MSG is made of just two components: sodium and glutamic acid, one of the most common amino acids in nature. Its chemical formula is C₅H₈NNaO₄, and it’s produced commercially through bacterial fermentation of plant-based sugars, a process similar to how yogurt, vinegar, and beer are made.
The Two Building Blocks
Monosodium glutamate is the sodium salt of L-glutamic acid. Think of it like table salt (sodium chloride) but with the chloride swapped out for an amino acid. Sodium makes up about 14% of MSG’s total weight, compared to 40% in regular table salt. That’s roughly one-third the sodium concentration, which is why some food manufacturers use MSG as a partial salt replacement to lower sodium content while keeping food flavorful.
Glutamic acid is one of the 20 amino acids that make up proteins in your body and in the foods you eat. Your body produces it naturally, and it’s abundant in high-protein foods. The glutamate in a packet of MSG is chemically identical to the glutamate found in tomatoes, parmesan cheese, or soy sauce. Your body processes both forms the same way.
How MSG Is Manufactured
Modern MSG production relies on a bacterium called Corynebacterium glutamicum, a harmless microbe originally isolated for its ability to produce large quantities of glutamic acid. Manufacturers feed this bacterium sugars derived from crops like sugarcane, corn, cassava, or beet sugar. As the bacteria consume the sugar, they convert it into glutamic acid and excrete it into the surrounding liquid.
The process works by carefully controlling the bacteria’s growing conditions. When the bacteria experience specific stresses, like limited availability of certain nutrients, channels in their cell membranes open up and release glutamic acid into the fermentation broth. Once enough glutamic acid accumulates, it’s collected, purified, combined with sodium, and crystallized into the white powder you see on store shelves.
This fermentation approach has been the industry standard since the mid-20th century. Before that, MSG was extracted directly from protein-rich foods like seaweed broth and wheat gluten, which was far more expensive and time-consuming.
Glutamate in Everyday Foods
The glutamate in MSG isn’t unique to the seasoning. Free glutamate occurs naturally in many foods, often in surprisingly high concentrations. Parmesan cheese contains about 1,680 mg of free glutamate per 100 grams. Soy sauce has roughly 1,264 mg, and fish sauce tops out around 1,383 mg. Even common vegetables carry meaningful amounts: tomatoes contain 246 mg per 100 grams, mushrooms have 180 mg, and broccoli has 176 mg.
Only “free” glutamate, the form not bound up in larger protein chains, triggers the savory taste known as umami. That’s why aged and fermented foods taste so rich. As proteins break down during aging, fermentation, or cooking, bound glutamate gets released into its free form, intensifying flavor. Parmesan aged for months, slow-simmered bone broth, ripe tomatoes: they all owe part of their depth to this same molecule.
For context, an average adult consumes about 13 grams of glutamate daily just from protein in regular food. Added MSG accounts for only about 0.55 grams per day in a typical diet.
How MSG Creates Flavor
Your tongue has dedicated receptors for glutamate, separate from the ones that detect sweet, salty, sour, or bitter. When free glutamate hits these receptors, you perceive umami, a deep savory taste that signals protein-rich food. MSG essentially delivers a concentrated hit of that signal without needing to add meat, cheese, or long-cooked sauces.
MSG amplifies existing flavors rather than adding a distinct taste of its own. A small amount in soup, stir-fry, or seasoning blends rounds out the overall flavor and makes other ingredients taste more like themselves. This is why it’s widely used in processed foods, restaurant cooking, and seasoning mixes across many cuisines.
Safety and Sodium
The FDA classifies MSG as “generally recognized as safe,” the same designation given to salt, sugar, and baking soda. A 1995 review commissioned by the FDA found that some sensitive individuals experienced short-term symptoms like headache, flushing, or tingling after consuming 3 grams or more of MSG on an empty stomach. A typical serving of food with added MSG contains less than 0.5 grams, making that threshold difficult to reach under normal eating conditions.
Because MSG contains only about one-third the sodium of table salt by weight, substituting some salt with MSG can meaningfully reduce a dish’s total sodium while maintaining flavor. A half-teaspoon of MSG contributes far less sodium than the same amount of salt, which makes it a practical tool for people watching their sodium intake.