The effect of riboflavin deficiency in rats on the absorption and distribution of iron.

1. Riboflavin may play a part in the transport of iron across the gastrointestinal mucosa. Fe absorption was measured in the rat by monitoring whole-body retention of a dose of 59Fe using a small-animal gamma-counter. 2. Female Norwegian Hooded rats were fed on a diet deficient in riboflavin (B2-) from 5 weeks of age. Control animals, fed on a complete diet (B2+), were weight-matched to rats fed on the B2- diet. After 7 weeks all rats were fed on a test meal extrinsically labelled with 59Fe and whole-body radioactivity measured for 15 d. 3. Riboflavin deficiency was associated with a reduction in the percentage of the dose absorbed and an increase in the rate of loss of Fe post absorption. 4. A smaller percentage of the absorbed dose was present in the livers of the riboflavin-deficient animals.