Fibre and Fluids: Why Water Makes Your Fibre Work Better

Many people try to eat more fibre and end up bloated and frustrated. Often the missing partner is water. Fibre draws in fluid as it moves through your digestive system, so the two work together. Understanding that relationship makes the whole thing less mysterious.

Two kinds of fibre

Soluble fibre dissolves in water to form a gel. It is found in oats, beans, apples, chia and flax. Insoluble fibre adds bulk and is found in wholegrains, vegetables, wheat bran and many seeds. Most plant foods contain both. Eating a mix is a better strategy than relying on a single supplement.

How much is enough?

Recommendations differ by country and by person, but many adults are advised to aim for somewhere in the region of 25 to 30 grams a day. Surveys in several countries show that most people eat less than this. Check your local guidelines, and don't worry about hitting an exact figure daily.

Raise it slowly

If your intake is low, increase gradually over two to three weeks. Add one new fibre food at a time. For example, put a teaspoon of ground flax in your porridge this week and add beans to a soup next week. A sudden big increase can cause gas, cramping and discomfort.

Drink up, gently

There is no magic number of glasses. Needs vary with body size, activity, climate and diet. A good guide is to drink regularly through the day and aim for pale-yellow urine. Water, tea, milk, soups and water-rich fruit and vegetables all contribute. When you add chia, which can absorb many times its weight in liquid, make sure it is soaked or taken with plenty of fluid, and never eat dry chia and follow it with too little water.

Common fibre pitfalls

One pitfall is relying on fibre supplements or fortified bars while eating few whole foods. Another is cutting out fibre completely after one uncomfortable day, instead of reducing and slowly rebuilding. A third is forgetting that very high fibre intake with very little fluid can make you feel more blocked, not less.

If a food truly upsets you, try a smaller portion, a different cooking method, or soaking, before giving it up for good.

Easy fibre-and-fluid pairs

Try porridge with chia and fruit, a lentil soup with a glass of water, a smoothie with oats and flax, or a salad with chickpeas and sunflower seeds alongside a jug of infused water. Making these pairs automatic is easier than counting grams.

If you have a bowel condition such as inflammatory bowel disease, diverticular disease or a history of obstruction, or difficulty swallowing, talk to your doctor before increasing fibre significantly. People with kidney or heart conditions who have been told to limit fluids should follow their doctor's guidance on how much to drink.

This article is general information, not medical advice.