Since the 1950s, the definition and recommended amounts of fibre has evolved as more and more research continues to show just how important fibre is for health and wellbeing.
Fast forward to 2015 and the UK’s Scientific Advisory Committee on Nutrition (SACN) published a big report recommending all adults should be eating 30g of fibre a day based on all the research to date.
The problem? Most people are not eating enough. In fact, there is a big fibre gap in the UK and as a nation, only 9% of people hit this target.
What exactly is fibre?
Fibre is a type of carbohydrate, but it’s different to other types (sugars and starches):
- Your body can’t digest fibre – your gut doesn’t have the enzymes to break it down, but your gut microbes do!
- Fibre isn’t a single entity - it’s an umbrella term and there are MANY types of fibre e.g. resistant starch, cellulose, pectin, fructans, the list goes on…
- It has far-reaching effects on health beyond gut health, including brain health and metabolic health.
Fibre is found in all plant-based foods including:
- Wholegrains
- Fruits
- Vegetables
- Nuts
- Seeds
- Herbs
- Spices
- Legumes
- Fresh, dried, frozen, and tinned (in water/natural juices) all count!
What does 30g of fibre actually look like over a day? Check out this handy guide.
Different fibres work in different ways
Fibre can have wide-ranging health benefits because different fibres work in different ways when they reach the gut. How they behave depends on their ‘traits’.
- Fermentability: Some fibres are fermentable and are rapidly broken down by gut microbes
- Viscosity: Some fibres are viscous and form a ‘gel’ when they reach the gut
- Solubility: Some fibres are insoluble and give bulk to poo
The missing link to health
Gut health
Insoluble fibres (found in wholegrains, skins of fruit and vegetables) can help normalise gut transit time (how long food takes to work its way through your gut), as well as bulking out poo so they’re soft and easy to pass.
On the other hand, fermentable fibres (such as fructans found in onion and garlic) ‘feed’ gut microbes.
In return, they release beneficial compounds into the gut environment, including short-chain fatty acids (SCFAs). SCFAs strengthen the gut lining and suppress growth of potentially harmful gut microbes.
Brain health
SCFAs can also travel outside of the gut and act on the brain.
In fact, studies have shown SCFAs produced from the breakdown of fermentable fibres by gut microbes may support cognition (e.g. learning and memory) and mental health.
What’s more, SCFAs are also thought to play a key role in reducing neuroinflammation (inflammation in the brain and spinal cord) which is linked to the development of brain disorders.
Heart health
Viscous fibres (such as beta glucans found in oats and barley) are known for their cholesterol-lowering effects and improved control of blood glucose levels.
They do this in a few ways 1. By slowing absorption of glucose which prevents rapid rises and keeps you feeling fuller for longer and 2. By binding to cholesterol in bile which limits how much cholesterol can be absorbed by the gut.
On top of that, SCFAs can reduce total cholesterol and ‘bad’ (LDL) cholesterol levels by lowering the rate of cholesterol production in the liver.
Are there any downsides to eating more fibre?
There are no downsides to eating more fibre. But, if you’re not used to eating lots of fibre-filled foods, it’s important to build up gradually to give your gut time to adapt and to minimise mild gut symptoms, such as bloating or wind.
For example, you could start by adding some lentils to a bolognaise or throwing some chopped vegetables into a tomato-based pasta sauce.
For certain groups, such as people with irritable bowel syndrome (IBS), tolerance to type and amount of fibre can vary. It’s important to work with a registered dietitian who can support with managing symptoms and maintaining fibre.
What should I look for on labels?
When you’re buying food products, check the nutritional information on the back of the pack. A product needs to contain 3g per 100g to be a ‘source of fibre’ and 6g per 100g to be ‘high in fibre’.
Unfortunately, fibre is not consistently labelled on all food products.
10 easy ways to add more fibre (without knowing it)
- Throw in a tin of beans to any pasta-based dish.
- Keep the skins on all fruit and vegetables (except the ones you can’t e.g. pineapple, bananas).
- Make your own meatballs with added oats.
- Load up pizza with veggies.
- Make your own smoothies – think frozen fruit, nut butters, nuts, seeds…
- Go for food products that say ‘whole’ on the label (e.g. wholegrain, wholemeal, wholewheat).
- Add a handful of nuts or seeds to salads, yogurt, sauces, rice, stir-fry…
- Keep high-fibre snacks to hand such as popcorn, dried fruit, wholegrain crackers with nut butter…
- Choose a high fibre breakfast such as porridge, wheat biscuits, shredded wheat, or wholegrain toast with chia seeds added to your jam.
- For the chocolate lovers, try dipping fruits into melted dark chocolate, drizzle chocolate on fruit-filled crepes, or try chocolate avocado mousse.
Want to learn more? Our 3 fave fibre recipe books
1. The Fibre Fuelled Cookbook: Inspiring Plant-Based Recipes to Turbocharge Your Health by Dr Will Bulsiewicz
2. The Gut-loving Cookbook: Over 65 deliciously simple, gut-friendly recipes by The Gut Stuff
3. The Food For Life Cookbook by Professor Tim Spector
Sources
Dietary fiber intervention on gut microbiota composition in healthy adults: a systematic review and meta-analysis. American Journal of Clinical Nutrition. (2018). Link.
Dietary fibre and the gut–brain axis: microbiota-dependent and independent mechanisms of action. Gut Microbiome. (2021). Link.
Fiber intake and fiber intervention in depression and anxiety: a systematic review and meta-analysis of observational studies and randomized controlled trials. Nutrition Reviews. (2023). Link.
SACN carbohydrates and health report. Scientific Advisory Committee on Nutrition. (2015). Link.
National diet and nutrition survey results from years 7 and 8 (combined) of the rolling programme (2014/2015 to 2015/2016). Public Health England. (2018). Link.
Short-chain fatty acids are potential goalkeepers of atherosclerosis. Frontiers in Pharmacy. (2023). Link.
The role of short chain fatty acids in inflammation and body health. International Journal of Medical Sciences. (2024). Link.
