Fibre 101: Why Fibre Matters

Fibre might not sound that exciting, but it’s essential to our overall health. In many ways it’s a bit of an unsung hero, quietly working away to keep our bodies, and mostly importantly our guts, in balance. Here’s a run through of why we need to eat fibre, where to find it and how much you need for optimum health.

What is Fibre?

Fibre is a type of carbohydrate found naturally in plants such as grains, vegetables, pulses, lentils, nuts, seeds and fruits. Our digestive systems are not able to fully break down or absorb fibre, so it remains in the gut where it creates the bulk of the stool, and this is why it is sometimes called ‘roughage’.

There are two types of fibre:

1. Soluble fibre

This type of fibre dissolves in water, forming a gel-like consistency. This is the more fermentable type of fibre, meaning it provides fuel for our gut bacteria (more on this below) and it is especially important for capturing waste products such as cholesterol, to ensure they are properly removed from the body. It helps us feel full after a meal. You find soluble fibre in ingredients like oats, carrots, blueberries, Brussels sprouts, broccoli, beans, figs, apples, citrus fruits, nectarines, flaxseed, sweet potatoes, barley, pears.

2. Insoluble fibre

This type of fibre doesn’t dissolve in water meaning it can be bulkier in its consistency. This triggers peristalsis (gets your gut moving) and ensures we have regular, formed stools that are easy to pass. Like soluble fibre, it helps keep us full after a meal and also keeps our blood sugar stable. You find insoluble fibre in wholegrains like brown rice, wholegrain bread, potato, chia seeds, green beans, leafy greens such as spinach and kale and chard, avocado, seeds, cauliflower.

Getting enough of both types is important. Though some foods contain more of one than another, many overlap, and if you eat a wide array of fibrous foods, you should find that you are getting a nice mix of both types.

6 reasons to eat more fibre

As well as supporting the gut and reducing our risks of developing colorectal cancers and digestive disorders, a higher fibre diet is also linked with reduced risks of type II diabetes (1) heart disease and stroke, as well as better mental health and immunity (2). This may be why a study conducted at Harvard School of Public Health found that those eating fibre rich grains had a 19% reduction in their overall risk of death, compared to those who didn’t eat much fibre (3).

1. Fibre is essential for good gut health

One of fibre’s most important jobs is to keep our microbiome - the essential bacteria that live in our body - healthy and balanced. Fibre does this by providing a fuel source for our bacteria to ferment and then feed off. These are sometimes called prebiotics due to their role in encouraging the natural ecosystem to flourish. Different fibres feed different strains of bacteria, so the more types of fibre we eat, the more diversity we are likely to have within our microbiome. The greater the diversity of our microbiome the better, as this is a good marker for gut health.

Our gut bacteria help us do many vital roles such as digest food, extract nutrients, keep our bowel regular and motile, synthesise nutrients (such K2 and B vits) and neurotransmitters (such as serotonin, 80% of which is located in the gut), reduce inflammation, eliminate toxins, fight off harmful bacteria and keep the gut wall healthy. Our microbiome is also integral to our immune system – around 70% of the body’s entire immunity is found within the gut, where it helps to provide a first line of defence against foreign invaders that may do us harm. Eating a fibre rich diet helps our immune system to produce important bug fighting T-cells, reduces inflammation and some studies have shown that it can also help to discourage autoimmunity (4) a growing problem in the western world.

The good news is that eating more fibre each day can begin to have positive impacts on our gut bacteria quickly – one study showed significant improvements in just two weeks, with higher levels of beneficial strains such as Bifidobacterium.

2. Fibre keeps you regular

You may have noticed that if you don’t eat enough fruits, vegetables, or wholegrains then you can experience constipation. Having regular bowel movements is essential for a healthy gut for many reasons – it clears toxic waste products from the body, keeps our digestive system clear of unwanted compounds and bacteria, and it makes room for new food to come in and be properly digested before the cycle begins again. This keeps our gut regular and helps to ensure that we don’t experience uncomfortable bloating, gas or abdominal pain.

Ideally, we should be able to open our bowels (or poop) once per day, though some find they naturally need to go 2 or 3 times, whilst others find that once every two days works for them. Whatever is normal for you, fibre is instrumental in keeping us regular so that we don’t go too much, or too little. Fibre keeps our stools soft and formed, making them easier to pass, which discourages issues such as piles and fissures. It also regulates the speed at which food moves through the gut to allow digestive processes enough time to get to work breaking down food and absorbing nutrients.

