After talking about the fictitious Finland syndrome, I have to mention Chinese Restaurant syndrome.
The Chinese Restaurant syndrome was named in the 1960s. It begins from that some American tourists experienced slight headache or other dysfunctions after eating Chinese cuisine. Some people suspected that some kinds of spices contaminated into Chinese cuisine were harmful. However, the Chinese restaurant syndrome had never reported since the 1970s.
Nowadays, it is generally believed that taking too much glutamate at once may cause sickness. Glutamate works as a neurotransmitter in the human brain. But it is unknown whether oral taking of glutamate confuses the synapse of the brain immediately.
Glutamate is one element of tastiness in the fish. So most Asian, including Chinese and Japanese, are fond of glutamate. After the artificial synthesis of glutamate and its introduction into the market by Ajinomoto, many Chinese and Japanese began to use glutamate for cooking. Nonetheless, the relationship between Chinese restaurant syndrome and glutamate has not been clarified yet. Some researches failed to recreate the phenomenon at the laboratory setting.
After all, Chinese restaurant syndrome should be deemed as an illusion. Simply. You need to eat what your body matches.