Fiber: Just Passing Through?

Compared with typical eating patterns today, our ancestors’ diets provided 4 to 6 times as much fiber. Does this matter? What is fibre, anyway? How much do we require for good health?  What are good sources?

Fibre is the part of plants that we do not digest. It gives plants their structure. In contrast, animals get structure from the bones that form their skeletons; animal products are fibre-free. Fibre is divided into two categories depending on its solubility in water. Most plant foods contain both types; generally two-thirds to three-quarters of our dietary mix is insoluble fibre.

Insoluble fibre (celluloses, some hemicelluloses, and lignins) is structural. In the wet environment of the intestine, these carbohydrate materials absorb water without becoming gluey. Most whole plant foods are good sources of insoluble fibre; the bran that forms the outer layer of wheat kernels is especially rich.

Soluble fibres are gel-forming; examples are pectins (that makes jelly gel), gums and mucilages. Oat bran is a rich source of soluble fibre; when mixed with water, it becomes sticky. Other good sources are beans (think of the gummy liquid around canned kidney beans), peas, numerous fruits, barley, some vegetables (such as okra), flaxseeds, and psyllium (used in some cereals and bulk fibre laxatives).

Diets that are centered on legumes (beans, peas, lentils), whole grains, vegetables, and fruits are far higher in fibre than those built on refined foods. The mix in an assortment of plant foods is far more valuable to health than a supplement that includes fewer types of fiber. Here are some benefits:

Fibre keeps our gastro-intestinal tract clean and healthy. Insoluble fibre functions as the roto-rooter of the gastro-intestinal tract, clearing away toxic substances and excess cholesterol. Fibre adds bulk to our stools and ensures that waste materials pass through quickly and easily. In the process, the muscles that surround our intestine keep fit and healthy. These actions help to protect us against diverticular disease, constipation, hemorrhoids, anal fissures, colorectal cancers, duodenal ulcers, gallstones, and irritable bowel diseases.

It helps to keep blood lipids and blood sugar under control and maintain blood cholesterol, triglyceride, and blood sugar levels within healthful ranges. Soluble fibre is mainly responsible for these benefits. It coats the inner lining of the intestine, slows the emptying of our stomach, and slow sugar absorption; in the process it may reduce insulin needs. Soluble fibre is thought to improve blood sugar control in people with diabetes and to reduce risk of heart disease. 

It increases our feelings of satiety after eating. Fibre-rich plant foods are bulky, making us feel full, and helping to control total food intake. As a result, high fibre intakes are linked to healthier body weights.

Most Canadians get about 14-15 grams of dietary fiber, only about half of the minimum 25-35 grams we need each day. Unfortunately, this is not enough to take full advantage of these health benefits. Vegetarians consume approximately 30-40 grams of fibre a day, with vegan intakes typically about 40-50 grams, intakes that are reflected in reduced rates of colon cancer among these population.

Often people are somewhat cautious about increasing their intakes of fibre-rich foods such beans, owing to their reputation in the aroma department.  However gaseous emissions are not an essential part of fibre-rich diets. Such eating patterns are used without ill effect by populations around the world.  For a more in-depth analysis of “International Solutions to The Gas Crisis”, see next month’s Nutrispeak column in Common Ground.

Explore delicious ways to increase your intake of plant foods by attending Taste of Health, EarthSave’s big annual event, on the weekend of October 1-2, 2005. From 10 am to 6 pm, for the very small fee of $7 (children under 12 free), you can enjoy hearing an excellent range of speakers, sample new healthy foods, attend food demonstrations, be wonderfully entertained, and meet wonderful people. This will be held at the Croatian Cultural Centre on 3250 Commercial Drive in Vancouver. For event schedule, see www.tasteofhealth.com  (also phone 604-731-5885.)

Vesanto Melina is a registered dietitian and author based near Fort Langley. She is co-author of  “Cooking Vegetarian“, “The New Becoming Vegetarian” (US title), “Becoming Vegetarian” (Canadian title), Food Allergy Survival Guide, Becoming Vegan, and Raising Vegetarian Children and will be speaking at Taste of Health, Oct 1-2. For personal consultations call 604-888-8325 (clinic) or 604-882-6782 (home office); web www.nutrispeak.com.

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