The effects of diets containing raw soya-bean flour on the vitamin B 12 status of rats.

I . There were statistically-significant relationships between the concentrations of vitamin Blz in the livers of rats and their urinary excretion of mcthylmalonic acid, both before and after the intraperitoneal injection of sodium propionate. 2. The effects of diets based on raw and heated soya-bean flour (SBF) on the growth rates, urinary excretion of methylmalonate and hepatic vitamin BIZ were compared in normal and vitamin R,,-depleted rats. 3. When female weanling vitamin BIZ-deficient rats were put on to the raw SBF diet they lost weight and became moribund after 3 weeks, even when the diet was supplemented with vitamin BIZ. Male adult vitamin BIZ-deficient rats lost weight but showed no other signs of severe vitamin Blz deficiency. 4. Stock weanling male rats were fed on raw SBF diets with or without added vitamin BIZ. The diets were given alone and supplemented with either mcthionine or a mixture of methionine, valine, threonine and tyrosine. The rats still did not grow as well as those fed on diets containing heated SBF. However, there was some evidence of increased methylmalonate excretion and lower hepatic concentrations of vitamin BI2 in the rats fed on the raw SBF diets.