Fibre in the spotlight
Fibre, the overlooked star of gut health
In the ever-evolving world of microbiome science, fibre is undergoing a serious glow-up. Previously dismissed as “roughage,” it now takes centre stage as a prebiotic powerhouse; fuel that nourishes the gut’s resident microbes and helps produce beneficial by-products called postbiotics. Every microbiome guardian should know these essential facts about fibre’s role in maintaining health and how to increase sources of fibre in the diet naturally.
Although the importance of fibre in the diet is widely accepted, fibre has a crucial role to play as a prebiotic substrate (aka food for your gut microbes). In other words: fibre doesn’t just keep you regular; it feeds the guts’ ecosystem.
Epidemiological and interventional studies show that high-fibre diets are associated with reduced risk of cardiovascular disease, type 2 diabetes, colorectal cancer and better weight control. No wonder fibre has become the focus of growing research attention.
Fibre also plays a significant role in oestrogen metabolism. A healthy diverse gut microbiome combined with adequate fibre intake helps bind oestrogens in the intestine, accelerates transit time and reduces the re-absorption of conjugated oestrogen, supporting hormone balance. Higher fibre intake is associated with lower abundance of bacteria that encode β-glucuronidase (an enzyme that enables re-activation of oestrogens) leading to reduced circulating oestradiol and oestrone levels. Fibre can be an essential part of your toolkit to support hormone health during perimenopause, for oestrogen-dominant states and hormone-sensitive conditions.
Found primarily in oats and barley, beta glucans are soluble fibres known for their cholesterol-lowering and blood glucose-regulating properties. They form viscous gels in the gut, slowing glucose absorption and promoting satiety. Sources of beta-glucans include oats, barley, mushrooms (especially oyster and shitake), rye and sorghum.
Fructo-oligosaccharides (FOS)
FOS are short-chain prebiotic fibres naturally present in foods such as onions, garlic, leeks, and asparagus. They selectively stimulate the growth of beneficial Bifidobacteria in the colon, contributing to improved gut barrier integrity and immune modulation. These can be incorporated daily through a variety of plant foods or via prebiotic supplements if tolerated. Food sources of FOS include Jerusalem artichoke, broccoli stalks, red onions, asparagus, Brussel’s sprouts, red cabbage, fennel bulb, leeks and white onion.
Galacto-oligosaccharides (GOS)
GOS are another class of prebiotic fibres that nourish Bifidobacteria and Lactobacilli, supporting a balanced gut microbiome and supporting digestive health. Food sources of GOS include legumes such as lentils, chickpeas, split peas and kidney beans. You can also supplement with GOS. Gradual introduction is recommended to minimise gastrointestinal discomfort, particularly for sensitive individuals.
Inulin
Inulin is a longer-chain prebiotic fibre which supports microbial diversity and the production of beneficial short-chain fatty acids (SCFAs), particularly butyrate. Including a range of inulin-containing foods in daily meals can enhance microbial resilience and metabolic health. Food sources of inulin include in chicory root, Jerusalem artichokes, garlic, onions, asparagus, sweet potato, garlic, shallots and bananas.
Pectin
Pectin is a soluble fibre with gelling properties that help regulate intestinal transit and improve stool consistency. It also contributes to reduced postprandial glucose levels and supports satiety. Pectin is abundant in blackberries, mandarins, oranges, papayas, pears, kale, parsnip and endives. Other good sources include apples, bananas, mangos, blueberries, raspberries, strawberries, avocado, carrots, sauerkraut, dates and pulses. Where possible consume whole fruits rather than juices to ensure optimal pectin intake. Fruit and vegetable peels are often a great source of pectin so keep them on where possible.
Resistant Starches
Resistant starch acts like soluble fibre by escaping digestion in the small intestine and fermenting in the colon, producing SCFAs such as butyrate that nourish colonocytes and support mucosal integrity. Good food sources of resistant starches include semi-ripe bananas, cooked and cooled potatoes, rice, and pulses.
Think beyond “30 g a day.” Think about which fibre, when, how much, and examine how it ties into your unique gut ecosystem. The future of gut health is not simply in adding microbes, but in feeding them well.
In the ever-evolving world of microbiome science, fibre is undergoing a serious glow-up. Previously dismissed as “roughage,” it now takes centre stage as a prebiotic powerhouse; fuel that nourishes the gut’s resident microbes and helps produce beneficial by-products called postbiotics. Every microbiome guardian should know these essential facts about fibre’s role in maintaining health and how to increase sources of fibre in the diet naturally.
