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16
Coronary disease
In recent annual reports I have called attention to the likely
association of coronary disease and other degenerative heart diseases with
diet. Overweight in itself, and more particularly perhaps excess of fat
in the diet, have been associated with these conditions. A great deal
of research work has been going on during the past year, and although
it seems even clearer that an association between diet and heart disease
exists it is also obvious that there must be a multiplicity of factors
concerned, many of which have yet to be unravelled. The chemical
substance cholesterol keeps cropping up in this connection, but it is
not yet apparent whether heart and artery disease may be caused by
excess cholesterol in the diet or whether the deposition of cholesterolcontaining
material in the arteries may be due to a more complex
chemical change in the body which in fact produces cholesterol even
when it is lacking in the diet. Nevertheless as I indicated last year the
association of the two conditions of coronary artery disease and a high
level of blood cholesterol makes one suspicious of foods containing a
large amount of cholesterol. These foods particularly include dairy
products, such as butter and eggs. There is some evidence that the level
of cholesterol in the blood varies more with the amount and type of fat
(as such) in the diet rather than with the amount of cholesterol.
Recently a wellknown research worker in nutrition has suggested that
most of the trouble is due to a deficiency of what are called the
unsaturated or "essential" fatty acids. These fatty acids occur naturally
in certain foods, more particularly fish oil and vegetable oil, and it is
pointed out that the whole tendency in the manufacture of foods which
contain fat or fatty acids is to turn the unsaturated fatty acids into
saturated fatty acids, as thereby keeping qualities are improved and
taste is also said to be improved. Nevertheless, comparing margarine
with butter, it is believed that margarine may have (according to how
it is prepared) up to five times the amount of essential fatty acids that
butter has, and it is also known to have considerably less cholesterol.
In a controlled experiment carried out in South Africa it was shown
that eating beef dripping, butter, hydrogenated ground-nut oil, and
eggs in large numbers was followed by rises in the level of a fat-protein
combination in the blood which is thought to be directly associated with
coronary disease; on the other hand if olive oil, ground-nut oil, seal
oil or pilchard oil were eaten there was a fall in the amount of this
substance in the blood. The Lancet in commenting on this states that
if the results are substantiated, coronary-artery disease becomes in part
a preventable disorder, and adds that "the hydrogenation plants of our
modern food industry may turn out to have contributed to the causation
of a major disease."
The following table shows deaths from various heart and circulation
causes in the borough in representative years from 1928, the last
columns showing various percentages:—