Translations:Vitamin B12/10/en

Vitamin B₁₂ deficiencies have a greater effect on the pregnant, young children, and elderly people, and are more common in middle and lower developed countries due to malnutrition. The most common cause of vitamin B₁₂ deficiency in developed countries is impaired absorption due to a loss of gastric intrinsic factor (IF) which must be bound to a food-source of B₁₂ in order for absorption to occur. A second major cause is an age-related decline in stomach acid production (achlorhydria), because acid exposure frees protein-bound vitamin. For the same reason, people on long-term antacid therapy, using proton-pump inhibitors, H₂ blockers or other antacids are at increased risk.