Eating foods high in fiber is important for promoting a healthy digestive system and reducing the risk of common chronic diseases such as heart disease, constipation, and colon cancer.

Although foods rich in these nutrients are associated with longer lives, lower rates of heart disease and cancer, and lower rates of obesity, most people do not meet their daily fiber needs.

What is fiber?

Fiber is a type of non-digestible nutrient found in plant foods. Unlike other nutrients, your body cannot digest or absorb fiber, so it passes through the small intestine into the large intestine intact.

Although fiber is indigestible, this nutrient plays an important role in health.

Generally, dietary fiber is classified based on its water solubility. Accordingly, there are two main types of fiber: soluble and insoluble.

Soluble fiber

Soluble fiber dissolves in water and can be fermented or broken down by gut bacteria, releasing gas and beneficial compounds called short-chain fatty acids (SCFAs).

Sources of soluble fiber include oats, fruits and legumes. There are different types of soluble fiber, each with different effects on health:

• Soluble, Viscous and Easily Fermentable Fiber: This fiber condenses in water and is easily fermented by gut bacteria. Examples include beta-glucan found in oats.
• Soluble, Viscous, Nonfermentable Fiber: This fiber condenses in water but resists fermentation. Examples include psyllium husks.
• Soluble, non-sticky, easily fermentable fiber: This fiber dissolves in water, but does not solidify. It is easily fermented by intestinal bacteria. Examples include inulin and wheat dextrin.

Insoluble fiber

Insoluble fiber does not dissolve and is poorly fermented by gut bacteria. This type of fiber passes through the digestive system properly. Insoluble fiber is concentrated in foods such as whole grains, nuts and seeds.

Most whole foods contain a mixture of insoluble and soluble fiber, but some are more concentrated in one than the other. Fiber supplements usually contain only one type of fiber, such as psyllium husk, which is a type of soluble fiber.

Why is fiber important?

Fiber is best known for its positive effect on the digestive system, but it also benefits health in other ways.

In a previous interview with Istanbul-based Al-Arabi, nutritionist Rola Allush explained that fiber is easy to digest and light in the gut, fights constipation, makes you feel full, and thus improves the health of the digestive system.

Improves digestive health

Both insoluble and soluble fiber help with regular bowel movements.

Insoluble fiber helps promote comfortable bowel movements, while soluble fiber attracts water to the stool, making it softer and easier to pass.

When gut bacteria ferment soluble fiber, they produce compounds called short-chain fatty acids (SCFAs), such as acetate and propionate, which positively affect gut health in several ways by feeding gut cells, regulating gut inflammation, and strengthening the gut lining.

Fiber-rich foods can help prevent and treat digestive conditions such as constipation and diverticulosis.

Reducing the risk of certain diseases

Eating a high-fiber diet can help reduce the risk of many health conditions, including colon cancer, heart disease, and type 2 diabetes.

Fiber is important for controlling gut inflammation, promoting a healthy body weight, and lowering cholesterol levels, all of which are needed to reduce disease risk.

Studies have shown that people who eat high amounts of fiber have a 21% lower risk of colon cancer compared to people who eat low amounts of fiber.

People who eat more fiber also live longer than people who eat less fiber.

Promote a healthy body weight

Fiber helps you feel full and satisfied after eating, which helps maintain a healthy body weight. Soluble fiber slows digestion and absorption of nutrients, helping you feel fuller for longer.

Diets associated with a healthy body weight, such as the Mediterranean diet and vegetarian diets, are rich in fiber-rich foods such as beans, vegetables, fruits and nuts.

Improve cholesterol levels

High cholesterol levels are associated with an increased risk of heart disease. A high-fiber diet can help increase blood lipid levels and protect the heart.

Fiber helps reduce the body’s absorption of fat and increases its excretion.

The most important foods that are rich in fiber

Fortunately, there are plenty of high-fiber foods that can help you meet your daily needs, and they fit into all kinds of diets.

• Vegetables: Mashed sweet potatoes, artichokes, steamed cabbage, collard greens and broccoli.
• Fruits: Avocado, guava, pear and all kinds of berries.
• Whole grains: quinoa, oats, barley, brown rice and teff.
• Nuts and seeds: chia, almonds, sunflower seeds, flaxseeds and pecans.
• Legumes: Lentils, black beans, chickpeas, white beans and cowpeas.
• Other high-fiber foods include: cocoa nibs, coconut flakes, psyllium husk powder, 80% dark chocolate, and whole grain bread.

How much fiber do you need per day?

Human requirements for fiber depend on gender and age.

The American Institute of Medicine (IOM) recommends consuming This amount of fiber Daily:

• One to three years: 14 grams for girls and boys.
• 4 to 8 year olds: 16.8 grams for girls, 19.6 grams for boys.
• 9 to 13-year-olds: 22.4 grams for girls, 25.2 grams for girls.
• 14 to 18 year olds: 25.2 grams for females, 30.8 grams for males.
• Ages 19 and 50: 25 grams for women, 38 grams for men.
• 51 years and older: 21 grams for women, 30 grams for men.