Eliminating waste is one of the gut’s most important jobs and it works closely with the liver, which passes detoxified compounds to the digestive system to be removed through our poop. This doesn’t happen efficiently without fibre, and so eating enough is one of the best things we can do for our detoxification, as well as for our gut heath.

3. Fibre helps stabilise blood sugar and energy levels

Soluble fibre is able to dissolve in water found in the gut, this process helps us to feel full after a meal as it fills the stomach and increases the viscosity of food moving through the digestive tract. This in turn keeps our energy levels higher for longer and is why a diet rich in fibre is associated with a lower BMI (5).

Fibrous foods also break down more slowly in the gut, meaning the sugars found in them get absorbed more slowly into the bloodstream, preventing a blood sugar roller-coaster of peaks and troughs over the course of the day. This is important for reducing the sugar cravings and energy dips that leave us reaching out for white carbs and sugar-laden drinks and snacks.  

In the same vein, fibre-rich diets also lessen the risks of developing type 2 diabetes by reducing the need to release high levels of insulin after a meal. This is the reason people who eat more fibre tend to have a lower blood glucose level.

4. Fibre helps reduce cholesterol

Fibre can have a positive impact on our cholesterol levels. There are different types of cholesterol in the body, but broadly speaking we should ideally have more of the HDL (high density lipoprotein) types over LDL (low density lipoprotein) because this is better for our long-term cardiovascular health. Fibre can help us achieve this balance by forming a gel like substance in the gut that binds to cholesterol, allowing it to be removed from the body via the stool.

We also know that a type of fibre called beta-glucan (found in oats and mushrooms) can help to regulate cholesterol levels by preventing the gut from absorbing too many of the wrong types of fat into the body. Beta-glucans also help support the balance of our gut microbiome, which has been shown to contribute to healthier cholesterol levels (6).

5. Fibre supports the immune system

Another positive outcome of supporting our gut microbiome with plenty of fibre is that we can increase the levels of important compounds known as short chain fatty acids (SCFAs), sometimes referred to as postbiotics because they are synthesized by an already thriving microbiome. Some of these include butyrate, acetate, and propionate.

SCFAs such as butyrate have powerful anti-inflammatory properties (7). They improve the pH of the gut (8) and keep the gut wall (the gatekeeper for what gets into our blood circulation) working effectively. They also aid blood sugar balance and may support brain health (9).

Recent studies are identifying links between our SCFAs and our immune system – acetate can help to increase secretory IgA, an important anti-body that is released by our gut wall to support immunity, discourage so-called ‘leaky gut’ and reduce inflammation. Acetate can also help secretory IgA to work more effectively by destroying harmful bacteria such as E-coli (10)(11).

So, there’s a lot going on in the gut to keep us healthy, and it’s clear that getting more fibre is one of the most effective ways to support all of this. But it doesn’t have to be complicated; one study found that eating just 100g of button mushrooms a day can help to increase secretory IgA levels in the gut (12).

How much fibre do I need?

We should be aiming for 30g of fibre each day. The current UK average is only 17g. A daily example of 30g would be:

Breakfast - Porridge oats with a handful of berries and chopped nuts 

Lunch – Broccoli, brown rice and edamame salad

Snack – 1 apple with 1 tablespoon of peanut butter

Dinner - Creamy roasted squash dahl with brown rice

Variety is key too. Aim to get as many different types of fibre into your diet as possible, as this not only delivers a large spectrum of vitamins, minerals and antioxidants, but also helps our gut bacteria to thrive. We should strive for a minimum of 30 different types of veg, fruit, grains, herbs, spices and legumes per week and be sure to get sources from all of these groups for the maximum gut health benefits.

If you don't currently have much fibre in your diet, start by increasing it slowly. This is especially the case if you have sensitive digestion. Though fibre is one of the best things you can give your gut, it can take some time to get used to and it’s also important to make sure you drink your recommended 2L (roughly 8 glasses) of water daily because soluble fibre does absorb water, so we need to stay hydrated to ensure stools remain soft and easy to pass.

If you are new to fibre, we have put together a plan for how you could start to incorporate it into your diet below.

