The World Turned Upside Down: The Second Low-Carbohydrate Revolution (2 page)

Whatever my misgivings about
diet-heart,
however, I didn't
question it very deeply. When I went back to the original literature to
find
the evidence supporting low-fat recommendations, as I had to do for
preparing
my lectures, it was a rude awakening. My assumption that there was at
least a
grain of truth in the diet-heart hypothesis was overly optimistic. If
it is not
a total sham, it is pretty close. One of the first papers that I came
across in
my literature survey was a report from the Nurses Health Study (NHS).
As
described by Wikipedia,

"established in 1976 ... [the NHS]
and the Nurses' Health
Study II, established in 1989 by Dr. Walter Willett, are the most
definitive
long-term epidemiological studies conducted to date on women's health...
121,700
female registered nurses since 1976 and 116,000 female nurses since
1989 to
assess risk factors for cancer and cardiovascular
disease....Participating
organizations ... include the Harvard Medical School, Harvard School of
Public
Health, and several Harvard-affiliated hospitals..."

Willett and his associate Frank Hu
[4]
examined the risk of cardiovascular disease from substitution of
different
kinds of fat. Obviously, important stuff for my lectures. The study
also asked
about substituting carbohydrate. I found the result astounding.
Figure
I-3
,
redrawn from the paper, shows the effects of substituting
one type of
fat for another or of substituting carbohydrate for fat.

Figure I-3
.
Estimated Changes in Risk of Coronary Heart Disease
Associated with
Isocaloric Substitutions (error bars show 95% confidence interval).
Redrawn
from Hu, et al.
[4]

The effect of these substitutions –
whether risk went up
(right side of the graph, red bars) or down (left, green bars) was
surprising.
Replacing saturated fat with either polyunsaturated fat (vegetable
oils) or
with monounsaturated fat (olive or canola oil) reduced risk
substantially.
That's what they've been saying so no surprise there. However, if the
polyunsaturated fat was replaced with carbohydrate, Hu,
et al
.
found an average
60 % increase in risk. What? Carbohydrate is worse than fat for
cardiovascular
risk? That's not how it was supposed to be. What about saturated fat?
Surely,
that's the bad guy. Replacing saturated fat with carbohydrate does
provide some
benefit according to the figure but there is something else.

In this kind of figure, the
(horizontal) error bars show the
spread of individual values which, in this case, was pretty large. In
other
words, regardless of the average benefit of substituting
monounsaturated fat
for saturated, some people had much more and some, much less. Some, in
fact,
were going the other way. How bad could saturated fat be, if some
people get
worse when they substitute carbohydrate for saturated fat. It's worse.
Without
going into the details of the statistics, the rule is that if the
(horizontal)
error bars cross the 0 line then there is no significant effect of the
substitution (tan bar). Substituting carbohydrate in place of saturated
fat was
at best neutral, or more precisely, was as likely to increase risk as
to lower
it. And the same for monounsaturated fat. Looking at
Figure
I-2
, it is hard to see a risk of fat – the authors were
explicit about
that – but hasn't risk from fat been the message all along? Certainly
the idea
that carbohydrate is a risk is not brought out in the media or the
pronouncements of health agencies. And then there was the authors'
summary of
the paper:

Our data provide evidence in
support of the hypothesis
that a higher dietary intake of saturated fat ... is associated with an
increased risk of coronary disease, whereas a higher intake of
monounsaturated
and polyunsaturated fats is associated with reduced risk. These
findings
reinforce evidence from metabolic studies that replacing saturated
fat...with
unhydrogenated monounsaturated and polyunsaturated fats favorably
alters the
lipid profile, but that reducing overall fat intake has little effect.

That's the concluding paragraph of
their
paper. No mention of
carbohydrate. The most striking thing to me was that if you looked at
the risk
from carbohydrates in comparison to the risk from saturated fat, that
is, the
risk of substituting one for the other, it didn't make any difference.
And
worse. Substituting carbohydrate for other fats
increased
risk. How could this be? Fat out.
Carbohydrate in. Wasn't that the clear recommendation for improved
health from
just about every health agency and every expert? The data said it
didn't
matter. Was it dishonest not to bring that out in the discussion in the
paper?
At best, it was an error of omission. The authors from the Harvard
School of
Public Health were, and still are, the more modest among those
vilifying fat,
insisting that it is only the type of fat that we need worry about. I
was
probably not alone, but I invented the term "lipophobes" for proponents
of
low-fat. It's a wise guy term and since I was still something of an
inside
player in the science world, I was reluctant to put it into print until
Michael
Pollan started using it without any sense of irony
[5]
.

This is the field that I was now
professionally involved in. I
did not adequately attend to the sense of being sucked into a whirlpool
from
which it would be hard to escape. And anyway, the data was there for
all to
see. It is the author's choice to play down the strongest result. I
suspect
that they thought that "reducing overall fat intake has little effect"
was the
major conclusion. It would still be surprising to many people even
without
knowing that substituting carbohydrate for fat raises risk.

