What’s the best way to stay healthy
in the face of so much conflicting nutrition information?
Well, ideally, you would go to the source.
The gold standard;
the peer-reviewed medical literature.
Read through stacks of the latest medical journals.
But who’s got time for that?
I do!
Welcome to the Nutrition Facts Podcast.
I’m your host, Dr. Michael Greger.
Today we hope to settle the debate once and for all
of the role of cholesterol in heart disease.
The cholesterol controversy is over.
In fact, you can argue it was over a century ago.
It seemed obvious in 1920 that high cholesterol levels in the blood
infiltrating your artery walls was the cause of coronary heart disease,
the #1 killer of men and women, confirmed as unequivocally
as the revelation that blood circulated throughout the body
or that the tuberculosis bacteria causes tuberculosis.
The question is why did it take so long?
What is so puzzling is why we have to work so hard
to sell the message given what seems to be
an unbeatable amount of hard evidence.
Many rejected the cholesterol- heart disease link because
so many patients were dying of coronary heart disease
despite so-called perfectly normal cholesterol levels.
Of course as I've detailed before, having normal cholesterol levels
in a society where it's normal to drop dead of a heart attack
isn't exactly saying much.
Ideally, we want to get our total cholesterol well under 150,
since having high cholesterol levels in your blood
is thought of as the only direct atherosclerotic risk factor.
All the other things -- smoking, high blood pressure, diabetes,
inactivity, obesity --
just exacerbate the damage caused by the high cholesterol.
Another factor may be the preoccupation of cardiologists
with all the new fancy gadgets and procedures out there.
It's like we train them to be highly-skilled,
high-tech fighter pilots to fight a war,
but then sent them on some boring preventive diplomatic mission.
But the reasons may be even more personal than that.
As an editorial in the Journal of the American Heart Association
asked nearly 50 years ago,
why do we pretend the cause of heart disease is mysterious?
There is no mystery as to why the incidence of heart disease,
like that of lung disease and of venereal disease --
sexually-transmitted disease --
continues to rise for many decades after the cause is established.
Why?
Because human beings, including physicians,
are eager for excuses, not to face annoying facts,
and so they continue to do things which are agreeable but hazardous.
People tend to reject new ideas, even when they don't impose
any change in our way of life, and it's almost impossible
for most men to accept any suggestion that it might be wise
to give up agreeable habits such as smoking, unsafe sex,
or eating their favorite foods.
This continuing challenge is represented by a senior professor
of medicine who questioned whether an alteration of diet would really
affect the course of heart disease.
These professors know the facts.
The problem is that they, like so many patients,
will not allow themselves to believe the message.
Eating rich food just means too much to too many people,
even when it's our gravest mortal threat.
Scientific consensus panels going back decades established
beyond a reasonable doubt that lowering LDL cholesterol
reduces the risk of heart attacks.
Consistent evidence unequivocally establishes that LDL
causes our #1 killer, atherosclerotic cardiovascular disease.
And what raises LDL cholesterol?
Saturated fat.
And where is cholesterol-raising saturated fat found?
The #1 source is dairy, the #2 source is chicken,
then pastries, pork, and burgers.
And it's not just saturated fat.
Dietary cholesterol has been known
as a dominant factor in the genesis of atherosclerosis since 1908,
which is why we should lower our intake of saturated fats,
trans fats and dietary cholesterol as much as possible.
This is consistent with how our biology evolved.
Extensive evidence clearly indicates that a plant-based diet
was the traditional eating pattern of our distant ancestors,
and so dietary cholesterol intakes were typically very low,
while at the same time we were packing in whole plant foods
containing components like fiber to help us eliminate cholesterol.
Where is dietary cholesterol coming from now?
Overwhelmingly eggs,
with the #2 source chicken, then beef, dairy, and pork.
So wait a second.
If the Institute of Medicine
recommends that individuals consume as little dietary
cholesterol as possible,
presumably that would mean cutting out foods like eggs entirely.
But does eating cholesterol actually raise your blood cholesterol?
We'll find out next.
The question, does egg feeding (in other words, dietary cholesterol)
affect the level of cholesterol in the blood, was answered 40 years ago.
Give someone half a cup of eggs a day and within 2, 3, 4 weeks
their cholesterol keeps going up, and then stop the eggs
by switching to an egg substitute and the cholesterol comes down.
Or start people on the egg substitute and not much happens,
but then start feeding eggs and their cholesterol shoots right up.
Put people on a cholesterol-free diet and their cholesterols drop.
But then add some egg yolk cholesterol and
their cholesterol goes up.
Take it away and their cholesterol goes down.
You could do this all year. And it's within days:
10 days of eggs and cholesterol shot up 50 points.
Take the eggs away and it comes back down.
You can reproduce this effect over and over and over and over,
though evidently penguin omelets are only about half as deadly.
Switch people from a high cholesterol diet
to a cholesterol free diet, and you can drop
blood cholesterol levels as much as a hundred points.
OK, but that was giving people more than a half cup of egg yolks a day.
But even just a single egg a day can increase people's LDL cholesterol 12%.
Put all the studies together in this 2020 meta-analysis,
more than 50 randomized controlled trials feeding people eggs,
and egg consumption significantly increases LDL-cholesterol, period.
Now studies funded by the Egg Board use a variety of methods
to try to minimize the reported negative health effects of eggs
by, for example, claiming that dietary cholesterol affects
only certain people.
That's actually been put to the test, and only 3% were even
potentially "nonresponders" to dietary cholesterol,
and even these probably evidenced some adverse response.
Wait, then how was the Egg Board able to design a study in which
egg intake did not change blood cholesterol?
By feeding them sufficiently large quantities of dairy and meat.
See, there's a plateau effect.
Though all lines of evidence converge to indicate that dietary cholesterol
is a major factor in promoting hardening of the arteries,
confusion about dietary cholesterol has arisen because
above a certain ceiling you basically max out cholesterol absorption.
Check it out. If you're eating a strictly plant-based diet
with a baseline of zero cholesterol intake, and you start adding meat,
dairy or eggs to your diet,
you can get a dramatic rise in blood cholesterol.
But as your diet starts out more and more meaty, you can saturate
your system and basically max out on the additional effect.
So no wonder the Egg Board packed in the extra meat and dairy
to mask the egg effect.
A systematic review of egg industry "Funding and Cholesterol Research "
sought out to see if industry-funded studies were more likely to report
conclusions that were not supported by their own objective findings.
Of the non industry-funded studies on the effect of egg ingestion on
cholesterol, cholesterol increases were reported in about 90%.
Among industry-funded studies,
cholesterol increases were reported in about 90%.
In other words, even the egg industry funded studies showed
eggs increased blood cholesterol, and not a single study
funded by anyone showed a significant decrease.
Okay, but here's the crazy part.
About half of the industry-funded studies reported conclusions
that were discordant with their own results.
In other words, they found that cholesterol went up,
but if you read their conclusions, they exonerated eggs.
That's why you can't just read the abstract.
You actually have to see what they found.
Readers, editors, and the public should remain alert
to funding sources in interpreting study findings and conclusions.
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To see any graphs, charts, graphics, images, or studies mentioned here,
please go to the Nutrition Facts Podcast landing page.
There you’ll find all the detailed information you need –
plus, links to all of the sources we cite for each of these topics.
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