What are Flavour Enhancer 621 (MSG) and 635?
Flavour enhancers 621 and 635 are food additives designed to intensify the savory, or umami, taste in processed foods. While their purpose is similar, their chemical composition differs. Flavour enhancer 621 is Monosodium Glutamate (MSG), the sodium salt of glutamic acid, an amino acid found naturally in many foods like cheese and tomatoes. Flavour enhancer 635, or Disodium 5′-ribonucleotides, is a more complex additive, a mixture of disodium inosinate (IMP) and disodium guanylate (GMP). It doesn't have a distinct umami taste on its own but is highly synergistic with glutamates, significantly boosting the flavor profile when combined with MSG.
Commercially, MSG is produced through the fermentation of sugar cane, sugar beets, or molasses. E635 can also be produced via bacterial or yeast fermentation, but can sometimes be sourced from meat, fish, or other animal-derived sources.
Reported Side Effects for Sensitive Individuals
For decades, the side effects of MSG have been debated, leading to the coining of the term 'Chinese Restaurant Syndrome'. This label has since been discredited as xenophobic, and health authorities have clarified that the symptoms are part of a sensitivity, not a true syndrome. While the vast majority of people experience no ill effects from these additives, a small portion of the population with sensitivities may experience a range of mild, short-lived symptoms.
Commonly reported symptoms for those sensitive to flavour enhancers include:
- Headaches and migraines: A frequent complaint, though not conclusively linked to MSG in controlled studies.
- Flushing, sweating, and tingling: Sensations of warmth, redness, and tingling in the face, neck, and chest.
- Gastrointestinal issues: Symptoms such as nausea, abdominal cramps, and diarrhea have been reported.
- Palpitations: A feeling of a rapid or fluttering heartbeat.
- Chest pain and tightness: Some individuals have reported chest discomfort after consuming large quantities of flavour enhancers.
- Numbness or burning: A burning or numbness sensation in the mouth or face.
- Skin reactions: Rashes, hives, and itchiness.
- Drowsiness and fatigue: General weakness or fatigue after consumption.
Comparison of Flavour Enhancers E621 and E635
| Characteristic | Flavour Enhancer 621 (MSG) | Flavour Enhancer 635 (Disodium 5′-ribonucleotides) |
|---|---|---|
| Chemical Name | Monosodium Glutamate | Disodium 5'-ribonucleotides (IMP+GMP) |
| Function | Provides the savory umami flavor | Amplifies other flavors, especially glutamates |
| Origin | Natural sources (tomatoes, cheese) or commercial fermentation | Yeast, bacterial fermentation, meat/plant sources |
| Sensitive Groups | Individuals with MSG sensitivity (MSG Symptom Complex) | Those with gout, asthma, or aspirin allergies |
| Specific Risks | Historically controversial, though deemed safe by health bodies | Metabolized to purines, exacerbating gout; linked to potential hyperactivity |
Specific Risks for Sensitive Populations
While the general population tolerates E621 and E635 well, certain groups should exercise caution due to specific health conditions.
Gout and Flavour Enhancer 635
Disodium 5′-ribonucleotides (E635) are metabolized into purines, which can increase the level of uric acid in the body. This is a critical concern for individuals with gout, a form of arthritis caused by the build-up of uric acid crystals in the joints. Excessive intake of E635 could potentially trigger or worsen gout attacks, so it is often recommended that gout sufferers avoid this additive.
Asthma and Flavour Enhancers
There have been anecdotal reports and some older studies suggesting a link between flavour enhancers, including MSG (E621) and E635, and asthma attacks. While recent, well-controlled studies have not consistently established a clear cause-and-effect relationship, some individuals with asthma or aspirin allergies may still be more sensitive to these additives. Asthmatic people are often advised to avoid products containing these additives as a precaution.
Consumption by Infants and Children
As a general precaution, food products containing food additives should not be given to infants under 12 months. Some reports have also suggested a link between flavour enhancers and hyperactivity or mood changes in children, although the evidence is not conclusive. Given the developing nature of a child's system, minimizing intake of highly processed foods with additives is generally recommended.
The Role of Dosage and Product Context
It's important to consider the dosage and the context in which these additives are consumed. The FDA notes that adverse reactions to MSG are most likely to occur in sensitive individuals after consuming 3 grams or more of MSG on an empty stomach. This is a very high dose, considering that a typical serving of an MSG-enhanced food contains less than half a gram. Additionally, E621 and E635 are often found in highly processed foods, which also contain high levels of salt, fat, and other ingredients. The side effects experienced might not be from the flavour enhancer itself, but rather from the high salt content or other ingredients in the product.
How to Identify and Reduce Intake
To reduce intake of these additives, reading food labels is essential. E621 and E635 will be listed explicitly by their E numbers or chemical names. Foods commonly containing E621 and E635 include instant noodles, savory snacks, processed meats, sauces, and seasoning blends.
Be aware that some products may be labelled 'No Added MSG,' but still contain other sources of free glutamates, such as yeast extract, hydrolyzed vegetable protein, or autolyzed yeast extract.
Conclusion
While regulatory bodies affirm the general safety of flavour enhancers E621 (MSG) and E635 (Disodium 5′-ribonucleotides) in moderate amounts, they can cause adverse reactions in a small, sensitive portion of the population. These reactions are typically mild and short-lived. Individuals with pre-existing conditions like gout, asthma, or an aspirin allergy, as well as infants and young children, may be particularly susceptible and should limit their intake. A key takeaway is that the dosage and the overall nutritional profile of processed foods containing these additives are often more significant than the additives themselves. Mindful consumption, along with careful label reading, empowers individuals to make informed dietary choices that suit their personal health needs.
For more information on food additives and sensitivity, consult health authorities like the Cleveland Clinic: https://health.clevelandclinic.org/is-msg-really-harmful.
