PERSON@1 is well-known for proving that bacteria PERSON@2 are the cause of most stomach ulcers , reversing decades of medical doctrine which held that ulcers were caused by stress , spicy foods , and too much acid .

PERSON@1 is well-known for proving that bacteria PERSON@2 are the cause of most stomach ulcers . This changed years of medical belief which said that ulcers were caused by stress , spicy foods , and too much acid .
