Final answer:
Vitamins are absorbed through the small intestine by villi and microvilli after digestion, with the liver then regulating their distribution throughout the body.
Step-by-step explanation:
Once digestion has released the vitamins, they are absorbed through the small intestine by special structures known as villi and microvilli. These finger-like projections increase the surface area of the intestine, enhancing the absorption efficiency of nutrients. Vitamins and other nutrients are absorbed into the bloodstream or the lymph system to circulate throughout the body. Fat-soluble vitamins (A, D, E, and K) are absorbed along with dietary fats and may require the presence of bile salts to form micelles that facilitate their transport to the surface of enterocytes. Water-soluble vitamins are typically absorbed by enterocytes directly into the bloodstream, with vitamin B12 as an exception, being absorbed in the ileum, the last part of the small intestine.
Absorbed nutrients are then carried into the hepatic portal vein leading to the liver, which regulates their distribution to the rest of the body and detoxifies substances, including excess vitamins and minerals.