Topic overview

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Vitamins A, D, E, and K are absorbed with dietary fat and depend on bile and pancreatic lipase for uptake in the ileum. They are transported in chylomicrons and stored in the liver and adipose tissue. Fat malabsorption and reduced fat intake increase deficiency risk. Each vitamin has distinct functions and clinical patterns: vitamin A is associated with vision and epithelial health; vitamin D with calcium, phosphate, and bone; vitamin E with protection of cell membranes; and vitamin K with hepatic activation of clotting factors and proteins C and S. Deficiency and toxicity findings help distinguish them, including visual and epithelial changes, bone disease, hemolytic or neurologic findings, and abnormal coagulation. The lesson also highlights important risk settings and interactions.