Yes there is a small study that showed improvement of GERD using a combination of melatonin and B vitamins. I would search around this forum for our other conversations on it.
Melatonin is not available here in the UK and I have thought about trying 5HT instead as your body can produce melatonin from that; however it's a complex pathway and more raw ingredients won't necessarily produce more of the desired end product. Having said that, if melatonin was available to me, I would have given it a try by now!
New stuff: GERD. Interstitial Cystitis
Lifelong stuff: Food allergies, eczema, asthma