Monosodium glutamate (MSG) is a widely used flavor enhancing amino acid and is generally accepted as safe. In Western countries, MSG is usually consumed in processed and packaged goods whereas in China, MSG is often added during home cooking. It is estimated that 650,000 tonnes of MSG are used worldwide each year. MSG intake has been found to increase the risk of insulin resistance, diabetes and obesity in studies done in rodents. In this study, researchers assessed the association between MSG intake and the risk of hyperglycemia after five years, based on a large population-based study in China, the Jiangsu Nutrition Study (JIN).
The study included 445 men and 611 women (n = 1056) with a fasting plasma glucose <5.6 mmol/l (FPG<100.9 mg/dl) in 2002 and without known diabetes. No differences in mean BMI, waist circumference, glucose, and energy intake were found (p > 0.05). The authors defined diabetes as FPG>7.0 mmol/l (FPG > 126 mg/dl) or having known diabetes and hyperglycemia as FPG>5.6 mmol/l (FPG>100.9 mg/dl). To determine the amount of MSG and other seasonings consumed by individuals, each household was asked about their usual monthly consumption of these items. Individual consumption of MSG was calculated according to the total amount of MSG consumed in the household divided by the number of individuals per household and then adjusted for the proportion energy intake and energy consumption by each individual. Cigarette smoking, alcohol consumption and physical activity were also evaluated in these participants.
In the results, the authors found the mean intake of MSG for the entire population was 3.8 g/day. The highest quartile of MSG intake was associated with a lower risk of incident hyperglycemia, even after adjustment for a number of covariates, including dietary patterns. In the study, age, BMI, central obesity and sedentary activity were positively associated with the risk of incident hyperglycemia, while an inverse association between daily alcohol consumption and the risk of hyperglycemia was found.
Based on the results of this study, the authors concluded that high MSG intake is associated with a decreased risk of hyperglycemia in Chinese adults. More research is needed to establish the causal links between MSG intake and hyperglycemia.
- The world is currently facing a diabetes epidemic with China having the highest absolute number of people with diabetes.
- The highest quartile of MSG intake was associated with a lower risk of incident hyperglycemia.
- In the sample, age, BMI, central obesity and sedentary activity were positively associated with the risk of incident hyperglycemia, while an inverse association between daily alcohol consumption and the risk of hyperglycemia was found.
Clinical Nutrition, November 2013