L-Tryptophan

L-Tryptophan is one of the essential amino acids, that must come from the diet, as it cannot be synthesised by the body.

In 1989 a contaminated batch of L-Tryptophan from a Japanese factory caused an outbreak of a rare illness in the USA, there were also fatalities. This lead to L-Tryptophan being banned, other countries (including the UK) followed suit and it remained so until around 2005. A new safety assessment was done and it was specified that in the UK (and EU) all L-Tryptophan had to be of European Pharmacopoeia standard (it is a higher standard than other Pharmacopoeias) and it is limited to a maximum daily dose of 220mg in the UK.