What Is E621 (MSG)? Side Effects & Safe Limits

Key Takeaways

E621, also known as monosodium glutamate or MSG, is considered safe for the general population when used in food at permitted levels. Major food safety authorities including the U.S. Food and Drug Administration, the European Food Safety Authority, the Joint FAO and WHO Expert Committee on Food Additives, and Food Standards Australia New Zealand have evaluated its safety.

In 2017, the European Food Safety Authority established a group Acceptable Daily Intake of 30 mg per kilogram of body weight per day for glutamic acid and glutamates E620 to E625, expressed as glutamic acid.

Some sensitive individuals may experience temporary symptoms after consuming large amounts of MSG, particularly when a large dose is consumed at one time. EFSA noted that symptoms associated with the MSG symptom complex have been reported at doses above approximately 42.9 mg per kilogram of body weight.

1. What Is E621?

E621 is the food additive code for monosodium glutamate, commonly known as MSG. It is used as a flavour enhancer.

Glutamic acid is an amino acid naturally present in the human body and in many foods containing protein. The glutamate released from MSG is chemically the same form of glutamate found naturally in foods such as tomatoes, cheese, mushrooms and many other foods.

The human body metabolises glutamate from MSG and naturally occurring glutamate through the same basic metabolic pathways.

MSG produces umami, which is recognised as one of the five basic tastes alongside sweet, sour, bitter and salty.

Natural Glutamate Content of Common Foods

Parmesan cheese contains approximately 12,000 ppm of free glutamate.

Tomatoes contain approximately 1,400 ppm.

Mushrooms contain approximately 420 ppm.

Soy sauce can contain approximately 4,120 to 12,640 ppm.

Fish sauce can contain approximately 7,270 to 13,830 ppm.

Pure MSG contains approximately 780,900 ppm of glutamate.

These figures are based on data published by the Centre for Food Safety in Hong Kong.

2. How MSG Is Made

MSG was historically produced using glutamate extracted from seaweed broth.

Modern commercial MSG is generally produced through fermentation using carbohydrate sources such as starch, sugar beets, sugar cane or molasses.

The process is similar in principle to fermentation processes used to produce foods such as yogurt, vinegar and wine.

The resulting MSG is chemically equivalent to monosodium glutamate regardless of whether the glutamate originated from fermentation or another source.

3. Regulatory Status and Safety Assessments

FDA United States

The U.S. Food and Drug Administration considers the addition of MSG to foods to be generally recognised as safe, commonly referred to as GRAS.

According to the FDA, an average adult consumes approximately 13 grams of glutamate each day from naturally occurring dietary protein.

Estimated intake of added MSG is approximately 0.55 grams per day.

Studies involving people who identify themselves as sensitive to MSG have not consistently been able to reproduce symptoms when MSG is compared with a placebo.

JECFA WHO and FAO

The Joint FAO and WHO Expert Committee on Food Additives established a group Acceptable Daily Intake for glutamic acid and its salts as not specified.

An ADI classified as not specified means that, based on the available toxicological information and expected levels of use in food, the committee did not consider it necessary to establish a numerical daily intake limit.

This group includes glutamic acid and its sodium, potassium, calcium, magnesium and ammonium salts.

EFSA European Union

In 2017, the European Food Safety Authority completed a comprehensive re-evaluation of glutamic acid and glutamates used as food additives.

EFSA established a group Acceptable Daily Intake of 30 mg per kilogram of body weight per day for E620 to E625, expressed as glutamic acid.

The value was derived from a no observed adverse effect level of 3,200 mg MSG per kilogram of body weight per day identified in a neurodevelopmental toxicity study.

EFSA applied an uncertainty factor of 100 when establishing the acceptable daily intake.

EFSA also concluded that estimated exposure can exceed the acceptable daily intake in some population groups.

At high estimated consumption levels, exposure may exceed the acceptable daily intake across several age groups.

EFSA also noted that estimated exposure among infants and children deserves particular attention because some high exposure estimates can approach or exceed doses associated with reported human effects.

FSANZ Australia and New Zealand

Food Standards Australia New Zealand has also reviewed the safety of MSG.

Its assessments have concluded that MSG does not represent a health concern for the general population at normal levels of dietary exposure.

JECFA did not establish a numerical acceptable daily intake because of the relatively low toxicity of MSG and the levels at which it is normally used in foods.

2025 Toxicological Studies

Two GLP compliant dietary studies involving Sprague Dawley rats were published in 2025.

The studies examined MSG exposure over approximately 28 days and 90 days.

No toxicologically significant findings were reported.

In the 28 day study, no adverse effects were observed at approximately 5,100 mg per kilogram of body weight per day in male rats and 4,800 mg per kilogram per day in female rats.

In the 90 day study, the highest tested doses were identified as the no observed adverse effect levels.

These doses were approximately 3,170 mg per kilogram of body weight per day for males and 3,620 mg per kilogram per day for females.

Animal toxicity studies do not directly determine safe intake levels for humans, but they form part of the evidence used in food safety assessments.

4. Side Effects and the MSG Symptom Complex

Some individuals have reported temporary symptoms after consuming relatively large amounts of MSG.

Reported symptoms include headache, numbness or tingling around the neck or back, facial flushing, muscle tightness, general weakness and heart palpitations.

When these reactions occur, they are generally temporary and have not been associated with lasting effects in the available controlled studies.

