Vitamin A as an anti-infective agent / by H.N. Green and E. Mellanby.

  • Green, H. N. (Harry Norman)
Date:
[1928?]
Catalogue details

Licence: In copyright

Credit: Vitamin A as an anti-infective agent / by H.N. Green and E. Mellanby. Source: Wellcome Collection.

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    has not yet been determined. Similar foci have also been observed in the spleen on two occasions. The prostate glands and seminal vesicles were frequent sites of suppuration, whilst occasionally the epididymis was acutely inflamed or suppurating. A purulent exudate was seen in the Fallopian tubes on one occasion. Pus was found in the nasal sinuses or in the middle ear on eighteen occasions, an incidence of 20 per cent. In one isolated case a small but definite abscess was found projecting from the wall of the left ventricle of the heart. The control animals received the basal diet ad lib., plus some source of vitamin D, with the addition of a source of vitamin A either in the form of dried cabbage or cod-liver oil or butter. Fifty rats fed under these con¬ ditions over periods as long as, or longer than, those which the deficient rats survived have been killed and examined. In no single case was evidence of gross infection found corresponding with that found in the vitamin A deficient rats. The only pathological findings were three cysts of the liver, of parasitic origin. Otherwise all the tissues appeared perfectly healthy. On the basis of these facts we suggest that vitamin A plays a significant part in raising the bodily resistance to infection. Perhaps this effect is solely due to the favour¬ able medium which obstruction by desquamated keratinized cells provides for bacterial growth. At any rate, this must be a factor. Possibly it is the combination of the kera¬ tinizing process and a diminished resistance which makes animals with vitamin A deficiency so prone to infection. The question arises as to what extent the part played by vitamin A as an anti-infective agent is specific. Would, for instance, the absence of any essential dietetic factor result in the infective and pyogenic conditions met with in this experimental work? We can offer no definite evidence that this is not the case, but an extensive expe¬ rience of nutritional work suggests that vitamin A is more directly related to resistance to infection than any other food factor of which we are aware. In a series of several hundreds of rats which have had adequate amounts of vitamin A and little or no vitamin D only two cases of gross infection have been found, both septic broncho¬ pneumonias associated with definite rickets. Experience with scurvy in man and animals does not lead to' the belief that vitamin C is concerned with infection in the same sense as vitamin A. Although, therefore, the speci¬ ficity of vitamin A and infection is not settled, the evidence obtained is in its favour. We are endeavouring to obtain additional evidence on this point by experiments in which infective material is injected into animals on A-deficient and control diets. Another point of importance is whether lack of vitamin A has any relation to the common suppurative processes found in man. Is it possible to relate inflammatory processes