I've actually used oat bran instead of wheat bran, simply because the store didn't have it. It seeemed to work just a good, but I was using the recipe for a child. So you can give it a try, if it don't seem to relieve the constipation then switch to the wheat bran.
Sorry it took me so long to get back to you. I'm up to my eyeballs with Christmas preperations, didn't it just seem to sneak up on us this year?