Chapter 5 - Nutrition

Abstract

The environmental and nutritional conditions under which laboratory animals are maintained can powerfully influence the experimental results measured. Nutrition is of major importance in toxicological bioassays and research, because diet composition and the conditions under which it is fed can affect the metabolism and activity of xenobiotic test substances and alter the results and reproducibility of long-term studies. It is known that ad libitum (AL)-overfed sedentary laboratory rodents suffer from an early onset of degenerative disease and diet-related tumors that lead to poor survival in chronic bioassays. AL fed animals are not well-controlled subjects for any experimental studies. However, a significant correlation among average food (calorie) consumption, adult body weight, and survival has been clearly established. The use of moderate dietary restriction (DR) of a nutritionally balanced diet results in a better controlled rodent model with a lower incidence or delayed onset of spontaneous diseases and tumors. Operationally simple, moderate DR of balanced diets significantly improves survival, controls adult body weight and obesity, reduces age-related renal, endocrine and cardiac diseases, and reduces study-to-study variability, increases treatment exposure time, and increases the statistical sensitivity of these expensive, chronic bioassays to detect a true treatment effect.