Does the flavour enhancer MSG, really have adverse health effects? By Lien Hoang. Photo by Jonny Edbrooke.

I don’t even remember where it came from, but at some point in my childhood, I heard that MSG was unhealthy and so, proceeded to declare war against the food additive. Among other things, I learned that it could cause bone damage, which is of particular concern for females, who are more susceptible to osteoporosis.

At my family’s house in Northern California, my Vietnamese mother kept the usual tins of sugar, salt, pepper — and MSG, or monosodium glutamate. She cooked with all of them, liberally, because Hue mothers can never have too many seasonings. When I started to turn against MSG, she would inexplicably reply that the salty crystals were like vitamins.

But it was only after I returned to Vietnam that MSG became a problem. I would eat street food way too often, and come home not knowing why my neck ached, especially after eating noodle soups. After a few months I finally made the connection, when a friend said that she loved a nearby pho restaurant but always left with a severe MSG reaction. Typical symptoms are headaches, flushing, sweating, facial pressure or tightness, numbness, tingling or burning in the face, neck and other areas, heart palpitations, chest pain, nausea and weakness, according to the Mayo Clinic, a leading research hospital in Minnesota.

Since then, I often would ask street vendors and restaurateurs whether they used bot ngot in their dishes before deciding if I should eat there. I was disappointed to find that one vegetarian cafe did, indeed, use MSG, because I thought vegetarians knew better. Some eateries around Ho Chi Minh City are starting to post “No MSG” signs, but it seems they’re catering to foreigners. Vietnamese, and Asians more generally, don’t care.

In 2012, Viet Nam News asked for readers to submit their thoughts on MSG.

“As Vietnamese, we grow up with the tendency to accept that our grandmothers and mothers use MSG frequently,” reader Le Duy Luong wrote. “That’s why many Vietnamese aren’t allergic to MSG. I think it’s quite hard to convince a typical Vietnamese that excessive use of MSG could cause things such as depression.”

That echoed what Vietnamese friends have told me, that they’ve probably built up a tolerance for MSG that westerners don’t quite have. So, back home in the United States, there’s far more anxiety about MSG in soups, processed meats and canned vegetables. And of course: in Chinese food (equally, Vietnamese food), which hasn’t helped that cuisine’s low-quality reputation.

Yet the US Food and Drug Administration (FDA) classifies MSG as “generally recognised as safe” (though it does require food manufacturers to include the flavour enhancer on their lists of ingredients). Call it naivete, but I did not even know this was up for debate and so many people considered MSG harmless.

The FDA, though, has its critics, who say the agency is more about promoting the food industry than protecting consumers. So I looked for other research instead, and what I found was surprising. There is much more literature seeming to debunk the belief that MSG is detrimental to our health, than research to support the thesis.

A team of five researchers in Japan studied the effects of MSG on mice, comparing them with a control group, and published their findings in 2013. They concluded that MSG did not cause obesity. Namely, “the present two-generation mice study found no impact of MSG ingestion on growth, body composition, fat accumulation, or blood biochemical indices for insulin resistance or fat metabolism.”

But there is a catch, and it is potentially fatal: at least one of the scientists works for Ajinomoto, a major MSG producer in Japan.

The team was trying to reproduce (or refute) the results of a similar mice experiment reported in the Journal of Lipid Research in 2008. That experiment linked MSG with non-alcoholic fatty liver disease and obesity, by showing an uptick in cholesterol or fat in the blood and fat storage genes in mice treated with MSG. The 2013 study did not argue the 2008 results were wrong, but that they could not be reproduced.

This is just a sample of research that suggests there has been no definitive evidence for either the pro- or anti-MSG camp. A friend told me his approach to these inconclusive health reports is to consume a little less of the questionable product than the average person. In other words, he would have some MSG, but less than most people. So if someday the world does learn that MSG is making us fat and destroying our bones, other people will succumb to it before we do.