Soluble vs. Insoluble Fiber: Food Sources

soluble vs insoluble fiberDietary fiber is something that’s healthy. In this article, we take a closer look at the two types of fiber and compare them: soluble vs. insoluble fiber.

As good as fiber is for the body, it is something that the average person does not get enough of.

By breaking down the different benefits of the two types of fiber, along with listing foods that are high in soluble and insoluble fiber, we hope readers can better identify which foods to choose.

Table of Contents

 

What is it Fiber and Why do We Need it?

multi grain bread Fiber is a type of carbohydrate found in plants. But unlike most food components that our bodies digest, fiber can’t be digested by our bodies nor absorbed into our bloodstream.

Instead, fiber just passes through our digestive system.

This is why fiber helps keep us full without adding to our weight.

It has zero calories and our bodies doesn’t digest it, but while it passes through our digestive tract, it takes up space that keeps us feel full during that time. Space that we otherwise would need food in to keep us from feeling hungry.

Benefits of Fiber in Our Diets

Additionally, it keeps us feel full longer. Fiber slows down the rate at which food travels through our digestive system.

Together, these 2 factors help keep us away from food making them contribute in weight loss.

Since fiber is found in plants, most plant food sources contain fiber. These include vegetables, seeds, nuts and whole grains.

Aside from keeping us satisfied longer, fiber has also been shown to have numerous other health benefits.

According to the Department of Internal Medicine and Nutritional Sciences Program at the University of Kentucky:

High intakes of dietary fiber appear to be at significantly lower risk for developing coronary heart disease, stroke, hypertension, diabetes, obesity, and certain gastrointestinal diseases. Increasing fiber intake lowers blood pressure and serum cholesterol levels

When it comes to fiber, there are 2 types: soluble fiber and insoluble fiber.

 

Types of Fiber: Soluble vs. Insoluble Fiber

Soluble Fiber

grain productsSoluble fiber dissolves in water.

This component, when mixed with water turns into a gelatin-like substance and expands in size. This helps slow down the digestion process.

Slowing down digestion helps keep us full longer. This helps with weight management and loss since it takes longer to feel hungry again.

The slower digestion also allows nutrient absorption by the body to be more distributed instead of immediate. This helps keep our blood sugar levels from spiking from carbohydrates.

Psyllium which is one of the most common fiber supplement types is a type of soluble fiber.

Benefits of Soluble Fiber

  • Soluble fiber has been shown to helps reduce our cholesterol levels which lowers our risk of heart disease.
  • It also helps slow down the speed at which carbohydrates are absorbed by the body. In doing so I helps regulate blood sugar so that there are no sudden spikes that are harmful to our health.

The University of Oklahoma Health Sciences Center’s Department of Nutritional Sciences reviewed 77 studies done on soluble fiber and its relation to serum lipid levels. Of the total, 88% (68 studies) saw a reduction in total cholesterol levels and 84% reported reduction in LDL cholesterol levels.

Also,

The Medicine School and Hospital Rio Hortega of the University of Valladolid in Spain ran a study to see the effects of soluble fiber on lipid and glucose levels. During the study they noted that soluble fiber helped reduce LDL cholesterol by 12.8% while bringing down blood glucose levels 12.3%.

Food High in Soluble Fiber (Chart)

Fruits & Vegetables

  • Avocado
  • Grapefruit
  • Figs
  • Oranges
  • Sweet potato
  • Brussels sprouts
  • Broccoli
  • Pear
  • Edamame
  • Apples
  • Peas
  • Blueberries

Grain Products

  • Psyllium husk
  • Oat Bran
  • Oatmeal
  • Brown rice
  • Rye Bread
  • Rolled Oats
  • Barley
  • Whole Wheat Pasta
  • Bran Cereal
  • Wheat Bran

Nuts, Beans & Seeds

  • Navy beans
  • Lima beans
  • Black beans
  • Soy nuts
  • Kidney beans
  • Tofu
  • Garbanzo beans
  • Flaxseed
  • Lentils
  • Pinto beans

 

Insoluble Fiber

nuts seeds and oatsInsoluble fiber does not dissolve in water. Hence, the name.

It maintains its form as it goes through our digestive system. This type of fiber adds bulk to stool as it absorbs water as it passes through the body, and has a laxative effect that helps prevent constipation.

Because insoluble fiber does not dissolve in water it moves faster through the intestine helping food pass quicker through the digestive process.

Insoluble fiber is found in whole grains, seeds, nuts and vegetables.

Benefits of Insoluble Fiber

  • Insoluble fiber helps improve bowel movement and prevents constipation.
  • It has been show to help against colon cancer by keeping the pH in the intestines at good levels by helping move the cancer causing substances and toxins out of the body much quicker.

Food High in Insoluble Fiber (Chart)

Fruits & Vegetables

  • Apricots
  • Blueberries
  • Raisins
  • Grapes
  • Dried figs
  • Pear
  • Dried prunes
  • Raspberries
  • Strawberries
  • Artichokes
  • Oranges
  • Kale

Grain Products

  • Bulger
  • Brown rice
  • Couscous
  • Barley
  • Oat Bran
  • Oatmeal
  • Quinoa
  • Wheat Bran
  • Whole Grain Pasta
  • Pumpernickel Bread

Nuts, Beans & Seeds

  • Almonds
  • Flaxseed
  • Peanuts
  • Sesame seeds
  • Split peas
  • Sunflower seeds
  • Walnuts
  • Black beans
  • Kidney beans
  • Lentils

 

Which Type of Fiber Should You Eat? Should I be getting more soluble or insoluble fiber?

beansWhenever the topic of soluble and insoluble fiber comes up, the question of one being better than the other always follows.

