Probiotics like Primal Defense can help with constipation and gas (and odor). Digestive enzymes can help him digest his food. Colon Cleanse products and parasite cleanse products would be helpful too. If he's trying to eat healthy, he should be receptive to doing some cleanses. Humaworm has parasite, colon, and other cleanses that might be helpful in helping him detox. Also, liver supportive herbs like dandelion and milk thistle.