Fibre is a type carbohydrate which gives plants their structure and rigidity. Fibre is indigestible by the human body, meaning that it is not broken down by gastric acid and digestive enzymes, or absorbed through walls of the intestine. Some types of fibre pass through the digestive system untouched, whereas other types are metabolized by the beneficial bacteria in the colon.
Adequate fibre intake is 14g for every 1000 calories consumed. This equates to a recommended daily intake of about 25g-30g per day for women, and 30-36g per day for men, but it will vary according to an individual’s caloric intake. Children and the elderly, who consume fewer calories, also need less fibre. Pregnant or breast-feeding women should increase their fibre intake slightly as they need to consume more calories than the average woman. The average person only gets 8-18g of fibre per day, which may explain why digestive disturbances, such as constipation and gas and bloating are so common.
This Article covers:
Benefits of Eating Fibre
Regulates Bowel Habits
Fibre increases the bulk of the stool which helps stimulate peristalsis (the natural contractions which help move matter through the colon). Both soluble and insoluble fibre promote more frequent bowel movements; however, only soluble fibre will help regulate the stool in cases of diarrhea because of it’s ability to absorb excess water; insoluble fibre will only exacerbate cases of diarrhea.
Soluble fibre binds with bile. Bile contains all the toxins that have been filtered out of the blood by the liver. When we get adequate fibre, bile and all the harmful toxins that it contains are carried out of the body with each bowel movement. Insoluble fibre is also critical in this regard as it “sweeps” out the colon. A diet low in fibre will result in bile which is more concentrated with toxins because, instead of being eliminated, the bile acids will be reabsorbed and recirculated through the system.
Nourishes Intestinal Flora
Certain fibres undergo fermentation in the large intestine. Fermentable fibres are known as “prebiotic” because they serve as fuel for the friendly bacteria that reside there. Friendly bacteria in the colon strengthens the immune response and also directly fights any harmful bacteria or microbes that enter the colon.
Increases Mineral Absorption
Some soluble and fermentable fibres help to increase the absorption of minerals such as calcium, magnesium, and iron. There are two reasons for this. First, fermentation lowers the pH of the intestines, so minerals are more easily drawn out from food, and secondly, because fermentable fibres improve the capacity of the epithelial cells of the intestine to absorb minerals.
Aids Weight Loss
Fibre intake assists weight loss in many ways. First, fibre provides bulk which helps one feel full and less likely to consume extra calories. Second, fibre stimulates the release of cholecystokinin (CCK), a hormone that sends the signals to your brain to indicate that you are full. Fibre also prolongs the elevation of CCK in the blood, which makes you feel full for longer periods of time. Third, certain fibres decrease the absorption of sugars in the diet, resulting in more balanced blood sugar levels and less unhealthy food cravings. And lastly, fibre also absorbs some calories from the foods you eat.
Reduces High Cholesterol
Soluble fibre binds with bile acids and transports them out of the body. This means that fewer bile acids are recycled and the liver will produce more. Since cholesterol is required for the synthesis of bile acids, the liver must pull cholesterol out of the blood to manufacture the bile, thus reducing LDL cholesterol levels in the blood.
Fibre will also decrease the amount of cholesterol that is actually synthesized. The short-chain fatty acids which are produced from the fermentation of certain types of fibre in the intestine, reduce the amount of cholesterol made by the liver.
Lowers the Risk of Heart Disease
Adequate fibre intake lowers cholesterol levels in the blood which means that there is less chance of cholesterol and other lipids accumulating in the arteries. When fats and cholesterol do build up in the bloodstream, they form a plaque in the arteries which leads to conditions such as atherosclerosis, angina, strokes, and heart attacks.
Fibre also helps to reduce high blood pressure because of its effect on the release of insulin. Hypertension is most often related to elevated insulin levels. Eating adequate fibre slows the absorption of glucose from carbohydrates which prevents insulin from fluctuating.
Lessens the Risk and Severity of Diabetes
Soluble fibre is helpful in both type 1 and type 2 diabetes. This is due to its effects on regulating blood sugar levels. Because a fibre-rich meal will lessen any sudden surges in blood sugar levels, those with diabetes will require less insulin. Balanced blood sugar levels mean that the insulin levels are not constantly fluctuating. This reduces stress on the pancreas and decreases the chance of individuals becoming insulin resistant and developing type 2 diabetes later in life. Fibre also helps maintain a healthy weight, preventing obesity, a major risk factor for developing type 2 diabetes.
