A paper from Bruce Wolffenbuttel and colleagues, released last February
Conclusion:
"Autoimmune gastritis is not a gastritis that needs acid suppression; rather, it may benefit from acid supplementation. The loss of stomach acid in AIG precedes nutrient deficiencies by several years. Hypochlorhydria affects digestion, micronutrient absorption, risk factors for benign and perhaps malignant diseases, as well as a range of gastrointestinal complications.
Betaine hydrochloride is a simple and readily available encapsulated form of acidification. Studies in humans are limited but show that betaine hydrochloride appears to be generally well tolerated. This paper proposes empiric mealtime acidification with betaine hydrochloride for patients with autoimmune gastritis. Acidification may ameliorate GI dysfunction, improve nutrient deficiencies, and bolster immunity. Research is needed in patients with AIG to assess tolerance and efficacy. Supplemental vitamin C is worthy of consideration in AIG, as it may decrease cancer risk in hypochlorhydria and improve iron absorption.
Autoimmune gastritis is more than B12 and iron deficiency. It is also an acid deficiency with broad effects. It is important for patients with AIG that the scope of their symptoms is recognized and, where necessary, further investigated. Research is needed to elucidate the pathophysiology of hypochlorhydria in AIG, explore patient experience, and investigate therapeutic options."