Why fibre deserves the spotlight
Dietary fibre refers to plant components that resist digestion in the small intestine and reach the colon relatively intact, where gut bacteria ferment at least some of them. Fibre includes non-starch polysaccharides and resistant oligosaccharides, whose main characteristics of solubility, viscosity and fermentability define their physiological behaviour.Although the importance of fibre in the diet is widely accepted, fibre has a crucial role to play as a prebiotic substrate (aka food for your gut microbes). In other words: fibre doesn’t just keep you regular; it feeds the guts’ ecosystem.
Epidemiological and interventional studies show that high-fibre diets are associated with reduced risk of cardiovascular disease, type 2 diabetes, colorectal cancer and better weight control. No wonder fibre has become the focus of growing research attention.
Fibre also plays a significant role in oestrogen metabolism. A healthy diverse gut microbiome combined with adequate fibre intake helps bind oestrogens in the intestine, accelerates transit time and reduces the re-absorption of conjugated oestrogen, supporting hormone balance. Higher fibre intake is associated with lower abundance of bacteria that encode β-glucuronidase (an enzyme that enables re-activation of oestrogens) leading to reduced circulating oestradiol and oestrone levels. Fibre can be an essential part of your toolkit to support hormone health during perimenopause, for oestrogen-dominant states and hormone-sensitive conditions.
Fibre: sources in the diet In the UK adults often consume only ~20 g fibre per day which is well below the 30 g/day target recommended by SACN.¹ Thankfully, it is not difficult for most people to increase dietary fibre. Beta-glucans FOS, GOS, inulin, pectin and resistant starches and are just some of the different types of fibre to consider. Here is a guide to these key players:
Beta glucansFound primarily in oats and barley, beta glucans are soluble fibres known for their cholesterol-lowering and blood glucose-regulating properties. They form viscous gels in the gut, slowing glucose absorption and promoting satiety. Sources of beta-glucans include oats, barley, mushrooms (especially oyster and shitake), rye and sorghum.
Fructo-oligosaccharides (FOS)
FOS are short-chain prebiotic fibres naturally present in foods such as onions, garlic, leeks, and asparagus. They selectively stimulate the growth of beneficial Bifidobacteria in the colon, contributing to improved gut barrier integrity and immune modulation. These can be incorporated daily through a variety of plant foods or via prebiotic supplements if tolerated. Food sources of FOS include Jerusalem artichoke, broccoli stalks, red onions, asparagus, Brussel’s sprouts, red cabbage, fennel bulb, leeks and white onion.
Galacto-oligosaccharides (GOS)
GOS are another class of prebiotic fibres that nourish Bifidobacteria and Lactobacilli, supporting a balanced gut microbiome and supporting digestive health. Food sources of GOS include legumes such as lentils, chickpeas, split peas and kidney beans. You can also supplement with GOS. Gradual introduction is recommended to minimise gastrointestinal discomfort, particularly for sensitive individuals.
Inulin
Inulin is a longer-chain prebiotic fibre which supports microbial diversity and the production of beneficial short-chain fatty acids (SCFAs), particularly butyrate. Including a range of inulin-containing foods in daily meals can enhance microbial resilience and metabolic health. Food sources of inulin include in chicory root, Jerusalem artichokes, garlic, onions, asparagus, sweet potato, garlic, shallots and bananas.
Pectin
Pectin is a soluble fibre with gelling properties that help regulate intestinal transit and improve stool consistency. It also contributes to reduced postprandial glucose levels and supports satiety. Pectin is abundant in blackberries, mandarins, oranges, papayas, pears, kale, parsnip and endives. Other good sources include apples, bananas, mangos, blueberries, raspberries, strawberries, avocado, carrots, sauerkraut, dates and pulses. Where possible consume whole fruits rather than juices to ensure optimal pectin intake. Fruit and vegetable peels are often a great source of pectin so keep them on where possible.
Resistant Starches
Resistant starch acts like soluble fibre by escaping digestion in the small intestine and fermenting in the colon, producing SCFAs such as butyrate that nourish colonocytes and support mucosal integrity. Good food sources of resistant starches include semi-ripe bananas, cooked and cooled potatoes, rice, and pulses.
Clinical Applications
- Aim for Variety
- Go low and slow
- Personalise where possible
Final thoughts on fibre
Fibre is no longer just roughage. It shapes microbiota diversity, supports metabolic health, can help balance hormones and modulate immunity. All these benefits and it is relatively easy to incorporate in the diet.Think beyond “30 g a day.” Think about which fibre, when, how much, and examine how it ties into your unique gut ecosystem. The future of gut health is not simply in adding microbes, but in feeding them well.
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