What is fibre?
Simply put, fibre is the non-digestible carbohydrate and lignin portion of intact plant foods. Dietary fibre includes non-starch polysaccharides (e.g. cellulose, pectin, gums, hemicellulose, β-glucans, and fibres contained in oat and wheat bran), plant carbohydrates that are not recovered by alcohol precipitation (e.g. inulin, oligosaccharides, and fructans), lignin, and resistant starch. In lay terms, these various fibre types are most often categorized simple as soluble and insoluble fibre.
What does fibre do?
Most of us are aware of the fact that we need fibre on a daily basis to help soften and give bulk to our stools for both regularity and ease of elimination. True enough. But the role of fibre goes much beyond that. Soluble fibres (pectins, gums, mucilages, and some hemicelluloses) readily mix with liquids forming a viscous gel that slows down digestion in the small intestines. The resulting gel increases satiety, eliminates blood lipids like cholesterol (by preventing reabsorption of bile), helps balance blood sugars (by prolonging stomach emptying) and is fermented by gut bacteria, thus promoting a healthy microbiome. Insoluble fibres (cellulose, lignins, and also some other hemicelluloses) pass through the bowels relatively intact and do not mix with water. They help speed up the movement of matter through the large intestines therefore preventing constipation and assisting in the rapid removal of toxic waste products. They also control the pH of the bowels. Either directly or indirectly, fibre may help prevent and treat many diseases including diverticulitis, diabetes, hemorrhoids, constipation, colon and breast cancer, crohn’s disease, heart disease, hypercholesterolemia, obesity and irritable bowel syndrome.
What kind of fibre do we need?
We need both soluble and insoluble fibres in our diet. Soluble fibres are predominant in oats and oatmeal, legumes (peas, beans and lentils), barley, fruits and vegetables (especially oranges, apples and carrots). We also need insoluble fibres. They are predominant in the skins of fruits and vegetables and the bran portion of whole grains such as wheat bran. On the average when eating a whole foods diet you will get a ratio of 3:1 of insoluble to soluble fibres. Most high fibre foods contain both soluble and insoluble fibres and some foods, such as flax seeds and psyllium husks, are rich in both. If you eat a balanced whole foods diet you don’t really need to worry about which type of fibre you are getting.
How much fibre you need
According to Health Canada, Canadian women need 25 grams of fibre per day and men need 38 grams of fibre per day. Most Canadians are only getting about half that much. It is also believed that our ancestors consumed up to 100 grams of fibre on a daily basis. Some of the reasons our meals are so lacking in fibre include the consumption of processed grain products (like white flours), our low intake of high fibre foods such as fruits, vegetables and legumes, and our excessive portion sizes of non-fibre foods such as meat, chicken and dairy. The bottom line is we don’t get enough. Calculate your fibre intake for a day or two to see if you are on average below recommended daily amounts. Aim for about 10-15 grams of fibre per meal and make sure you relate the grams back to the serving size on the package!
What are functional fibres?
The reality is many of us are not getting enough fibre from our diets. The health industry has stepped up to offer us a plethora of fibre supplements to fill in the gaps. Some of these supplements such as ground hemp, flaxseed, chia seed powder, are simply ground up whole foods. These supplements offer not only fibre but also the richness of other nutrients such as healthy fats, proteins, vitamins and minerals. Other “functional fibres” consists of isolated or purified fibres. These supplements may serve more specific functions. These supplements may serve more specific functions. There are a number of popular soluble fibre isolates including beta-glucans, pectins, glucomannan, inulin and acacia gum powder. These supplements are often recommended for the following uses:
• Beta-glucans: diabetes and high cholesterol; sourced from oats and barley
• Glucomannan: obesity, constipation, heart disease
• Acacia gum: high cholesterol, diabetes; sourced from acacia tree sap
• Pectin: high cholesterol, diarrhea, and may have a role in some cancers (as modified citrus pectin); sourced from beetroot apples and citrus.
• Fructans (Inulin, oligofructose, fructooligosaccharides or FOS): feeds good bacteria; often referred to as probiotics; sourced from chicory root.
The double edge sword
Fibre supplements can be helpful to those of us who cannot yet manage to eat a primarily whole foods vegetarian diet. Adding a couple of tablespoons of ground flaxseeds to yogurt, cereal or a protein shake, for example, is a great way to get our daily quotas met. However, for some people, added fibres can cause gas and/or bloating and other digestive issues, especially when using isolates. If this is more than a temporary issue, seek the guidance of a professional.