The ongoing discussion around acceptable levels of monosodium glutamate (MSG) to be included in packaged food brings into focus the role that biochemistry plays in the foods consumed by us.
The human body uses a complex mechanism for converting the food we eat into simpler compounds that provide nutrition. The proteins we eat are broken down into amino acids. Glutamic acid is one such amino acid derived from proteins. In fact, glutamine is the most abundant amino acid present in the body.
Monosodium glutamate (MSG) on the other hand is the sodium salt of free glutamic acid and provides a flavour function that occurs naturally in food. Free glutamate is also found in some of the foods we eat everyday such as cheese, mushrooms, milk, tomatoes, and chicken among others. Glutamate is responsible for the special ‘Umami’ (sweet, sour, bitter and salty) flavour and taste in these foods. It is important to note that the glutamate amounts originating from our foods are still considerably lower than the amount the body produces. Food-derived protein-bound, free glutamate and glutamate derived from food additives are similarly metabolised in the human body.
While MSG has a long track record of being safe, some studies have questioned its safety in public domain. There is a broad consensus, however, in the scientific community and amongst international regulatory bodies such as WHO, that MSG when consumed in appropriate amounts is safe. These conclusions are based on numerous biochemical, toxicological and medical studies conducted over four decades. A 1979 study found it to be safe even for pregnant mothers and unborn babies. In 1988, MSG was evaluated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). They concluded that conventional toxicity studies using dietary administration of MSG in several species did not reveal any specific toxic or carcinogenic effects.
Although MSG is perceived to contain high levels of sodium, in fact, it contains less than a third the amount of sodium we consume as common salt. When MSG is added, the dish requires less common salt than normal, reducing the total sodium intake.
Today, we buy and using a variety of packaged and processed foods. Food manufacturers are continuously looking for innovative ways of adding nutritional value and enhancing the health benefits of these foods. As consumers we need to learn more about food safety and quality and rely on scientific and rational evidence in making our choices.(The author is former director of National Institute of Nutrition, India Council of Medical Research)