Scientists from the Institute of Life Sciences from Ajinomoto Co. report that diets containing 0.5 or 5 percent MSG did not affect levels of inflammatory compounds or inflammation itself in the lungs of asthmatic mice.
“The results of this study did not reveal acute effects of MSG ingestion on asthmatic symptoms in the mouse model. In addition to a functional assessment, the current study included histological and cytological examinations to confirm the safety of MSG ingestion for asthmatics,” wrote scientists in Food and Chemical Toxicology.
“These results provide a scientific basis for the observed safety of general MSG intake in asthmatic patients,” they added.
MSG intensifies and enhances flavor without having a taste of its own, and also has the properties to act as a nutrient, as well as a dietary and 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.
Japanese firm Ajinomoto dominates the amino acid market, with more than 25 per cent of the market for lysine alone and 30 per cent of the MSG. ADM and BASF also figure in the handful of players that dominate the landscape.
Concerns over the additive first surfaced in the late 1960s following description of the 'monosodium glutamate symptom complex' or 'Chinese restaurant syndrome'. The concerns centered on indications that MSG may worsen asthmatic symptoms.
“Although some reports indicate the possible involvement of food additives, including Food, Drug, and Cosmetic Act (FD&C) approved dyes, benzoate, and tartrazine in the cause of allergic hyper-responsiveness, many adverse reactions reported to additives were anecdotal or characterized by poorly controlled challenge procedures,” wrote the researchers.
“[Several reports between 1981 and 1987] reported a relationship between MSG intake and asthma; however, their studies lacked proper control groups,” they added.
The Ajinomoto scientists used BALB/c mice to study the effects of MSG in relation to allergic inflammation and asthma. According to the European Federation of Allergy and Airway Diseases Patients Association (EFA), over 30m Europeans suffer from asthma, costing Europe €17.7bn every year. The cost due to lost productivity is estimated to be around €9.8bn.
Animals were fed a diet containing 0.5 or 5 percent MSG for one week and then received an injection ovalbumin in order to induce asthma-like symptoms in their lungs. The MSD diets were continued for an additional three weeks.
At the end of the study, the researchers state that no affects were observed in either group regarding the production of Th2 cytokines, circulating levels of IgE, nor airway hyper-responsiveness
In addition, there was no effect on the number of eosinophils – white blood cells associated with an allergic or asthmatic immune response – said the researchers.
“The present study provides a scientific basis for the conclusion [that there is no scientific evidence indicating adverse effects for asthmatic patients from general ingestion of MSG], as use of an animal model enabled us to investigate the effects of MSG in detail through histological and cytological analyses,” stated the researchers.
“The dosages of MSG tested here (5% both in the diet and in solution) are considered much higher than the general intake of MSG in humans. A diet containing 5% MSG corresponds to a daily intake of 5 g/kg, a level that is over 100 fold higher than the average daily human exposure to MSG,” they added.
Source: Food and Chemical Toxicology
Published online ahead of print, doi: 10.1016/j.fct.2010.10.032
“Effects of oral monosodium glutamate in mouse models of asthma”
Authors: J. Yoneda, K. Chin, K. Torii, R. Sakai