Fibre is the part of plants that is resistant to digestion and absorption in the small intestine. When we eat plants or plant-based foods, some parts are broken down entirely and absorbed by the body, but fibre passes through the small intestine to the large intestine, where it is either completely or partially fermented.
You will find fibre in everything from corn and cashews to broccoli and baked beans. But additional fibre, such as Hi-Maize, is added to up the fibre in breads, breakfast cereals, drinks and yoghurts.
incorporating more fibre into a diet
Because fibre adds bulk, it helps create softer stools that are easier to pass; preventing or relieving constipation. But a high fibre intake can also help prevent the development of diverticulitis – the development, infection and possible rupture of small, bulging pouches of tissue that press outward from the bowel wall.
Although The National Health and Medical Research Council recommends the fibre intake amounts listed (see below) as adequate for general health, there are also additional recommendations for chronic disease prevention. These are called suggested dietary targets (SDT) and are higher than the adequate intakes shown. To help prevent chronic disease, the SDT to aim for are 38g/day for males and 28g/day for females.
What’s an adequate intake (AI) of fibre?
|Gender and age||Adequate intake (grams)|
|Boys and girls 1-3 years||14|
|Boys and girls 4-8 years||18|
|Boys 9-13 years||24|
|Girls 9-13 years||20|
|Boys 14-18 years||28|
|Girls 14-18 years||22|
|Men 19+ years||30|
|Women 19+ years||25|
A week’s worth of ways to boost your fibre
Monday: Add 30g mixed nuts to your yoghurt (total fibre: 2g).
Tuesday: Sneak 30g bran or LSA (linseed, sunflower seeds and almonds) into your smoothie (total fibre: 6g).
Wednesday: Serve your stir-fry with 1 cup brown rice instead of white rice (total fibre: 3g).
Thursday: Add a small tin of kidney beans or chickpeas to your salad (total fibre: 6g).
Friday: Add blueberries (100g) to your breakfast cereal (total fibre: 4g).
Saturday: Eat wholegrain bread instead of white bread (total fibre: 5g).
Sunday: Add 1 cup cooked broccoli to your evening meal (total fibre: 7g)
If you’re planning to switch to a high-fiber diet, remember to do it gradually to give your body time to adjust.
Abdominal discomfort, cramps and even diarrhea are common side effects if you ramp up your fiber intake too quickly.
Thoughts on fibre supplements (are they necessary?)
There’s no evidence that daily use of fiber supplements — such as psyllium or methylcellulose — is harmful. It’s best to get fiber from food, because supplements don’t provide the vitamins, minerals and other nutrients that fiber-rich foods do. But fiber supplements can contribute to the recommended daily intake.
Fibre supplements are mostly ineffective for weight loss, with the exception of a powerful type of fibre called glucomannan. Getting your fiber from whole plant foods is the best and healthiest approach.
Fiber supplements can decrease the absorption of certain medications and can also reduce blood sugar levels, which may require an adjustment in your medications or insulin if you have diabetes.
Fiber supplements can help treat constipation, including for those who have chronic constipation or IBS (21).
This is because fermentable fiber is used as food by the bacteria in your gut, resulting in the production of gases in your large intestine.
This could cause an increase in gas production in your gut, which might make your symptoms worse.
Examples of soluble fiber supplements include:
- Psyllium:Psyllium husk and Metamucil
- Methyl cellulose:Citrucel
- Glucomannan:Glucomannan capsules or PGX
- Inulin:Benefibre, Fiber Choice or Fibersure
- Partially hydrolyzed guar gum:Hi-Maize
- Wheat dextrin:Benefiber
Psyllium is often considered to be the best choice.
How fibre can help with weight loss.
Diets high in fiber may protect against unwanted weight gain via several mechanisms that involve effects on satiety and glucose and insulin responses.
- Slows digestion and absorption of food
Fibre can help lower a food’s glycaemic index (GI), and low-GI foods give you sustained energy. High-fibre, low-GI foods also keep you feeling full, making you less likely to overeat at your next meal.
Fibre May Reduce Your Appetite, Helping You Eat Less Without Trying
While I don’t believe that counting calories is necessary, it is a simple fact that we need to be in calorie deficit to lose weight.
That is, more calories (energy) need to be leaving the body than entering it.
Anything that reduces our appetite can make us take in fewer calories without having to think about it.
Fiber is often believed to have this effect… that is, making us feel more satiated so that we eat less.
However, according to the evidence, only a specific type of fiber does this.
- Balances ‘good’ and ‘bad’ gut bacteria
Prebiotics are natural types of fibre that stimulate the growth of probiotics such as bifidobacteria, ‘friendly’ bugs that research links to good health. Wheat, garlic and onion contain the prebiotic fibre inulin.
The Good Bacteria Help Fight Inflammation, a Key Driver of Obesity and Disease
Gut bacteria have long been known to have an effect on inflammatory pathways (10).
They produce nutrients for the body, including short-chain fatty acids that feed the cells in the colon.
- Ferments to produce short-chain fatty acids
Short-chain fatty acids keep the colon lining healthy by fuelling its cells and promoting blood flow. They also help the body absorb minerals, enhance fat and glucose metabolism in the liver, and have anti-diarrhoeal and anti-inflammatory properties.
- Removes waste
Fibre absorbs toxins and creates bulk in the colon, thereby promoting the elimination of waste.
- Speeds up transit time of waste
During digestion, any fibre that remains intact and passes into the large colon adds bulk to your stool. This bulk is healthy, as it speeds up waste’s transit time in your colon and prevents constipation.