DIET AND DISEASE
163
With regard to the practical dietetic management of diseases now known to
be due to specific dietetic faults, the degree of divergence between the methods of
twenty-five years ago and of the present day is distinctly less than would have
been expected from a consideration of the knowledge available then and now.
Specific remedies in medicine have again and again been discovered empirically
and this is true in the realm of dietetics. The treatment recommended twenty-
five years ago by at least some enlightened authorities for many of the diseases
now spoken of as deficiency diseases would prove satisfactory enough to-day,
although such treatment was based on no actual knowledge of the dietetic factors
involved. Scurvy was treated by giving fresh fruit and fresh vegetables,
rickets and osteomalacia by giving cod liver oil and milk, beriberi by increasing
the ' nitrogenous ' constituents and diminishing the carbohydrate of the diet —some
individuals were even claiming that it could be prevented by adding rice
polishings to the diet of highly polished rice which was usually eaten in districts
where this disease occurred—and finally pellagra was to be treated by cutting
maize out of the diet.
This list of diseases comprises most of those commonly regarded to-day as
vitamin deficiency diseases, and there are not lacking critics of modern nutri-
tional research who profess to be un-impressed by its practical value in clinical
medicine because many of its obvious applications had been forestalled by
empirical methods of treatment. Such arguments fail to recognise the frequency
with which valuable methods of treatment fall into disuse or are replaced at
least temporarily by worthless imitations when little or nothing is known of the
physiological action of the agents effective in alleviating the symptoms of
disease. Thus the value of fresh lemon juice in curing scurvy was known in the
eighteenth century, but was forgotten for long periods, and far inferior therapeu-
tic agents were sanctioned by high authorities as late as the present century.
Similarly the value of cod liver oil for the cure of rickets had been appreciated for
many years before the discovery of vitamins, but this did not prevent the
subsequent recommendation of inert vegetable fats as satisfactory substitutes.
It is not argued that empirical treatment has no stable foundation in thera-
peutics, for clinical medicine still makes use of many old-established therapeutic
measures which have as yet no scientific basis. But it is no less certain that the
scientific demonstration of a definite cause for a disease offers the best chance for
the discovery of satisfactory preventive and curative treatment, and when the
cause is proved to be a comparatively simple deficiency in the diet, there should
be no excuse whatever for allowing such knowledge to sink into oblivion.
It is now proposed to show how the conception of food deficiencies as a cause
of disease has developed during the past twenty-five years. The great stimulus
to the remarkable activity shown in this field of medical investigation during this
period was undoubtedly the discovery of the vitamins, but the success rapidly