Lower fiber diets tend to be associated with a higher risk of constipation,[1][2][3] and increasing fiber intake can benefit constipation[4][5] More research is needed to better understand which fiber-rich foods are best in this regard.
Prunes, being high in sorbitol, can have a laxative effect and may therefore help with constipation.[6] However, sorbitol can provoke unpleasant GI symptoms (abdominal pain, bloating) in certain individuals.[7]
A few studies have found mineral water (not to be confused with mineral oil) can be helpful for constipation, possibly due to the magnesium, sulfate, and bicarbonate it contains.[8][9]
Kiwifruit seems to be beneficial for people with constipation.[10][11][12]