@annabannana I agree with @merpreb about speaking to a nutritionist. When your husband cheats, he knows the possible consequences so, as I remind myself when I do the same, "it's all on me!" I have a tendency towards gout, and usually pay very close attention to my diet. Eating healthy when you are experiencing a variety of disorders, is so important! If he has internet access, he can learn many good tips for his colitis issue. There may be some information at this link https://connect.mayoclinic.org/discussion/ulcerative-colitis-at-62/ It is good your husband wants to look into how best to handle his diet, and we look forward to hearing about what he finds out.
Ginger