Final answer:
Vitamin B12 is the only vitamin found exclusively in animal products and requires a unique absorption process involving an intrinsic factor in the small intestine.
Step-by-step explanation:
The vitamin that's only found in food of animal origin and is absorbed in the small intestine is Vitamin B12. Vitamin B12 absorption is unique compared to other vitamins because it is a very large molecule that requires an intrinsic factor secreted by the stomach for its absorption. This intrinsic factor binds to Vitamin B12, creating a complex that binds to receptors in the terminal ileum of the small intestine, where it is then absorbed by endocytosis. It is important to note that Vitamin B12 is essential for proper nerve function and the production of red blood cells.