Fiber-Rich Dietary Patterns and Foods in Laxation and Constipation

Abstract

The consumption of healthy dietary patterns with adequate dietary fiber (>25 g/day or 14g/1,000 kcals), recommended fluid intake, and regular physical activity, are especially beneficial in preventing and alleviating constipation. Fiber mechanisms associated with improved laxation and alleviated constipation include: increasing stool weight and bulk volume (through fiber and microbiota physical volume and water holding capacity), and gas volume trapped in the stool to increase bowel movement frequency and quality, especially in constipated individuals. Adequate intake of fiber from cereal, fruits, vegetables and common fiber-rich food ingredients including polydextrose, psyllium, chicory inulin and prebiotics or synbiotics have the potential to increase population-wide levels of regularity and provide constipation relief. In general, less fermentable dietary fiber tends to increase fecal weight to a greater amount than more fermentable fibers. Wheat bran is the most widely studied fiber; when baseline transit time was >48 h, each extra g/day of wheat bran significantly increased total stool weight by 3.7 g and reduced transit time by 45 min. Increased fiber intake did not change transit time in individuals with an initial time of <48 h. However, in people with an initial transit time ≥48 h, transit time was reduced by approximately 30 min per gram of cereal, fruit or vegetable fiber, regardless of fermentability. Several RCTs suggest that daily intake of prunes (dried plums) and/or kiwi fruit can help in relieving constipation symptoms similarly to psyllium.