Can eating nuts cause stomach ulcers?
Hello and welcome,
Nuts do not commonly cause stomach ulcers, but the high fiber content and other characteristics can make them difficult to digest and cause cramps and pain in the intestinal tract. It is controversial whether it can also cause diverticulitis which is inflammation of outpouchings in the intestines.
I recommend he eliminate nuts right now until his gut quiets down - probably a couple of weeks. Then reintroduce them in small amounts, perhaps a teaspoon at first and very gradually increase his intake.
A couple of other things to think about:
An allergy to nuts is possible to develop at any time and can produce gastrointestinal pain. Usually also a rash/hives, but not necessarily.
If he continues to have pain even days after discontinuing the nuts, or if he develops a fever, he should be seen by his doctor (or at an urgent care clinic) for the possibility of diverticulitis.
Most likely things will clear up after he discontinues them for awhile and then reintroduces them very gradually.
I hope this helps.