Now Double Strength 5-HTP – Supports Positive Mood With Glycine, Taurine & Inositol! NOW Double Strength 5-HTP Has Twice The 5-HTP As In Our Regular Strength Product! Supports Positive Mood With Glycine, Taurine & Inositol! 5-HTP, the intermediate metabolite between the amino acid L-tryptophan and serotonin, is extracted from the seed of an African plant (Griffonia simplicifolia). NOW Double Strength 5-HTP has twice the 5-HTP (200 mg per capsule) as in our regular strength product (100 mg per capsule). Note: Manufacturers continually change product specifications. While we try our best to keep product descriptions up to date, they do not necessarily reflect the latest information available from the manufacturer. We are not responsible for incorrect or outdated product descriptions and/or images.