Hello, yes, I am passionate about food science, and would like to share my knowledge with you all.
MSG was initially discovered by Japanese chemist Kikunae Ikeda. As the story goes, he was just enjoying a very nice bowl of soup at a family dinner in 1907, and realized something about the kombu made it so wonderfully delicious. He went on to give us the word umami to describe the flavor compound shared between some foods – glutamate, the ionic form of glutamic acid.
By 1908, Kikunae Ikeda isolated the glutamic acid within kombu, and added salt. This monosodium glutamate – literally MSG – is the chemical basis for the flavor of umami. He called it Ajinomoto, and figured out how to mass produce it within a year.
However momentous this discovery was, it's worth differentiating that the substance itself is not the invention here. Humans have been combining glutamate-high ingredients with salt since time immemorial. This is the entire idea behind every variety of fish sauces and gravies, or just, you know... salting certain foods.
MSG exists just as much in little jars of Ajinomoto as it does some flaked salt on a fresh tomato! It is unavoidable, and for good reason! This flavor compound is the signal to your brain that you are eating food with important nutrients.
So, why the MSG scare? Simple: uninformed fear mongering and racism.
There was already exoticism surrounding MSG, and the 1960's saw a rise in consumer concerns regarding unfamiliar additives. A now-infamous New England Journal of Medicine published doctor's letter mused that he experienced heart palpitations and arm pain after eating at Chinese restaurants.
That letter set off a snowball effect: first readers reporting similar experiences, then studies citing that first letter, and eventually a media frenzy about Chinese Restaurant Syndrome. It was such a phenomenon that medical professionals and establishments considered this a real ailment. Certain doctors still treat it as such, despite all evidence maintaining that MSG in any form is entirely safe.
But do you know what can cause heart palpitations, headaches, and general unwellness from overconsumption? Sodium.
MSG is an incredible compound, but it's still sodium. American food, especially American takeout, tends to be heavily salted. If you eat several portions of that, continue to graze on it the followind days, and have regularly salted meals/snacks besides? A lot of people can get dehydrated from that much salt. Just drinking more water will really help rebalance your electrolytes!
As a final note: there are plenty of umami seasonings on the market. These are mostly capitalizing on the above fear, but like... they're fine. Fundamentally, these are still MSG powders. They're just more expensive, less potent, and contain other flavor compounds. Most are primarily salt and mushroom powder (including button, shiitake, and cremini); onion, kelp, mustard seed, nutritional yeast, etc. often make an appearance. This is a straight powder of these things, too, meaning it can pose an allergy risk for some people. Otherwise, enjoy them if you like them! Just don't feel like you have to for some perceived health or safety factor.
If there's anything you take away from this, let it be two things. First: humans are behind science, thus science is prone to human bias. Second: it's a travesty that pleasure from food is treated as a moral failing rather than celebrated as your brain doing its job.