Monosodium Glutamate vs Sulfur Dioxide: which is worse?

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.

What is Sulfur Dioxide?

Sulfur dioxide (SO2) is a colorless gas used as a food preservative and antioxidant. It is the primary active form of the sulfite family of food additives. It is generated by burning sulfur or as a byproduct of certain chemical processes. In food use, it is released from various sulfite salts (E221-E228) and directly applied to some foods.

Documented risks

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.

Sulfur Dioxide: Same as sodium sulfite: sulfite-sensitive individuals (1% of population, 5% of asthmatics) can experience severe reactions. SO2 in wine has been identified as a contributor to wine-induced headache and asthmatic episodes. Occupational exposure to SO2 gas causes respiratory irritation, bronchospasm, and lung damage at higher concentrations — relevant to workers in winemaking and food processing but not typical dietary exposure levels.