Medical Conditions, Surgeries, and Medications Lack of intrinsic factor (a protein made in the stomach thats needed for B12 absorption) - this condition is called pernicious anemia Thyroid disease HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome) Autoimmune diseases like type 1 diabetes, where the immune system in the body attacks its own tissues Gastric bypass surgery (weight loss surgery) Chronic gastritis surgery Certain medications like heartburn drugs (proton pump inhibitors) which reduce stomach acid production Who Is At Risk of Vitamin B12 Deficiency
Jayatilake N, Mendis S, Maheepala P, Mehta FR
Global burden of 369 diseases and injuries in 204 countries and territories, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019
The strongest published finding is from the foundational Biochemical Pharmacology study by Neelakantan et al.: in diet-induced obese mice, daily 5-Amino-1MQ administration produced reductions in body weight, white adipose tissue mass, and adipocyte size without any significant change in food intake
This is supported by the fact that several ME/CFS outbreaks have occurred in the same geographical region simultaneously (12)
The Bottom Line Vitamin B12 is a water-soluble vitamin obtained via diet or supplements