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HIGH FAT DIETS
This last few years we have been hearing a good deal about the danger of
diets high in animal fat. Fat meat, fat pork, bacon, and butter are the main
items. It is said that a high animal fat diet is the main cause of the increase of a
substance called cholesterol in the blood stream, and this in turn causes the
arteries to harden and thicken and leads to coronary disease of the heart with
restriction of blood supply to the heart muscle itself, giving danger of early
death from coronary thrombosis.
Racial Differences.
In South Africa an experiment was carried out in which three groups of
people were compared as regards their diets and rate of death from coronary
artery disease. In Capetown there are Europeans, Cape coloured population,
and the Bantu. The Europeans have the highest standards of living and have
always enough money for plenty of food. The Bantu occupy the lowest social
grades ; they are mainly labourers with the poorest wages and they live mainly
on cheap starchy foods, such as maize-meal, porridge and bread. The Cape
coloured population occupy a position midway between the Bantu and the
Europeans. By comparing the diets it was shown that as the standard of living
rises so does the amount of animal fat consumed per person. A similar association
was noted in the amount of cholesterol in the blood and also in the number
of deaths from coronary disease, those in the Europeans being highest, the Cape
coloured intermediate, and the Bantu lowest.
We must not make the mistake of confusing cause with effect or both with a
third factor. Thus if sedentary workers are less active, they also earn more
money and so tend to live on a more generous diet ; but they may also be more
worried because of the greater load of responsibility they carry. However, the
mental stress of administrative responsibility may be no greater than the mental
stress of extreme poverty.
The Problem.
Fat is an important source of energy to all of us. 4 ounces of fat are worth 9
ounces of starchy foods in energy value. If then we gave up eating animal fat
we should have to supply our energy in some other way, either by more of the
highly expensive protein foods of which we all need some, or by substituting the
less expensive but bulky starchy foods, such as bread, or by a different form of
fat which is not harmful. Still better would be the discovery of the reason why
the animal fats are harmful, and a means of overcoming the difficulty.
In another experiment2 it was noted that the increase in blood cholesterol
and the high rate of death from coronary thrombosis did not seem to be associated
with high intake of vegetable oils derived from peanuts, sunflower seeds,
soybeans, cotton seeds, olive oil, arachis oil, and with oils derived from fish,
such as pilchard and seal oil. Different types of fats and oils were given to
volunteers to see what effect they had on the blood cholesterol level. It was
found that the vegetable and fish oils which contain essential or unsaturated
fatty acids like linoleic acid lowered the amount of cholesterol in the blood,
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