A trip to the supermarket tells you
that these results from
the Nurses' Health Initiative had little effect; the low-fat story is
still
with us. More striking is that two meta-analyses – a questionable
statistical
procedure of trying to average many different studies – came to the
same
conclusion.
[6-8]
.
Siri-Tarino,
et al.
,
in particular,
concluded that "...there are few epidemiologic or clinical trial data
to
support a benefit of replacing saturated fat with carbohydrate"
[8]
although they neglected to
cite the low-carbohydrate
studies that supported the position. In March of 2014, yet another
meta-analysis came to the same conclusion. What will turn out to be
most
remarkable about all of these studies is that they present a
re-analyses of
studies that had found no effect of saturated fat to begin with. One
has to ask
why the results were not accepted when first published. Some of them
are twenty
years old.

...from
what we
know now, from the current state of research, with the exception of
well-defined genetic abnormalities...there may be no predictable effect
on
heart disease from your diet.

How is it possible that, in this most
scientific period in
history, our society runs on incorrect scientific information? That's
one of
the questions that I will try to answer  in this book – or at
least describe. I
am not sure that there is an answer. Looking ahead, I will suggest the
revolutionary idea that, from what we know now, from the current state
of
research, with the exception of well-defined genetic abnormalities like
familial hypercholesterolemia, there is no predictable effect of your
diet on
heart disease. It is an hypothesis and we may know more as we
understand the
genetics but the diet-heart hypothesis remains only a conjecture
without experimental
support. It will be one of the themes in this book and one of the
battle
grounds for the second low-carbohydrate revolution.

About this book. Who
it's for. Why I wrote it.

Two big influences in my life: food
and chemistry. Food is
close to biochemistry. The beauty of biochemistry is that it relates
the
movement of electrons to what's on your plate and I thought I could
explain it.
I like writing about biochemistry. Sometimes we can see it all fit
together and
if we take a lot of the things that we know for granted, thinking about
what we
don't know can make us curious, the defining feature of the scientific
life. If
you want to know how it works, you are the person I had in mind when I
started
the book.

This is a book for scientists. Not
particularly for guys
with an atomic-force microscope in their lab, but for people who want
to look
at nutrition from a scientific point of view. Science is less about
sophisticated measurements, than it is about basic honesty. It is true
that
scientific fields can be very mathematical or intellectually profound –
the
warning that if you think you understand quantum mechanics you are
already on
the wrong track has been attributed to many physicists, probably
because most
of them have actually said it – but all sciences, even quantum
mechanics, are
tied to logic and common sense, and are frequently directly accessible.
Part of
the game, most researchers feel, is to make the results easy to
understand.
Einstein is widely quoted as saying that we want to make it simple but
not too
simple. Modern medicine, despite its reliance on technology, explicitly
accepts
an obligation to explain things logically to the patient. It doesn't
always
fulfill this obligation well but that is the goal.

I will try to fill some of the gaps
and define words. For
the tough spots, you have to read it like a scientist. How do we read?
We're
all specialists and most of us can't read a technical article,
sometimes even
in our own field, without some bumps. Skip over the bumps and see if
you can
get the big picture and maybe come back to it later. And a lot of the
details
are just a Google away.

If you write a book about
biochemistry, it's about chemistry
but if you write a book about nutrition, it's about everything. So not
every
chapter in this book is for everybody. I have tried to provide a
continuous
thread but different subjects require different kinds of discussion.
The goal
was to make the individual discussions self-contained and to provide
technical
background as we go but some topics are necessarily technical and I
include
those that are important. You can skip them but I suggest giving them a
shot.

And you can't escape the sociology
and politics of medicine.
Establishment medical journals and the private and government health
agencies have
insisted on low-fat, low-calorie dogma in the face of all its failures.
This
breakdown in scientific practice is deeply discouraging to me and is an
additional motivation for my writing the book.

Beyond the corruption of science is
the harm to the patient.
A major focus of this book is the concept of the metabolic syndrome.
The idea
that superficially different physiologic states – overweight, high
blood
pressure, the so-called atherogenic dyslipidemia (the lipid markers
that are
assumed to contribute to cardiovascular disease) – are tied together
and in
combination indicate risk of disease is, in my view, a great
intellectual
insight. That the common effector is likely the hormone insulin points
to the
importance of controlling dietary carbohydrate, the major stimulus for
insulin
secretion.

The resistance of the medical
profession to dietary
carbohydrate restriction in the treatment of metabolic syndrome and,
more
important, to its most obvious risk, diabetes, I find incomprehensible.
Everybody knows somebody with diabetes. Echoes of the early days in
Brooklyn
made it very upsetting to see pictures of Jackie Robinson taken shortly
before
his death from diabetes complications at age 52. Because it is
progressive, the
disease is an under-appreciated source of suffering. Clinicians will
tell you
that it is like cancer in its devastating effects. Diabetes is the
major cause
of amputations after accidents and the major cause of acquired
blindness. That
is a motivation for writing this book and why you may find it important.

It is a scandal at the level of
Semmelweis, an early
nineteenth century Viennese physician. To reduce the incidence of
puerperal
fever (infection after childbirth), Semmelweis suggested that
physicians wash
their hands after performing autopsies and before delivering babies.
They
refused; it was too much trouble. But it was the nineteenth century
before the
germ theory was established and that's some kind of excuse. It's hard
to know
how we will describe the actions of the American Diabetes Association
(ADA) who
believe that for people with diabetes: