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Dietary fiber refers to the cell wall components in plants: namely, pectin, beta-glucans, hemicellulose, cellulose, lignin, fructans, and gums. All vegetables and fruits contain these dietary fiber components. The fiber content and composition, however, varies depending on the fruit or vegetable maturity, type, growing environment, etc.
Depending on the composition (proportion of pectin, hemicellulose, cellulose or lignin), the nutritional value and physiological effect of dietary fiber from vegetables or fruits can vary.
Vegetables harvested at younger growth stage are likely to contain higher pectin and hemicellulose (soluble fibers) and less cellulose and lignin (insoluble fibers) than when harvested at later growth stages. Generally, the concentration of the insoluble fiber components increases with maturity of the vegetable or fruit, where as the reverse is true to the soluble fiber components.
Dietary fiber can be partly digestible or completely indigestible by the bacteria in the colon. The dietary fiber components that are partly digestible include pectin, hemicellulose and cellulose. Lignin is not digestible at all by the bacterial enzymes in the colon. Lignin also lowers the digestibility of the other fiber components.
For good health, the National Cancer Institute and American Diabetes Association recommend routine consumption of high fiber foods. They suggest daily dietary fiber intake of 20 – 35 g per day. The USDA 2005 dietary guidelines recommend 5 to 9 servings of fruits and vegetables, and a minimum of 1.5 whole grain food servings (for babies of 2 -3 years old) per day. The number of all fiber food servings increases with age. For a person of 9 years and older, the recommended whole grain serving is 3 – 6 per day.
The following are examples of one dietary fiber servings.
Example 1: One fruit and vegetables fiber servings:
- a small glass of 100% fruit or vegetable juice (3/4 cup or 6 oz)
- a medium-size piece of fruit (an orange, small banana, medium-size apple)
- 1 cup of raw salad greens
- ½ cup of cooked vegetables
- 1/2 cup of cut-up fruit or vegetables
- 1/4 cup of dried fruit
- 1/2 cup of dried beans or peas
Example 2: Whole grain fiber servings :
- 1/2 cup cooked rice, pasta, or cooked cereal
- 1 ounce dry pasta, rice or other dry grain
- 1 slice bread
- 1 small muffin (weighing one ounce)
- 1 cup ready-to-eat cereal flake
Table 1: A list of good dietary fiber sources with estimates of their fiber content (listed high to low). The chart includes foods that are among the highest in fiber content from about 850 food products analysed by the USDA Nutrient Data Laboratory.
| Dietary fiber sources |
Fiber content in grams per 100 grams food |
| Cereals ready-to-eat, KELLOGG, KELLOGG'S ALL-BRAN Original |
29.33 |
| Bulgur, dry |
18.29 |
| Barley, pearled, raw |
15.60 |
| Oat bran, raw |
15.43 |
| Wheat flour, whole-grain |
12.17 |
| Beans, navy, mature seeds, cooked, boiled, without salt |
10.49 |
| Buckwheat flour, whole-groat |
10.00 |
| Beans, pinto, mature seeds, cooked, boiled, without salt |
9.01 |
| Beans, black, mature seeds, cooked, boiled, without salt |
8.72 |
| Peas, split, mature seeds, cooked, boiled, without salt |
8.32 |
| Dates, deglet noor |
7.98 |
| Lentils, mature seeds, cooked, boiled, without salt |
7.88 |
| Chickpeas (garbanzo beans, bengal gram), mature seeds, cooked, boiled, without salt |
7.62 |
| Beans, kidney, red, mature seeds, cooked, boiled, without salt |
7.40 |
| Cornmeal, degermed, enriched, yellow |
7.39 |
| Cornmeal, whole-grain, yellow |
7.30 |
| Cornmeal, self-rising, degermed, enriched, yellow |
7.10 |
| Lima beans, large, mature seeds, cooked, boiled, without salt |
7.02 |
| Beans, great northern, mature seeds, cooked, boiled, without salt |
7.01 |
| Beans, baked, canned, with franks |
6.91 |
| Cowpeas, common (blackeyes, crowder, southern), mature seeds, cooked, boiled, without salt |
6.51 |
| Cowpeas (blackeyes), immature seeds, frozen, cooked, boiled, drained, without salt |
6.41 |
| Beans, kidney, red, mature seeds, canned |
6.41 |
| Lima beans, immature seeds, frozen, baby, cooked, boiled, drained, without salt |
6.00 |
| Soybeans, mature cooked, boiled, without salt |
5.99 |
| Candies, semisweet chocolate |
5.89 |
| Lima beans, immature seeds, frozen, fordhook, cooked, boiled, drained, without salt |
5.82 |
| Peas, green, frozen, cooked, boiled, drained, without salt |
5.50 |
| Artichokes, (globe or french), cooked, boiled, drained, without salt |
5.42 |
| Refried beans, canned (includes USDA commodity) |
5.32 |
| Cowpeas (Blackeyes), immature seeds, cooked, boiled, drained, without salt |
5.03 |
| Couscous, dry |
5.03 |
| Lima beans, large, mature seeds, canned |
4.81 |
| Beans, white, mature seeds, canned |
4.81 |
| Soup, bean with ham, canned, chunky, ready-to-serve, commercial |
4.61 |
| Bulgur, cooked |
4.51 |
| Tomato products, canned, paste, without salt added |
4.50 |
| Chickpeas (garbanzo beans, bengal gram), mature seeds, canned |
4.42 |
| Raspberries, frozen, red, sweetened |
4.40 |
| Beans, baked, canned, with pork and sweet sauce |
4.19 |
| Beans, baked, canned, plain or vegetarian |
4.09 |
| Beans, baked, canned, with pork and tomato sauce |
3.99 |
| Chili con carne with beans, canned entree |
3.92 |
| Pears, asian, raw |
3.60 |
| Soup, bean with pork, canned, prepared with equal volume water, commercial |
3.40 |
Dietary fiber data source: USDA National Nutrient Database for Standard Reference, Release 18 (2005).
High fiber foods generally contain low contents of fat, especially saturated fatty acids, and cholesterol.
For health benefits of consuming high fiber fruits, vegetables and cereals, read this: Dietaty fiber food and health.
For more lists of dietary fiber sources and content, visit these pages:
Total dietary fiber, soluble fiber, insoluble fiber content of foods (vegetables, fruits, and nuts)
List of low fiber food sources
Dietary fiber: Daily Reference Intakes (DRIs) for fiber
Definitions of dietary fiber food
Diabetes management: Low carbohydrate diet --an overview
Diabetes management: carbohydrate restriction and weight loss
Diabetes management: Low carbohydrate diet and glycemic control
Diabetes management: Low carbohydrate diet , postprandial hyperglycemia and dyslipidemia
Diabetes management: Low carbohydrate diet, insulin resistance and hypertension
Diabetes management: Low carbohydrate diet -- conclusion
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