I'm trying to discern if there is any correlation between the amount of serotonin reduction and the collagen type. A product available locally is Webber Naturals Marine Type II Collagen. It is paired with lysine, albeit in a minuscule amount (I'm currently trying Lysine at about 1-2 g per day as a trial to see if it helps with my symptoms, as I have the MAO-A defect, in concert with Famotidine). I noticed folks on this forum have championed Great Lakes collagen, which appears to be of Type I. My attempts to discern what amino acids are in Type II have not been successful, and to compare them to what is present in Type I.