How eating fibre-rich grains contributes to your gut health

Updated: Jun 17, 2020

Fibre food swap - wholegrain bagel

There is a lot of buzz around gut health and its effect on your broader physical and mental wellbeing, with new gut-friendly products popping up on the market.

But did you know that one of the best ways to boost your gut microbiome is by upping your intake of fibre-rich grains – a core staple of many store cupboards and diets.

We’ve looked through some existing research and expert advice* to inform ourselves on the topic and derive some practical advice for our diets. We hope this will be as informative for you as it has been for us!

How do fibre-rich grains contribute to a healthy gut?

Fibre is a prebiotic – it feeds the good bacteria in your gut. When bacteria digests fibre, they produce short-chain fatty acids that nourish the gut barrier, improve immune function and can prevent inflammation, which reduces the risk of cancer. A diet low in fibre can lead to the good bacteria dying off, reducing the diversity of the microbiome.

There has been a growing body of research linking diets high in dietary fibre with reduced risks in Type II diabetes, cardiovascular disease and certain cancers.

What is the difference in the levels of fibre in wholegrain and refined flour?

While flours vary broadly in their fibre content, wholegrain will generally have much higher fibre levels than its refined flour equivalent.

For example, according to USDA FoodData Central, per 100g, wholegrain wheat has 13.1g of fibre, while all-purpose refined wheat can have as little as 3g. This is in line with the fibre content we observe in some popular flour brands in the UK – e.g. essential Waitrose Plain White Flour has 2.9g while its strong Wholemeal Bread Flour has 9.5g per 100g.

Practical tip: most ingredient labels of baked products won’t tell you whether wholegrain or refined flour has been used, however, you can use the fibre content as a guide. The darkness of the loaf (if it’s not burnt!) might also be an indication if it's wholegrain. However, if you’re at a bakery and you want to be sure, it is best to ask!

Wholegrain rye bread

What is the difference in the levels of fibre in rye and wheat flour?

Comparing like for like, rye tends to be higher in fibre than wheat.

For example, Doves Farm Organic White Rye Flour has 7.6g fibre per 100g, while its Plain White (Wheat) Flour has 4.5g. Doves Organic Stoneground Wholemeal Rye Flour also has a higher fibre content at 13.4g compared to its Organic Strong Wholemeal Bread Flour at 11.2g.

Practical tip: choosing rye over wheat when the alternative is available could be a simple way to boost your dietary fibre intake. Also many bakeries that bake with rye flour tend to use the wholegrain variety as it has a deeper flavour and darker colour that is distinctive to rye bakes.

What is the difference between soluble fibre & insoluble fibre?

Soluble and insoluble fibre are two types of dietary fibre, which serve different functions.

Soluble fibre attracts water and slows down direction, in turn lowering blood glucose spikes after eating. Insoluble fibre is the ‘bulking fibre’ that promotes healthy bowel movements.

Whole grains are high in both types of fibre, however, different types of foods will have varying levels of each (e.g. skins of vegetables are higher in insoluble fibre).

What is the recommended daily fibre intake?

According to the British Nutrition Foundation, we are consuming way less dietary fibre than we should – adults are recommended to have 30g per day, while on average we consume around 18g. Intake is also below recommended levels for children (see below).

Recommended Daily Intake according to BNF

2-5 year olds: 15g

5-11 year olds: 20g

11-16 year olds: 25g

17 and over: 30g