Reported Trigger Doses

EFSA reviewed human studies examining several effects associated with relatively high MSG exposure.

The MSG symptom complex has been reported at doses above approximately 42.9 mg per kilogram of body weight.

Headaches have been associated with doses above approximately 85.8 mg per kilogram.

Increased insulin levels have been reported at doses above approximately 143 mg per kilogram.

Increased blood pressure has been reported at approximately 150 mg per kilogram.

For a person weighing 70 kilograms, 42.9 mg per kilogram corresponds to approximately 3,000 mg.

By comparison, EFSA's acceptable daily intake of 30 mg per kilogram corresponds to approximately 2,100 mg per day for a 70 kilogram adult.

This means that the dose associated with the MSG symptom complex in EFSA's assessment is above the acceptable daily intake established for glutamates.

However, EFSA also noted that the available human studies did not provide a sufficiently clear dose response relationship to establish a health based guidance value directly from these symptoms.

Causality Remains Uncertain

Controlled studies have produced mixed results regarding MSG sensitivity.

A double blind placebo controlled study published in 1997 reported that symptoms could be reproduced in some people who identified themselves as MSG sensitive when relatively large doses were given without food.

An apparent response threshold of approximately 2.5 grams was reported in that study.

Symptoms including headache, muscle tightness, numbness, tingling, weakness and flushing occurred more frequently after MSG than after placebo in some participants.

However, subsequent reviews and international assessments have noted that reactions are not consistently reproduced under controlled conditions.

The FDA states that researchers have not been able to consistently trigger reactions in people who identify themselves as MSG sensitive when MSG and placebo are compared.

Important Context

Reported reactions generally involve doses much larger than the amount of MSG present in a typical serving of food.

FDA information notes that mild, short term reactions have mainly been observed in some sensitive individuals consuming 3 grams or more of MSG without food.

A typical serving of food containing added MSG generally contains substantially less than this amount.

5. How Much MSG Are You Actually Consuming?

EFSA's exposure assessment found that some population groups may exceed the acceptable daily intake depending on their dietary patterns and the amount of glutamates present in the foods they consume.

Children and toddlers may have higher exposure relative to their body weight.

High consumers may also exceed the acceptable daily intake.

An acceptable daily intake is designed as a conservative level that can be consumed every day over a lifetime without appreciable health risk.

Occasionally exceeding an ADI does not automatically mean that harm will occur.

Using EFSA's acceptable daily intake of 30 mg per kilogram of body weight, a child weighing 30 kilograms would have an acceptable daily intake of approximately 900 mg.

An adult weighing 70 kilograms would have an acceptable daily intake of approximately 2,100 mg.

Actual exposure varies substantially depending on diet, portion size, product formulation and the amount of glutamates used in individual foods.

6. Where Is MSG Found?

MSG is commonly added to savoury foods because it enhances umami flavour.

It may be found in crisps and savoury snacks, instant noodles, soups, sauces, dressings, processed meat products, processed fish and poultry products, seasoning mixtures and other savoury processed foods.

The permitted use of MSG in foods for infants and young children varies according to national and regional food regulations.

Label Identification

When MSG is deliberately added to packaged food, food labelling rules generally require it to be identified in the ingredient list according to the regulations of the country where the product is sold.

Depending on the jurisdiction, it may appear as monosodium glutamate, MSG, flavour enhancer 621 or E621.

Other glutamate food additives are identified by codes ranging from E620 to E625.

Some ingredients naturally contain substantial amounts of free glutamate.

Examples include hydrolysed vegetable protein, autolysed yeast, yeast extract, soy extracts and some protein isolates.

These ingredients are not chemically identical to added MSG as ingredients, but they can contribute free glutamate to a food.

Rules governing claims such as No MSG or No Added MSG vary by jurisdiction.

Regulatory authorities including the FDA and the Hong Kong Centre for Food Safety have warned that such claims should not mislead consumers when a product contains ingredients that naturally provide significant amounts of free glutamate.

7. Summary

E621 is monosodium glutamate, commonly known as MSG.

It is a flavour enhancer that produces the savoury taste known as umami.

Major food safety authorities have evaluated MSG and generally consider its authorised use in food safe for the general population.

The FDA classifies added MSG as generally recognised as safe.

JECFA established an acceptable daily intake classified as not specified for glutamic acid and its salts.

EFSA established a group acceptable daily intake of 30 mg per kilogram of body weight per day for glutamic acid and glutamates E620 to E625.

Some sensitive individuals may experience temporary symptoms after consuming relatively large doses of MSG, particularly when MSG is consumed without food.

EFSA noted that symptoms associated with the MSG symptom complex have been reported at doses above approximately 42.9 mg per kilogram of body weight.

These reported symptom levels are above EFSA's acceptable daily intake, and controlled studies have not consistently reproduced MSG sensitivity in all individuals who report experiencing it.

For most people, normal dietary exposure to MSG is not considered a health concern.

People who repeatedly experience symptoms after foods containing MSG can choose to limit their intake and discuss persistent or severe symptoms with a qualified healthcare professional.

Sources

U.S. Food and Drug Administration

European Food Safety Authority

Joint FAO and WHO Expert Committee on Food Additives

Food Standards Australia New Zealand

Centre for Food Safety, Hong Kong

Peer reviewed toxicological research published in 2025