Assessment of Early and Delayed Responses in Vitamin B₁₂ Absorption during Antibiotic Therapy in Tropical Malabsorption

1. Vitamin B₁₂ absorption was measured in 18 patients with tropical malabsorption.

2. Absorption was particularly impaired in patients with severe mucosal lesions.

3. Sequential measurements with ⁵⁷Co- and ⁵⁸Co-labelled vitamin B₁₂ were made before and 48 h after the start of tetracycline therapy. A rapid improvement (on average 22% increase in absorption) occurred in four of six patients with marked mucosal lesions. Further improvement occurred in four of five patients measured after 4 weeks' tetracycline, including the two who failed to improve initially.

4. These rapid changes in vitamin B₁₂ absorption after antibiotics occur too early to be due to mucosal recovery and suggest that bacterial metabolism is an important factor in the malabsorption in these patients.