The first book I wrote, “Excitotoxins: The Taste That Kills,” was on the harmful effects of adding glutamate extracts (such as MSG) to foods and drinks. Since the publication of the book, an enormous amount of research has expanded our understanding of how additives such as glutamate (and the artificial sweetener aspartame) harm our bodies.

While the book concentrates on the effects of excitotoxins on the central nervous system, newer studies have shown that glutamate receptors exist on virtually every tissue and organ in the body, including the heart, lungs, GI tract, blood vessels, kidneys, skin, eyes, hearing organs, and adrenal glands.

High levels of ingested glutamate have been shown to dramatically increase free radical and lipid peroxidation formation for prolonged periods, even after a single dose. And glutamate is added to a great many processed foods.

In one study, researchers found that feeding MSG to mice not only caused obesity and insulin resistance (Type 2 diabetes), but also caused prolonged inflammation and free radical generation in the animals’ livers, which led to an accumulation of fat in the liver — a condition called nonalcoholic fatty liver disease (NAFLD). This disorder, which can lead to liver cancer, is increasing exponentially in our society, even in young children.

The histological changes in the animals’ livers were indistinguishable from human cases of NAFLD. After the initial dose of MSG, the researchers observed increased liver inflammation, even after a year following the MSG exposure.

Some have observed that inflammation within blood vessels following a single dose of MSG can last a lifetime, which would dramatically increase the development of atherosclerosis.

The persisting harmful effects of MSG after an initial exposure was also demonstrated in the brain, with damage to brain cell mitochondria and a dramatic fall in antioxidant enzymes occurring long after the MSG exposure.

The only way to avoid excess glutamate is to avoid all processed foods and eat only freshly prepared, organic foods.