Saccharin vs Monosodium Glutamate: which is worse?

What is Saccharin?

Saccharin is the oldest artificial sweetener, discovered accidentally at Johns Hopkins in 1879. It is a sulfonamide compound approximately 300-400 times sweeter than sucrose with no caloric value. It has a slightly bitter metallic aftertaste at higher concentrations. Saccharin's sodium salt (sodium saccharin) is the form used in most food applications.

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

Saccharin: Saccharin's carcinogenicity history is one of the most tumultuous in food regulatory history. In 1977, the FDA proposed banning saccharin after studies found it caused bladder cancer in rats at very high doses. Congress passed the Saccharin Study and Labeling Act, which put a moratorium on the ban and required a cancer warning label on saccharin products ('Use of this product may be hazardous to your health. This product contains saccharin which has been determined to cause cancer in laboratory animals.'). By 2000, saccharin was removed from the US National Toxicology Program's Report on Carcinogens after subsequent research determined that the bladder cancer in male rats was caused by a rat-specific mechanism — high pH, high protein, and calcium phosphate in rat urine — that does not apply to human urine. The cancer warning label requirement was repealed. IARC also removed saccharin from its Group 2B list in 1999. However, Canada maintained its ban on food use saccharin, citing continued precautionary concern. A 2022 study in Cell found saccharin was among the artificial sweeteners most significantly altering gut microbiome composition and glucose tolerance in previously non-sweetener-using participants. Saccharin showed the largest effect on glucose tolerance among the sweeteners studied (saccharin, sucralose, aspartame, stevia). Saccharin passes through the placenta and appears in breast milk, raising questions about infant exposure that have not been fully resolved.

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.