The Nutracheck nutrient guide to: fibre

Amy Wood - Nutritionist | 13 Nov, 2022

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We place a lot of emphasis on the number of calories in our diets as this is central to our weight loss success, however we mustn't overlook the importance of the nutrients we need too. After all, the food on our plates is made up of different nutrients in varying proportions – calories are just the total energy they all provide.

To help you understand a little more about the nutrients in your food and why they're so important, we're putting together the ultimate series of guides to bust the myths and equip you with all the nutritional 'know-how' you need to make informed choices about your diet and your health. We’ve covered carbohydrates and protein – next up is...fibre!

The basics

Okay, so technically, fibre is a type of carbohydrate. But it's a really important one that many of us aren’t eating enough of, and it does behave differently within the body.

The main difference is that, unlike starch and sugar, we cannot digest fibre. Our bodies don’t produce the right enzymes for this to happen. This is where our gut bacteria come into play. We have as many as 10 trillion little bacteria inhabiting our gut lining, and fibre is their favourite nutrient!

Dietary fibre is generally classified as either ‘soluble’ or ‘insoluble’, although there have been recommendations to modify the classification based on other characteristics, such as how thick it is and how well it breaks down. Most plant-based foods contain a mixture of soluble and insoluble fibre in varying quantities.

  • Soluble fibre includes plant pectin and beta-glucans. It’s mainly found in fruit, oats, seeds, beans, and pulses. This kind is able to dissolve with water in the gut to form a gel.
  • Insoluble fibre, including cellulose, is primarily found in whole grains and nuts. This type cannot mix with water, and instead draws water into the large intestine.
Fibre foods

Why is fibre so good for us?

High-fibre diets have been linked with lots of positive health outcomes. In fact, people who eat a high-fibre diet are more likely to live longer than those eating less fibre!

First of all, eating fibre can help lower cholesterol to healthy levels. The gel that soluble fibre forms in the gut binds with cholesterol, reducing the amount we re-absorb into the bloodstream. High cholesterol levels, particularly ‘bad’ LDL cholesterol, can increase your risk of cardiovascular disease, so keeping cholesterol levels down by eating a fibre-rich diet could be a great way to promote a healthy heart. Beta-glucans, found in oats and barley, are particularly known for their cholesterol-lowering properties, so be sure to opt for a yummy bowl of porridge in the mornings if you’re looking to follow a cholesterol-friendly diet.

Eating a variety of different sources of fibre can improve the diversity of our gut microbiome, meaning there’s lots of different bacteria at work. Once these friendly bacteria break down the fibre in our diets, they produce a host of essential molecules for us, including vitamins, hormones, and short-chain fatty acids. These clever little molecules play roles in reducing chronic inflammation and improving immune function, skin health, and even mental wellbeing. To read more about improving the health of your gut microbiome, read our blog here.

Not only is fibre good for the bacteria in your gut, it’s also amazing for the overall function of your gut and bowels. Fibre provides bulk to the stool within the colon, and also improves stool consistency, making visits to the toilet quicker and easier. In fact, consuming dietary fibre, particularly whole grains, reduces the risk of developing bowel cancer. Different types of fibre can help with different bowel issues – soluble fibre may help ease diarrhoea, while insoluble fibre can relieve constipation.

Can fibre aid weight loss?

Yes, it can! Research shows that people who eat lots of fibre tend to have lower BMIs, but why is this?

As we’re unable to digest fibre, we can’t properly harness the energy (calories) when we eat it. It’s estimated we may only absorb around 1.5-2 calories per gram of fibre. Foods high in fibre are more likely to be lower in calories for this reason.

Additionally, fibre is great for helping us to feel more satiated (fuller for longer). Fibrous foods often increase how much we chew, which reduces the speed at which we eat, allowing us more time to recognise we’re full. Once we’ve eaten fibre-rich foods, the fibre can delay how quickly we absorb nutrients like fat, increasing feelings of satiety.

As we’ve already touched on, our gut bacteria digest the fibre in our diets to produce short-chain fatty acids. Amongst their various roles within the body, these short-chain fatty acids have an impact on our appetite. They tell the body it's full, decreasing the production of the hunger hormone ghrelin and increasing the production of the 'I'm full' hormone leptin. This mechanism may further delay feelings of hunger, minimising the temptation to snack more and exceed our body’s calorie needs.

Eating porridge

How much fibre should I be eating?

In the UK, it’s recommended all adults aim to eat at least 30g of fibre a day. This figure is a minimum amount, so more than 30g is even better. It’s estimated our hunter-gatherer ancestors consumed as much as 150g of fibre every day! Now we’re not suggesting you eat that much, but certainly increasing your intake to reach that magic number of 30g could have real benefits to your health.

Some gastrointestinal conditions can cause sensitivity to high-fibre foods, so if your doctor has advised you follow a low-fibre diet, it’s really important you follow their recommendations.

How can I include more fibre in my diet?

If you're looking to up your fibre intake, here are some easy tips to get you started:

  • Swap any 'white' carbs in your diet for wholegrain varieties, such as wholegrain bread, wholewheat pasta, brown rice, and wholegrain breakfast cereals.
  • Incorporate more grains into your diet. Oats, barley and quinoa are all great sources of fibre.
  • For a quick win, sprinkle nuts and seeds onto your food. I particularly recommend chia seeds and flaxseeds for sprinkling, as they're high in fibre, protein and healthy omega-3 fatty acids!
  • Try including more beans and pulses in your diet. These are really high in fibre while also being low in saturated fat and very cheap to buy. Toss them into whatever you're cooking, or as a replacement for meat. If you aren't cooking, choose ready-made products that contain beans and pulses – they'll still boost your fibre intake, even baked beans!
  • Enjoy your fruit and veg with the skins on – this is where much of the insoluble fibre is stored.

When increasing fibre, it's best to do it slowly and make sure you're drinking plenty of fluids. Perhaps aim for an increase of 3-4g per day for a week, and then another 3-4g per day the following week and so on, until you reach the ideal 30g per day recommendation. Keep an eye on how you're feeling and if you experience any out-of-the-ordinary bloating or changes to bowel movements, maybe slow down the increase to give your body time to adjust. Fibre is very nutritious, but introducing a lot all at once can sometimes be a bit much for our digestive systems.

To realise just how much of a difference simple swaps can make, check out our bread fibre-o-meter below. Just two slices of bread can provide over a quarter of your 30g target if you choose wisely!


Nutritionist Amy Wood (ANutr), MSci BSc Nutrition has a keen interest in the relationship between diet and health. Having been published in the European Journal of Nutrition, Amy is passionate about making evidence-based nutrition accessible to everyone and helping others to adopt a food-focused approach to taking control of their health.

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