In rodents, a low-phosphate diet up-regulates the efficiency of intestinal phosphate absorption; this has been traced to an increase in jejunal expression of the NaPi-2 b transporter. If this effect is pertinent to humans, it might lessen the protective utility of measures intended to limit dietary bioavailable phosphate. To the extent that niacin administration can counteract an induced up-regulation of NaPi-2 b expression, it could be a good complement to such measures.