Assuming you're not one of the few dinosaurs to resist having an e-mail address, chances are good you've received one of the latest chain messages to sweep the continent. Its subject line is "MSG”¦ You need to know this!" and within it is a ton of disturbing information about monosodium glutamate. To some, the flavour enhancer is as harmless as pepper, but to others it's a nasty substance that's making people sick.

Much of the content in the mass e-mail is drawn from The Slow Poisoning of America, a 2003 book written by John E. Erb and Michelle Erb. Among the ailments associated with MSG, the pair claims, are Alzheimer's disease, diabetes, autism, epilepsy, attention deficit hyperactive disorder, and schizophrenia. The two also argue that monosodium glutamate is the seasoning of choice of so many fast-food restaurants because it is addictive. Since it makes people want to eat more, MSG is a key factor contributing to North America's obesity epidemic, they write. The food manufacturers that produce MSG, on the other hand, argue that the substance makes food tastier and is scientifically proven to be safe.

According to MedicineNet.com, monosodium glutamate is a sodium salt of the amino acid glutamic acid. It's made by fermenting corn, potatoes, rice, and sugar cane and looks like fine white crystals. It doesn't have any taste itself, but it boosts the flavours of meat, poultry, seafood, and vegetables. In China, MSG is known as wei jing, which translates as "flavour essence".

There are two types of glutamate: bound glutamate, which is found in the human body and in plants and animals; and free glutamate, which exists naturally in some foods, like tomatoes and Parmesan cheese. It's the processed form of free glutamate that can supposedly cause adverse or allergic reactions.

The additive is commonly associated with certain types of Asian food. The "Chinese-restaurant syndrome" was first described in 1968 among people who had eaten dishes loaded with MSG. Symptoms included headache, dizziness, lightheadedness, facial pressure, tightness of the jaw, burning or tingling sensations over parts of the body, chest pain, and back pain. MedicineNet.com also reports that large amounts of MSG may lead to widening of the arteries.

Today the affliction is more appropriately known as MSG-symptom complex, and the additive is hardly limited to Asian restaurants. Although the current chain e-mail says that people might be shocked to see that monosodium glutamate shows up in thousands of foods, that fact will come as no surprise to those who take the time to read ingredient labels. Sure enough, MSG is found in countless canned soups and vegetables, crackers, cookies, potato chips, salad dressings, condiments, frozen meals, processed meats, infant formulas, and more.

Complicating matters for consumers is that processed free glutamic acid is present but unlabelled in such ingredients as autolyzed yeast, sodium caseinate, yeast extract, calcium caseinate, sodium caseinate, textured protein, and hydrolyzed protein.

That the term monosodium glutamate itself might not appear in a product's list of ingredients is one concern of the on-line Truth in Labeling Campaign, which vehemently opposes the widespread use of MSG. Its Web site screams "If MSG isn't harmful, why is it hidden?" The group states that any claims that the additive is safe stem from glutamate-industry propaganda.

The Washington, DC–based Glutamate Association, however, maintains that MSG is a "safe and extremely effective flavor enhancer". The group's Web site (www.msgfacts.com/) cites the results of several studies that show the safety of consuming MSG. One report, from a 1993 issue of Food and Chemical Toxicology, "failed to demonstrate statistically significant sensitivity reactions to high levels of MSG".

In 1995, the U.S. Food and Drug Administration released a backgrounder on monosodium glutamate, saying that it and related substances "are safe food ingredients for most people when eaten at customary levels". However, the backgrounder also referred to a 1995 report by the Federation of American Societies for Experimental Biology, which described MSG-symptom complex as occurring in an "unknown percentage of the population" and being characterized by a burning sensation in the chest, forearms, and neck; tingling, warmth, or weakness in the face, temples, upper back, neck and arms; facial pressure or tightness; chest pain, headache, nausea, rapid heartbeat, difficulty breathing, drowsiness, and weakness. The report said that the complex tends to occur within an hour of eating three grams or more of MSG. "A reaction is most likely if the MSG is eaten in a large quantity or a liquid, such as a clear soup," the report says.

People with severe asthma might be at greater risk of developing MSG-symptom complex, the FDA states. Vancouver Coastal Health lists monosodium glutamate as a trigger for the respiratory condition (along with sulphites).

The Mayo Clinic states that symptoms of the complex are usually mild and don't require treatment. "However, some people report more severe reactions," notes its Web site (www.mayoclinic.com/). "The only way to prevent a reaction is to avoid foods containing MSG."

Local naturopath Nigma Sciortino told the Georgia Straight she believes that monosodium glutamate is addictive. "MSG has a negative impact on health," said Sciortino, who works at the West Vancouver Wellness Centre ( www.healthydoc.com /). She noted that the substance contributes to obesity and the desire to overeat and that since it came on the market, MSG has been added in greater amounts to processed foods.

Sciortino said the best way to avoid MSG is to stick to whole, unprocessed foods, items that don't come in a can or other packaging.