The influence of dietary cod liver oil and vitamin E upon Babesia rodhaini in mice

Abstract

1. (i) The multiplication of Babesia rodhaini was partially suppressed in mice given a diet similar to one used by Keppie (1953). The degree of suppression varied in individual mice and in different experiments. 2. (ii) An increase in dietary cod liver oil markedly suppressed the piroplasm, although similar quantities of olive oil, maize oil and cream were without effect. The basic diet without cod liver oil was only slightly suppressive. 3. (iii) The multiplication of B. rodhaini was still suppressed in mice fed on high cod liver oil diets supplemented with adequate amounts of water soluble vitamins. Large amounts of cod liver oil in the powdered cube diet also suppressed the parasites. 4. (iv) The unsaturated fatty acid fraction of cod liver oil was the only fraction which showed anti-parasitic activity. 5. (v) Large doses of vitamin E, given as α-tocopheryl acetate, completely reversed the suppressive action due to cod liver oil alone. The reversal occurred even when the vitamin E was given at the time of inoculation of parasites. 6. (vi) Tetra-ethyl thiuram disulfide and ascorbic acid, both of which are anti-oxidants, were also able to reverse the suppressive action of cod liver oil. 7. (vii) No morphological abnormalities were seen in parasites from the blood of mice given high cod liver oil diets. 8. (viii) An hypothesis is put forward for the suppressive action of dietary cod liver oil and its reversal by vitamin E. It is suggested that the unsaturated fatty acids of the cod liver oil are oxidized by the host to peroxides. These create a pro-oxidant state in the internal environment which is inimical to the piroplasm. Vitamin E prevents the peroxidation by virtue of its anti-oxidant properties. Several suggestions are also put forward for the anti-parasitic action of the peroxides.