1. ¹Department of Nutrition, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
2. ²Department of Epidemiology, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
3. ³Department of Nutrition, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
4. ⁴Department of Epidemiology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
5. ⁵Department of Epidemiology, Fu Wai Hospital and Cardiovascular Institute, Chinese Academy of Medical Sciences, Beijing, China
6. ⁶Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
7. ⁷Guangxi Medical University, Nanning, China
8. ⁸Yu County Hospital, Shanxi, China

Correspondence: Jeremiah Stamler (j-stamler@northwestern.edu)

^*Deceased.

The first two authors contributed equally to this research.

Received 7 July 2007; Accepted 16 February 2008; Published online 22 May 2008.

Abstract

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 humans. We conducted a cross-sectional study involving 752 healthy Chinese (48.7% women), aged 40–59 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 multipass 24-h recalls. Participants were asked to demonstrate MSG amounts added in food preparation. Amounts shaken out were weighed by trained interviewers. Overweight was defined as BMI 25.0 or 23.0 kg/m²(based on World Health Organization recommendations for Asian populations). Eighty-two percent of participants were MSG users. Average intake was 0.33 g/day (s.d. = 0.40). With adjustment for potential confounders including physical activity and total energy intake, MSG intake was positively related to BMI. Prevalence of overweight was significantly higher in MSG users than nonusers. For users in the highest tertile of MSG intake compared to nonusers, the multivariable-adjusted odds ratios of overweight (BMI 23.0 and 25.0) were 2.10 (95% confidence interval, 1.13–3.90, P for trend across four MSG categories = 0.03) and 2.75 (95% confidence interval, 1.28–5.95, P = 0.04). This research provides data that MSG intake may be associated with increased risk of overweight independent of physical activity and total energy intake in humans.