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Fat-soluble vitamins A, D, E, and K are stored mainly in the liver and adipose tissue, so deficiency generally develops more slowly; prolonged excess intake can pose toxicity risks. Water-soluble vitamins are usually stored in smaller amounts, and renal loss can hasten depletion when intake is inadequate. Folate and vitamin B₁₂ are important exceptions because their larger stores delay deficiency. The source compares individual vitamins by recommended intake and reserve duration, from short-lived thiamine stores to years of B₁₂ reserves. It also notes that fat malabsorption can impair uptake of fat-soluble vitamins, while factors such as antibiotics or alcohol can affect particular deficiency risks. These patterns provide a framework for understanding why storage matters in nutrition and clinical assessment.