Difference between Soluble and Insoluble Dietary Fiber
Dietary fiber is an essential component of a balanced diet. It is a type of carbohydrate that our body can’t digest like other carbohydrates. It is found in the plant foods such as cereals, pulses, fruits and vegetables. It is the edible part of the plant cell walls which is resistant to digestion.
Dietary fiber is of two types: soluble fiber and insoluble fiber. Both types are undigested which means they are not broken down and absorbed into the bloodstream. They simply pass through the entire digestive tract without providing calories or energy. However, they help you feel fuller after eating a meal containing fibers.
According to recent studies, both types of dietary fibers are good for health and should be included in the diet. The recommended fiber intake for adults is 20-35 grams per day. Let us see how soluble fiber differs from insoluble fiber:
Soluble Fiber:
Soluble fiber absorbs water in the stomach and intestine during digestion to form a gel-like substance which slows digestion. It is fermented by bacteria in the digestive tract which releasing gases and few calories. It helps soften stool so that it could easily pass through the gastrointestinal tract (GI). It also tends to bind to sugar and cholesterol thereby prevents or slows down their absorption into the bloodstream. Thus, it helps regulate blood sugar levels and also protects against heart diseases by lowering blood cholesterol. Furthermore, soluble fibers also help increase the population of good bacteria in the gut. Some of the scientific names for soluble fibers are pectins, gums, mucilage etc.
Sources of Soluble Fibers:
- Fruits: berries, banana, apple, pears etc.
- Root tubers: sweet potato, onions
- Vegetables: broccoli, carrot
- Legumes: peas, soybean, lentils
- Oats, oatmeal, etc.
Insoluble Fiber:
Insoluble fiber, which is commonly known as roughage, does not absorb water in the stomach and intestine. It remains more or less unchanged as it passes through the digestive tract. It is not fermented by the bacteria and does not provide calories or energy. Insoluble fiber adds bulk to the food which makes defecation easier. Thus, its presence in the food helps speed up the digestion and movement of food in the digestive tract thereby helps prevent constipation and gastrointestinal blockage. Cellulose and lignins are some of the scientific names for the insoluble fiber.
Sources of Insoluble Fibers:
- Whole grain foods
- Wheat and corn bran
- Legumes such as bean and peas
- Nuts and seeds
- Brown rice, whole-wheat pasta
- Green leafy vegetables
Benefits of Eating Dietary Fibers (both types):
- Help reduce food cravings by making you feel fuller
- Helps prevent diabetes by reducing the glucose absorption into the bloodstream
- Reduces the risk of varicose veins
- Reduces the chances of hormonal imbalances
- Boosts the immune system
- Reduces the risk of constipation and hemorrhoids
Based on the above information, some of the key differences between soluble and insoluble fibers are as follows:
| Soluble Fiber | Insoluble Fiber |
|---|---|
| It absorbs water in stomach and intestines during digestion. | It does not absorb water or any other gastrointestinal fluid in stomach and intestines. |
| It forms a gel-like substance in the digestive tract after absorbing water. | It remains unchanged while it passes through the digestive tract. |
| It is fermented by the bacteria. | It is not fermented by the bacteria. |
| It helps reduce blood sugar level. | It is vital for healthy digestion and helps lose weight. |
| It slows down the digestion. | It adds bulk and water to the stool. |
| It tends to slow the movement of food in the digestive tract. | It tends to increase the movement of food through the digestive tract. |
| Common sources include fruits like berries, banana, apple, pears; vegetables like broccoli, carrot; legumes like peas and lentils; oats etc. | Common sources include whole grain foods, brown rice, whole-wheat pasta, nuts, seeds and green leafy vegetables. |
| Scientific names for soluble fiber are pectins, gums, mucilage etc | Scientific names for insoluble fiber are cellulose, lignins etc. |