Where are iron and folate primarily absorbed in the GI tract?

• A. Iron primarily in the duodenum; folate mainly in the duodenum and proximal jejunum.
• B. Iron primarily in the ileum; folate mainly in the ileum and colon.
• C. Iron primarily in the jejunum; folate mainly in the ileum.
• D. Iron primarily in the duodenum; folate mainly in the stomach.

Answer: (A)

The main idea is where these nutrients are taken up most efficiently in the small intestine. Iron is absorbed primarily in the duodenum, the first segment of the small intestine, where enterocytes are equipped to take up iron after it’s converted to the easier-to-absorb Fe2+ form. Folate, on the other hand, is absorbed mainly in the proximal parts of the small intestine—the duodenum and the upper jejunum—via transport systems that work best there. The stomach isn’t a major site for folate absorption, and the ileum contributes less for iron and folate than the duodenum and proximal jejunum. So the pattern that iron enters mainly in the duodenum while folate is absorbed mainly in the duodenum and proximal jejunum aligns with how these nutrients are processed in the GI tract.