A preliminary study on the assessment of glutamate intake and the impact factors of restaurant diners in seven provinces and cities in China

ObjectiveTo assess the risk of exposure in the population in 7 provinces and cities in China， the intake of glutamates （calculated for glutamic acid） in Chinese restaurant diners was calculated and compared with the recommended intake.MethodsA multi-stage stratified and population-proportional whole-group random sampling method was used to randomly select condiments in seven provinces/municipalities： Beijing， Chongqing， Liaoning， Shandong， Guangxi， Jiangsu， and Shaanxi. Ultra-performance liquid chromatography-tandem mass spectrometry method was used to determine the glutamate content of collected condiments. The glutamate intake was calculated based on individual consumption and body weight data obtained during the investigation based on a simple distribution model of restaurant diners.ResultsThe highest levels of glutamates were found in flavoring agents and enhancers， followed by chicken essence/chicken powder， solid compound condiments other than chicken essence， liquid compound condiments， soy sauce， semi-solid compound condiments based on animal ingredients， spices， and brewing preparation sauces， etc. The lowest levels of glutamates were found in salt and salt substitutes. The mean glutamate intake of a meal for restaurant diners was 47.87 mg/kg·BW， accounting for 39.89% of the ADI set by JECFA. The mean glutamate intake for a day was 61.33 mg/kg·BW when considering food consumed outside the restaurant during the day， accounting for 51.11% of the ADI. Among diners of different restaurant sizes， medium-sized restaurants had the highest intake of glutamates during a meal， with a median intake of 44.46 mg/kg·BW， followed by large restaurants and small restaurants， with significant differences （P<0.05） observed in glutamate intake among all three groups. All mean values were < 50% of ADI. In different regions， the median intake of glutamate among diners in Guangdong Province was the highest at 64.22 mg/kg·BW， and the lowest was 18.66 mg/kg·BW in Beijing. Two-by-two comparison showed that the intake levels differed between provinces and cities （P<0.05）， except for Shandong Province and Shaanxi Province where the difference was not statistically significant （P>0.05）， and the mean values as a proportion of ADI were <80%. When comparing urban and county cities， the intake of urban restaurant diners was significantly higher than that of county cities （P<0.05）， and the mean values were < 50% of the ADI.ConclusionThe level of glutamate in condiments consumed in Chinese restaurant diners is still at an acceptable level. However， the level of glutamate intake varied between different provinces and cities， and cities and counties.