Association of monosodium glutamate intake with overweight in Chinese adults: the INTERMAP Study

Animal studies indicate that monosodium glutamate (MSG) can induce hypothalamic lesions and leptin resistance, possibly influencing energy balance, leading to overweight. This study examines the association between MSG intake and overweight in the human species. We conducted a cross-sectional study of 752 healthy Chinese (48.7% women), ages 40 to 59 years, randomly sampled from three rural villages in north and south China. The great majority of participants prepared their foods at home, without use of commercially processed foods. Diet was assessed with four in-depth multi-pass 24-hour recalls. Participants were asked to demonstrate MSG amounts added in food preparation. Amounts shaken out were weighed by trained interviewers. Overweight was defined as body mass index ≥25.0 kg/m2 or ≥23.0 (based on World Health Organization recommendations for Asian populations). Eighty-two percent of participants used MSG. Average intake was 0.33 gram/day (standard deviation=0.40). With adjustment for potential confounders including physical activity and total energy intake, MSG intake was positively related to body mass index. Prevalence of overweight was significantly higher in MSG users than non-users. For users in the highest tertile of MSG intake compared to non-users, the multivariable-adjusted odds ratios of overweight (body mass index ≥23.0 and ≥25.0) were 2.10 (95% CI, 1.13–3.90, P for trend across four MSG categories=0.03) and 2.75 (95% CI, 1.28–5.95, P=0.04). This research provides human data that MSG intake may be associated with increased risk of overweight independent of physical activity and total energy intake.