WHY FIBRE IS VITAL FOR GOOD HEALTH
WHAT IS FIBRE?
Fibre is a very broad term used to describe the various components derived from plant foods that confer health benefits.
In a nutshell, fibre is found in wholegrains, vegetables, legumes, fruits, nuts, seeds, fungi and sea vegetables, but let's take a closer look at the different types of fibres and the health benefits they exert.
Fibre is normally categorised into two main types - soluble and insoluble fibre, however there is considerable overlap in terms of solubility, fermentability and viscosity of fibres within these groupings.
Characteristics of fibre (O’Grady, O’Connor & Shanahan, 2019).
Soluble fibres are fermentable and include:
Inulin-type fructans such as inulin, fructooligosaccharides (FOS) or oligofructose, and are found in asparagus, artichokes, garlic, onions and rye; galactooligosaccharides (GOS) found in legumes, cow milk and whole wheat; and xylooligosaccharides (XOS) found in bamboo shoots, honey, fruits and vegetables);
Beta-glucans found in the cell walls of wholegrains (e.g. oats, barley), shiitake and maitake mushrooms, yeast and seaweed;
Pectins found in the flesh and skin of fruits such as apples, mango and citrus, and in carrots and sweet potato;
Gums such as guar found in guar beans, and agar found in seaweed.
Insoluble fibres include:
Resistant starch which is slowly fermented and occurs in 5 different compositions, with resistant starch types 1, 2 and 3 providing the biggest benefits to health:
- Type 1 is found in high amounts in wholegrains such as brown rice, rye, sorghum and buckwheat, in nuts and seeds, and in legumes such as chickpeas, kidney beans, butter beans and lentils;
- Type 2 is found in green bananas, raw plantains, raw rolled oats and raw potato (or flour made from these products), however in order to preserve this starch these products must not be cooked, which makes them unsuitable or difficult to consume;
- In comparison, type 3 resistant starch (or retrograde starch) is formed during cooling and storage, so foods such as wholegrains (including wholegrain pasta), legumes, plantains and root vegetables (including carrots, beetroot, potato, turnip, parsnip and sweet potato) become even more nutritious when cooked and cooled before consumption - perhaps this is why vegetable-rich soups, stews, curries and casseroles always taste better the next day!
Chitin, which is found in mushrooms and fungi. If you're not a vegetarian/vegan, you could also try consuming prawn shells - salted crispy prawn shells are often served as part of a Japanese teppanyaki meal - or indulge in a culinary tour of Thailand where insects such as crickets and beetles play a key role in the diet. Recent research indicates chitin is fermentable.
Cellulose, hemicellulose and lignins, which are found in the skin and cells of fruits and vegetables, nuts, seeds and wholegrains. Opinions on the fermentability of these fibres vary, but recent research demonstrates fermentability.
WHAT ARE PREBIOTICS?
You may have heard the term ‘prebiotic’ used in relation to fibre and gut health. There are numerous definitions of this term published in scientific literature, however the International Association for Probiotics and Prebiotics (ISAPP, 2016) defines prebiotics as “a substrate that is selectively utilized by host microorganisms conferring a health benefit”.
Prebiotics are fibres which are selectively utilised by certain gut bacteria in the colon. The gut bacteria produce metabolites during the fermentation of the prebiotic fibres. These metabolites, sometimes referred to as postbiotics, confer health benefits.
Research is constantly evolving in the world of prebiotics. Both soluble and insoluble fibres can have prebiotic effects, however it is the selective utilisation by a limited number of microbes that currently distinguishes prebiotics from other fibres - so whilst all prebiotics are fibre, not all fibres are prebiotic. The fibres currently defined as prebiotics are inulin, FOS and GOS, however it is important to consume a variety of soluble and insoluble fibres as they all have an important role to play in maintaining a healthy gut.
WHAT DOES FIBRE DO?
There has been an explosion of interest in fibre over the last decade, and rightfully so - the positive effects of fibre consumption are significant. The fermentation of fibre produces metabolites such as short chain fatty acids (SCFAs), which:
nourish and promote the growth of beneficial bacteria, which in turn inhibits the growth of potentially pathogenic bacteria (referred to as competitive inhibition);
enhance the integrity and thickness of gut mucosa, which acts as a barrier to prevent damage to the gastrointestinal tract and protect against the development of cancer and digestive diseases;
reduce inflammation and lower gut pH, which enhances inhibition of pathogens;
enhance digestive enzyme activity, and synthesis of B vitamins and vitamin K;
increase colonic motility, and bulking and softening of stools to enhance removal of wastes.
Effects of fibre in the intestinal tract (Thompson et al, 2021).
Fibre also:
enhances satiety, lipid metabolism, blood sugar control and nutrient absorption;
reduces constipation and haemorrhoids;
reduces cholesterol and body weight;
reduces the risk of cardiovascular disease, diverticular disease, diabetes, obesity, and bowel and colon cancer.
The systemic benefits of fibre consumption (Guo, Tan & Kong, 2022).
HOW MUCH FIBRE DO WE NEED?
