A Possibility that a Deficiency in Dietary Fiber Causes Depression

The aim of the present study was to clarify whether a deficiency in dietary fiber intake causes depression by analyzing behavior of mice in the forced swim test (FST). The FST is widely used to evaluate the activity of antidepressant drugs. In the test, immobility of mice is considered as depression-like behavior. Mice were divided into two groups: experimental group and control group. A cellulose deficient diet that contained no cellulose was given to the mice of the experimental group, and a diet that contains 5.0% cellulose was given to the mice of the control group. After 3 or 4 weeks, immobility times of the mice in the experimental group were significantly longer than those in the control groups. On the other hand, there were no significant differences in body weights between the mice in the two groups. Based on these results, it is speculated that a deficiency in dietary fiber intake causes depression by factors other than obesity.