Lead a hectic, on-the-go lifestyle? Why not start taking L-Tryptophan as part of your pre-bed routine? An essential amino acid involved in the production of serotonin and melatonin. Each capsule of Swanson health is packed with 500mg. Lead a hectic, on-the-go lifestyle? Why not start taking L-Tryptophan as part of your pre-bed routine? An essential amino acid involved in the production of serotonin and melatonin. Each capsule of Swanson health is packed with 500mg. An essential amino acid. 500mg of L-tryptophan per capsule. Consume pre-bed as part of an active lifestyle. 60 capsules per pack L-Tryptophan 500mg by Swanson Health contains 500mg of L-Tryptophan, which supports the synthesis of serotonin and melatonin. Read more!