Dietary fibre defined
Dietary fibre is a carbohydrate from plant sources that is resistant to digestion and absorption in the intestines (a.k.a. breakdown by digestive enzymes and mechanical food processing in the digestive tract). Most carbohydrates are broken down into sugar molecules that can be absorbed and used for energy. Fibre, however, passes through without being digested because the body does not have the enzymes needed to make these special carbohydrates absorbable.
Just because the fibre isn’t being digested and absorbed for energy doesn’t mean that it isn’t helping in other ways. The fibre is fermented by the microbes that live in our digestive system and provides bulk to form stool which keeps things moving along. In fact, there are all sorts of benefits of eating fibre that we’ll review later.
Types of fibre: Soluble vs. insoluble
Fibre is classified based on its solubility in water, so the two types of fibre are called soluble and insoluble. There are benefits that are more specifically attributable to each type of fibre, but many foods contain both types of fibre in varying amounts.
What happens to fibre in the digestive system?
Soluble Fibre
- Absorbs water and forms a gel.
- The body can absorb some calories from soluble fibre, but much less than simple carbohydrates like table sugar or white bread.
- The microbes in the large intestine ferment soluble fibre as it passes through the later stages of digestion
Insoluble Fibre
- Does not absorb water.
- The body does not absorb any calories from insoluble fibre.
- Provides bulk to stool allowing for elimination to be easier and more comfortable.
What are good sources of fibre?
Soluble fibre
- Grains like oats and whole wheat
- Legumes and pulses (dried edible seeds) like kidney beans and lima beans
- Vegetables like raw cauliflower, eggplant, beets and celery
- Fruits like plums, strawberries, mango, and peach
- Nuts and seeds like flaxseeds and almonds
Insoluble fibre
- Grains like barley, wheat germ, oatmeal and whole wheat
- Legumes and pulses (dried edible seeds) like peas, kidney beans, white beans and lentils
- Vegetables like broccoli, carrot, beets, spinach, turnips and green onions
- Fruits like kiwi, unpeeled apple, pear and pineapple
- Nuts and seeds like flax, sesame seeds, almonds, walnuts, or sunflower seeds
- When comparing the good sources of soluble and insoluble fibre, you may have noticed that there are some repeated foods across both types. This is because most plant foods contain both types of fibre in different ratios. While the types of fibre are divided from a nutrition science standpoint, the main thing that you should strive for is the overall amount of fibre, soluble and insoluble that you eat each day.
The health benefits of fibre
Higher intake of dietary fibre is associated with a lower risk of certain health conditions. These health benefits exist because of the various functions of fibre.
Here’s a quick summary:
- Adds bulk to the diet (and stool) which can help reduce appetite for weight management, support regularity and prevents constipation.
- Forms a gel in the intestines, trapping less desirable nutrients (like simple carbohydrates and fat) which may help to keep blood glucose steady and reduce cholesterol.
- Promotes optimal pH in the intestines and speeds passage of food through the digestive system.
- Fermented by healthy bacteria in the digestive system to support the microbiome which may support everything from mood to reducing inflammation.
How can you increase your fibre intake
With all those health benefits, you’re probably already trying to think of ways to get more fibre into your diet! Here are a few ideas to get you started:
- Add beans, peas or lentils to anything you can. Having a salad, throw in some chickpeas. Making nachos, don’t forget to sprinkle on some black beans. Indulging in chili, throw in some kidney beans to chili. This will make your meals more filling and nutritious.
- Go for convenience. If you are more likely to eat the pre-cut pineapple from the grocery store than the whole one that will sit on your counter because you don’t feel like dealing with the mess, buy the pre-cut. Keep a tray of cut veggies in your refrigerator for quick snacking.
- Keep a delicious veggie soup in your refrigerator for a quick snack or lunch.
- Experiment with new ways of preparing veggies for dinner. Frozen green beans with butter is a fine way to eat a veggie, but it can get boring. There are endless ways to prepare vegetables, from roasting to preparing with culturally-inspired sauces. You can even find some recipes to keep things interesting.
- Trade up to whole wheat breads and pastas.
- Sprinkle some flaxseeds on your yogurt. Flaxseeds are an incredible source of fibre, so load up on these tiny seeds for giant benefits.
Start slow when increasing fibre intake. Coming too strongly out of the gate can result in gas and discomfort. It’ll only take a couple of weeks to get your digestive system primed and ready to handle all of that health-promoting fibre.
Also read: How to spot hidden sugars
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