Dietary fibre benefits and digestion: the facts about fibre

Dietary fibre benefits and digestion go hand in hand because fibre feeds your gut bacteria, supports regular bowel movements, and helps you feel satisfied after meals. If you want a simple next step, aim for more whole plant foods each day and keep your fibre intake varied across the week.

What is Dietary Fibre?

Dietary fibre refers to the parts of plant foods that your body cannot fully digest. Most dietary fibre is classified as carbohydrate, although some are lignans. A key feature of dietary fibre is that it resists digestion in the small intestine but may be partly or completely fermented in the colon (large intestine) by the gut microbiome.

The most recent NZ Nutrition Survey showed that New Zealanders get most of their fibre from bread (17%), veges (16%), potatoes, kumara, taro and fruit (16% each). However, average intakes were around 10 grams lower than the recommended 25 grams a day for women and 30 grams a day for men, so there is clear room for improvement. Dietary fibre has traditionally been categorised as soluble or insoluble, however nutritionists have lately preferred the more functionally descriptive terms fermentable and or viscous. Fermentable fibres are, as you would expect, fermented by the gut bacteria, whereas viscous fibres absorb water and thicken, increasing intestinal transit time. Recently resistant starch has been included in definitions as a functional fibre.

What does Dietary Fibre do?

• Helps you move your bowels. This effect accounts for the protective action of fibre against conditions such as hiatus hernia, diverticulitis and haemorrhoids.
• Helps reduce blood cholesterol levels and regulate blood sugar, thereby reducing the risk of cardiovascular disease and diabetes
• Reduces the risk of gastric and bowel cancer
• May help regulate body weight by reducing the energy density of your meals and helping you feel full for longer
• Promotes good intestinal function. A healthy intestine with a balanced microbiome means you absorb nutrients and experience fewer issues such as bloating, excessive gas or pain. Healthy insides also help keep your immunity up to par.
• When fermented, fibres such as β-glucan from oats and pectins from apples produce short-chain fatty acids which help balance the pH of the colon, inhibit the growth of pathogenic bacteria and provide energy to the intestinal cells.

An emerging area of research around dietary fibre is as prebiotics, that is, the impact they have on the gut microbiota. Dietary fibre is a major fermentation substrate for gut bacteria and the type and quantity of fibre you consume can quickly impact the richness and diversity of the microbiome. That can influence digestion, immunity, inflammation, nutritional status and mood. Research into the role of specific fibres on the microbiome has also been used by researchers to develop products such as Livaux™, which is in Puraz Probiotic+, and you will find an article dedicated to that functional ingredient here. If your goal is daily microbiome support, you can also browse the gut health collection to compare formulas and formats.

How to get enough Dietary Fibre

So what can you do to ensure an adequate fibre intake, nurture your microbiome and keep Grandma happy? Eat plant foods, with the fibre intact. Whole grains, legumes, vegetables, fruit, nuts and seeds. Your microbiome likes variety so aim to consume 30 different types of whole plant foods every week, and if taking a fibre supplement remember to increase your fluid intake. With a bit of effort it is not too hard to get the fibre you need to live life with a happy tummy.

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FAQ

What are dietary fibre benefits and digestion changes you can notice first?

Many people notice more regular bowel movements and less sluggish digestion first. Fibre adds bulk and can help stool move through the gut more smoothly. Increase fibre gradually and drink more water so your gut can adapt comfortably.

How much fibre should adults aim for each day?

A practical target is 25 grams a day for women and 30 grams a day for men. This helps support healthy bowel function and overall gut health. If you are far below that, add one high fibre food at a time to avoid discomfort.

What is the difference between fermentable and viscous fibre?

Fermentable fibre is used by gut bacteria and can produce helpful short-chain fatty acids. Viscous fibre absorbs water and thickens, which can slow digestion and support steadier blood sugar. Most people do best with a mix of both from varied plant foods.

Are oats and apples good sources of fibre for the microbiome?

Yes, oats provide β-glucan and apples provide pectins, both of which can be fermented in the colon. Fermentation can support a healthy gut environment and nourish intestinal cells. Try including them a few times per week alongside other plants for variety.

Can fibre help with feeling full and managing weight?

Fibre can help you feel fuller because it increases meal volume without adding much energy. Some fibres also slow digestion, which can support longer lasting satiety. Pair fibre rich foods with protein and healthy fats for an even steadier appetite.

Do prebiotic fibres always cause gas or bloating?

They can at first, especially if you increase intake quickly. Gut bacteria adapt as your fibre intake rises, which can reduce symptoms over time. Start small, spread fibre across meals, and prioritise a wide range of plant foods.

What are the best high fibre foods to eat daily?

Whole grains, legumes, vegetables, fruit, nuts and seeds are reliable everyday options. Each group contributes different fibre types and additional nutrients. Aim to rotate choices across the week to support microbiome diversity.