What Are the Facts?
Fiber is found only in plants. It is from the plant cells, particularly the cell walls. The plant fiber that we eat is called dietary fiber. It is unique from other components of the plant because humans lack the enzymes necessary to digest it.
Dietary fiber is made up of two types of fiber: soluble and insoluble. Soluble means that when the fiber is mixed with a liquid, it forms a gel-like solution. Insoluble fiber does not mix with liquid and passes through the digestive tract largely intact. Both types of fiber help maintain bowel regularity.
Diets high in fiber have been associated with reduced risk of death due to cardiovascular disease (including heart attack and stroke), cancer, obesity, and type 2 diabetes.
Soluble Fiber
When eaten as part of a low-fat, low-cholesterol diet, soluble fiber can help lower cholesterol and may help lower your risk cardiovascular disease. Examples of foods high in soluble fiber include oatmeal, beans, peas, and citrus fruits.
Insoluble Fiber
Insoluble fiber is important for normal digestive health. Insoluble fiber speeds up movement through the small intestine and helps to alleviate
constipation. Foods that are high in insoluble fiber include apple skin, wheat cereal, whole-wheat breads, and carrots.
How Much Fiber Do I Need?
The Academy of Nutrition and Dietetics recommends that women consume 25 grams of fiber daily, while men consume 38 grams. Fiber needs drop after the age of 50. Women older than 50 should consume 21 grams of fiber daily, and men should consume 30 grams daily. This includes both soluble and insoluble fiber. The following table lists how much fiber you can find in some common foods.
| Food |
Serving size |
Total Fiber
(grams)
|
Soluble Fiber |
Insoluble Fiber |
|
Vegetables
|
| Broccoli, cooked |
½ cup |
1.5 |
1 |
0.5 |
| Brussels sprouts, cooked |
½ cup |
4.5 |
3.0 |
1.5 |
| Carrots, cooked |
½ cup |
2.5 |
1 |
1.4 |
| Artichoke, fresh |
½ cup |
4 |
3 |
1 |
|
Fruits
|
| Apple |
1 medium |
4 |
1 |
3 |
| Banana |
1 medium |
3 |
1 |
2 |
| Blackberries |
½ cup |
4 |
1 |
3 |
| Nectarine |
1 medium |
2 |
1 |
1 |
| Citrus fruit (orange, grapefruit) |
1 medium |
2-3 |
1 |
1-2 |
| Peach |
1 medium |
2 |
1 |
1 |
| Pears |
1 medium |
4 |
2 |
2 |
| Plums |
1 medium |
1.5 |
1 |
0.5 |
| Prunes |
¼ cup |
3 |
1.5 |
1.5 |
|
Legumes
|
| Black beans, cooked |
½ cup |
5.5 |
2 |
3.5 |
| Kidney beans, cooked |
½ cup |
6 |
3 |
3 |
| Lima beans, cooked |
½ cup |
6.5 |
3.5 |
3 |
| Navy beans, cooked |
½ cup |
6 |
2 |
4 |
| Northern beans, cooked |
½ cup |
5.5 |
5 |
0.5 |
| Pinto beans, cooked |
½ cup |
7 |
2 |
5 |
| Lentils, cooked |
½ cup |
8 |
1 |
7 |
| Peas, cooked |
½ cup |
6 |
1 |
5 |
|
Whole grain cereals
|
| All Bran cereal |
1/3 cup |
8 |
0.7 |
7.3 |
| Oatmeal, cooked |
½ cup |
2 |
1 |
1 |
| Oat bran |
½ cup |
3 |
2 |
1 |
| Shredded wheat |
2/3 cup |
3 |
0.3 |
2.7 |
| Wheat germ |
2/3 cup |
8 |
1 |
7 |
| Pearl barley, cooked |
½ cup |
5 |
2 |
3 |
| Brown rice |
½ cup |
4 |
0.5 |
3.5 |
|
Seeds
|
| Psyllium seeds |
1 tablespoon |
6 |
5 |
1 |
Source: Journal of Family Practice. 2006;9:761-769