Effect of different starches on the choice of diet by rats.

I n the experiment reported here an attempt has been made to determine whether rats offered a free choice between two compound diets, identical except in their starch content and both deficient in the vitamin B complex, would select the one on which they could synthesize the required vitamins by refection. In the process of refection, first investigated by Fridericia (1926), rats are able to utilize the products of an endogenous bacterial synthesis of the vitamin B complex, occurring mainly in the caecum. Refection takes place in rats only when certain carbohydrates are present in the diet. Kon (1931) has shown that raw potato starch as a rule allows refection, whereas steamed potato starch and raw rice starch do not, and Baker, Nasr & Morrice (1949) found that raw maize starch does not.