Reduces Systemic Inflammation
When fibre is fermented in the large intestine, short-chain fatty acids are produced. Short-chain fatty acids help regenerate and heal the epithelial cells of the intestine, aiding their ability to respond to pathogens and bacteria in the gut. If not kept in check, microbes and their products produce a chronic inflammatory response. Soluble fibre also increases the production of interleukin-4, an anti-inflammatory protein.
Helps Modulate the Immune System
The short-chain fatty acids produced from the fermentation of soluble fibre nourish the epithelial cells of the colon. These cells provide the barrier which protects against infections. A thicker, healthier barrier means that the good bacteria can colonize and fight infection.
The intestines are also an organ of the immune system. Gut-associated lymphoid tissue (GALT) makes up 70% of our bodies lymphatic tissue and contains lymphocytes (T and B cells), macrophages, and microfold cells (M cells), which all have important functions in protecting the body against pathogens.
Decreases the Risk of Colon Cancer
Improved immune function is one way that fibre can help ward off cancer, but there are more specific benefits that make it particularly beneficial against the formation of colon cancer. The production of short-chain fatty acids, particularly butyrate, not only stimulates the growth of the healthy cells in the intestinal mucosa, but also inhibits the growth of tumour cells in the colon. Butyrate is shown to stimulate cell death in abnormal cells and balance the intestinal pH, making the environment less conducive for the spread of cancer.
Helps Balance Hormone Levels
Fibre helps regulate sex hormones in both men and women because it increases the sex hormone-binding globulin, which as the name indicates, binds to sex hormones (testosterone and estrogen) in the bloodstream.
Fibre also helps the reabsorption of these hormones into the bloodstream, because after they are processed by the liver, testosterone and estrogen enter the digestive tract. In the colon, the hormones are absorbed by fibre which helps carry them out of the body in the stool. More balanced estrogen levels in women mean that symptoms of PMS and menopause are significantly reduced, as is the risk of developing breast cancer. In men, the risk of prostate cancer is reduced when testosterone levels are more balanced.
Types of Fibre
Insoluble vs. Soluble
Dietary fibre is usually classified as soluble or insoluble. Although many types of fibre are a mixture of both, fibre is categorized by which type is more predominant All plant-based foods contain both soluble and insoluble fibre in varying degrees.
Insoluble fibre comes from the structural part of the plant. It is found in the husks of grains, the skin of fruits and vegetables, and also in most nuts, seeds, beans, and legumes. Insoluble fibre does not dissolve in water.
Insoluble fibre gets through the digestive system unchanged. It also makes stools softer and bulkier. The added bulk stimulates the easy passage of fecal matter through the colon. Insoluble fibre can be thought of as a broom that “sweeps” the colon.
Types of insoluble fibre include cellulose, certain hemicelluloses, lignin’s, chitin, and some pectins.
Soluble fibre comes from structures within the cells of the plant. It is found in beans, legumes, and whole grains, oats having a particularly high content of soluble fibre. It is also found in vegetables and fruits. Soluble fibre dissolves and swells in water, forming a jelly-like consistency.
Soluble fibre absorbs toxins from the digestive tract; its action is more like a sponge. Soluble fibre also forms a coating in the colon which encourages the fecal matter to slide through more easily.
Types of soluble fibre include mucilages, gums, beta-glucans, pectins, and some hemicelluloses.
Fermentable vs. Non-Fermentable
Some fibres are fermented by the bacteria in the colon, whereas others are not are not metabolized by intestinal bacteria. Insoluble fibres are typically non-fermentable whereas soluble fibres are partially or completely fermented in the large intestine.
Fermentable fibres are also known as prebiotic because they feed the good bacteria in the colon. In addition to this, the fermentation produces short-chain fatty acids (butyrate, acetate, and propionate) which are absorbed by the epithelial cells of the intestines, where they are metabolized and provide energy.
Fermentable fibre is found in oats, barley, rice, legumes, and fruits and vegetables, especially bananas, potatoes, artichokes, garlic, and onions. Beta-glucans, pectins, gums, inulin, and oligosaccharides are types of fermentable fibre.
As previously stated, non-fermentable fibres are not broken down by the intestinal flora. Non-fermentable fibres are usually insoluble. Cellulose, lignins, resistant starches, and some types of hemicellulose have low fermentability.
Dietary vs. Supplemental Fibre
Dietary fibre is fibre which naturally occurs in the foods that we eat. This includes fibres found in fruits, vegetables, nuts, seeds, whole grains, and legumes.
Supplemental fibre, also known as “functional fibre”, is fibre that we take in addition the foods we eat. This includes fibre that is added to packaged foods to increase their fibre content.
