[Growth and longevity of Wistar rats receiving a diet whose protein content is rapidly lowered in relation to aging]

Growth and longevity of the Rats were the same when: (i) the diet was rich in casein (21%), from weaning to death: (ii) the casein content of this diet (without B12) was progressively lowered from weaning to 200 days of age, and thereafter was 7%. When the casein level had been too rapidly lowered, inducing retardation of growth after 75 days, maximal growth was lowered and life span was increased.