Experts addressed common concerns about MSG and considered relevant literature.
These concerns included the likelihood of glutamate crossing the placental or blood-brain barriers, whether MSG has adverse effects on immune function or lung health, and the risks of certain
consumers being sensitive to MSG.
Total intake of glutamate from food in European countries was found to be stable at between 5 to 12 g/day. New evidence on immune function was scarce. In one study, 109 people with asthma were
tested after consumption of oriental food or oral glutamate to establish tolerance. No adverse reactions were noted.
Two studies investigating the impact of glutamate on lung function found no effect.
There was no new evidence to support the idea that specific individuals experience sensitivity to glutamate.
Turning to concerns about the metabolic fate of glutamate, the expert panel spent some time considering whether the blood brain barrier (which restricts passage of substances from the
bloodstream to the brain) was vulnerable to high intakes of MSG.
It was agreed that, provided the blood brain barrier was intact, passive influx of glutamate into the brain was likely to be insignificant.
However, several diseases are known to impair the blood brain barrier and it can’t be ruled out that a single high dose of glutamate may have adverse effects in such cases.
At present, there is no data to suggest that raised blood levels of glutamate would translate into high brain glutamate concentrations.
Data from animal studies indicate that very high concentrations of glutamate in maternal blood do not find their way across the placenta.
This suggests that maternal consumption of MSG would have minimal implications for foetal development. Interestingly, breast milk in Western countries has been found to contain measurable
amounts of free glutamate, increasing the likelihood that infants have a higher intake of free glutamate than they do later in life.
No ill-effects of this were noted.
The expert panel regarded a dose of 16mg/kg body weight to be a safe maximum intake of MSG for adults. It was concluded that current use of glutamate salts (monosodium-L-glutamate and others)
as food additives was “harmless for the whole population” and, at low doses, could help to improve appetite in the elderly.