What are dietary fibers?

Dietary fibers are the indigestible components of plant foods in the diet. They consist mainly of polysaccharides such as cellulose, hemicellulose and pectin. They are primarily known to support the digestive system, but they have many other positive effects on the human body.

What types of dietary fiber are differentiated between?

A basic distinction is made between soluble and insoluble dietary fibers, which are contained in various foods:

Soluble dietary fiber: These dissolve in water and form a kind of gel. Soluble fibers include pectin (found in foods such as apples and citrus fruits), inulin (found in foods such as chicory and artichokes) and guar gum. Soluble fiber slows down the digestive process and also helps regulate blood sugar and cholesterol levels.

Insoluble dietary fiber: Cellulose (in foods such as wholegrain products and vegetables) and lignin (in foods such as root vegetables and wholegrain cereals) enter the digestive tract unchanged and promote gut health by supporting a healthy microbiome, as they serve as food for healthy bacteria in the gut. This also increases stool volume and prevents constipation.

How does dietary fiber support general health? 

Dietary fiber supports intestinal health by promoting a healthy gut microbiome. This is because dietary fiber is primarily food for beneficial intestinal bacteria. A healthy microbiome in turn has a positive effect on general health. A diet rich in fiber is therefore essential for general well-being. In addition, insoluble and soluble fibers slow down the absorption of sugar from the intestine into the blood and thus regulate blood sugar levels [1]. At the same time, insoluble and soluble fibers bind so-called bile acids in the intestine. Bile acids are substances that are formed in the liver from cholesterol. By promoting their excretion, they stimulate the liver to use cholesterol to produce new bile acids. By lowering the cholesterol level [2], this also reduces the risk of cardiovascular disease [3]. Another effect: a high-fiber diet influences the feeling of satiety and can therefore also help to reduce calorie intake [4].

Which foods are particularly high in fiber?

There are many different plant-based high-fiber foods that should be part of a healthy diet: 

• Fruits: Apples, oranges, bananas, berries
• Vegetables: Carrots, broccoli, Brussels sprouts, spinach
• Pulses: Beans, lentils, chickpeasVollkornprodukte: Vollkornbrot, Haferflocken, brauner Reis
• Nuts and seeds: Almonds, chia seeds, flaxseed

What is the recommended daily intake of dietary fiber?

The German Nutrition Society (DGE) recommends a daily intake of at least 30 grams of fiber in the diet for adults. A high-fiber diet is important to reap the many health benefits, such as promoting digestive health, regulating blood sugar levels, lowering cholesterol and aiding weight control.

Dietary fiber intake by age group and gender

• Adults: At least 30 grams of fiber per day
• Children and adolescents: The recommended amount varies depending on age. Children aged 1 to 4 years should consume about 10-14 grams of fiber per day, while older children and adolescents need up to 25-30 grams per day. Guide values: 10 + 1 gram per year of life (up to 15 years) as a general rule of thumb.

Four simple tips for integrating high-fiber foods into your diet

Whole grain products instead of refined foods: Instead of wheat pasta or bread, opt for pasta and bread made from high-fiber wholemeal flour; instead of white rice, opt for brown, unprocessed rice.

Fruit and vegetables as a snack between meals: When you get a craving between meals, which snacks do you reach for? Instead of fruit gums, cookies or chocolate, reach for high-fiber foods such as apples, pears, carrots and co.

Eat pulses several times a week: Beans, lentils and peas are not only excellent sources of vegetable protein, but are also extremely high in fiber.

Don't forget nuts and seeds: Almonds, chia seeds and linseed are high-fiber additions to meals and snacks - for example in your morning muesli or salad.

Two tips to make dietary fiber better tolerated

Do not increase your intake of high-fiber foods suddenly, as this could lead to digestive problems such as flatulence and abdominal cramps; make sure that your body gets used to the change in diet slowly.

Drink plenty of water, as fiber needs a lot of liquid to be digested properly.

Sources 

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5883628/

[2] https://pubmed.ncbi.nlm.nih.gov/9925120/

[3] https://www.health.harvard.edu/heart-health/eat-more-fiber-rich-foods-to-foster-heart-health

[4] https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1110748/full