Another follow up question often comes in the form of “should I get more soluble or insoluble fiber?”

When we start asking this question I think we are already over thinking things.

Soluble and insoluble fibers were created as classifications to define the composition of fibers in the foods.

With those being easily dissolved in water classified as soluble and those that aren’t easily dissolved in water as insoluble.

  • Soluble fibers are generally better for cardiovascular health, suppressing appetite and blood sugar regulation.
  • Insoluble on the other hand helps with food passage through the digestive system and helps prevent constipation.

Most foods that contain fiber have a combination of both soluble and insoluble fiber. They can’t be separated from one another. Some foods do have more of one type or the other though, so you can choose which foods to eat more of.

The overall idea with good health though is to get balance, with everything in moderation.

You can focus on one or the other if you have specific health issues you want to address like taking more soluble fiber to help with your high cholesterol levels or taking more insoluble fiber because you’re suffering from constipation.

But for regular daily health getting a good balance of both is what we’re after since they all work together to make one system, our body function well and make us feel healthy and good.

 

How much fiber should We Get?

mixedOften we’re told that:

  • The average male aged 50 and below needs 38 grams of fiber daily, and 30 grams of fiber after the age of 50.
  • For women, it’s 25 grams daily if you’re 50 and younger, and 21 grams for ages 51 and over.

Let’s take that a bit further because the figures are a bit of a simplification.

After all a person who’s 5’6” for example doesn’t need as much food, nor fiber as someone who’s 6’4”.

The figures listed above were based on 2,700 calories for men and 1,800 calories for women.

The U.S. Department of Agriculture (USDA) guidelines, explains this in more detail. Instead of the fixed numbers set above, the recommended daily intake is 14 grams of dietary fiber per 1,000 calories consumed.

This means that if you consume 2,000 calories a day, them aim for 28 grams of fiber.

This way you adjust based on your body mass and caloric requirements. There’s a bit of math involved but it offers a more accurate estimate custom to each individual.

The USDA further mentions that it estimates that the average American only gets 15 grams of fiber daily which is way short of the suggested daily intake.

To add to that, majority of the fiber from food comes from less than ideal food sources like breads, rolls, and even pizza. It also recommends inclusion of better sources of fiber like whole grains, seeds, nuts, beans, fruits and vegetables to increase daily dietary fiber intake.

 

Should You Take Fiber Supplements?

fiber supplementSince our diets often fall short of the healthy fiber requirements, what about fiber supplements?

Fiber supplements were developed by pharmaceutical companies where they isolate or extract fiber from plants or animals.

Today, supplements come in both tablet form as well as powder form that’s to be mixed in water.

Fiber supplements don’t have any taste and they’re odorless, making them easier to consume however it often takes a lot of them to get the needed daily requirements.

In general, fiber supplements have been shown to provide weight loss and other benefits provided by food based sources of fiber.

As long as you take them as prescribed and know their possible side effects (see below), using supplements has been shown to be relatively safe.

Nutritionists and health experts however, agree that getting fiber from food is the healthiest way to do so. It is a natural way to get dietary fiber plus you also benefit from the other nutrients present in the foods, including vitamins and minerals.

Other issues with using fiber supplements include:

  • They interact with some medication. Depending on the type of fiber used in the supplement, it may interact or interfere with the absorption of certain medications.
  • They can decrease absorption of vitamins and minerals. Other fiber supplements interfere with mineral absorption, for example guar gum reduces absorption rates of lycopene and beta-carotein when they are taken close to one another.
  • Getting too much fiber too soon. Part of using fiber supplements is learning how to use them and how much to take. Many individuals will just straight to the recommended serving which often leaves them feeling gassy and bloated. Starting with small amounts and gradually increasing it, along with increasing your water intake helps prevent the discomfort.

 

How Do Fiber Supplements Help with Weight Loss?

fiber for weight lossFiber from food has been shown to help with weight loss as well as improving risk factors for cardiovascular disease and metabolic syndrome.

Do fiber supplements do the same?

The question brings us to a few points of discussion. One being the the type of fiber used in supplements. Depending on the brand and manufacturer you buy from, you’ll probably be getting a different type of fiber.

Because the fibers are extracted or isolated from different plants and each brand uses different types of functional fibers in their supplement tablets, capsules or powders.

The type of fiber used makes a big difference on whether or not you get any health benefits.

One common functional fiber used in supplements in Psyllium:

The School of Public Health at the Curtin University of Technology in Australia ran a study where they divided overweight/obese adults into 4 groups, including a group that was given fiber supplements (psyllium), and another group that used a healthy diet plus fiber supplements.

After 12 weeks, weight, BMI and body fat percentages of the 2 groups supplemented with fiber showed significant reductions. Cholesterol and LDL cholesterol also dropped.

Taking fiber supplements improves both lipid profile as well as helps with weight loss. But eating healthy along with taking fiber supplements offer the best improvements.

In another study, glucomannan, guar gum and alginate were studied:

In a study done by the Institute of Clinical Medicine at the University of Tromsø in Norway. The 3 fiber supplements were tested on 176 men and women. The research team concluded that Glucomannan was able to cause a reduction in body weight whereas alginate and guar gum weren’t able to cause additional weight loss.

This leads us back to the use of fiber supplements in that choosing the right type of supplement brand and composition can make a difference between getting benefits from the supplementation or not.

Comparing the items on the store shelves before purchasing thus plays an important role here.

With food sources, on the other hand, there is no need to do so.