No effects of monosodium glutamate consumption on the body weight or composition of adult rats and mice

Monosodium glutamate (MSG) is pervasively consumed as a flavor enhancer so there are important implications to understanding its physiological actions, particularly its effects on body weight. Previous studies suggest that MSG increases, decreases, or has no effect on the body weight of rodents. However, most of these studies involved administration of MSG to immature rodents and consequently may not be relevant for understanding human obesity. We report here five experiments in which we measured the body weights of a total of 32 groups of 10-12 adult rats or mice given various diets to eat and MSG to eat or drink. We found no evidence that MSG influenced body weight, energy intake, or body composition. To the extent that experiments in rodents illuminate mechanisms involved in human obesity and body weight control, our results suggest that MSG is unlikely to be a useful anti-obesity supplement but neither is it responsible for exacerbating obesity.

► Drinking monosodium glutamate solution had no effect on the development of diet obesity. ► This was true for Sprague Dawley rats, obesity-prone rats and C57BL/6J mice. ► This was true for several diet formulations. ► MSG is not a useful anti-obesity supplement nor is it responsible for exacerbating obesity.