Which sequence correctly describes dietary folate metabolism?

Which sequence correctly describes dietary folate metabolism?

• A. Folate is converted to monoglutamate by jejunal enzymes for entry into the intestinal cell, then reduced before entering portal circulation for reabsorption via enterohepatic circulation.
• B. Dietary folate is absorbed unchanged and enters portal circulation directly.
• C. Folate is degraded in the stomach and absorbed as monoglutamate.
• D. Folate bypasses the liver and is excreted in bile.

Answer: (A)

Folate must be prepared for absorption and then circulated through the liver, with a recycling step that helps maintain levels. In foods, folate exists mostly as polyglutamates, which are not ready for uptake. Jejunal brush-border enzymes deconjugate them to monoglutamate, allowing entry into the enterocyte. Inside the cell, folate is reduced to the dihydrofolate and then tetrahydrofolate forms, which are then released into the portal circulation toward the liver. The liver processes and can later secrete folate back into bile, which is reabsorbed in the intestine, completing enterohepatic circulation. This sequence—deconjugation to monoglutamate, intracellular reduction to active forms, transport to the liver, and enterohepatic recycling—explains why the described pathway is correct. Folate is not absorbed unchanged, it isn’t degraded in the stomach, and it doesn’t bypass the liver.

Folate must be prepared for absorption and then circulated through the liver, with a recycling step that helps maintain levels. In foods, folate exists mostly as polyglutamates, which are not ready for uptake. Jejunal brush-border enzymes deconjugate them to monoglutamate, allowing entry into the enterocyte. Inside the cell, folate is reduced to the dihydrofolate and then tetrahydrofolate forms, which are then released into the portal circulation toward the liver. The liver processes and can later secrete folate back into bile, which is reabsorbed in the intestine, completing enterohepatic circulation. This sequence—deconjugation to monoglutamate, intracellular reduction to active forms, transport to the liver, and enterohepatic recycling—explains why the described pathway is correct. Folate is not absorbed unchanged, it isn’t degraded in the stomach, and it doesn’t bypass the liver.