Glutamate intolerance

In a so-called glutamate intolerance , colloquially Chinese restaurant syndrome called, is a short-term symptoms , after describing some people with them after taking glutamates , the salts of the non- essential amino acid glutamic acid , occurs.

Glutamic acid occurs naturally in all living things as a building block of proteins and also has the function of an excitatory (exciting) neurotransmitter in the central nervous system . It is a natural component in numerous foods in significant concentrations. Glutamates are also artificially added to food as a flavor enhancer in preparations, especially in Asian cuisine or convenience food products. Scientific studies suggest that it is not glutamate or glutamic acid, but other nutritional components or situational influences that are the cause of the symptoms described. They are certainly not the result of intoxication , intolerance or allergy .

Occurrence of glutamates

→ Main articles : Monosodium glutamate # Natural occurrence  and Umami # Occurrence of glutamates

In 1866, the chemist Heinrich Ritthausen isolated glutamate for the first time as a pure substance from natural substances . It is found in almost all foods bound to proteins and peptides . The German Nutrition Society estimates that the common European mixed diet contains around 8 to 12 g of glutamate per day. In European food, yeast extract , stock cubes , seasoning mixes, cheese (especially Parmesan ), anchovies and ripe, concentrated or dried tomatoes contain particularly high levels of natural glutamates. Even more natural glutamates are found in Asian food, especially in soy sauce and fish sauce . These sources of glutamate are classified as flavorings or foods not as food additives and do not receive an E number (see food law ).

In 1907 Ikeda Kikunae from the University of Tokyo first developed a synthesis process for sodium glutamate. He also patented a process for mass production. Nowadays, monosodium glutamate is made from starchy plant products by fermentation by Corynebacterium glutamicum . Since then, glutamates have been used in large quantities as a food additive, especially in Asian cuisine and in almost all finished or semi-finished products in the food industry, including potato chips and packet soups .

Chinese restaurant syndrome

In 1968, in a letter to the New England Journal of Medicine, an American doctor first described a series of acute complaints of the above-mentioned kind that he regularly experiences after visiting Chinese restaurants, and he named them Chinese Restaurant Syndrome . When numerous other cases of intolerance reactions after eating in such restaurants became known, a publication followed in 1969 in which other authors first hypothesized that there was a causal connection between the complaints and glutamates artificially added to the food. Already 10 to 20 minutes after ingestion of the substances considered to be the trigger, there should be dry mouth , tingling or numbness in the oral cavity, itching in the throat, reddened skin areas (e.g. cheeks) with sensation of heat, palpitations , (temples) headaches, stiff muscles , Neck stiffness, body aches and nausea.

criticism

Since then there have been numerous case reports in the medical literature . However, fundamental methodological errors cannot be controlled in such reports , and therefore case reports according to the rules of evidence-based medicine are not conclusive. In any case, it was not convincing that a group of substances that are ingested with "normal" food in amounts of around ten grams per day without symptoms should lead to symptoms when additionally consumed as a flavor enhancer. In the controlled studies published to date on this question , in particular in the most meaningful blind studies , it could not be proven that glutamates additionally consumed with food trigger symptoms such as in the "Chinese restaurant syndrome". This also applies to those test persons who considered themselves sensitive to glutamate. In contrast, a nocebo effect was increasingly demonstrated in them: the mere fear that they were consuming glutamate leads to allegedly glutamate-specific complaints, even if this is not the case in the experiments. In a further research report, the study situation is summarized as follows:

"[...] studies indicate that the symptoms observed in some experiments are not specific to MSG ingestion and can also be elicited by other foods. Studies in which MSG was administered in food rather than in pure form have generally shown a lack of symptoms altogether. Thus, a causal relationship between MSG and acute, temporary and 'self-limiting' adverse reactions is far from established. "

“Studies show that the symptoms observed in some experiments are not specific to MSG consumption and can also be caused by other foods. Studies in which MSG was given in food instead of pure, all generally show a lack of symptoms. Consequently, a causal relationship between MSG and acute, temporary and "self-limiting" side effects is far from being proven. "

These and other studies show that the symptoms observed in some experiments are not specific to the uptake of glutamates, but can also be triggered by other foods such as shrimp, peanuts, fish and soy sauce or special herbs and additives. In particular, studies in which glutamates were added to food, i.e. not administered in pure form, did not provide any clear indications of glutamate-related symptoms. Even in people who stated that they suffered from Chinese restaurant syndrome, double-blind tests did not reveal any evidence of glutamate as the cause of their complaints, the expert panel of the Food and Agriculture Organization (FAO) and the World Health Organization (WHO), the Joint FAO / WHO Expert Committee on Food Additives (JECFA). A connection between glutamates and acute or temporary complaints has therefore not been proven.

