The best sources of fiber are ordinary plant-based foods: whole grains, legumes, vegetables, berries, fruits, nuts, and seeds. Getting enough fiber usually does not require a special diet, but rather combining several fiber-rich foods across different meals throughout the day.
Adults should aim to get around 25–35 grams of fiber from food each day. Many people consume less than this, even though fiber intake can be increased quite easily, for example by replacing refined grain products with whole-grain alternatives, eating legumes regularly, and adding berries, vegetables, and seeds to familiar meals.
What is fiber and why do we need different sources?
Dietary fiber is a type of carbohydrate found in plant-based foods that human digestive enzymes do not break down in the same way as ordinary carbohydrates. Fiber passes into the large intestine, where some of it serves as food for gut microbes and some increases the bulk of intestinal contents.
Fiber is often divided into soluble and insoluble fiber. Soluble fiber binds water and can form a gel-like structure in the digestive tract. It is found in foods such as oats, barley, beans, lentils, fruits, and berries. Insoluble fiber, on the other hand, increases the bulk of intestinal contents and supports the movement of food through the digestive tract. Sources include whole grains, bran, nuts, seed hulls, root vegetables, and many other vegetables.
Most plant-based foods contain both types of fiber in different proportions. There is no need to calculate them separately, because a varied diet usually provides both soluble and insoluble fiber.
What are the best sources of fiber?
The best sources of fiber should not be judged solely by how much fiber a food contains per 100 grams. Typical serving size and how regularly the food is eaten also matter.
For example, bran and seeds can contain large amounts of fiber, but they are usually eaten in relatively small quantities. Vegetables often contain less fiber per 100 grams, but several hundred grams can be eaten over the course of a day.
For a high-fiber diet, the best sources are foods that are easy to use regularly as part of everyday meals.
1. Whole grains
Whole grains are one of the most important sources of fiber in the Finnish diet. Whole-grain products contain all parts of the grain kernel, which means they contain more fiber than comparable refined grain products.
Good sources of whole grains include:
- Oatmeal
- Rye bread
- Whole-grain pasta
- Barley
- Brown or whole-grain rice
- Whole-grain cereals
- Bran
Breakfast is an easy opportunity to increase fiber intake. Porridge can be made, for example, from gluten-free oats or from gluten-free hemp-oat porridge containing oats and hulled hemp seeds.
A bowl of porridge can be topped with berries, pieces of fruit, nuts, seeds, or a small amount of fiber-rich meal. This makes it possible to get fiber from several different sources in a single meal.
2. Beans, lentils, and peas
Legumes are excellent sources of fiber because they combine fiber, plant protein, and slowly absorbed carbohydrates.
Good options include:
- Green and red lentils
- Chickpeas
- Kidney beans
- Black beans
- White beans
- Fava beans
- Peas
Green lentils work well in soups, stews, salads, and vegetable patties. Lentils can also be used to replace part of the minced meat in dishes such as tomato sauces or casseroles.
Legumes should be added to the diet gradually if they have not previously been eaten regularly. This gives the digestive system time to adapt to the fermentable fibers they contain.
3. Berries and fruits
Berries and whole fruits are easy sources of fiber for breakfast, snacks, and desserts.
Fiber-rich options include:
- Raspberries
- Blackcurrants
- Redcurrants
- Gooseberries
- Cloudberries
- Pears
- Apples
- Oranges
- Plums
Fruit is generally better eaten whole rather than as juice. Whole fruit contains the fiber found in the flesh and often the peel, whereas juice contains considerably less fiber.
Frozen berries are a practical option throughout the year. They can be added to porridge, yogurt, quark, smoothies, or overnight oats.
4. Vegetables and root vegetables
Vegetables and root vegetables help complete the day’s fiber intake, even though their fiber content per 100 grams is not always as high as that of seeds, bran, or meals.
