Abstract
Rats have been raised on rations containing alpha-protein as the sole source of nitrogen, and growth and liver vitamin A levels have been observed as a function of the rate of methionine supplement in the presence and absence of DDT. Increasing the level of methionine supplement in increments from zero to 4 g/kg produced a progressive increase in the growth of male rats. Females showed maximum growth when the methionine level was 1.0 g/kg. In the absence of added methionine DDT depressed growth, but at levels greater than 1.0 g/kg DDT stimulated growth. The level of vitamin A stored in the liver was depressed by feeding DDT, with the response being dependent on the level of methionine in the diet. The most pronounced reduction was observed with the unsupplemented ration, and the DDT effect was virtually eliminated when methionine was added at a level of 4 g/kg. A mechanism has been proposed for this interaction based on the action of DDT and methionine on the processes responsible for the absorption and transport of vitamin A.