The first evidence-based British Dietetic Association guideline for chronic constipation (2025) recommends a high-fiber eating pattern: 25–30 g of fiber per day with 1.5–2 L of fluid, built around whole grains, berries, legumes and dark leafy vegetables — while cutting back on refined grains and highly processed fatty foods.
The 2025 British Dietetic Association (BDA) guideline — the first evidence-based dietary guideline specifically for chronic constipation in adults — recommends combining 25–30 g of daily fiber with 1.5–2 L of daily fluid. Fiber and fluid work together: fiber adds bulk, and fluid keeps that bulk moving. The guideline also highlights an overall high-fiber eating pattern rather than single foods or supplements.
Oats, quinoa, barley and other intact whole grains — the backbone of a 25–30 g fiber day.
Blueberries, raspberries and blackberries deliver both soluble and insoluble fiber in a senior-friendly texture.
Chickpeas, lentils and beans — fiber-rich and easy to add to soups and stews.
Spinach, kale and collards — a practical way to raise fiber without raising calories.
White bread, white rice and pastries strip away the fiber that helps regularity.
Fast food and fried snacks tend to be low in fiber and high in fat, which can slow digestion.
Constipation can also be caused by medications, thyroid problems or other medical conditions. If symptoms are new, severe, or accompanied by pain, bleeding or unintended weight loss, see a physician before changing the diet. Fiber and fluid should be increased gradually so the gut can adjust.