I've been using Zantac twice a day to address what I think is likely Mast Cell Activation Disorder. My main symptom is flushing and feeling unwell after eating trigger foods high in histamine. Zantac is helping a lot and I've yet to increase to the full dose. But I'm concerned about what I've read about H2 blockers like Zantac blocking absorption of nutrients by limiting stomach acid. I am thinking I could just increase my dose of the supplements that it is thought to deplete, as well as add in some of the other supplements it depelets that I don't currently take (such as B12 and folate). I don't know if that would help enough. Also aren't there issues with people with CFS taking B12 and folate or no? Could adding in one of those supplements that increases stomach acid help counter Zantac's effect of blocking nutrient absorption? I don't take the Zantac for stomach issues at all, just for my flushing episodes. I've noticed my sleep pattern (delayed circadian rhythm) has worsened since increasing Zantac and I'm attributing that to possibly lower vitamin D and other vitamin levels, since vitamin D and its cofactors seemed to have greatly improved my circadian rhythm previously before the Zantac. I can't seem to do without the Zantac but don't want to be further depleted of necessary nutrients either. Any ideas?