Getting adequate fibre from a balanced diet is ideal. When we eat whole foods, we get all the fibre we need plus the vitamins, minerals and antioxidants that those foods contain. However, supplementation with fibre can be beneficial, especially for people with dietary restrictions or for individuals who are on a temporary cleansing regime. Supplemental fibre is also a good way to ensure adequate fibre intake when you do not have the consistency of a whole food diet, such as in times of travel or during other periods when you have an irregular routine.
When a supplemental fibre is required, there are a lot of choices. Supplemental fibre can be found in powders, capsules, tablets, and wafers. It is best to take a pure powder form, as the other forms usually have unhealthy additives.
Here are the fibre supplements that are most common and easy to use:
Common Fibre Supplements
Wheat bran is the out layer of the wheat berry. It is an insoluble fibre that is partially fermentable. Wheat bran is the most well-known bulk-forming laxative. Wheat Bran is often used in baking, especially in muffins and bread. It is also a common ingredient in packaged breakfast cereals.
Oat bran is the outer layer of the oat grain. It is soluble and has good fermentability. Oat Bran is sold as a breakfast cereal and is commonly added to pancake mixes, muffins, cookies, and bread.
Psyllium husk is the outer coating of the psyllium seed. It contains both soluble and insoluble fibre, but is has a higher a soluble fibre content. Psyllium is one of the more common mucilages. It is popular because it is a bulk-forming laxative that also has a soothing effect on the intestinal tract. Although it is quite gentle, it can cause some gut irritation in people with a very delicate gastrointestinal tract or in people with IBS.
Psyllium is the main ingredient in the branded fibres such as Metamucil, Konsyl, Hydrocil, Fiberall, and Lamar to name a few. It is best to avoid the branded psylliums because they often have other additives and are also much more expensive than plain psyllium husk.
Flaxseed, also called linseed, is a whole food, rather than an extracted source of fibre. It contains high amounts of both soluble and insoluble fibre. Flaxseed also has some fermentability. It is a gentle fibre with a broad range of benefits and also contains other nutrients including omega-3 fatty acids.
As a fibre supplement, the flaxseed can be ground and used in baking or added to smoothies, cereals, yoghurt, and sauces. Be sure to mill the seed before using flax; otherwise, the seed will not be broken down.
Chia seed is harvested from Salvia hispanica, a plant in the mint family. It is another whole food containing a very high amount of dietary fibre as well as omega-3 fatty acids, protein, and other nutrients. Chia contains both soluble and insoluble fibre and have some fermentability.
Chia seed can be eaten whole or milled. Chia absorbs many times its weight in water. Because of this, it is not recommended to eat the seeds dry, when eaten dry they can cause stomach pain, constipation, and can even pose a choking hazard.
The most common way to eat chia seeds is by making chia pudding. Soak 1/4 cup of seeds in 1 cup of liquid (milk, nut milk, juice, or water) for a minimum of 15 minutes and add a sweetener, spices, cocoa, or fruit. Chia can be added to other foods, but if you do use them without soaking them first, be sure to take a lot of fluid with them.
Pectin is a vicious fibre found in the cell walls of plants. Commercial sources of pectin are usually extracted from apple pulp or citrus peels. Most pectins are soluble and are readily fermented.
Pectin is found in all fruits; apples, oranges, grapefruit, peaches and apricots contain the highest amount. Vegetables such as tomatoes, carrots, potatoes, and peas also contain a significant amount of pectin as do legumes and nuts. Pectin is the standard thickener used in making jams and jellies.
Also know as gum arabic, acacia is harvested from the sap of Acacia senegal tree. The sap is dried and ground into a fine powder. Acacia is a soluble and fermentable fibre. It is very gentle on the stomach and soothing to irritated mucous membranes. Acacia is good for anyone with gastrointestinal distress or IBS as it does not create a lot of gas or cause the painful release of gas
Acacia dissolves completely in liquids and does not alter the taste of what you add it to. Acacia is sometimes added to foods to thicken them or to help emulsify oil and water.
Inulin fibre is a simple carbohydrate which is found in certain plants. The foods with the highest inulin content are Jerusalem artichokes (sunchokes), garlic, dandelion root, and chicory. Inulin is also found in asparagus, bananas, burdock root, jicama, leeks, onions, sweet potatoes, and wheat.
Inulin is a soluble fibre and also one of the most fermentable fibres. It is known for its prebiotic properties and for its ability to increase the absorption of minerals when taken with food or supplements.
Inulin has a pleasant, slightly sweet taste that blends into food and beverages without altering the taste or consistency. It will dissolve well into hot or cold beverages as well as into moist foods such as applesauce, yoghurt, sauces, and soups. Inulin can also be added to baked goods such as muffins or cookies.
