John_Yudkin_-_Pure_White_and_Deadly_revised_1986_OCR

Eat sugar and see what happens
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Eat sugar and
see what happens
By the early 1960s I had decided that there was
enough evidence from epidemiology to suggest that sugar might be
one of the causes of coronary disease. The time had arrived, therefore,
to begin to do some experiments to see what effects were produced
by sugar in the diet. Since it seemed that the large increase
in sugar consumption in Western countries was accompanied by a
decrease in starch consumption to about the same extent, we fed
our rats and some other animals in the laboratory with diets that
contained all the protein, fat, carbohydrate, vitamins and mineral
salts that they needed, but varied the relative amount of starch and
sugar in the carbohydrate part of their diets. Mostly the carbohydrate
consisted either entirely of starch or entirely of sugar; sometimes
it was a mixture of the two in a predetermined proportion. I
should say that similar experiments were being carried out in other
laboratories, notably by Professor Aharon Cohen of Jerusalem, who
was however looking into the possible role of dietary sugar in producing
diabetes rather than heart disease.
In our experiments with human volunteers, we asked them to
record in detail the food and drink they took for a period of two
weeks or more, with every item accurately weighed or measured,
and written down at the time it was being consumed. They were
then asked to increase the sugar they took - more sugar in tea and
coffee and on their breakfast cereal, and more jam, confectionery
and other sugar items - while at the same time reducing the amount
of starchy foods such as bread and potatoes. By the time they were
due to change, we had calculated the amounts of all the elements of
their ordinary diets during the preliminary period, and could now
give them advice about how to make the change while maintaining
the same total intake as before of carbohydrate, protein, fat and
other substances. This of course was not absolutely precise because
we did not want to interfere with their normal lives more than we
had to, but since they went on weighing and measuring their food,
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we knew whether and how much they deviated from the new diet.
Mter two or three weeks on the high-sugar diet they went back to
their usual diet while continuing to weigh and measure their intake
for a further two or three weeks.
In our first laboratory experiment, we looked to see what sugar
did in rats to the quantities of fatty substances such as cholesterol
and triglyceride in the blood. We found that the amount
of triglyceride in the blood was enormously and rapidly increased
when rats ate sugar; the amount of cholesterol on the other hand
did not change. Moreover, switching the diets resulted in very rapid
change in the amount of triglyceride, which not only increased on
the change from starch to sugar, but decreased again as sugar gave
way to starch.
It later appeared, mostly through the research of other workers,
that rats make and dispose of cholesterol quite differently from the
way in which human beings deal with it. In other species, however,
sugar was found to produce an increase in the amount of cholesterol,
sometimes a considerable increase, as well as an increase in
triglyceride. This occurs in baboons, chicks, pigs and rabbits. In
the spiny mouse, a desert animal, feeding with sugar produces such
a considerable rise in cholesterol in the blood, and to a lesser extent
in triglyceride, that these fatty materials give the blood a distinctly
milky appearance. Moreover, while the liver of the rat becomes
enlarged by some 25 per cent, the liver of the spiny mouse increases
to twice its normal size when the diet contains sugar.
In addition to the experiments on rats with normal diets, we have
also used diets containing abnormal types of fats. By adding very
saturated fats instead of the unsaturated fat that we usually use, and
by adding a large amount of cholesterol to the diet too, we have
produced much higher levels of cholesterol and of triglyceride.
When we then substituted sugar for starch in these diets, there was
a still greater rise in cholesterol and triglyceride.
Sugar produces many changes in rats beside the increases in cholesterol
and triglyceride. I· do not know how many and which of
these will be found to be related to changes concerned with the
development of atherosclerosis and coronary disease in humans. But
I shall mention a few of the effects of sugar that at present seem to
be linked to these conditions. I shall discuss still other changes later
on in connection with other conditions in people.
Many research workers have studied the mechanisms by which
the body makes and stores fat; the idea is that factors affecting these
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