Effects of Prolonged Oral Intake of Monosodium Glutamate (MSG) on Body Weight and Its Correlation to Stomach Histopathological Changes in Male Rats

Monosodium glutamate (MSG) is a food additive found in many commercial food products. The safe use of MSG has generated much controversy regarding weight gain and health effects. In the present study, the effects of MSG administration for different periods of time on weight gain and on the structure of gastric mucosa in rats were investigated. Thirty-two adult male rats were used and randomly divided into two treated and two control groups (n=8, each). The rats in the treated groups received a daily oral dose of 395 mg/kg bw of MSG for 3 and 6 weeks, respectively, while the control rats received distilled water for similar periods. The body weight and food consumption were measured. At the time of sacrifice, the stomach was dissected and fixed for routine histological procedures. Results revealed a steady increase in body weight and food consumption untill the 4th week in the treated groups. This was followed by a reduction in body weight, although food consumption continued to increase. The gastric mucosa of the rats treated for 3 weeks showed a number of pathological alterations which were more pronounced in the group treated for 6 weeks. These results indicate that prolonged administration of MSG causes an initial increase in weight gain followed by terminal suppression, independent of food consumption. This may be explained by the induced gastric mucosal damage. In conclusion, it appears that prolonged intake of MSG induces gastric damage which, consequently, leads to decreased body weight