Dietary fiber, also known as roughage or bulk, is the part of plant-based foods that your body can't digest or absorb. Unlike proteins, fats, and carbohydrates, which your body breaks down and absorbs for energy, fiber passes through your digestive system largely intact.
What are the benefits of dietary fiber?
Dietary fiber offers numerous health benefits:
- Promotes digestive health: Fiber adds bulk to your stool, making it easier to pass and preventing constipation. Mayo Clinic highlights this benefit, stating that fiber "supports the movement of material through the digestive system and adds bulk to stool."
- Helps manage weight: Fiber makes you feel fuller for longer, reducing overall calorie intake and aiding in weight management. MedlinePlus emphasizes fiber's role in weight control: "Fiber helps control your weight by making you feel full faster."
- Reduces the risk of chronic diseases: Studies consistently link high-fiber diets to a lower risk of heart disease, type 2 diabetes, and certain types of cancer. Eufic notes that "Fibre-rich foods such as fruits, vegetables and whole grains have been consistently shown to benefit our health and reduce our risk of disease."
Types of Dietary Fiber
Fiber is broadly categorized into two types:
- Soluble fiber: Dissolves in water, forming a gel-like substance that can help lower cholesterol and blood sugar levels. Examples include oats, barley, apples, and beans.
- Insoluble fiber: Doesn't dissolve in water and adds bulk to the stool. Examples include wheat bran, vegetables, and whole grains.
Sources of Dietary Fiber
Excellent sources of dietary fiber include:
- Fruits (berries, apples, bananas)
- Vegetables (broccoli, spinach, carrots)
- Whole grains (brown rice, oats, quinoa)
- Legumes (beans, lentils)
- Nuts and seeds
The composition of fiber varies depending on the plant source. Wikipedia notes that dietary fiber consists of "non-starch polysaccharides and other plant components such as cellulose, resistant starch, resistant dextrins, inulins, lignins," among others. ScienceDirect further specifies that dietary fiber is defined as "plant polysaccharides and lignin, which are resistant to hydrolysis by digestive enzymes in man." The recommended daily intake is generally between 25 to 35 grams, but most people consume significantly less. Harvard's Nutrition Source points out this discrepancy: "Children and adults need at least 25 to 35 grams of fiber per day for good health, but most Americans get only about 15 grams a day."