Archaeological studies show that ancient hunter-foragers ate a whopping
135g per day (on average) of insoluble fibre, yet we know that most Australian adults only consume an average of 20g per day, and this is mainly obtained from breads and cereal foods.
The suggested daily target of total fibre intake for adults is
28g per day for women
and 38g per day for men,
to reduce the risk of chronic disease.
To achieve this, we need to be consuming a wide range of fruits, vegetables, legumes, nuts and seeds - aiming to consume 5 serves of vegetables/legumes and 2 serves of fruit each day to promote a healthy gut.
Rather than getting caught up in whether a food is soluble or insoluble, the focus should be on ensuring that plant-based foods make up the bulk of each meal.
If you wish to go a step further to really enhance the diversity of gut microbiota and promote optimal wellbeing, we need to be consuming a very diverse range - 30+ different types - of brightly coloured fruits, vegetables, legumes, nuts, seeds, herbs and spices each week.
It is estimated that for every 100g of fermented fibre, 30g of bacteria are produced - so in theory if we are consuming around 30-40g of fibre a day we are producing around 60-90g of beneficial bacteria each week!
To help keep track of your fibre intake and keep motivated to eat a diverse range of plant foods, subscribe to receive a free copy of our Plant Diversity Challenge Checklist and challenge yourself!
Or if you prefer using tech, apps designed specifically to track fibre and vegetable intake include: Rainbow Diet Food Journal (iPhone), 30 Plants a Week (Android & iPhone), Eat 5 Build Healthy Habits (iPhone) and Fiber Tracker & Counter (iPhone).
HOW CAN WE BOOST FIBRE INTAKE?
Here are some easy ways to boost the fibre in your diet:
Add freshly ground flaxseeds to smoothies, sprinkle over meals
Swap meat-based protein for plant-based protein such as tofu, tempeh and legumes
Choose wholegrain pasta and unrefined cereals
Download a vegan or vegetarian recipe app to help plan fibre-rich meals
Aim to consume 2 serves of fruit and 5 serves of vegetables daily
Keep tins of legumes on hand (go for brands that contain less than 200mg sodium and no preservatives) and add these to meals e.g. add to pasta sauces, soups, curries and casseroles
Add fruits, nuts and seeds to yoghurts, cereals and porridge
Try zoodles (zucchini noodles) instead of pasta
Swap quick oats for wholegrain rolled oats
Add nuts and seeds to salads
Buy organic fruits to avoid the need for peeling the skin off
Swap regular bread for wholegrain fermented sourdough (artisan bakery varieties)
Add kimchi or saurkraut to salads or as a side to curries and stir-fries
Roast large batches of root vegetables and chill for consumption later in the week
Shred seaweed sheets into thin strips and sprinkle over meals
Swap out white rice for brown, black or even red rice varieties
If time is a factor, frozen vegetable are a great option and can easily be added to soups, stews, stir-fry and curry to add nutrients and bulk up the quantity
Use hummous or home-made pesto in place of salad dressings or sauces
DOES FIBRE CAUSE GUT PROBLEMS?
When increasing your fibre intake it is important to do so gradually, and ensure adequate hydration (e.g. consume 1.5-2 litres of water per day) so as to avoid any uncomfortable gastrointestinal symptoms.
Consuming too much fibre can result in excessive gas, bloating, constipation and pain. However for some people, even small amounts of some types of fibre produce uncomfortable gut symptoms, which may indicate an imbalance in gut microbiota (also known a dysbiosis), irritable bowel syndrome (IBS), FODMAP sensitivity or small intestinal bacterial overgrowth (SIBO) and it is important to investigate this issue further.
It is common for people experiencing gut symptoms to avoid fibre-rich foods and restrict their diet. Long-term dietary restrictions, especially those removing vital fibre-rich foods, can result in nutrient deficiencies and have a detrimental impact on health and wellbeing. Not to mention the food-related anxiety it brings and negative impact on quality of life.
Are you having tolerating fibre?
Do you experience bloating, excessive gas, pain or discomfort after eating foods such as lentils, fruits, vegetables, grains or other high-fibre foods?
Do you want to include more fibre in your diet, but not sure how to do so?
Do you want to overcome restrictive dietary patterns?
For personalised guidance on how to boost your fibre intake, overcome uncomfortable symptoms and improve your overall health and wellbeing,
click here to book an appointment with Gut Mechanic today!
Disclaimer: The information provided herein is for general information purposes and should not be construed as medical advice. Any reliance on the information provided is done at your own risk. This information is not intended to serve as a substitute for professional health care and should not be used for diagnosis or treatment. If this information has raised some concerns for you, or you wish to make changes relating to your health, or you suspect you have a health problem, you should consult a qualified health professional for advice relating to your specific circumstances. Whilst the author makes every effort to provide accurate information, the author makes no guarantees or promises and assumes no liability regarding the accuracy, reliability or completeness of the information presented. Any third-party materials or content referenced does not necessarily reflect the author’s opinion, standards or policies, and the author does not assume any liability for them whatsoever.
References
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