Good options include:
- Cabbages
- Broccoli
- Carrots
- Parsnips
- Beetroot
- Swede
- Corn
- Green peas
- Potatoes with the skin on
The importance of vegetables comes mainly from the fact that they can be eaten in large quantities throughout the day. Salads, grated vegetables, vegetable soups, roasted root vegetables, and vegetable-based sauces can help increase fiber intake without the need for separate fiber supplements.
Vegetables can also be added to familiar dishes. Grated carrot works well in bread roll dough, root vegetables in soups and oven dishes, and cabbage in stews and stir-fries.
5. Nuts and seeds
In addition to fiber, nuts and seeds contain unsaturated fats, protein, and several minerals. They can be used in porridge, yogurt, salads, baking, and snacks.
Good options include:
- Almonds
- Walnuts
- Hazelnuts
- Peanuts
- Flaxseeds
- Chia seeds
- Sunflower seeds
- Pumpkin seeds
- Sesame seeds
- Hemp seeds
The outer shell of a seed often contains a large proportion of its fiber. For this reason, whole seeds are generally higher in fiber than hulled seeds.
Whole hemp seeds work well in baking, muesli, porridge, and as a topping for salads. Hulled hemp seeds contain less fiber, but their soft texture makes them easy to add to smoothies, porridge, and warm dishes.
From a fiber perspective alone, whole seeds are the better choice. Hulled seeds, on the other hand, are a good source of protein and unsaturated fats.
6. Bran and fiber-rich meals
Bran and fiber-rich meals are concentrated sources of fiber. They can be used when you want to add a small amount of extra fiber to ordinary meals.
Options include:
- Oat bran
- Wheat bran
- Rye bran
- Flaxseed meal
- Seed meals
- Hemp meal
Hemp meal contains plenty of fiber and plant protein. It can be added to porridge, yogurt, smoothies, bread dough, vegetable patties, and soups.
Meals do not need to be used in large quantities. Even a small serving can help supplement daily fiber intake, but it does not replace whole grains, vegetables, berries, or legumes.
7. Hemp protein and other fiber-containing protein products
Not all protein powders contain significant amounts of fiber, but plant-based protein products can contain quite a lot.
For example, hemp protein contains plenty of fiber in addition to protein. It can be used in:
- Smoothies
- Porridge
- Yogurt
- Pancakes and crepes
- Bread roll dough
- Vegetable patties
Hemp protein does not have to be thought of only as a sports-related product. It can be used as an ordinary cooking ingredient when you want to add both plant protein and fiber to a meal.
Other sources of plant protein that contain fiber include pea protein, legume flours, and various seed flours. Fiber contents vary between products, so it is worth checking the nutritional information on the packaging.
How can you add more fiber to your diet?
It is better to spread fiber intake across different meals rather than trying to consume the entire amount at once.
Easy ways include:
- Replace white bread with whole-grain bread
- Choose whole-grain pasta instead of regular pasta
- Eat oatmeal for breakfast
- Add berries, seeds, or meal to porridge
- Use beans and lentils in soups and sauces
- Eat fruit whole instead of drinking juice
- Add vegetables to every main meal
- Choose fruit and a small portion of nuts as a snack
Fiber intake should be increased gradually, especially if the diet has previously contained only small amounts of whole grains, legumes, and vegetables. Increasing fiber too quickly can cause bloating, gas, or abdominal discomfort.
At the same time, it is important to drink enough fluids, because fiber binds water. Insufficient fluid intake can reduce the beneficial effects of fiber on bowel function.
Variety is more important than any single superfood
The best sources of fiber are not limited to a single food. Whole grains, legumes, vegetables, berries, fruits, nuts, and seeds complement each other and provide different types of fiber.
Fiber-rich meals, whole seeds, and plant-based protein products can be used to supplement the overall diet, but the foundation should consist of ordinary, varied plant-based foods.
In practice, the most effective way to increase fiber intake is to make a few lasting changes: choose whole grains instead of refined grain products, use legumes regularly, add vegetables to different meals throughout the day, and supplement porridge, snacks, or baking with nuts, seeds, or fiber-rich meals.
