What is Dietary Fiber?
Dietary fiber is a type of complex carbohydrate that is found in all types of plants, including whole grain, vegetables, fruits, and pulses. Unlike other carbohydrates (such as starch and sugars), fiber does not get enzymatically digested and absorbed in the small intestine. Instead, it passes relatively intact into the large intestine and colon – cleans our digestive system and feeds the friendly gut bacteria.**
Types of Dietary Fiber
Nutritionists commonly classify dietary fiber as either "soluble" or "insoluble". These terms refer to whether – or not – the fiber dissolves in our small bowel.
• Water-insoluble fiber: Insoluble fiber includes lignin, cellulose, and hemicellulose, which build up the structural parts of plant cell walls. Insoluble fiber does not dissolve but absorbs water as it moves through the digestive system. Some forms of insoluble fiber, such as resistant starches, can be fermented in the colon by gut bacteria (= "prebiotics"). Both, insoluble and soluble fiber promote gastrointestinal motility and regularity, supporting healthy bowel movements and help soften the stools by adding bulk. Water-insoluble fiber is found in whole grain wheat – as it includes bran, oats, corn, nuts, fruits, and vegetables (especially the skins).**
• Water-soluble fiber: Soluble fiber includes gums, pectins, mucilage, and glucomannan, which are dissolved in the digestive system into a gel-like material. Soluble fiber helps slow down the rate of digestion, promoting satiety, nutrient absorption, as well as healthy glycemic control, and is supportive of weight management. Furthermore, this fermentable fiber supports the microflora balance. When water-soluble fiber is broken down, short-chain fatty acids (SCFA) are produced. These by-products of the fermentation process are an important energy source for the colon and have protective effects for healthy colon cells. Good sources of water-soluble fiber include flaxseed, psyllium and oat bran.**
In general, the more natural and unprocessed the plant-based food, the higher it is in fiber. There is no natural fiber in dairy, meat, or sugar. Refined foods, such as white rice, white bread, cakes, and pastries have had all or most of their fiber removed.
Dietary Fiber and its Function
• Maintaining bowel health: Water-soluble fiber and some water-insoluble fiber function as prebiotics. That means that they support the growth of friendly bacteria needed to help maintain a healthy gut. Furthermore, by-products of the fermentation process (SCFAs) are an important energy source for the colon and have protective effects for healthy colon cells.**
• Stimulating healthy bowel movements: Fiber helps to bulk up the stools in the large intestine and pass it along the digestive tract more easily. Fiber also makes stools softer, which is a natural support for regular defecation.**
• Supportive for weight management: Fibrous foods take more chewing and are more filling, so you are likely to eat less and stay satisfied longer. Furthermore, fibrous foods tend to be less energy-dense, which means they have fewer calories for the same volume of food.**
• Supporting healthy glycemic control: Fiber helps regulate the body's use of sugars: Particularly soluble fiber can slow down the absorption of sugar and help regulate blood sugar levels.**
Dietary Fiber – What Should Be Considered?
To boost your fiber intake, go for whole grains for pasta and bread, brown rice, snack fruits, and include plenty of vegetables with meals. This healthy way to get more fiber not only provides fiber but also vitamins, minerals, and other beneficial nutrients.**
If you want to increase your fiber intake with an additional supplement, go slow. High-fiber foods are good for health, but increasing this essential nutrient too quickly can cause some uncomfortable side effects, like bloating, cramping, and gas. Increase fiber in your diet gradually over a few weeks. Also, be sure to drink plenty of fluids every day – consider that fiber works best when it absorbs water, making your stool bulky and soft. If you have intestinal problems, such as Crohn’s disease or a history of bowel blockage, ask your doctor before taking a fiber supplement.**
Also, consider that fiber supplements may interact with some medicines. They can impair the absorption of certain medications, such as carbamazepine (Epitol, Carbatrol, others), aspirin and others, and may require an adjustment in insulin or your medications if you have diabetes. If you are taking medications, check with your doctor or pharmacist before taking fiber supplements.
Dietary Fiber – How Much Do We Need?
The optimal dietary fiber intake depends on a person’s age and gender. The current Dietary Guidelines for Americans (by the USDA and HHS) recommend the following approximate daily amounts:
|Gender and age
||Dietary fiber, grams
- Dreher M.L.: Whole Fruits and Fruit Fibre Emerging Health Effects. Nutrients. 2018 Dec; 10(12): 1833.
- https://health.gov/dietaryguidelines/2015/resources/2015-2020_Dietary_Guidelines.pdf . Access date: 2019/08/26
- https://www.hsph.harvard.edu/nutritionsource/carbohydrates/fibre/ . Access date: 2019/08/26
- https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fibre/art-20043983 . Access date: 2019/08/26
**These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.