Vitamin B12 is predominantly stored in the liver because it has a unique ability to bind to plasma proteins, allowing it to accumulate in significant amounts. The liver serves as the primary storage site, housing enough vitamin B12 to meet the body's needs for several years. This storage capacity is crucial because vitamin B12 absorption is complex and dependent on intrinsic factor, making continuous dietary intake less critical in the short term. Deficiencies often take years to manifest clinically due to these large hepatic stores. In contrast, vitamins like C and B6 are water-soluble and not stored extensively, and vitamin K is primarily involved in clotting with limited storage.

Reference: Harrison's Principles of Internal Medicine, Jameson et al., 20th Edition.