Glutamate intolerance (also known as Chinese restaurant syndrome) may occur after ingestion of glutamic acid  salts. Glutamic acid is a natural component of numerous foods. However, glutamates are also artificially added to food, especially to Asian dishes and convenience food in the form of flavour enhancers.

Occurrence and symptoms

Yeast extract, bouillon cubes, seasoned salt, 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. Large quantities of glutamates are used as additives especially in Asian cooking and in almost all ready-to-eat foods and other convenience foods of the food industry, but also in potato crisps and instant soup.
Dry mouth, flushing (e.g. cheeks) and heat sensations, palpitations, itching throat, headaches (temples), rigidity of the facial muscles, stiff neck, pain in the limbs and sickness may occur even ten to twenty minutes after ingestion.

Regulatory limits

According to Regulation (EC) No. 1129/2011 amending annex II to Regulation (EC) No. 1333/2008 on food additives, a specific maximum level of 10 g/kg, will be in place for the glutamate-based additives E620-E625 (indivually or combined, expressed as glutamic acid) as of June 1, 2013.