Dietary fiber is non-digestible carbohydrate that passes through the small intestine without digestion or absorption however, it passes through the large intestine with partial or complete fermentation.
Fiber is commonly classified as soluble and insoluble, depending upon its solubility in water. The amount of soluble and insoluble fiber varies in different plant foods.
Soluble fiber Sources
This type of fiber dissolves in water to form a gel-like material. It can help lower blood cholesterol and glucose levels. Soluble fiber is found in oats, peas, beans, apples, citrus fruits, carrots, broccoli, barley, and psyllium.
Insoluble fiber Sources
This type of fiber promotes the movement of material through your digestive system and increases stool bulk, so it can be of benefit to those who struggle with constipation or irregular stools. Whole-wheat flour, wheat bran, nuts, beans, and vegetables, such as cauliflower, green beans, and potatoes, are good sources of insoluble fiber.
Benefits of High Fiber Diet
- Fiber increases food volume by increasing the caloric content thus providing satiety.
- Fiber forms viscous gel which slows the emptying of the stomach, and forms shielding on carbohydrates which reduces blood sugar spikes by decreasing the release of sugar into the blood.
- Fiber reduces total cholesterol and LDL cholesterol, which may reduce the risk of cardiovascular disease.
- Fiber slows the digestion of carbohydrates, which reduces blood sugar and insulin spike in the blood and may lower the risk of diabetes.
- Fiber adds bulk to stool which relieves constipation.
- Fiber is necessary for healthy gut.
Recommended Fiber Intake
| Men (age 50 or under) | 38 g per day |
| Men (above 50) | 30 g per day |
| Women (age 50 or under) | 25 g per day |
| Women (above 50) | 21 g per day |
22 High Fiber Foods
| Food | Fiber per 100 g |
| Rye flour | 13.7 g |
| Barley flour | 12.8 g |
| Almond, raw, whole | 10.8 g |
| Whole wheat flour | 10.5 |
| Chickpea, boiled | 7.6 g |
| Mung bean, boiled | 7.6 g |
| Kidney bean, boiled | 6.4 g |
| Peas, boiled | 5.5 g |
| Broccoli, boiled | 3.3 g |
| Carrots, raw | 3.1 g |
| Pears | 3.1 g |
| Eggplant, raw | 3.0 g |
| Bitter gourd, raw | 2.8 g |
| Eggplant, boiled | 2.5 g |
| Apple with skin | 2.5 g |
| Spinach, boiled | 2.4 g |
| Cauliflower, boiled | 2.3 g |
| Potatoes, Baked with skin | 2.2 g |
| Bitter gourd, boiled | 2.0 g |
| Beet, boiled | 2.0 g |
| Tomato, red, ripe, raw | 1.2 g |
How to Boost Fiber Intake?
Switching from a low-fiber diet to a higher-fiber diet increases bloating (increased abdominal pressure). Dietary fiber is partially or totally fermented in the small intestine and colon, which leads to the production of gases. One way to prevent intestinal gas is to gradually increase the fiber in your diet.
Plant protein (beans, legumes, nuts, seeds, wheat, and soy) are rich source of oligosaccharides. Oligosaccharides are soluble and highly fermentable fiber that enhances gas production. Legumes contain soluble and fermentable fibers including resistant starch, pectin, guar gum, and inulin, which are moderate in gas production. The increase in bloating was reduced by substituting high-fiber sources of protein with high-fiber sources of carbohydrates.
Does Whole Foods Give Satiety?
Satiety is the satisfied feeling of being full after eating. The degree of refinement is related to more hunger and appetite. Eating a whole apple is more satisfying (thus high satiety) as compared to apple juice. Thus the onset of appetite is delayed after eating the whole apple.
Similarly, barley and oats give more satiety as compared to white flour. Both barley and oat contain β-glucan (a viscous soluble fiber) that enhances satiety. Viscous soluble fibers thicken in water, forming a gel-like substance that sits in the gut. Gel slows the emptying of the stomach, increasing digestion and absorption times. The result is a feeling of fullness and reduced appetite.
Viscous Fiber and Satiety
Viscous fibers include:
- Beta-glucan (found in oat, barley, rye, and whole wheat)
- Pectin (found in apples, citrus fruits, apricots, carrots, and plums)
- Guar gum
- Psyllium
All these fibers are viscous fiber and delay the emptying of the stomach thus producing satiety.
Source
[1] Reynolds, A. G., Mann, J., Cummings, J. H., Winter, N., Mete, E., & Morenga, L. T. (2019). Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet, 393(10170), 434–445. https://doi.org/10.1016/s0140-6736(18)31809-9
[2] https://fdc.nal.usda.gov/fdc-app.html#/food-search
[4] Zhang M, Juraschek SP, Appel LJ, Pasricha PJ, Miller ER 3rd, Mueller NT. Effects of High-Fiber Diets and Macronutrient Substitution on Bloating: Findings From the OmniHeart Trial. Clin Transl Gastroenterol. 2020 Jan;11(1):e00122.
[5] Slavin, J., & Green, H. (2007). Dietary fiber and satiety. Nutrition Bulletin, 32(s1), 32–42.
Leave a Reply