Up to how many carbon atoms can fatty acids be absorbed directly through the intestinal villi?

• A. 8
• B. 10
• C. 12
• D. 14

Answer: (B)

Short- and medium-chain fatty acids are absorbed directly into the portal circulation from the intestinal villi, bypassing the lymphatic system. The boundary for this direct absorption is about ten carbon atoms; fatty acids with up to ten carbons can enter portal blood readily, while longer-chain fatty acids are typically re-esterified and packed into chylomicrons for transport via the lymphatics. This difference in transport explains why certain fatty acids reach the liver directly, while longer ones go through the lymphatic system first.