Diet and Nutrition

What Is Soluble and Insoluble Fiber?

What Is Soluble and Insoluble Fiber?

Key Takeaways

  • Fiber is a type of carbohydrate. 
  • There are two types of dietary fiber: soluble and insoluble. 
  • Fiber has a lot of health benefits not only for the gastrointestinal system but for the entire body. 

What is fiber?

Dietary fiber is a type of carbohydrate, but unlike other types of carbohydrates, it can’t be broken down into digestible carbohydrate molecules. For this reason, fiber gets through the gastrointestinal system relatively intact. However, while they pass through the gastrointestinal system intact, they do a lot of work.

Fiber is divided into two varieties: soluble and insoluble fiber. They both have an important role in the human body as they help work during digestion, weight management, cholesterol maintenance, and acts as a blood sugar regulator. When fiber is regularly included in your daily diet, it can decrease your risk of developing cancer. Many foods contain both soluble and insoluble fiber. However, their content may vary among other food types.

Good sources of fiber include:

  • Oatmeal
  • Blueberries
  • Apple
  • Barley
  • Beans
  • Lentils
  • Peas
  • Citrus fruits
  • Brown rice
  • Cauliflower
  • Wheat
  • Cucumber
  • Potato
  • Tomato
  • Nuts
  • Carrots

According to the National Academy of Medicine, women under the age of 50 should consume about 25 grams of fiber a day, while those who are over 50 years old must consume about 21 grams a day. Men below the age of 50 should consume about 38 grams of fiber a day, while those over 50 years old must consume about 30 grams a day.

Where does fiber in food come from?

A high-fiber diet is always healthy. Fiber, which should be a part of our daily diet, comes from plants. Fiber is divided into soluble and insoluble fiber, and they pass through the digestive system without breaking down into energy. Different types of food contain soluble or insoluble fiber, but oatmeal, for example, is rich in both types of fiber. Try to include as many high-fiber foods in your diet as possible.

Fiber in food mostly comes from vegetables, nuts, fruits, and whole grains. For example, fruits like apples or pears should be eaten along with their skin. When eaten unpeeled, these fruits are packed with insoluble fibers.

What is soluble fiber?

Soluble fiber dissolves in water. In the human body, soluble fiber dissolves and forms a gel-like substance. Soluble fiber is very beneficial for the human body as it helps decrease the levels of sugar in the blood and normalize blood cholesterol levels. Some types of soluble fiber are gum, pectin, and mucilage. Great sources of soluble fiber include beans, peas, citrus fruits, apples, blueberries, lentils, oatmeal, and citrus fruits.

The Health Benefits of Soluble Fiber 

  • Protection against diabetes As they are not well-absorbed in the human gastrointestinal system, they do not contribute into spikes of sugar in the blood, lowering an individual's risk of developing type II diabetes. In cases when a person is already diagnosed with diabetes, regardless if it is type I or type II diabetes, keeping soluble fiber as part of one's diet can help maintain blood glucose levels under control.
  • Protection against health diseases – Soluble fiber attaches to cholesterol particles and help eliminate them from the body. If cholesterol is eliminated regularly from the body, its levels will be lower. When cholesterol levels are within the normal range, the risk of developing various heart diseases including atherosclerosis, heart attack, and stroke is lower. Oatmeal is a great cardiovascular protector.
  • Helps lose extra pounds – High-fiber foods are low in calories. Soluble fiber helps stimulate the gastrointestinal system by increasing digestion and bowel movements. You will feel a lot better and you will be able to keep a healthy weight as you will easily feel full. If you feel full, you won’t have the need to eat and you won’t get hungry as quickly as when eating other types of food, which are not rich in fiber.
  • Maintains regular and healthy bowel movements – They soak in water from the body while they pass through the gastrointestinal system. This way, soluble fiber helps prevent constipation and diarrhea. The stool is also easier to pass through the system as fecal bulk is increased.

What is insoluble fiber?

Insoluble fiber does not dissolve in water. In the human body, insoluble fiber retains its shape and passes through the gastrointestinal system in an intact form. Insoluble fiber speeds up the passage of food through the digestive system, preventing constipation. Insoluble fiber makes the stool easier to pass through the gastrointestinal system, as they increase the fecal bulk. Great sources of insoluble fibers are potatoes, tomatoes, brown rice, cucumber, cauliflower, and wheat. Insoluble fiber is mostly found in seeds and fruit skin.

The Health Benefits of Insoluble Fiber

  • Helps lose extra pounds – Just like soluble fiber, insoluble fiber also prevents you from feeling constantly hungry while improving your digestive health and regular bowel movements.
  • Keeps the gastrointestinal system healthy – by preventing constipation, providing regular bowel movements, improve hemorrhoids, and fecal incontinence.

