Dietary Interventions for Constipation

Sources of Fiber

• The American Gastroenterological Association recommends that wheat bran is the most effective, increasing fecal weight by 7.2 g per gram consumed, compared to 4.4 g/g for cooked wheat bran 1, 2, 3
• Oat bran increases fecal weight by 3.4 g per gram consumed 1, 2
• Corn generates an increase of 2.9 g/g 1, 2
• The recommended dose is 10-30 g of wheat bran per day, although high dropout rates are seen due to bloating 4
• Vegetables reduce the risk of constipation by 58% (OR 0.42) when comparing the highest consumers to the lowest, using a definition based on frequency and consistency of stools 2, 5, 6
• Vegetable fibers increase fecal weight by 6 g per gram consumed 1, 2, 3
• All types of vegetables are effective - vary colors and types 7
• Consume at least 5 portions of vegetables per day 7
• Fruits increase fecal weight by 6 g per gram of fiber consumed, equivalent to vegetables 1, 2, 8
• All sources of fiber (grains, fruits, vegetables, legumes) significantly reduce constipation when using frequency as the only criterion 2, 5, 6
• Legumes, such as soy, generate the smallest increases in fecal weight (1.5 and 1.3 g/g respectively) 1, 2, 8
• Despite their lower efficacy, consume legumes at least twice a week 7

Purified Fibers and Specific Supplements

• Psyllium causes less adverse effects (gas, distension, pain) than wheat bran 4
• Effective dose: 7-10.8 g per day 4
• Glucomannan shows proven efficacy, with a meta-analysis of 5 randomized controlled trials showing an increase in stool frequency (OR 1.19; P < 0.05) 2, 3, 5, 6, 8

Dietary Habits

• Choose lean proteins (chicken, turkey) rather than red meat 7
• Reduce processed meats and foods high in salt and sugar 7
• Eat 4-6 small meals per day rather than large meals 7
• Avoid late meals and wait 2-3 hours after eating before lying down 7
• Separate liquids from solids during meals to reduce gastric distension 7