John_Yudkin_-_Pure_White_and_Deadly_revised_1986_OCR

Pure, White and Deadly
keeping the heart beating than others. Thirdly, the outcome
depends on whether the relevant section of the heart has blood vessels
coming to it from a different direction, which can rapidly expand
and bring enough blood to it by this alternative route.
If the affected section of the heart is small or relatively unimportant,
the heart will stop for only a short time or not at all. If a portion
of the heart has permanently lost its blood supply, that portion may
die. This is called myocardial infarction and can be seen years later
in the heart where the dead tissue has become replaced with scar
tissue.
It seems that something quite different occurs in sudden death.
It is probably also associated with severe atherosclerosis of the coronary
arteries, but what appears to happen in this instance is that
the heart stops beating normally and goes into a sort of very rapid
shivering, known as 'ventricular fibrillation'. This renders ineffective
the heart's job of forcibly and regularly pumping blood round
the body, and death ensues very rapidly indeed.
It is important to remember that it is possible to have quite extensive
atherosclerosis without any symptoms at all. If so, it will be
impossible to diagnose the condition unless some of the atheroma
has proceeded to the extent of becoming chalky so that it shows in
an X-ray film. Most if not all adults in the well-off countries live
with at least a fair degree of atheroma but if they have no symptoms
it is usually impossible to tell whether they do have atherosclerosis,
and if so how much or where.
I hope you do not think that this has nothing to do with the subject
of this book. One of my main reasons for taking up research in this
field was that I became more and more uneasy about the prevalent
simplistic view of how people get coronary disease - the idea that it
is just a matter of cholesterol levels in the blood. This idea is now
so firmly held by so very many people that they end up believing
that anything that increases cholesterol in the blood is likely to cause
coronary disease, that anything that reduces cholesterol helps to
prevent the disease or even cure it, and that anything that does not
invariably increase the cholesterol in the blood must have nothing
whatever to do with the cause of heart disease.
I know I am biased, but this picture - in my view a rather
naive one - has hindered a proper understanding of the disease and
its causes and so a proper understanding of its prevention.
In fact, people with coronary disease are afflicted with very much
more extensive disturbances than just a rise in the level of cholesterol
Coronary thrombosis, the modern epidemic
~n the blood. For Ol~e thing, there is a rise in other fatty components
m the blood, especlally the triglycerides, sometimes called neutral
fats; many people believe this rise occurs more frequently than does
the rise in cholesterol. There is also a fall in the H D L cholesterol.
Secondly, other biochemical changes take place including disturbance
of the metabolism of glucose or blood sugar in the same direction
as that found in diabetes. There is often a rise in the level of
insulin and other hormones in the blood, and sometimes a rise in
uric acid. There are alterations in the activity of several enzymes.
The behaviour of the blood platelets is changed.
One could produce a list of at least twenty indicators that often
register abnormally high, or abnormally low, in people that have
severe atherosclerosis, and only one of these is the frequent though
not at all universal rise in the level of cholesterol.
If you seek further evidence about the possible role of sugar or
?ny o.ther factor in producing heart disease in man, you should bear
ill mmd the complexity of manifestations of the disease. This is
particularly important in the sort of experiments my colleagues and
I have conducted with laboratory animals. I shall talk about these
in more detail in the next chapter.
The first proponent of the idea that fat could be a cause of coronary
thrombosis, and since then its most vigorous defender, was Dr
A~cel Keys of Minneapolis. In 1953 he drew attention to the fact
that there was a highly suggestive relationship between the intake
of fat in six different countries and their death rate from coronary
disease. This was certainly one of the most important contributions
made to the study of heart disease. It has been responsible for an
avalanche of reports by other research workers throughout the
world; it has changed the diets of hundreds of thousands ofueople'
and it has made huge sums of money for producers of foods ~hat ar~
incorporated into these special diets.
As a result, too, a very great deal is now known about the effect
of dif~erent diets upon the processes of metabolism in the body, and
especially upon the processes of fat metabolism. And yet there is a
sizeable minority of research workers, of whom I am one, who
believe that coronary disease is not largely due to fat in the diet.
Let me start to argue the case by looking more closely at the
epidemiological evidence of the relationship between diet and coronary
disease. From the beginning, a few people were a little uneasy
about Dr Keys's evidence. Figures for coronary mortality and fat
consumption existed for many more countries than the six referred