Monosodium Glutamate vs Tertiary Butylhydroquinone: 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 Tertiary Butylhydroquinone?

Tertiary butylhydroquinone (TBHQ) is a synthetic phenolic antioxidant preservative derived from butane. It is one of the most potent antioxidants for polyunsaturated fats and oils and is commonly used in fast-food frying oils. Its chemical formula is C10H14O2.

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.

Tertiary Butylhydroquinone: At high doses in animal studies, TBHQ has been shown to cause precancerous stomach lesions (squamous cell hyperplasia) in female rats. A study in Food and Chemical Toxicology documented these dose-dependent precancerous changes. The FDA limits TBHQ to 0.02% of fat content, reflecting dose-dependent safety thresholds. Immune function concerns emerged from research published around 2019-2020. A study (Farouk Musa and colleagues) found that TBHQ impaired the adaptive immune response to influenza in mouse models, including reduced effectiveness of influenza vaccination. EWG highlighted this research in its analysis. These findings have not been confirmed in human clinical trials but raised new dimensions of concern beyond cancer. Neurotoxicity: animal studies have documented TBHQ can cause precursors to certain types of cell injury in neural tissue at high doses, though effects at typical dietary exposure are not established. Allergic reactions including urticaria and contact dermatitis from TBHQ-containing cosmetics and personal care products are documented in dermatology literature. Japan banned TBHQ for food use. The EU restricts it in baby food (completely banned) and in adult food categories with maximum permitted levels. Australia and the UK restrict it.