What it is?
Did you know dietary fibre is not a single fibre, rather it consists of many components and types of fibres that provide different benefits. Fibre is known for its beneficial effects on our bowel movements, however goes beyond just that.
When we eat foods that contain fibre, the fibre is not actually digested or absorbed, rather it stays intact in the intestine which impacts our digestion as well as stool formation. There are 2 main types of fibre that we’ll discuss, soluble and insoluble.
1. Soluble Fibre: This fibre is made of carbohydrates and will dissolve in water. This leads to a gel like formation from the absorption of water and helps soften our stools and slows our bowel movements. Soluble fibre will gets completely fermented in the large bowel and helps increase formation of Short Chain Fatty Acids (SCFA). SCFA are the food for the “good bacteria” in our intestine that helps maintain our intestinal homeostasis or environment. SCFA also have immunomodulating properties and help accelerate healing and regeneration of the intestinal walls as well as have anti-inflammatory activity. This will also lower the pH in our colon (making it more acidic) which helps stimulate the growth of beneficial microflora while inhibiting growth of pathogens. All good things that help our gut microbiota!
2. Insoluble Fibre: This fibre comes from plant cell walls and does not dissolve in water. Insoluble fibre helps bulk up the stool and helps soften stools to make them easier to pass as it helps food move more quickly through GI tract. This fibre tends to be used for treatment of constipation.
Why we need it?
Both types of fibres have very important roles that go beyond our poops! Increasing intake of fibre has been shown to:
– Decrease risk of heart disease, stroke, and type 2 diabetes
– Reduces systemic pressures (impact on blood pressure)
– Helps reduce total cholesterol levels and hyperglycemia in patients with impaired glucose tolerance
– Soluble fibre specifically reduces total cholesterol and LDL (“bad” cholesterol)
– Improves insulin sensitivity
– Reduces systemic inflammation
There have also been multiple studies completed linking higher intakes of dietary fibre with decreased risk of colonic adenomas and colon cancer. World Cancer Research Fund found that for every 10 gr per day increase in fibre consumption there was a significant reduction of colon cancer risk by 10%. This sounds amazing right! Yes, except there are limitations to the study and to the amount of fibre that we can consume, as excess amounts of fibre (over 70 gr/d) can lead to major side effects and can impact the absorption of other important vitamins and minerals.
Another study showed a possible mechanism for fibres role in reducing colon cancer through its impact on our gut microbiota, particular a bacteria called Fusobacterium Nucleatum (FBN) which appears to play a role in stimulating colorectal carcinogenesis. Higher long-term intake of dietary fibre was associated with a lower risk of FBN positive colorectal cancers.
However, there are many OTHER components of our diet that will impact our risk of cancer and other diseases.
Recommendations
So where does that leave us…
We should be eating more high fibre foods, such as fruits, vegetables, and whole grains! Aim to have fibre coming from whole plant sources as this will provide other important micronutrients. Increase intake of soluble fibre to help with diarrhea and constipation. Soluble fibre may be easier to digest compared to insoluble fibre and may cause less bloating and cramping with increased intake.
Recommended intake:
– Adults: 20-35 gr/d
– Children (2yrs and older): 5-20 gr/d + age. Up to max of 30 gr/d
– Optimum intake of fibre for toddlers under the age of 2 is unknown
High intake of fibre can also have side effects including bloating and gas. If you are not regularly consuming fibre start small and build up amount of fibre consumed daily.
Sources
Soluble Fibre: ground Flaxseed, tofu, lentils, okra, green beans, collard greens, berries, kiwi, sweet potato, squash, quinoa, oatmeal, seaweed, apple, citrus fruits
Insoluble Fibre: whole what flour, wheat bran/wheat germ, nuts, beans, cauliflower, green beans, potatoes, fruits with skin
*see attached for full list of high fibre foods