Although the umami compound
monosodium glutamate (
MSG) is a widely used
flavor enhancer, controversy still persists regarding the effects of
MSG intake on
body weight. It has been claimed, in particular, that chronic
MSG intake may result in excessive
body weight gain and
obesity. In this study we assessed the effects of chronic (16 weeks) ad libitum
MSG on
body weight and metabolism of C57BL6/J mice. Adult male mice were divided in four experimental groups and fed with either a low-fat (LF) or high-fat (HF) diet and with either two bottles of plain water or one bottle containing 1%
MSG and another one containing water according to a factorial design. Mice were monitored weekly for
body weight and food/fluid intake for 15 weeks. At the end of the experiments, the circulating levels of
leptin,
insulin, total
protein, total
cholesterol,
triglyceride, blood
urea nitrogen, and non-
esterified fatty acids were also analyzed. Our results show that
MSG intake did not influence
body weight in either LF or HF groups. Interestingly, although animals overall displayed strong preferences for
MSG against water, preferences were relatively higher in LF compared to HF group. Consistent with the
body weight data, while significant differences in
leptin,
insulin, total
cholesterol, and non-
esterified fatty acids were found between HF and LF groups, such an effect was not influenced by
MSG intake. Finally, indirect calorimetry measurements revealed similar energy expenditure levels between animals being presented water only and
MSG only. In summary, our data does not support the notion that ad libitum
MSG intake should trigger the development of
obesity or other metabolic abnormalities.