Sodium Sulfite vs Monosodium Glutamate: which is worse?

What is Sodium Sulfite?

Sodium sulfite is an inorganic sulfite salt used as a food preservative and antioxidant. It releases sulfur dioxide when it contacts water or acid, which acts as the active antimicrobial and antioxidant agent. Part of the broader sulfite family of food additives (including sulfur dioxide E220, sodium bisulfite E222, and others).

What is Monosodium Glutamate?

Monosodium glutamate (MSG) is the sodium salt of glutamic acid, a naturally occurring non-essential amino acid found in many proteins. It is used as a flavor enhancer to intensify umami (savory) taste. MSG was first isolated from seaweed in 1908 by Japanese chemist Kikunae Ikeda and has been used commercially since then.

Documented risks

Sodium Sulfite: Sulfites are among the more significant food allergy/intolerance triggers. An estimated 1 in 100 people, and up to 5% of asthmatics, are sulfite-sensitive. Reactions can include urticaria, angioedema, bronchospasm, and in severe cases anaphylaxis. Sulfite-induced asthma can be severe; several deaths attributable to sulfite-triggered anaphylaxis have been documented. The FDA banned sulfites from fresh produce and restaurant salad bars in 1986 after several deaths and severe reactions were linked to sulfite-treated salads. FDA mandates that sulfite content above 10 ppm be declared on US food labels. All forms of sulfites (E220-E228) share these sensitization concerns.

Monosodium Glutamate: MSG safety has been one of the most extensively debated food additive questions in the past 50 years. The 'Chinese Restaurant Syndrome' — a cluster of symptoms (headache, flushing, sweating, chest tightness) reported after eating Chinese food — was attributed to MSG in a 1968 letter in the New England Journal of Medicine. This set off decades of controversy. Multiple rigorous double-blind, placebo-controlled trials have failed to consistently demonstrate that MSG at doses present in food causes these symptoms when participants do not know whether they received MSG or a placebo. A comprehensive 1993 review by the FDA-commissioned Federation of American Societies for Experimental Biology (FASEB) found that while some sensitive individuals may experience symptoms at high doses (>3g of pure MSG on an empty stomach), the doses in typical food servings do not consistently produce symptoms in double-blind conditions. The FDA classifies MSG as GRAS (generally recognized as safe). EFSA's 2017 re-evaluation set an ADI of 30 mg/kg body weight per day, acknowledging that very high doses could affect neurological function but concluding typical dietary exposure is safe. Critics including Dr. Russell Blaylock and advocacy groups have argued that MSG is an 'excitotoxin' — a compound that overstimulates glutamate receptors in the brain and could cause neuronal damage. While glutamate is indeed a neurotransmitter and high-dose glutamate can cause neurotoxicity in animal models, the blood-brain barrier and normal metabolic regulation are generally considered sufficient to prevent dietary MSG from affecting brain glutamate levels. A 2018 EFSA re-evaluation noted that combined exposure to glutamates from all sources (including naturally occurring glutamate in protein-rich foods and other added glutamates E621-E625) could approach the new lower ADI in high consumers — a concern particularly for children with high processed food intake.