Yes, it was. The reason for that was that one Asian company, out of the dozens that make it worldwide, took shortcuts in its manufacturing process and created a toxic product.
The FDA banned all sales of L-Tryptophan for many years based on that incident.
Thanks, TE. Didn’t recall the circumstances.
It wasn’t so much that the Asian company “took shortcuts in its manufacturing process” (that’s the official story) but that the tryptophan products were genetically engineered material, and the FDA knew about it and fraudulently shifted the blame onto “dangerous” supplements to protect the GMO business - http://www.supplements-and-health.com/l-tryptophan.html