Cholesterol is not bad for you

My Times column on the U-turn over cholesterol
and saturated fat:

 

If you are reading this before breakfast, please
consider having an egg. Any day now, the US government will
officially accept the advice to drop cholesterol from its list of
“nutrients of concern” altogether. It wants also to “de-emphasise” saturated fat,
given “the lack of evidence connecting it with cardiovascular
disease”.

This is a mighty U-turn, albeit hedged about in caveats, and
long overdue. The evidence has been building for years that eating
cholesterol does not cause high blood cholesterol. A 2013 review by the American Heart Association and
the American College of Cardiology found “no appreciable
relationship between consumption of dietary cholesterol and serum
[blood] cholesterol”.

Cholesterol is not some vile poison but an essential ingredient of life, which makes
animal cell membranes flexible and is the raw material for making
hormones, like testosterone and oestrogen. Your liver manufactures
most of the cholesterol found in your blood from scratch, and
adjusts for what you ingest, which is why diet does not determine
blood cholesterol levels. Lowering blood cholesterol by changing
diet is all but impossible.

Nor is there any good evidence that high blood cholesterol
causes atherosclerosis, coronary heart disease or shorter life. It
is not even a risk factor in people who have already had heart
attacks. In elderly people — ie, those who have the most heart
attacks — the lower your blood cholesterol, the greater your risk
of death. Likewise in children.

From the very first, the studies that linked the ingestion of
cholesterol and saturated animal fats to cardiovascular disease
were not just flawed, but tinged with scandal.

In the 1950s, an upsurge in heart disease in American men
(probably caused mostly by smoking) led the physiologist Ancel Keys
to guess that dietary cholesterol was to blame. When that seemed
not to fit, he switched to saturated fat as a cause of high blood
cholesterol. To make his case he did things like leave out
contradictory data, shift points on graphs and skate over
inconvenient facts. He then got big charities and state agencies on
side and bullied his critics into silence.

His most famous study, the seven-country study, started out much
larger; he dropped 16 countries from the sample to get a
significant correlation. Add them back in and it vanishes. Hidden
in his data is the fact that people in Corfu and Crete (in the same
country) ate the same amounts of saturated fats, but the Cretans
died 17 times more frequently of heart attacks.

In the 1970s, the famous Framingham Heart Study stumbled on the
fact that people with high cholesterol over the age of 47 (long
before most people have heart attacks) lived longer than those with
low cholesterol, and that those whose cholesterol dropped faced
higher risk of death. But the consensus ignored this and sailed
on.

If challenged to show evidence for low-cholesterol advice, the
medical and scientific profession has tended to argue from
authority — by pointing to WHO guidelines or other such official
compendia, and say “check the references in there”. But those
references lead back to Keys and Framingham and other such dodgy
dossiers. Thus does bad science get laundered into dogma. “One of
the great commandments of science is ‘Mistrust arguments from
authority’,” said Carl Sagan.

Eventually, the medical profession began to distinguish between
cholesterol and the proteins that carried it, with a distinction
emerging between “good” high-density lipoproteins, and “bad”
low-density ones. The fatty plaques in arteries are made partly of
cholesterol, true, but they form on scars and irregularities caused
by other problems: smoking, infections, damage, age. The
lipoproteins and cholesterol are part of the repair kit. You don’t
blame a fire engine for a fire. We’ve confused effect with
cause.

The battle is not over. The medics and scientists who have been
insisting for 20 years that the cholesterol emperor has no clothes,
and that low-carb, high-fat diets are safer, have been ostracised
as quacks and flat-earthers for so long that the habit will die
hard. People such as Uffe Ravnskov in Sweden, author
of Ignore the Awkward: How the Cholesterol Myths are
Kept Alive and Malcolm Kendrick, a GP in Macclesfield,
author of The Great Cholesterol
Conand Doctoring Data, will not soon be
welcomed back into the fold. A scientific consensus can be very
intolerant of heretics.

Nonetheless, the medical establishment here too is tiptoeing
away from its previous advice to avoid eating cholesterol and
saturated fat. It is covering the retreat with a smokescreen,
redirecting its fire on trans fats (with more justification), or on
sugar. That’s what lies behind all this talk about the dangers of
sugar these days — a huge paradigm shift away from the low-fat,
low-cholesterol diet. I am not about to say the advice about sugar
will also prove wrong.

Indeed, the evidence that insisting on low-fat diets caused
people to eat more carbohydrates, and that led to the explosion in
obesity and diabetes, looks pretty strong — so far. After all, the
main route by which the body lays down fat is to manufacture it
from excess sugar in the liver. But why did carbohydrate
consumption start to increase so rapidly in the 1960s? At least
partly because of the advice to avoid meat and cheese. Obesity and
diabetes are the price we have paid for getting fat and cholesterol
so wrong.

How about a full, drains-up inquiry into how the medical and
scientific profession made such an epic blunder and caused so much
misery to people? Consider not just the damage that was done to
people’s lives by faulty advice, but to the livelihoods of dairy
and beef farmers and egg producers (I declare an interest as a very
small producer of free-range eggs). Which has more sugar: an apple
or an egg?

But what about statins? In men they lower cholesterol and they
prevent heart disease. True, but the connection is not necessarily
causal. Statins do a lot of other things, including reducing
inflammation, which may be why they deter heart attacks. There are
statin sceptics, too, who think the side-effects of taking them are
not worth it, and that far too much of the evidence in favour of
them comes from the pharmaceutical industry.

We like to think clinging stubbornly to dogmas was a habit of
doctors in past centuries, but it still goes on. Medicine needs to
get better at changing its mind.