What is Dietary Fibre?
Dietary fibre, also known as roughage or bulk, includes the parts of plant foods your body can't digest or absorb. Unlike other food components, such as fats, proteins or carbohydrates — which your body breaks down and absorbs — fibre isn't digested by your body. Instead, it passes relatively intact through your stomach, small intestine and colon and out of your body.
Fibre is commonly classified as soluble, which dissolves in water, or insoluble, which doesn't dissolve.
Soluble fibre. This type of fibre dissolves in water to form a gel-like material. It can help lower blood cholesterol and glucose levels. Soluble fibre is found in oats, peas, beans, apples, citrus fruits, carrots, barley and psyllium.
Insoluble fibre. This type of fibre promotes the movement of material through your digestive system and increases stool bulk, so it can be of benefit to those who struggle with constipation or irregular stools. Whole-wheat flour, wheat bran, nuts, beans and vegetables, such as cauliflower, green beans and potatoes, are good sources of insoluble fibre.
The amount of soluble and insoluble fibre varies in different plant foods. To receive the greatest health benefit, eat a wide variety of high-fibre foods.
Benefits of a high-fibre diet:
Normalises bowel movements. Dietary fibre increases the weight and size of your stool and softens it. A bulky stool is easier to pass, decreasing your chance of constipation. If you have loose, watery stools, fibre may help to solidify the stool because it absorbs water and adds bulk to stool.
Helps maintain bowel health. A high-fibre diet may lower your risk of developing haemorrhoids and small pouches in your colon (diverticular disease). Studies have also found that a high-fibre diet likely lowers the risk of colorectal cancer. Some fibre is fermented in the colon. Researchers are looking at how this may play a role in preventing diseases of the colon.
Lowers cholesterol levels. Soluble fibre found in beans, oats, flaxseed and oat bran may help lower total blood cholesterol levels by lowering low-density lipoprotein, or "bad," cholesterol levels. Studies also have shown that high-fibre foods may have other heart-health benefits, such as reducing blood pressure and inflammation.
Helps control blood sugar levels. In people with diabetes, fibre — particularly soluble fibre — can slow the absorption of sugar and help improve blood sugar levels. A healthy diet that includes insoluble fibre may also reduce the risk of developing type 2 diabetes.
Aids in achieving healthy weight. High-fibre foods tend to be more filling than low-fibre foods, so you're likely to eat less and stay satisfied longer. And high-fibre foods tend to take longer to eat and to be less "energy dense," which means they have fewer calories for the same volume of food.
Helps you live longer. Studies suggest that increasing your dietary fibre intake — especially cereal fibre — is associated with a reduced risk of dying from cardiovascular disease and all cancers.
If you aren't getting enough fibre each day, you may need to boost your intake. Good choices include:
- Whole-grain products
- Fruits
- Vegetables
- Beans, peas and other legumes
Nuts and seeds
Refined or processed foods — such as canned fruits and vegetables, pulp-free juices, white breads and pastas, and non-whole-grain cereals — are lower in fibre. The grain-refining process removes the outer coat (bran) from the grain, which lowers its fibre content. Enriched foods have some of the B vitamins and iron added back after processing, but not the fibre.
Fibre supplements and fortified foods
Whole foods rather than fibre supplements are generally better. Fibre supplements — such as Metamucil or Citrucel — don't provide the variety of fibres, vitamins, minerals and other beneficial nutrients that foods do.
Another way to get more fibre is to eat foods, such as cereal, granola bars, yogurt and ice cream, with fibre added. The added fibre usually is labelled as "inulin" or "chicory root." Some people complain of gassiness after eating foods with added fibre.
However, some people may still need a fibre supplement if dietary changes aren't sufficient or if they have certain medical conditions, such as constipation, diarrhoea or irritable bowel syndrome. Check with your doctor before taking fibre supplements.
Tips for fitting in more fibre
Need ideas for adding more fibre to your meals and snacks? Try these suggestions:
Jump-start your day. For breakfast choose a high-fibre breakfast cereal — 5 or more grams of fibre a serving. Opt for cereals with "whole grain," "bran" or "fibre" in the name. Or add a few tablespoons of unprocessed wheat bran to your favourite cereal.
Switch to whole grains. Consume at least half of all grains as whole grains. Look for breads that list whole wheat, whole-wheat flour or another whole grain as the first ingredient on the label and have at least 2 grams of dietary fibre a serving. Experiment with brown rice, wild rice, barley, whole-wheat pasta and bulgur wheat.
Bulk up baked goods. Substitute whole-grain flour for half or all of the white flour when baking. Try adding crushed bran cereal, unprocessed wheat bran or uncooked oatmeal to muffins, cakes and cookies.
Lean on legumes. Beans, peas and lentils are excellent sources of fibre. Add kidney beans to canned soup or a green salad. Or make nachos with refried black beans, lots of fresh veggies, whole-wheat tortilla chips and salsa.
Eat more fruit and vegetables. Fruits and vegetables are rich in fibre, as well as vitamins and minerals. Try to eat five or more servings daily.
Make snacks count. Fresh fruits, raw vegetables, low-fat popcorn and whole-grain crackers are all good choices. A handful of nuts or dried fruits also is a healthy, high-fibre snack — although be aware that nuts and dried fruits are high in calories.
High-fibre foods are good for your health. But adding too much fibre too quickly can promote intestinal gas, abdominal bloating and cramping. Increase fibre in your diet gradually over a few weeks. This allows the natural bacteria in your digestive system to adjust to the change.
Also, drink plenty of water. Fibre works best when it absorbs water, making your stool soft and bulky.