Foods High in Fiber That You Should Be Eating

As previously mentioned, high-fiber foods are very healthy and should be a part of your daily diet. Unfortunately, some people around the world do not get the necessary amount of fiber in their diet. As fiber possesses various health benefits, the high-fiber foods that you should be eating include:

  • Corn – any version of it from pink to black or blue is very healthy and packed with antioxidants. One ear of corn contains about 2 grams of fiber. If you prefer popcorn, it contains about 3.5 grams of fiber. Whenever you are looking for a snack, especially while watching a movie, choose popcorn over candies, cookies, and other sweet treats.
  • Whole wheat bread – is healthier than bread made from white wheat flour. Instead of buying white flour bread, choose whole wheat bread.
  • White beans – are not only rich in fiber, but they also contain high levels of iron, potassium, and proteins. The only problem with beans is excessive gas, but that should not stop you from eating white beans as they are very healthy.
  • Black beans – are not rich in fiber just like the white beans, but they also contain high levels of proteins and antioxidants. One cup of black beans contains about 15 grams of fiber.
  • Kidney beans – just like the other types of beans mentioned above, kidney beans are very healthy and beneficial for humans. They are not only rich in fiber but also have a high iron and protein content.
  • Avocado – a great tropical fruit is very helpful. Two tablespoons of avocado contain about 2 grams of fiber, while there are about 10 grams of fiber in one single avocado. Include avocado in your daily diet as it can be included in many dishes.
  • Whole wheat pasta – are healthier compared to regular pasta. They contain more fiber and in grocery stores, you can find different types of whole wheat pasta. Choose the ones you prefer and include them in your regular diet.
  • Brown rice – as you might have heard, brown rice is a much healthier choice than white rice. One cup of brown rice contains about 3.5 grams of fiber. According to a study from Harvard University, constantly eating white rice a couple of times a week significantly increases your risk of developing type 2 diabetes. However, when white rice is replaced with brown rice, the risk for type 2 diabetes is decreased.
  • Edamame – also called as immature soybeans are rich in fiber. A serving of only half a cup of edamame beans contains about 9 grams of fiber.
  • Lentils – a cup of lentils contains about 15.6 grams of fiber. Lentils are not just high in fiber, but they are rich in iron, vitamins, proteins, and other minerals.
  • Oatmeal – is very healthy as it contains a special type of fiber known as beta-glucan. Beta-glucan is very powerful when it comes to lowering the levels of cholesterol in the human body, which means that it has great protective effects on the heart and the entire cardiovascular system. Oatmeal due to beta–glucan is a great booster of the immune system as well. Oatmeal contains both soluble and insoluble fiber.
  • Pear – should be eaten with its skin. One medium-sized pear contains about 5.5 grams of fiber. Make sure to eat pears unpeeled.
  • Apples – just like pears, apples should be eaten unpeeled as their skin is rich in insoluble fiber. One medium-sized apple contains about 4.4 grams of fiber.
  • Raspberries – are high in fiber and antioxidants. They are superstars when it comes to nutrition benefits. Try to eat them as much as possible either fresh or frozen.
  • Artichoke – contains about 10.3 grams of fiber. It is also healthy due to the fact that it is rich in antioxidants, silymarin, and many other nutrients.
  • Peas – are foods high in fiber. One cup of peas contains about 16.3 grams of fiber. Regardless if they are fresh or frozen, peas should be a part of your high-fiber diet.
  • Broccoli – is a powerful superfood that belongs to the group of cruciferous vegetables. Only one cup of boiled broccoli contains about 5.1 grams of fiber. Broccoli is not only rich in fiber but it also possesses great anticancer properties.
  • Brussels sprouts – should not be excluded from your diet as they are a great source of fiber, proteins, vitamins, and other nutrients. There are different recipes that include Brussels sprouts as an ingredient.
  • Almonds – just like all the other nuts, almonds are very healthy due to many reasons. They are packed with fiber along with proteins and healthy fats. Eat almonds as a snack or include them in many dishes, especially in salads.
  • Chia seeds – are not just rich in fiber, but they are also rich in proteins, several vitamins, minerals, and omega-3 fatty acids. One tablespoon of chia seeds contains about 5.5 grams of fiber. Include chia seeds in your salads, smoothies, and other dishes based on your preference. The health benefits of chia seeds are incredible.

Foods Low in Fiber 

High-fiber foods are always recommended for a good overall health as they have various benefits. However, not everyone should consume high-fiber foods. In certain cases, fiber should be avoided when the gastrointestinal system needs to take a rest, especially for people diagnosed with Crohn’s disease. However, in other cases, foods low in fiber should be avoided. Foods that are low in fiber include:

  • Red meat – including beef, veal, lamb, and pork contain no fiber at all. In general, animal-based foods do not contain fiber, but they contain other health benefits. Normally, these foods should be a part of our diet, but should be combined with side dishes, which are packed with fiber.
  • Fish and seafood – like tuna, crab, shrimps, oysters, salmon, swordfish, and other types of fish contain no dietary fiber. Instead, they provide us with other vitamins, minerals, and proteins.
  • Eggs and poultry – including chicken, duck, and turkey contain no fiber at all. You won’t get any fiber from eggs as well. However, they have other health benefits. They contain high levels of vitamins, proteins, and minerals, including potassium.
  • Beverages - like water, tea, coffee, cranberry juice, different cocktails, and soft drinks do not contain fiber. On the other hand, fruit juices, smoothies, and all the other drinks that are rich in fruits or fruit pulp contain a variable amount of fiber.
  • Dairy products – such as yogurt, ice cream, sour cream, cheese, butter, and milk, do not contain fiber. However, they are rich in calcium, iron, potassium, phosphorus, vitamin A, and vitamin D.

Other foods that are low in fiber:

  • White rice
  • White bread
  • Plain white pasta
  • Canned vegetables
  • Well-cooked vegetables (as they lose most of their health benefits when cooked)
  • Dried fruits
  • Prune juice
  • Popcorn
  • Coconut
  • Seeds and nuts
  • Dried beans
  • Lentils or dried peas
  • Tofu

It is impossible to eliminate foods that are low in fiber from our diet as they have many other health benefits. However, it is still the best to consume a well-balanced diet, which contains both types of food, those high in fiber and those low in fiber for a better overall health.