Did you know there’s more than one type of dietary fibre? Eating a wide range of plant foods will help your body to function at its best.
Everyone knows fibre is important for effective digestion, but most people still don’t eat as much fibre as they should, and few realise the importance of eating both types of fibre.
What is fibre, and how much do you need?
Simply put, fibre is the structural component of plant foods, so it’s found in vegetables, whole fruits, beans and grains (such as corn or brown rice). Despite being found in a multitude of foods, the Nutrition Society states that 8 out of 10 individuals fall short of meeting the fibre recommendation of 25 grams a day*.
If you don’t eat as much fibre as you should, it’s best to gradually increase the amount you eat gradually over a few weeks. Adding too much fibre to your diet too quickly can lead to abdominal discomfort and gas, so take it slowly to allow your system time to adjust. Also, drink plenty of liquid to allow the fibre to soften and swell.
What are the different types of fibre & what do they do?
There are two broad classes of dietary fibre: soluble and insoluble.
Soluble fibres are found in the highest concentration in apples, oranges, carrots, potatoes, oats, barley and beans. As the name suggests, soluble fibres dissolve in water. When these fibres dissolve, they thicken up, which helps to keep you full. Soluble fibre also fuels the healthy bacteria in the lower digestive tract, and slows the absorption of glucose (sugar) from the blood stream; helping to keep blood sugar levels stable throughout the day.
Insoluble fibres also support digestive health, but in the opposite way. Instead of dissolving in water, insoluble fibres absorb water in the lower tract, which makes them more bulky. This type of fibre (found in the highest concentrations in vegetables, wheat bran, corn bran, rice bran and other whole grains) speeds the passage of waste through the digestive system; helping to keep you regular.
There’s one other interesting type of fibre, called ‘resistant starch’. Fruits, vegetables, grains and beans contain 3 different types of carbohydrates: sugars, starches and fibre. Usually, the starches are broken down into individual sugars during the digestive process, but some foods such as beans, bananas and oats simply defy digestion. Since resistant starch doesn’t break down (staying more or less intact as it travels through the digestive tract) it traps water, adds bulk and helps with regularity. They also promote the development of healthy bacteria in the lower intestine, and can blunt rapid rises in blood sugar, much like soluble fibre.
How to tell if a fibre is soluble or insoluble…
It is relatively easy to tell which is which. For example, when you boil potatoes, the liquid thickens up because potatoes are high in soluble fibre. When you cook brown rice, it doesn’t get sticky because the insoluble fibre doesn’t dissolve. Instead, it absorbs water as it cooks, causing the grains to swell.
Another easy way to see the difference is to open up a can of beans (soluble fibre) and a can of corn (insoluble fibre). Both the beans and corn are water-packed, but if you look at the liquids in the can, they look very different. Since the corn fibre is insoluble, the liquid that it’s packed in looks watery, whereas the liquid in the can of beans is much thicker because the soluble fibre has thickened up the water.
Tips for increasing fibre intake
- Eat whole fruits with skin more than fruit juices.
- Use whole fruit as a dessert.
- Eat a variety of whole vegetables – cooked and raw.
- Use 100% whole grain breads, waffles, cereals, crackers, etc. instead of those made with refined white flour.
- Use brown rice, wild rice, millet, barley, and cracked wheat as alternatives to white rice.
- Add beans to soups, stews and salads.
- If you have trouble meeting your fibre intake, try a fibre supplement to help you reach your RDI.
Written by Susan Bowerman, MS, RD, CSSD, FAND. Susan is a paid consultant for Herbalife.