One food group that can be hard to digest is dairy, mainly because of lactose, the sugar found in milk and other dairy products.
Tomato sauce and citrus fruits, such as lemons, limes, oranges, and grapefruit, are acidic and can irritate the stomach lining, causing digestive problems.
Fatty foods stimulate contractions in the digestive tract, which can either slow down the emptying of the stomach and worsen constipation, or speed up movement, leading to or worsening diarrhea.
The problem with fried foods is the same as with fatty foods they can move, undigested, through the body too quickly, leading to diarrhea, or stay in your digestive tract too long, causing you to feel full and bloated.
Processed foods also often contain preservatives and artificial coloring, Kim says, and people with allergies or sensitivities to these additives will feel their effects during bouts of digestive trouble.
The artificial sweetener perhaps most associated with digestive problems is sorbitol.
Alcohol is toxic to the stomach lining and changes liver metabolism, drinking too much can cause indigestion, among other health problems.