A proposed intestinal mechanism for the effect of riboflavin deficiency on iron loss in the rat.

The effect of riboflavin deficiency on gastrointestinal Fe distribution and loss was studied in weanling rats. Riboflavin deficiency was associated with a significant increase in crypt depth in the upper and mid small intestine and a twofold increase in the rate of crypt cell production compared with weight-matched and ad lib.-fed control rats. The rate of loss of endogenous Fe, measured as faecal 59Fe after intraperitoneally administered 59Fe, was twice that from riboflavin-deficient rats compared with weight-matched controls. We suggest that while there may be a contribution from turnover of enterocytes with an enhanced Fe content, enhanced Fe loss associated with riboflavin deficiency is due predominantly to an accelerated rate of small-intestinal epithelial turnover.