When it occurs naturally in foods, Monosodium Glutamate, or MSG, is a carefully regulated neurotransmitter and breaks down slowly during the digestive process. Originally used in Asian cooking and made from a variety of seaweed, today it is made from fermenting sugar beet molasses.
MSG has no specific flavour of its own but it fools the brain into thinking food tastes better than it actually does. The blood-brain barrier protects this free glutamate from entering the brain. However, artificially adding high concentrations of free glutamate to food upsets this balance. If blood levels remain high, glutamate gradually seeps into the brain.
Behavioural Problems
Research has shown both glutamate and aspartate cause destruction of retina cells in mice and kill vital neurons in the brain itself. MSG has also been linked to impaired learning and behavioural problems in children, anger, obesity and diabetes. Children should avoid MSG as their brains are more susceptible than adults.
Appetite Stimulator
Now, there is also concern that MSG, along with the artificial sweetener aspartame, may contribute to obesity as well. Although aspartame has virtually no calories, studies have shown that it may stimulate the appetite. This may also be the case with MSG. In studies conducted as far back as 1968, rats fed with MSG all became grossly obese. Since then, other studies have confirmed that MSG causes gross obesity in animals. However, until recently, the relationship between MSG consumption and weight had not been assessed in humans.
Latest Research
That changed at the end of August with the publication of a study in the journal Obesity. The study, which took place in China, looked at the relationship between MSG consumption and the BMI (body mass index) of 752 men and women aged between 40-59. The participants were divided into three groups, according to MSG consumption. Compared to those in the lowest consumption group, those in the highest were found to be 2.75 times more likely to have a BMI of more than 25.
There may be several reasons for these results. One could be that MSG led individuals to eat more food or be less active. However, this was accounted for in the study, meaning the link between MSG consumption and increased body weight appears to be independent of these factors.
This suggests MSG may have one, or several, metabolic effects on the body which may predispose people to weight gain. Giving MSG to animals has been shown to induce various changes that promote fat accumulation including suppression of fat breakdown.
References: Blaylock, R, (2006). Health and Nutrition Secrets. New Mexico: Health Press
