What does dietary fiber do and four reasons to eat more of it!

what does dietary fiber do, fibre

Dietary fiber is essential to our health. But fiber as a ‘nutrient’ is still under appreciated. I am sure you’ve heard advice to eat more fiber and seen the wealth of products on offer specifically to provide you with more fiber – fiber rich cereal, breakfast bars and so on. However, often times these marketing efforts also focus only on getting us also to eat more whole grains. This is great but it’s also limited. There is a whole other world out there in the category of fruit and vegetables! So what does dietary fiber do? Why is it good for us? What foods should we eat to get more fiber? What’s the difference between soluble and insoluble fiber? Read on to find out the answers!

What is Fiber?

Fiber is a type of carbohydrate. As carbohydrates are comprised of sugar molecules called monosaccharides (i.e. single sugar). So fiber is simply a string of sugar molecules. Fiber is specifically found in plant cell walls and provides the skeletal structure that gives the plant it’s shape. Humans cannot digest fiber and so it passes through our digestive tract largely intact. This is also what separates fiber from other carbohydrates which can be broken down by enzymes. But while enzymes can’t digest it, bacteria in our gut can in fact break down certain types of fiber and feed on it.

Fiber is divided into two groups; soluble and insoluble. The term soluble refers to the ability to dissolve in water so as the name suggests, soluble fiber can dissolve in water while the other type can’t. Within each category, there are many types of different fiber.

  1. Soluble Fiber: this fiber tends to be digested by bacteria in the gut and moves through your digestive system quite slowly. As it is digested, it ferments and so it can produce gas and by products. And example is pectin.
  2. Insoluble Fiber: Because it’s insoluble, insoluble fiber tends to move faster through our digestive systems. Some of these fibers can ferment and also produce gas and by-products. An example is cellulose.

This is probably the most common way to classify fiber. You can of course also look at fermentable and nonfermentable types.

what does dietary fiber do fibre

What Does Dietary Fiber Do?

Fiber provides a lot of benefits for the body. Soluble fiber is a great way to feed the bacteria in the gut. In this way, fiber is seen as a prebiotic. Soluble fiber, on the other hand, helps with gut motility and overall digestive health. There is no ‘better’ or ‘worse’ – both soluble and insoluble fiber are beneficial and should be consumed. The general guideline is to aim for 25-30g of fiber per day. From an optimal point of view, you can increaase to 40g.

Too Much Fiber?

As with anything, it is possible to over do it. As there is a close relationship between fiber and your gut bacteria, it makes sense that eating too much fiber (and also eating the wrong sources) can be not so good for your gut microbiome. These bacteria love to feed on fibre but given that most types are fermentable, too much (or too much of the wrong kind) can result in digestive issues like flatulence, bloating, diarrhea, constipation, acid reflux and cramps. These symptoms can also occur if introducing fiber too quickly into the diet. So just be careful to take it slow!

If you notice any of these symptoms, some ways to counteract include reducing fiber intake, trying a FODMAP approach, eating fermented foods, drinking lots of water and/or exercise. Please note that this blog post should not replace medical advice. Consult with a health professional before making any changes.

Four Reasons to Eat More Fiber

All in all, it is very unlikely that you are eating too much fiber. In fact, most people are seriously lacking and get only about 10-15g per day. To convince you that little bit more, here are three key reasons you need to get proactive with your fiber intake:

  • It’s great for your gut! As mentioned already, fibre
  • provides food for the bacteria in the gut. Not only does this keep them happy, but in the process of digestion bacteria product by products that benefit us. For example, Vitamin K and short chain fatty acids for energy.
  • It helps digestion: By keeping our bacteria happy, the nutrients that food provides can be better absorbed in the body. Not only that, but insoluble fiber helps to keep everything moving.
  • It helps with detoxification! Insoluble fiber mops up any by products of detoxification and helps to remove them. For example, excess cholesterol and estrogen are both removed in our stool.
  • It helps to prevent heart disease: Healthy Heart: Research is showing that fibre can help to keep triglycerides, blood pressure and cholesterol in check. All of this means we keep our heart healthy!

Sources of Fiber

  • Soluble: flaxseeds, nuts, beans, lentils, peas, berries.
  • Insoluble: brown rice, barley, most vegetables: root veg especially, broccoli, carrots, green beans

Is there any Fiber I should avoid?

Not all fiber is created equal. The types that you see in fortified packaged goods is not the same as that found in nature. As it is quite a popular term, manufacturers often use marketing tactics and slogans like ‘a great source of fibre’ so as to entice the consumer enough to buy. This also means we see fiber added to products where it naturally wouldn’t occur like yogurt, refined grain products like cereal and snack bars and even protein bars. Supplements too often contain artificial types of fibre that aren’t well processed by the body.

Spotlight on Buckwheat!

Buckwheat is a great source of dietary fiber. Technically a seed, buckwheat is also a good substitute for anyone who has a wheat or gluten intolerance. Aside from just finer, buckwheat also contains manganese, copper, magnesium and phosphorus along with others. One cup of buckwheat contains about 6g of fiber which helps to both fill you up and improve transit time. It can also be fermented to make products like sourdough and in this way also provide probiotic benefits.

A number of iRaw products contain buckwheat. Take your pick! They’re all delicious!

If you like something a little sweet….


what does dietary fiber do

what does dietary fiber do

And if you’re after the more savoury…

what does dietary fiber do

sunshine raw vegan crackers

So there you have it, the answer to the question “What does dietary fiber do?”.

Lyda Borgsteijn

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