health. But his findings were ridiculed and his reputation ruined. How did the world’s top nutrition scientists get it so wrong for so long?
by Ian Leslie
On 23 September, 1955, US President Dwight Eisenhower suffered a heart attack. Rather than pretend it hadn’t happened, Eisenhower insisted on making details of his illness public. The next day, his chief physician […] cited the research of a nutritionist at the University of Minnesota, Ancel Keys.
Keys’ “diet-heart hypothesis” was that an excess of saturated fats in the diet raised cholesterol, which was deposited inside arteries narrowing them and restricting blood flow, leading to detrimental effects on the heart. Unfortunately Keys seemed to relish the limelight and his personality may have played a large part in the erroneous path taken by all who followed.
Ancel Keys was brilliant, charismatic, and combative. A friendly colleague at the University of Minnesota described him as, “direct to the point of bluntness, critical to the point of skewering”; others were less charitable. He exuded conviction at a time when confidence was most welcome. The president, the physician and the scientist formed a reassuring chain of male authority, and the notion that fatty foods were unhealthy started to take hold with doctors, and the public.
This was not received enthusiastically by everyone and a UK nutritionist, John Yudkin, was sceptical, having observations and data to the contrary. He came up with an alternative “sugar hypothesis”.
Ancel Keys was intensely aware that Yudkin’s sugar hypothesis posed an alternative to his own. If Yudkin published a paper, Keys would excoriate it, and him. He called Yudkin’s theory “a mountain of nonsense”, and accused him of issuing “propaganda” for the meat and dairy industries. “Yudkin and his commercial backers are not deterred by the facts,” he said. “They continue to sing the same discredited tune.”
Yudkin seemed to be the complete opposite of Keys, a mild-mannered man, and did not respond. Big industry (sugar) also rubbished him. Keys on the other hand rose to considerable power and influence, as did his allies, and they then shaped the future.
From these strongholds, they directed funds to like-minded researchers, and issued authoritative advice to the nation.
In 1970 Keys and his colleagues published a huge study which supported his hypothesis, but now seems like cherry-picking since he included seven nations in Europe, leaving out France and West Germany which had relatively low rates of heart disease despite rich diets. This study, which did not exclude the possibility that the causative factor in heart disease was something other than the saturated fats, led to government guidelines.
The US Dietary Guidelines issued in the 1980s were the basis of doctors’ advice and commercial food formulations. They there also highly influential in the UK. However, it is now looking as if that advice was profoundly flawed and Yudkin, whose ideas were originally taken very seriously before being discredited, was right.
We tend to think of heretics as contrarians, individuals with a compulsion to flout conventional wisdom. But sometimes a heretic is simply a mainstream thinker who stays facing the same way while everyone around him turns 180 degrees.
Again, that sounds chillingly familiar in the climate debate.
Today, as nutritionists struggle to comprehend a health disaster they did not predict and may have precipitated, the field is undergoing a painful period of re-evaluation. It is edging away from prohibitions on cholesterol and fat, and hardening its warnings on sugar, without going so far as to perform a reverse turn. But its senior members still retain a collective instinct to malign those who challenge its tattered conventional wisdom too loudly…
Recent studies on women were expected to support the benefits of a low-fat diet but found, contrary to expectations, that those eating the recommended diet were no less likely than the control group to contract cancer or heart disease.
The study’s principal researcher, unwilling to accept the implications of his own findings, remarked: “We are scratching our heads over some of these results.” A consensus quickly formed that the study – meticulously planned, lavishly funded, overseen by impressively credentialed researchers – must have been so flawed as to be meaningless. The field moved on, or rather did not.
Bigger and better studies have started to show up contrary data on cholesterol – that lower cholesterol correlates with higher rates of death from heart disease – and fat, and the subject has come under the scrutiny of a congressional review thanks largely to a journalist, who now finds herself vilified.
In September last year she wrote an article for the BMJ (formerly the British Medical Journal), which makes the case for the inadequacy of the scientific advice that underpins the [US] Dietary Guidelines. The response of the nutrition establishment was ferocious: 173 scientists – some of whom were on the advisory panel, and many of whose work had been critiqued in Teicholz’s book – signed a letter to the BMJ, demanding it retract the piece.
The letter lists “11 errors”, which on close reading turn out to range from the trivial to the entirely specious.
Having been invited to be part of a panel at the National Food Policy conference the journalist now finds herself dis-invited, following pressure from other panelists. Again, where have we heard that before?
It’s a compelling read – do read the whole thing.