As runners, we tend to pay a lot of attention to what we’re putting in our body. One of the things we’ve historically steered clear of? MSG, or monosodium glutamate.
You’ll find the phrase “No MSG” slapped on everything from steak seasoning to chicken broth to Chinese restaurant menus. Yet it doesn’t deserve its bad reputation, which all stemmed from a 1968 opinion piece published in the New England Journal of Medicine.
In that article, the physician named R.H. Kwok, discussed feelings of weakness, heart palpitations, headaches, and pain radiating in his arms—all after frequenting Chinese restaurants. He posited that cooking wine, monosodium glutamate., or salt might be to blame. The title of the paper: “Chinese-restaurant syndrome.”
Around the same time, a published study demonstrated what happened when scientists subcutaneously injected neonatal mice with large doses of MSG. Those rodents that took the 25,000 mg/kg megadose experienced rapid brain deterioration.
When the mice grew to be adults, they were notably smaller in stature, obese, and had trouble reproducing. The author of that paper extrapolated this information to suggest that pregnant women should avoid MSG for fear of the same neural effects for their newborns.
So, to summarize, the findings that characterized MSG as evil were based on an opinion letter and a rodent study. And, to date, no peer-reviewed research since has duplicated these findings.
That said, four out of 10 people still actively avoid MSG according to International Food information Council Foundation.
I’m here to tell you, as a registered dietitian, that you don’t have to avoid MSG.
If that’s not enough for you, consider that in January 2018 the International Headache Society removed MSG from its list of causative factors for headaches after studiesdisproved any connection.
In December 2018, John Fernstrom, Ph.D., professor of psychiatry and pharmacology at the University of Pittsburgh, published a study review on the supposed ill effects of MSG.
His team’s conclusion: “Findings from our data and other human studies provide important evidence that MSG in the food supply presents no hazard to the human brain. Not only does oral ingestion of glutamate not cross the blood brain barrier.”
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Americans consume about 500 mg/day (or about 7 mg/kg/day for a 70 kg person). That number is higher in Asian cultures, but is nowhere near the 25,000 mg/kg (3000-5000 mg/kg) megadose of the now notorious mice study.
Don’t fear MSG, largely because MSG makes food taste good.
“Umami is a really important factor in terms of making foods taste delicious—and MSG is an concentrated form of umami,” says Ellie Krieger, R.D.N., host of Ellie’s Real Good Food. “I think one of the biggest issues with MSG is the company it keeps—meaning the foods it’s often found in. It’s not MSG itself that’s of concern, but it can make poor-quality food taste great too so they may be more appealing than they would otherwise be.”
But there’s also a governor chip of sorts that comes with monosodium glutamate. “MSG intake is self-limiting,” says Fernstrom. “A small amount gives food an amazing flavor, whereas too much tastes unpleasant, limiting the amounts you are likely consume.”
Unless, of course you’re a lab rat.