What Exactly is INS 621?
INS 621 is the International Numbering System code for monosodium glutamate, or MSG. It is a sodium salt derived from glutamic acid, an abundant, non-essential amino acid found naturally in many foods. MSG is known for enhancing the savory, or 'umami,' flavor profile in food, making it a popular additive for over a century. Commercially, it is produced through the fermentation of carbohydrates like sugar cane or sugar beet.
Natural vs. Synthetic Glutamate
One of the most common points of confusion is the difference between naturally occurring glutamate and added MSG. The human body does not distinguish between the two sources; both are metabolized in the same way. Free glutamate, whether from a tomato or from added MSG, imparts the same umami taste. Here is a list of foods rich in naturally occurring glutamate:
- Aged cheeses (like Parmesan)
- Soy sauce
- Mushrooms
- Tomatoes
- Walnuts
- Anchovies
- Fermented bean products
The "Chinese Restaurant Syndrome" and Scientific Scrutiny
The MSG controversy largely stems from a letter written to the New England Journal of Medicine in 1968, reporting symptoms after eating Chinese food. This led to the creation of the term "Chinese Restaurant Syndrome," later renamed "MSG Symptom Complex" (MSC). Alleged symptoms included headaches, flushing, and tingling. While the initial report and subsequent media coverage fueled public fear, controlled, blinded scientific studies have repeatedly failed to establish a definitive link between MSG and these widespread symptoms in the general population. In fact, some researchers have pointed to racial biases in the initial reports that ignored other possible causes for the reported symptoms.
Modern Regulatory Stance on INS 621 Safety
Today, major food safety authorities worldwide have reviewed the extensive data on MSG and confirmed its safety for consumption at normal levels. For example, the FDA has maintained its 'Generally Recognized As Safe' (GRAS) status since the 1950s. The European Food Safety Authority (EFSA) and the Joint FAO/WHO Expert Committee on Food Additives (JECFA) have also concluded MSG is safe, setting a high Acceptable Daily Intake (ADI) level. These conclusions are based on rigorous reviews of animal and human studies.
Potential for Sensitivity
While most people tolerate MSG without issue, a very small subset of the population (estimated at less than 1%) may experience mild, transient symptoms referred to as MSG Symptom Complex. These reactions typically occur when consuming very large doses (more than 3 grams) of MSG on an empty stomach, which is far beyond typical dietary intake. Typical symptoms might include:
- Headache
- Sweating
- Flushing
- Numbness or tingling
- Muscle tightness
It is important to note that these are not true allergic reactions but rather hypersensitivity-type responses.
INS 621 and Broader Health Concerns
Over the years, MSG has also been linked to other health concerns, including obesity and brain toxicity. Older animal studies showing a link between MSG and metabolic issues often involved highly imprecise methods, such as injections, which do not reflect how humans consume MSG. Current research, including human studies, does not support a causal link between dietary MSG consumption and these conditions. Furthermore, dietary glutamate has little to no impact on brain function as it does not effectively cross the blood-brain barrier.
A Broader Look at Processed Foods
The presence of INS 621 in many processed and packaged foods raises a different, more nuanced health consideration. While MSG itself is not considered harmful, the foods it often flavors—instant noodles, snacks, and ready-to-eat meals—can be high in sodium, unhealthy fats, and refined carbohydrates. The MSG enhances the flavor of these cheap ingredients, potentially masking their low nutritional quality. A diet dominated by such foods can lead to genuine health issues like obesity and high blood pressure, but the blame should be placed on the overall dietary pattern, not just the MSG.
Using MSG can actually help reduce sodium content in some applications. Because MSG enhances the perception of saltiness, manufacturers can use less table salt while maintaining flavor.
Comparison of INS 621 Safety Assessments
| Regulatory Body | Year(s) of Assessment | Safety Conclusion | Key Findings |
|---|---|---|---|
| U.S. FDA | Ongoing (GRAS since 1950s) | Generally Recognized As Safe (GRAS) | Extensive review found no evidence linking MSG to severe illness; acknowledges MSG Symptom Complex in a small group. |
| JECFA (WHO/FAO) | Multiple, including 1987 | Acceptable Daily Intake (ADI) "Not Specified" | Considered of very low toxicity; total dietary intake from normal use does not pose a health hazard. |
| EFSA (European Food Safety Authority) | 2017 | Acceptable Daily Intake (ADI) of 30 mg/kg body weight/day | Based on studies showing no adverse effects on test animals; ADI well above typical human consumption. |
| FSANZ (Food Standards Australia New Zealand) | 2003 | Safe for consumption at current levels | Concluded no convincing evidence MSG causes severe reactions; acknowledged rare sensitivity. |
Conclusion
Based on decades of scientific research and the consensus of major global food safety authorities, INS 621 (monosodium glutamate) is not harmful to the vast majority of the population when consumed in typical dietary amounts. While a small percentage of individuals may experience mild, temporary hypersensitivity symptoms from very large doses, these effects are not life-threatening. The more significant health concern lies not with MSG itself, but with the overall nutritional profile of the processed foods it is often added to. For those concerned about their MSG intake, reading food labels and focusing on whole, unprocessed foods is the most effective strategy.
For additional context on food safety evaluations, you can explore the FDA's official information on MSG.