However, the very clear scientific data situation has not resulted in relevant self-help groups , internet forums , suppliers of nutritional supplements , mass media , alternative practitioners , representatives of paramedicine and others fundamentally questioning the traditional idea of ​​glutamate intolerance . The weekly magazine Focus 2009 headed an article with the statement "Glutamate intolerance - sick from Chinese food" and at the end referred to a named oecotrophologist of the German Allergy and Asthma Association for further advice .

Regulations

Based on the studies mentioned above, glutamates are classified as harmless to health by the health authorities of the USA and most European countries. In 1991 the Scientific Committee for Food (SCF) of the European Union therefore did not set a permitted daily dose for glutamate. In Germany, sodium glutamate is only banned as an additive in baby food . Otherwise, six glutamic acid compounds are approved as additives for use in food. According food labeling regulations (LMKV) § 6, the class name (flavor enhancer) followed by the product name (name of the relevant or corresponding Glutaminsäureverbindung E-number ) to be indicated. The "E numbers" E 620 to E 625 on the list of food additives stand for the permitted glutamates. Even foods without a list of ingredients (e.g. loose goods) must be labeled with the words “with flavor enhancer” on or next to the goods or as a notice. The maximum permitted concentration of glutamate additives is 1% in canned meat and fish and ready meals, 2% in sauces and 50% in condiments. Foods with the ingredients yeast extract or seasoning do not contain synthetic glutamates and may therefore be labeled “without flavor enhancers”, but they contain more natural glutamates.

literature

• Ian Mosby, 'That Won-Ton Soup Headache': The Chinese Restaurant Syndrome, MSG and the Making of American Food, 1968-1980 . In: Social History of Medicine 22: 1, 2009, pp. 133-151. doi: 10.1093 / shm / hkn098

Web links

• Is Glutamate Harmful? (39 kB) German Nutrition Society, 2003

Individual evidence

1. ↑ University of Jena 2011: Overview of food intolerances and their diagnosis Basics of nutritional physiology - BE 2.2 (BEBW 7) ( Memento from February 1, 2014 in the Internet Archive )
2. ↑ DGE: Is the flavor enhancer glutamate harmful to health? 2003. dge.de
3. ↑ ^{a b c d} Alex Denton: If MSG is so bad for you, why doesn't everyone in Asia have a headache? , The Guardian of July 10, 2005, accessed December 1, 2015.
4. ^ Robert Ho Man Kwok: Chinese restaurant syndrome. In: N. Engl. J. Med. 18, 178, 1968, p. 796
5. ^ HH Schaumburg, R. Byck, R. Gerstl, JH Mashman: Monosodium L-glutamate: its pharmacology and role in the Chinese restaurant syndrome. In: Science. Volume 163, Number 3869, February 1969, pp. 826-828, ISSN  0036-8075 . PMID 5764480 .
6. ↑ Prawirohardjono et al. a .: The administration to Indonesians of monosodium L-glutamate in Indonesian foods: an assessment of adverse reactions in a randomized double-blind, crossover, placebo-controlled study. 2000. jn.nutrition.org ( Memento of the original dated January 31, 2017 in the Internet Archive ; PDF) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
7. ^ Simon: Additive-induced urticaria: experience with monosodium glutamate (MSG). 2000. jn.nutrition.org ( Memento of the original from May 27, 2016 in the Internet Archive ; PDF) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
8. ↑ Glutamate is not a health risk? Chinese Restaurant Syndrome: Fact or Fiction. Heilpraxisnet.de, 2011. heilpraxisnet.de
9. ↑ RS Geha, A. Beiser, C. Ren, R. Patterson, PA Greenberger, LC Grammer, AM Ditto, KE Harris, MA Shaughnessy, PR Yarnold, J. Corren, A. Saxon: Review of alleged reaction to monosodium glutamate and outcome of a multicenter double-blind placebo-controlled study. In: The Journal of Nutrition , Volume 130, Number 4S Suppl, April 2000, pp. 1058S-1062S, ISSN  0022-3166 . PMID 10736382 . (Review).
10. ↑ German Nutrition Society DGE-aktuell 08/2003 of June 10, 2003 Is the flavor enhancer glutamate harmful to health?
11. ^ R. Walker, JR Lupien: The safety evaluation of monosodium glutamate. In: J Nutr. 130 (4S Suppl), 2000, pp. 1049S-1052S; PMID 10736380 ; jn.nutrition.org ( Memento of the original from January 13, 2012 in the Internet Archive ; PDF) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English) 
12. ↑ Glutamate intolerance - sick from Chinese food. In: Focus , April 2, 2009.

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !