Consuming more than 5g of MSGper day increases the risk for metabolic disorder, according to a studypublished in the journal Nutrition & Metabolism.
Monosodium glutamate, a flavorenhancing food additive, is the sodium salt of glutamic acid. It is used in foodssuch as concentrated soups, sauces, chips, meat products, puddings, seasoningsand many processed foods. Better known as MSG, it is widely used in Asiancuisine. MSG is consumed daily in the rural area of Thailand and is a commonadditive in Thai cuisine with an average intake of 4g per day.
Earlier studies have showed thatthere is a relation between consumption of MSG and being overweight, and thatthose who consume MSG at an average of 0.33g per day in the diet aresignificantly more overweight than persons who don't use the substance,irrespective of physical activity and energy intake. Similarly, animal studieshave also shown that elevated MSG intake leads to increased serum triglyceride,fasting glucose, and insulin levels, all of which are metabolic disorderbio-markers.
So, Tonkla Insawang fromDepartment of Biochemistry, Faculty of Medicine, Khon Kaen University,Thailand, and colleagues conducted a study in rural Thai adults to determinewhether MSG is associated with metabolic syndrome, irrespective of physicalactivity and calorie intake.
The study was completed in 349adults aged 35 to 55 years from 324 families. The families were provided 250 gof MSG to be used as the sole source of MSG in meal preparation for 10days. The total consumption at the endof 10 days was recorded and the daily consumption of MSG per person wascalculated. These adults were then evaluated for energy and nutrient intake,physical activity, and tobacco smoking. The incidence of being overweight,obesity, insulin resistance and metabolic syndrome were also evaluated.
The results showed that prevalence of metabolic syndrome was higher inthe group that consumed the highest amount of daily MSG. They also found thatrisk of metabolic syndrome increased with every 1g increase in MSG intake,irrespective of physical activity level and calorie intake.
Although the investigators founda significant trend for increasing insulin levels and prevalence of insulinresistance with high MSG intake, the fasting blood sugar did not differ. Thisimplies that MSG can raise insulin levels without altering glucoseconcentration and glucose tolerance.
Interestingly, despite therebeing significant relationship between insulin resistance, being overweight,and metabolic syndrome with MSG intake, the researchers found that MSG consumption does not significantlyincrease risk of insulin resistance after adjusting for the factors such asage, gender, family history of diabetes, smoking status, physical activity, anddaily energy intake. Therefore, the metabolic syndrome associated with MSGintake, they hypothesized, 'may not be due to the energy-intake-induced obesityleading to insulin resistance' but rather, the MSG may push the dietary glucose towards fat synthesis and activate theenzymes involved in fat biosynthesis and storage of fat in adipose tissue.
The researchers thus concludedthat 'Higher amounts of individual MSG consumption are associated with the riskof having the metabolic syndrome and being overweight independent of othermajor determinants'.
Source:Insawang, Tonkla, et. al. Monosodium glutamate(MSG) intake is associated with the prevalence of metabolic syndrome in a ruralThai population. Nutrition &Metabolism 2012, 9:50