How are fat-soluble vitamins absorbed and transported?

• A. They are not dependent on bile
• B. Absorbed with dietary fats in micelles and chylomicrons, require bile for emulsification, and are transported via lymphatics
• C. Absorbed as free vitamins and carried in plasma
• D. Absorbed only in the colon with short-chain fatty acids

Answer: (B)

Fat-soluble vitamins require lipid absorption processes to get into the body. Bile salts emulsify dietary fats and form micelles that solubilize vitamins A, D, E, and K, so these vitamins can cross the intestinal brush border. Inside the enterocytes, they’re packaged with lipids into chylomicrons, which are too large to enter blood capillaries directly. Instead, these chylomicrons enter the lymphatic system via the intestinal lacteals and eventually reach the bloodstream through the thoracic duct. This pathway—solubilization in micelles with fats, assembly into chylomicrons, and lymphatic transport—explains why fat-soluble vitamins depend on bile, are absorbed with dietary fats, and are carried via the lymphatics rather than directly in plasma. They’re not absorbed as free vitamins in plasma, and absorption doesn’t occur primarily in the colon with short-chain fatty acids.