Fat versus sugar
At a World Health Organization meeting in 1955
Keys’s hypothesis was met with great criticism, but in response he designed the
highly influential Seven Countries Study, which was published in 1970 and
showed a strong correlation between saturated fat (Keys had moved on from fat
to saturated fat) and deaths from heart disease.11 Keys did not
select countries (such as France, Germany, or Switzerland) where the
correlation did not seem so neat, and in Crete and Corfu he studied only nine
men. Critics pointed out that although there was a correlation between
countries, there was no correlation within countries and nor was there a
correlation with total mortality. Furthermore, although the study had 12 770
participants, the food they ate was evaluated in only 3.9%, and some of the
studies in Greece were during Lent, when the Greek Orthodox Church proscribes
the eating of animal products. A follow-up study by Keys published in 1984
showed that variation in saturated fat consumption could not explain variation
in heart disease mortality.12
An analysis of the data from the Seven Countries
Study in 1999 showed a higher correlation of deaths from heart disease with
sugar products and pastries than with animal products.13 John Yudkin from
London had since the late 1950s proposed that sugar might be more important
than fat in causing heart disease,4 but Keys dismissed
his hypothesis as a “mountain of nonsense” and a “discredited tune.” Many
scientists were sceptical about the saturated fat hypothesis, but as the
conviction that the hypothesis was true gripped the leading scientific bodies,
policy makers, and the media in the US these critics were steadily silenced,
not least through difficulty getting funding to challenge the hypothesis and
test other hypotheses.
A series of interventional studies was carried
to test the fat hypothesis, but they were small, short term, and suffered from
the problem of changing more than one variable at once. A Lancet
editorial in 1974 said that little could be concluded from them.14 Certainly they
didn’t show strong support for the saturated fat hypothesis.
A report from the American Heart Association in
1961 was the first to recommend substitution of polyunsaturated fats (corn or
soybean oil) for saturated fat,15 and a later
report in 1970 recommended reduction in total fat. At that time E H Ahrens, a
lipid researcher from New York who believed that carbohydrate was more
important than fat in causing heart disease, worried that mass adoption of low
fat diets might lead to increases in obesity and chronic disease.
Teicholz explains how through the political process
the fat hypothesis led to a massive change in the US and subsequently
One congressional staffer, Nick Mottern, wrote a report recommending that fat
be reduced from 40% to 30% of energy intake, saturated fat capped at 10%, and
carbohydrate increased to 55-60%. These recommendations went through to Dietary
Guidelines for Americans, which were published for the first time
in 1980.16 (Interestingly, a recommendation from
Mottern that sugar be reduced disappeared along the way.)
Powerful lobby groups
It might be expected that the powerful US meat
dairy lobbies would oppose these guidelines, and they did, but they couldn’t
counter the big food manufacturers such as General Foods, Quaker Oats, Heinz,
the National Biscuit Company, and the Corn Products Refining Corporation, which
were both more powerful and more subtle. In 1941 they set up the Nutrition
Foundation, which formed links with scientists and funded conferences and
research before there was public funding for nutrition research.
Despite continuing doubts, it became, and still
the global orthodoxy that saturated fat was an important cause of
cardiovascular disease and that people should eat low fat diets. The biggest
test of the saturated fat hypothesis came with the Women’s Health Initiative,
which enrolled 49 000 premenopausal women in a randomised trial of the low fat
diet and cost $725m (£460m; €580m).17 The women were
followed for 10 years, and those in the low fat arm successfully reduced their
total fat consumption from 37% to 29% of energy intake and their saturated fat
from 12.4% to 9.5%. But there was no reduction in heart disease or stroke, and
nor did the women lose more weight than the controls.
