3 - Health issues relating to monosodium glutamate use in the diet

Abstract

Monosodium Glutamate (MSG) improves the taste acceptability of foods with lowered salt content, suggesting that its use in low-salt foods will make it easier for people to establish and maintain a low-salt diet. It is the sodium salt of Glutamic Acid (GLU), a non-essential amino acid for humans and other mammals. It is the dominant amino acid in dietary proteins, comprising about 10% of the total amino acid content. In the body, GLU serves a number of important functions, aside from its role in taste. However, despite the “indispensability” of GLU to the normal functioning of the body, its use in food as a flavor enhancer (primarily as MSG) has been reputed in the past to be toxic, leading to brain damage and a host of other adverse effects in humans and animals. If such is the case, this chapter presents the questions how its use can be permitted as a food additive, and more to the point, how the body can “survive” the flood of GLU that enters every day as a natural constituent of foods. The chapter provides answers to these questions. The issue of GLU (and MSG) safety in food was raised over 35 years ago. In the intervening period, a great deal of research has been conducted on this issue, particularly in humans, and has led to the broad conclusion that GLU and MSG are safe to consume. The chapter provides an overview of the GLU content of foods, discusses the two broad issues that have been the primary foci of concern about dietary MSG safety over the past 35 years: (a) effects of dietary GLU and MSG on nervous system development and function and (b) allergic and non-specific effects of dietary MSG.