3beta-hydroxy-7-oxo-5beta-cholan-24-oate + NADH + H(+) => 3beta,7beta-dihydroxy-5beta-cholan-24-oate + NAD(+)
3beta-hydroxy-7-oxo-5beta-cholan-24-oate + nadh + h(+) => 3beta,7beta-dihydroxy-5beta-cholan-24-oate + nad(+)