The Saturated Fat Studies: Set Up to Fail
"The Saturated Fat Studies: Set Up to Fail" Where did these consensus guidelines to dramatically
lower saturated fat consumption come from? From literally hundreds of metabolic ward experiments,
which means you don’t just ask people to change their diets. You essentially lock them in a room, for weeks if
necessary, and have total control over their diet. You can then experimentally change their level
of saturated fat intake however you want and see the corresponding change
in their cholesterol levels.
And the results are so consistent you can create
an equation, the famous Hegsted Equation, where you can predict how much of their cholesterol will go up based on how much saturated fat you have them eat. So if you want your LDL cholesterol to go up 50 points, all you have to do is eat like 30% of your calories: saturated fat. When you plug in the numbers, the change in
cholesterol shoots up right as predicted. The experiments match the predictions. In fact, you can do it at home with
one of those home cholesterol testing kits. Eat a stick of butter every day, watch your
cholesterol climb – not rocket science. And look at this, this was 1965; we’ve
known about this for 50 years that even if you keep calorie intake the same, increases in saturated fat intake are associated with
highly significant increases in LDL bad cholesterol. Now your good cholesterol
goes up a bit too, but that increase is smaller
than the increase in bad, which would then translate into
increased heart disease risk overall. So if you feed vegetarians meat even just once a day,
their cholesterol jumps nearly 20% within a month.
You know, to prevent heart disease we ideally
need to get a total cholesterol under 150, which you can see these vegetarians were, but then even just once a day with the
meat and their cholesterol shot up 19%. But the good news is that within just two
weeks of returning to their meat-free diet, their cholesterol dropped
back down into the safe range. Now note that their HDL good
cholesterol hardly moved at all, so their ratio went from low risk of heart
attack to high risk in a matter of weeks with just one meat-containing meal a day. And indeed randomized clinical trials show that dietary saturated fat reduction doesn’t
just appear to reduce cholesterol levels, but subsequent cardiovascular events
like heart attacks as well. So we have randomized clinical trials,
controlled interventional experiments. These are our most
robust forms of evidence, so no wonder there’s a scientific
consensus to decrease saturated fat intake. You’ll note, though, that the Y-axis here is
not cholesterol, but change in cholesterol. That’s because everyone’s
set point is different.
Two people eating the same diet,
the same amount of saturated fat, the same number of chicken nuggets a day
can have very different cholesterol levels. One person can eat 10 chicken nuggets
a day and have a LDL cholesterol of 90. Another person can eat, you know, 10 a day,
could start out with an LDL of 120. It depends on your genes. But while our genetics may be different,
our biology is the same, meaning the rise and drop in cholesterol
is the same for everyone. So if both folks cut out the nuggets, the 90 might drop
to 85, whereas the 120 would be expected to drop to 115. Wherever you start, we can lower our
cholesterol by eating less saturated fat, but if I just know what your saturated fat
intake is, how many nuggets you eat, I can’t tell you what
your starting cholesterol is.
All I can say with certainty is that, look,
you eat less, your cholesterol will likely improve. But because of this extreme
“inter-individual variation,” this wide variability in baseline cholesterol
levels for any given saturated fat intake, if you take a cross-section of the population, you can find no statistical correlation between
saturated fat intake and cholesterol levels, because it’s not like everyone who eats
a certain set amount of saturated fat is
going to have over a certain cholesterol.
So there’s like three ways you could
study diet and cholesterol levels: controlled feeding experiments,
free-living dietary change experiments,
or cross-sectional observational studies. As we saw there is a clear and strong relationship
between change in diet and change in serum
cholesterol in the interventional designs, but because of that inter-individual variability,
in cross-sectional designs you can get zero correlation. In fact if you kind of do the math
that’s what you’d expect you’d get. In statistical parlance, one would say
a cross-sectional study doesn’t have the
power for detecting such a relationship. Thus because of that variability, these kinds
of observational studies would seem an inappropriate
method to study this particular relationship.
So since diet and serum cholesterol
have a zero correlation cross-sectionally, an observational study of the relationship
between diet and coronary artery disease
incidence will suffer from the same difficulties. So again, if you do the math, observational studies would unavoidably
show nearly no correlation between
saturated fat and heart disease. These prospective studies can
be valuable for other diseases, but the appropriate design demonstrating
or refuting the role of diet in coronary heart
disease is a dietary change experiment. And those dietary change
experiments have been done. They implicate saturated fat,
hence, the lower saturated fat guidelines
from basically every major medical authority.
In fact, if we lower saturated fat enough, we may be able to even reverse heart disease,
opening up arteries without drugs, without surgery. But wait a second. Let’s put our Big Cheese & Chicken hat back on. Observational studies would show no correlation,
mathematically could show no correlation. We’ve known since 1979 that observational studies
simply don’t have the power to show the relationship.
Bingo! All we need now is a friendly researcher. How about Ronald M. Krauss? Funded by
the National Dairy Council since 1989. Also the National Cattleman’s Beef Association,
as well as the Atkins Foundation—perfect. Then you just combine together all
the observational studies that don’t have
the power to provide significant evidence and what do you know, no
significant evidence was found. This 2010 meta-analysis was basically
just repackaged for 2014, using
the same and similar studies. As the Chair of Harvard’s
Nutrition Department put it, their conclusions regarding the type
of fat being unimportant are seriously
misleading and should be disregarded, going as far as suggesting
the paper be retracted, even after the authors corrected
a half dozen different errors.
But it’s not like they falsified or
fabricated data; they didn’t have to. They knew beforehand the limitations
of observational studies. They knew they’d get the “right”
result and so they published it, helping to “neutralize the negative impact of milk and
milk fat by regulators and medical professionals.” "And it’s working", brags the dairy industry. Perceptions about saturated fat in
the scientific community are changing. "This is a welcome message to consumers, who may
be tired of hearing what they shouldn’t eat." They don’t have to convince
consumers, just confuse them. Confusion may easily be misused by the
food industry to promote their interests. It’s like that infamous tobacco
industry memo again, right? “Doubt is our product.” “Doubt is our product since it’s the best
means of competing with the body of fact that exists in the mind
of the general public.” They don’t have to convince the public
that smoking is healthy to get people
to keep consuming their products.
They just need to establish a controversy. Some science says it's bad;
some science say it’s not bad. Conflicting messages in nutrition cause
people to become so frustrated and confused they may just throw their hands up in
the air and eat whatever they want, which is exactly what saturated fat suppliers want,
but at what cost to the public’s health?.
