Source Naturals L-Tryptophan with Coenzyme B-6, 500mg - 120 Tablets

Our verdict

Source Naturals L-Tryptophan with Coenzyme B-6, 500mg - 120 Tablets works out to $0.14 per serving of l-tryptophan, at 500mg per serving in tablet form. That puts it below the median of the 38 l-tryptophan products we can price per dose, where the typical serving costs $0.17, a Value Index of 1.2 where the median product is 1.0. One container lasts 120 days at the label dose of 1 serving a day, about $4.13 a month. We could not verify a third-party certification for Source Naturals in a public registry. Worked out from the current retail price as of 2026-11-13; confirm the live price on Amazon.com before buying.