Since fibre (fiber) plays a vital role in metabolism, it is important to understand the types of fibre, their characteristics and where to find good sources of fibre for a high-fibre diet. Fibre helps regulate blood glucose levels, may help lower the risk of heart disease, aids weight management, can suppress hunger and promotes bowel regularity. The American Heart Association recommends a daily fibre intake of 25–30 grams. The 2015–2020 US Dietary Guidelines recommend 14 grams of fibre per 1,000 calories consumed. There are two main types of fibre: soluble and insoluble.
Types of fibre
| Soluble fibre | Insoluble fibre | |
|---|---|---|
| What it does | Increases the water in the bowel and turns to gel during digestion to slow the digestive process, lowering cholesterol levels and increasing absorption of nutrients | Adds bulk to stools and increases the rate of stool formation |
| Choose it if you have | Loose stools, diarrhoea alternating with constipation, or incomplete stool production | Constipation |
| Common food sources | Oat bran, barley, nuts, seeds, beans, apples, oranges, grapefruit, vegetables | Wheat bran, flaxseed, vegetables, wholegrains, fruit with edible peel |
| Common fibre supplements | Citrucel®, Benefiber®, Fiber Choice® and Metamucil® | FiberCon® |
There are four characteristics of fibre
- Solubility: whether fibre dissolves in water.
- Viscosity: whether fibre thickens the liquid it is mixed in.
- Gel-forming: whether fibre holds liquid as it comes into contact with liquids.
- Fermentation: whether fibre is broken down by the body's natural bacteria (microbiome) in the gut.
Ways to increase fibre in your diet
- Include vegetables with meals
- Snack on fruit or nuts
- Choose wholegrains over refined grains
- Add chia or flaxseed to shakes
- Choose whole fruit and vegetables instead of fruit juice
- Add grains to salads
Fibre-rich foods and amount of fibre
Portions converted from US cup measures are approximate.
| Food | Portion | Fibre |
|---|---|---|
| Oat bran, raw | 28 g | 12 g |
| Wheat bran, raw | 28 g | 12 g |
| Corn bran, raw | 28 g | 22 g |
| Rice bran, raw | 28 g | 6 g |
| Fiber One bran cereal | approx. 30 g | 14 g |
| All-Bran cereal | approx. 30 g | 10 g |
| Fiber One chewy bars | 1 bar | 9 g |
| Lima beans, cooked | approx. 170 g | 14 g |
| Broad beans (fava), cooked | approx. 170 g | 9 g |
| Black beans, cooked | approx. 170 g | 15 g |
| Chickpeas, cooked | approx. 165 g | 12 g |
| Lentils, cooked | approx. 200 g | 16 g |
| Kidney beans, cooked | approx. 175 g | 16 g |
| Haricot (navy) beans, cooked | approx. 180 g | 19 g |
| White beans, small, cooked | approx. 180 g | 19 g |
| Pinto beans, cooked | approx. 170 g | 15 g |
| Raspberries, raw | approx. 125 g | 8 g |
| Blueberries, raw | approx. 150 g | 4 g |
| Strawberries, raw | approx. 150 g | 3 g |
| Blackberries, raw | approx. 145 g | 8 g |
| Amaranth, grain | approx. 50 g | 6 g |
| Barley, pearl, cooked | approx. 155 g | 6 g |
| Popcorn, air-popped | approx. 25 g | 4 g |
| Oats (rolled), dry | approx. 40 g | 4 g |
| Rye flour, dry | approx. 25 g | 7 g |
| Quinoa, cooked | approx. 185 g | 5 g |
| Wild rice, cooked | approx. 165 g | 3 g |
| Wholemeal flour, dry | approx. 30 g | 4 g |
| Brown rice, cooked | approx. 195 g | 4 g |
| Bulgur, cooked | approx. 180 g | 8 g |
| Wholemeal bread | 1 slice | 2 g |
| Wholemeal spaghetti, cooked | approx. 140 g | 6 g |
| Banana | 1 medium | 3 g |
| Pear | 1 medium | 6 g |
| Orange | 1 medium | 4 g |
| Apple | 1 medium | 4 g |
| Prunes, dried | approx. 85 g | 6 g |
| Raisins | approx. 40 g | 2 g |
| Peaches, dried | approx. 40 g | 3 g |
| Figs, dried | approx. 75 g | 8 g |
| Kale, cooked | approx. 130 g | 3 g |
| Cauliflower, cooked | approx. 125 g | 5 g |
| Broccoli, cooked | approx. 155 g | 5 g |
| Brussels sprouts, cooked | approx. 155 g | 6 g |
| Red cabbage, cooked | approx. 150 g | 4 g |
| Courgette, cooked | approx. 180 g | 3 g |
| Acorn squash, cooked | approx. 205 g | 9 g |
| Spaghetti squash, cooked | approx. 155 g | 2 g |
| Almonds | 28 g | 4 g |
| Pistachios | 28 g | 3 g |
| Cashews | 28 g | 1 g |
| Peanuts | 28 g | 2 g |
| Walnuts | 28 g | 2 g |
| Brazil nuts | 28 g | 2 g |
| Sunflower seeds | approx. 35 g | 3 g |
| Pumpkin seeds | approx. 65 g | 3 g |
| Sesame seeds | approx. 35 g | 4 g |
| Flaxseed | approx. 40 g | 4 g |
Increase your fibre intake gradually, drink plenty of fluids and discuss your fibre goals with your bariatric dietitian.
Sources
- Dietary Guidelines 2015–2020. health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/appendix-7/
- NIH U.S. National Library of Medicine. MedlinePlus. Soluble and Insoluble Fiber. medlineplus.gov/ency/article/002136.htm
- Palmer S. The Top Fiber-Rich Foods List. Today's Dietitian. 2008;10(7):28.
This article is for general information only and does not replace personal medical advice. Always discuss your situation, blood test results and supplementation with your bariatric team or healthcare provider.