Intakes of MSG ranging from 2.5 to 9 times those observed in ‘non-users’ were not associated with weight gain over a five year period, scientists from Jiangsu Provincial Centre for Disease Control and Prevention, the South Australian Department of Health and the University of Adelaide report in the British Journal of Nutrition.
Of mice and men
The authors of the new study note that some public concern has been raised over the link between the flavour enhancer and an increase in the risk of gaining weight, based on data from animal studies and one human observational study from the University Of North Carolina. The UNC Intermap study was also based in China and reported in 2008 that the risk of being overweight was increased by 175 per cent in people with a high intake of MSG.
Writing in the Nature journal Obesity (Vol. 16, pp. 1875-1880), the UNC researchers stated: “Ours is the first study to show a link between MSG use and weight in humans.”
The findings have now been challenged by a new analysis, which included 1,282 Chinese men and women participating in the Jiangsu Nutrition Study.
“To our knowledge, this is the second human study to investigate a possible association between MSG intake and obesity, but more importantly it is the first to determine whether a greater MSG intake is associated with a clinically significant weight gain over 5 years,” wrote the Chinese and Australian researchers.
Over five years of study, no link between MSG intake and weight gain was recorded.
MSG intensifies and enhances flavour without having a taste of its own, and also has the properties to act as a nutrient, as well as a salt substitute. The use of the ingredient, popular in many Asian cuisines, looks set to increase its presence in the west.
Indeed, the global market for fermentation products is expected to rise by 4.8 per cent per year, to reach €13.6 billion in 2009. Lysine and monosodium glutamate (MSG) are the largest products in this category.
The study was welcomed by Ailbhe Fallon for International Glutamate Information Service, who told this website that the results of the “detailed evaluation are welcome though unsurprising.
“The amount of glutamate added to food as seasoning is a small fraction of our daily intake - glutamate is one of the most abundant amino acids in our diet. In fact, seasoning with MSG facilitates the creation of low sodium and even reduced fat recipes that taste delicious thanks to the umami,” added Fallon.
The researchers, led by Zumin Shi from Jiangsu Provincial Centre for Disease Control and Prevention, assessed dietary intakes of glutamate in almost 1,300 Chinese people with an average age of about 50 using food frequency questionnaires.
After crunching the numbers, the researchers observed no link between MSG intake and weight gain, even in people with relatively high intakes of the flavour enhancer.
“These findings indicate that when other food items or dietary patterns are accounted for, no association exists between MSG intake and weight gain,” concluded the researchers.
Dr Zumin Shi told FoodNavigator that research at a population level is limited in assessing the association between MSG and obesity, and that further research is needed. Indeed, the researchers note that studies should be undertaken to investigate if dietary glutamate intake is associated with weight gain in people with poor protein and energy status.
Source: British Journal of Nutrition
Published online ahead of print, doi:10.1017/S0007114510000760
“Monosodium glutamate is not associated with obesity or a greater prevalence of weight gain over 5 years: findings from the Jiangsu Nutrition Study of Chinese adults”
Authors: Z. Shi, N.D. Luscombe-Marsh, G.A. Wittert, B. Yuan, Y. Dai, X. Pan, A.W. Taylor