Translations:Vitamin B12/20/en

Vitamin B₁₂ deficiency is most commonly caused by malabsorption, but can also result from low intake, immune gastritis, low presence of binding proteins, or use of certain medications. Vegans—people who choose to not consume any animal-sourced foods—are at risk because plant-sourced foods do not contain the vitamin in sufficient amounts to prevent vitamin deficiency. Vegetarians—people who consume animal byproducts such as dairy products and eggs, but not the flesh of any animal—are also at risk. Vitamin B₁₂ deficiency has been observed in between 40% and 80% of the vegetarian population who do not also take a vitamin B₁₂ supplement or consume vitamin-fortified food. In Hong Kong and India, vitamin B₁₂ deficiency has been found in roughly 80% of the vegan population. As with vegetarians, vegans can avoid this by consuming a dietary supplement or eating B₁₂ fortified food such as cereal, plant-based milks, and nutritional yeast as a regular part of their diet. The elderly are at increased risk because they tend to produce less stomach acid as they age, a condition known as achlorhydria, thereby increasing their probability of B₁₂ deficiency due to reduced absorption.