Factor UC CD
smoking --- +++
appendectomy --- +/0
dietary factors
high fat + +
high dietary fiber - -
high fruit/vegetable - -
high sugar + +
fast food + +
vitamin D deficiency + +
medications
antibiotics + +
NSAIDs + +
oral contraceptives/hormone therapy + +
anti-TNF-α therapy + +
breastfeeding -/? -/?
hygiene hypothesis
pet in childhood/farm environment -/? ?
Helicobacter pylori - -
helminthiasis - -
measles ? ?
vaccination against measles ? ?
"cold chain" 0 +/?
infectious gastroenteritis in childhood ? ?
urban environment + +
stress +/? +/?
”-”: decreased risk; ”+”: increased risk; ”0”: no effect; ”?”: question of debate
Table 1: Environmental risk factors of UC and CD.