Metamucil clear and Benefibre are brand name inulin powders that do not have additives; however, you will pay for the branding, so is better to buy bulk inulin that has not been branded.
Beta-glucan is a viscous fibre which has been extracted from the cell walls of oats, barley, certain mushrooms (reishi, shitake, maitake), yeast, and algae. Beta-glucans are soluble and readily fermentable.
Beta-glucan has the benefits of other fibres, but has also been shown to have added immune-boosting potential. It is usually marketed as an immune system modulator and is most commonly found in capsule form.
Chitin and Chitosan
Chitin is found in the cell walls of plants, fungi, and in the exoskeletons of crustaceans such as crabs, lobsters, and shrimp. It is similar in structure to cellulose. Chitin is insoluble and non-fermentable. Chitosan is similar to Chitin and is found in the cell walls of fungi and crustaceans. Is soluble in an acidic environment, and somewhat fermentable.
Chitosan is available in capsules and is often touted as a weight loss aid.People with allergies to shellfish should avoid Chitin and Chitosan because it may be sourced from crustaceans.
Glucomannan, otherwise know as Konjac is extracted from the elephant yam, an Asian tuber. Konjac flour is a traditional ingredient in foods from China, Japan, and Southeast Asia.
Glucomannan is soluble and fermentable. It is the most absorbent of all the fibres, taking in many times its own weight in water. It gels and lumps very quickly, so when adding it to water, make sure you stir continuously. Glucomannan gels more quickly in hot water, so make sure you mix it into a paste with cold water before adding it to hot foods. Glucomannan has very little taste. It is often used in place of cornstarch as a thickener in sauces, gravies, and soups.
Because of glucomannans swelling properties, it may pose as a choking hazard when taken in tablets or capsules. Avoid Glucomannan altogether if you have structural abnormalities of the esophagus or intestines.
Synthetic Fibre Supplements
There are synthetic forms of fibre available, but with so many natural types of fibre supplements, there is no reason to take these fibres which are completely unnatural and contain unhealthy additives. Examples of synthetic fibre supplements include Citrucel, which is comprised of methylcellulose, and Fibrecon and Equalactin which are made from calcium polycarbophil.
Synthetic fibre supplements are not fermentable, so their benefit is that they will not cause intestinal gas, but the health risks in taking them do not outweigh the benefits. It takes the body a short time to adjust to increased fibre so just be sure to increase your fibre intake gradually.
Tips for Using Supplemental Fibre
♦ Take fibre supplements on an empty stomach, away from medications and supplements. This is very important because the absorption of drugs and supplements will be reduced when taken at the same time as supplemental fibre. Soluble fibre has “sponge-like” qualities, which is great when it comes to absorbing toxins and bacteria, but unfortunately, the fibre will also absorb some of the substances we want to keep in our body. As a rule, take medications and supplements one hour before fibre supplementation or two hours after. The exception to this rule is in the case of prebiotic oligosaccharides, which actually increase the absorption of minerals from food.
♦ Start with a small dose of fibre and work your way up to a higher dose as needed, this will prevent or minimize the undesirable side effects (flatulence, bloating, diarrhea, constipation, abdominal fullness) which may occur when fibre intake is increased abruptly.
♦ Always drink plenty of water when you increase the amount of fibre in your diet. Drinking enough water will reduce any uncomfortable symptoms that may occur with increased fibre intake. Without adequate fluid intake the likelihood of gas, bloating, and constipation occurring is increased.
♦ It is important to get your intake of fibre from a variety of sources. Not one type of fibre will give all the benefits. We need a good balance of insoluble, soluble, and fermentable fibres.
♦ Fibre intake should be spread out throughout the day if you want it to do its job properly. Try balance out your intake of high-fibre foods across your meals and if you take a supplement, have it near your lowest fibre meal.
- Claude Remacle, Brigitte Reusen, Functional Foods, Ageing and Degenerative Disease
- Schely pD, Field CJ, The Immune-enhancing effect of dietary fibres and prebiotics, Br J Nutr. 2002 May;87 Suppl 2:S221-30
- Abrams SA, Griffin IJ, Hawthorne KM, Liang L, Gunn SK, Darlington G, Ellis KJ. A combination of prebiotic short- and long-chain inulin-type fructans enhances calcium absorption and bone mineralization in young adolescents. American Journal of Clinical Nutrition 2005; 82:471-6.
- The Fiber Manifesto – www.thepaleomom.com
Fibre – Why it Matters More Than You Think – www.experiencelife.com
- Glucomannan – drugs.com
- Ray Sahelian, Fiber supplement benefit, food source, diet, and side effects
- Fibre – Linus Pauling Institute – Micronutrient Information Centre