A 2008 review by the Food and Agriculture
Organization concluded that “there is no probable or convincing evidence” that
a high level of fat in the diet causes heart disease.18 A 2012 Cochrane
review of 24 comparisons with 65 508 participants found no benefit from total
fat reduction and no effect on cardiovascular or total mortality but a small
reduction (relative risk 0.86 (95% confidence interval 0.77 to 0.96)) in
cardiovascular events in men (not women).19
Recognising that the fat hypothesis was falling
apart, some scientists, particularly Walter Willett, professor of epidemiology
at Harvard (whom I’ve also met), began to promote the Mediterranean diet, which
comes in many forms but is essentially lots of fruit, vegetables, bread and
grains (including pasta and couscous), little meat and milk, and plenty of
olive oil. Such a diet is much easier to eat than a low fat diet, and a
combination of vested interests, including the International Olive Oil Council
and a public relations company Oldways, which promoted the diet, has—together
with the natural seductiveness of the Mediterranean region—made the diet
popular. But the science behind it is weak, as a Cochrane review found,20 and some of the
evidence comes from R B Singh, whose research is suspect.21
Rise and fall of
Saturated fats such as lard, butter, and suet,
which are solid at room temperature, had for centuries been used for making
biscuits, pastries, and much else, but when saturated fat became unacceptable a
substitute had to be found. The substitute was trans-fats, and since the 1980s
these fats, which are not found naturally except in some ruminants, have been
widely used and are now found throughout our bodies. There were doubts about
trans-fats from the very beginning,22 but Teicholz
shows how the food companies were highly effective in countering any research
that raised the risks of trans-fats. It was Dutch research published in 1990
that signalled the beginning of the end for trans-fats by showing that a diet
high in trans fats led not only to raised LDL (low density lipoprotein)
cholesterol but also lowered HDL cholesterol.23 Willett of the Mediterranean
diet did for trans-fats in the US when he said, “We are really conducting a
very large human-scale, uncontrolled, unmonitored national experiment.”24
The Food and Drug Administration in 2003 called
trans-fats to be included on food labels and in 2014 banned them. The
requirement for labelling had already signalled the end, and when the FDA
issued its ruling some 42 720 processed foods in the US contained trans fats.
The impossibility of going back to saturated fat (because the idea that it is
bad is so deep in our beliefs and continues to be supported by the American
Heart Association) meant that food manufacturers have had to find a new
substitute, interesterified fats, which may prove just as bad as trans fats.
Again it’s a mass uncontrolled experiment.
Another consequence of the fat hypothesis is that
around the world diets have come to include much more carbohydrate, including
sugar and high fructose corn syrup, which is cheap, extremely sweet, and “a
calorie source but not a nutrient.”2 5 25 More and more
scientists believe that it is the surfeit of refined carbohydrates that is
driving the global pandemic of obesity, diabetes, and non-communicable diseases.2 5 25 26 27 They dispute the
idea that we get fat simply because energy in exceeds energy out, saying
instead that the carbohydrates “trigger a hormonal response that drives the
portioning of the fuel consumed as storage as fat.”26 This hypothesis
would say that poor people are fat (which is true in many communities) not
because they overeat or are particularly lazy but because they consume high
levels of refined carbohydrates, the cheapest energy source, which causes them
to become fat.1
Atkins and Ornish
Thinking along these lines led to the diet
advocated by the US physician Robert Atkins that drastically restricted
carbohydrates but allowed any amount of protein and fat. The diet was a
rediscovery of the diet promoted by a London undertaker, William Banting, in
1864 in his best selling Letter
on Corpulence and
widely recommended by medical authorities until the 1950s.1 28 The diet was
tested in the A TO Z Weight Loss Study in 311 overweight or obese premenopausal
women over a year against three other diets, including that advocated by Dean
Ornish, another US physician, which requires that fewer than 10% of energy
comes from saturated fat.29 30 Women on the
Atkins diet lost more weight and “experienced more favourable overall metabolic
effects,” including a fall in diastolic blood pressure of 4.4 mm Hg, against
2.1 mm Hg for those on the Ornish diet.30
Reading these books and consulting some of the
original studies has been a sobering experience. The successful attempt to
reduce fat in the diet of Americans and others around the world has been a
global, uncontrolled experiment, which like all experiments may well have led
to bad outcomes. What’s more, it has initiated a further set of uncontrolled
global experiments that are continuing. Teicholz has done a remarkable job in
analysing how weak science, strong personalities, vested interests, and
political expediency have initiated this series of experiments.3 She quotes Nancy
Harmon Jenkins, author of the Mediterranean
and one of the founders of Oldways, as saying, “The food world is particularly
prey to consumption, because so much money is made on food and so much depends
on talk and especially the opinions of experts.”31 It’s surely time
for better science and for humility among experts.
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