eliminating grains and krap industrial oils generally help heal issues like this. your husband may also want to add a good probiotic and fermented foods to his day. it won't work overnight but he will get there.
As I ate the oysters with their strong taste of the sea and their faint metallic taste that the cold white wine washed away, leaving only the sea taste and the succulent texture, and as I drank their cold liquid from each shell and washed it down with the crisp taste of the wine, I lost the empty feeling and began to be happy and to make plans.
– Ernest Hemingway