Several factors can impair B12 absorption: Reduced stomach acid production (achlorhydria or hypochlorhydria), common in older adults and those taking proton pump inhibitors or H2-receptor antagonists long-term, impairs the release of B12 from food proteins Pernicious anaemia , an autoimmune condition destroying parietal cells and reducing intrinsic factor production, completely blocks the primary absorption pathway Gastrointestinal disorders including Crohn's disease, coeliac disease, or surgical removal of stomach or ileum sections directly damage absorption sites Metformin , commonly prescribed for type 2 diabetes, may reduce B12 absorption through unclear mechanisms
Understanding what falls within the normal range helps you distinguish between expected adjustment and genuine concern
Quick Summary If youre short on time, heres what you need to know
Most supplements should be taken with water and food for better absorption, particularly fat-soluble vitamins like Vitamin D, which should be taken with a meal containing fat or oil for best absorption
"Vitamin B12 in Health and Disease"
