The Effect of Fat Level of the Diet on General Nutrition IX. The Relationship of Radiation Injury in the Rat to the Fat Content of the Diet

Abstract

No differences were noted in the susceptibility of rats to x-irradiation injury as related to the fat content of the diet when the animals (on the diets for three to 4 weeks) were subjected to 650 or 850 r in a single dose. On the other hand, when rats (on the diets for 12 weeks) were treated with a series of sublethal doses of x-irradiation at weekly intervals (2,400 r over 10 or 14 weeks in 300 r doses), the rats receiving fat in their diets were found to be more resistant, and survived over a longer interval than did those on the fat-free regimen. The protective effect of fat was approximately as satisfactory when cottonseed oil was incorporated in the diet at a 2% level as when it comprised 15 or 30% of the diet. The beneficial action of fat is therefore believed to be related to its content of essential fatty acids. In one series of tests on young rats (two to three months old), the protective effect of fat was evident only in the male rats and not in the female rats. However, in a test with older rats (18 months), both sexes were protected to an equal extent by the incorporation of fat in the diet. In spite of the beneficial results produced by fat in lowering the mortality rate of rats following exposure to x-irradiation, no concomitant improvements were noted in such indices of x-irradiation injury as hemoglobin level or leukocyte count.