MSG May Lead to Weight Gain

Summary
It has been proposed that monosodium glutamate could be associated with weight gain, and hence obesity, by disrupting the hormonal balance in the body. The objective of this study was to examine the association between monosodium glutamate (MSG) intake and the occurrence of obesity. Using surveys, the diet, which included monosodium glutamate intake, of nearly 10,000 Chinese people was examined. It was observed that the cumulative mean intake of monosodium glutamate was around 2 g/day and this was positively associated with being overweight in Chinese adults.

Introduction
MSG has been used as a flavoring agent for more than 100 years. The use of this substance in food products varies largely within and across populations. A survey in the 1990s estimated an average intake of 580 mg/d for the general population in the United Kingdom. It was, however, two-folds higher in Japan and Korea. It is also speculated that the use of MSG could be much higher than the above statistics. Results from animal research and human studies have shown that monosodium glutamate could be associated with obesity. Thus, this study used an ongoing survey to establish the link between monosodium glutamate and obesity.

Methodology

  • The China Health and Nutrition Survey (CHNS), an ongoing nationwide health and nutrition survey was used in this study. Around 10,095 Chinese adults aged between 18 and 65 years were questioned between the years 1991 to 2006.
  • Details on the diet were obtained by examining the food purchased for 3 consecutive days. It was also done by a 24-hour recall. The levels of MSG were estimated.
  • Data on physical parameters, exercise and calories consumed were also obtained. The level of leptin, a hormone that suppresses appetite was estimated in a few participants.

Results

  • The median intake of monosodium glutamate was 1.8 gram/day and men had a higher intake than the women.
  • The incidence of overweight people was higher if the intake of MSG was higher. Participants with higher intakes of MSG were 33 percent more likely to become overweight.
  • The average leptin concentration was 7.2 nanogram/mL of blood and the level of MSG was positively related to leptin concentrations.

Shortcomings/Next steps
A major limitation of this study was regarding the accuracy of the MSG measurement. Like other food additives the intake of monosodium glutamate was difficult to measure accurately. The fact that only a few people had a high body mass index made it inconvenient to establish a straightforward link between obesity and MSG consumption.

Conclusion
MSG is classified in the “generally recognized as safe” category, by the US FDA. It was observed that the intake of monosodium glutamate was associated with the incidence of obesity. This was independent of baseline body mass index and physical activity. It was noted that a higher intake of the food flavoring agent could increase the risk of being overweight by 33%. With the underlying mechanisms being unclear, the authors hypothesize that monosodium glutamate could induce hormonal disturbances and weight gain. The leptin levels estimated in this study coincided positively with the levels of MSG. More evidence could be obtained with a larger and diverse study population.

For More Information:
Consumption of monosodium glutamate in relation to incidence of overweight in Chinese adults
Publication Journal: The American Journal of Clinical Nutrition, April 2011
By Ka He, Shufa Du
From the University of North Carolina, Chapel Hill, NC

*FYI Living Lab Reports Are Summaries of the Original Research.

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