Example week 1 & 2

Switch white rice, bread and pasta to wholegrain/brown, and change processed breakfast cereals for wholegrain options such as porridge, muesli or overnight oats. Aim to add in 1 or 2 vegetables or fruit with each meal - such as berries or avocado at breakfast, salad leaves and cucumber at lunch, and roasted carrots or steamed broccoli at dinner. Herbs and spices count too so add in fresh parsley, coriander and spices like fresh ginger or garlic, as these are a great way to bring diversity and flavour.  

Example week 3 & 4

Continue to add in more vegetables where possible and don’t be afraid to be a little more adventurous – spring greens stir-fried in olive oil and garlic, a carrot and red cabbage slaw, or roasted aubergine with Moroccan spices and a tahini dressing. Add in a sprinkle of nuts and seeds at meals such as cashews, almonds or seeds (some people find these easier to digest when soaked first, such as when cooked into porridge) or add in nut butter to breakfasts, smoothies or dressings. Aim to get one meal containing beans such as black beans or chickpeas every couple of days, or try adding in hummus or other dips that contain beans such as edamame.

Example week 5 & 6

Add in more meals with lentils such as curries, ragus or soups, and aim to add different nuts and seeds to meals or snacks twice per day. Aim to get get a minimum of 5-a-day portions of fruit and veggies in meals and snacks and remember the more different colours, the better. This goes too for spices such as turmeric, cinnamon and mustard seeds, fennel seeds and cumin, which add flavour to dishes as well as bringing beneficial properties.

Example week 7 & 8

Continue to try more different types of beans, lentils and grains such as quinoa and buckwheat. You can also try pasta and noodles made with grains such as buckwheat, spelt or soba noodles. By this point you should be getting 20 different fruit/vegetables per week, along with different legumes, grains and nuts/seeds. Add in a tablespoon of fermented foods such as kimchi, sauerkraut or pickled onions to salads, as well as high fibre foods such as flaxseed and chia (best when soaked first in yoghurt or plant-based milks to make a chia ‘pudding’).

Remember, everyone is different and needs to do this at their own pace. The above is a guide so feel free to go more quickly or slowly to your preference, and remember it is the long term changes that make the difference.

Disclaimer: As with all information on Deliciously Ella, this is no substitution for individual medical or nutritional advice. Pregnant women and anyone on medication should always consult a doctor before embarking on a new diet. 

References

1.  Meyer KA, Kushi LH, Jacobs DR Jr, Slavin J, Sellers TA, Folsom AR. “Carbohydrates, dietary fiber, and incident type 2 diabetes in older women.” Am J Clin Nutr. 2000 Apr;71(4):921-30.

2.  Schley PD, Field CJ. The immune-enhancing effects of dietary fibres and prebiotics. Br J Nutr. 2002 May;87 Suppl 2:S221-30.

3.  Geng Zong, Alisa Gao, Frank B. Hu & Qi Sun, “Whole Grain Intake and Mortality from All Causes, Cardiovascular Disease, and Cancer: A Meta-analysis of Prospective Cohort Studies,” Circulation, online June 13, 2016.

4.   Berer K, Martínez I, Walker A, Kunkel B, Schmitt-Kopplin P, Walter J, Krishnamoorthy G. Dietary non-fermentable fiber prevents autoimmune neurological disease by changing gut metabolic and immune status. Sci Rep. 2018 Jul 11;8(1):10431. 

5.  Gibson R, Eriksen R, Chambers E, Gao H, Aresu M, Heard A, Chan Q, Elliott P, Frost G. Intakes and Food Sources of Dietary Fibre and Their Associations with Measures of Body Composition and Inflammation in UK Adults: Cross-Sectional Analysis of the Airwave Health Monitoring Study. Nutrients. 2019 Aug 8;11(8):1839.

6.  Joyce Susan A., Kamil Alison, Fleige Lisa, Gahan Cormac G. M. The Cholesterol-Lowering Effect of Oats and Oat Beta Glucan: Modes of Action and Potential Role of Bile Acids and the Microbiome. Frontiers in Nutrition. 2019. 6:171.

7.  Kuo SM. The interplay between fiber and the intestinal microbiome in the inflammatory response. Adv Nutr. 2013 Jan 1;4(1):16-28.

8.  Scott, K.P., Duncan, S.H. and Flint, H.J. (2008), Dietary fibre and the gut microbiota. Nutrition Bulletin, 33: 201-211.

9.  Li M, van Esch BCAM, Henricks PAJ, Folkerts G, Garssen J. The Anti-inflammatory Effects of Short Chain Fatty Acids on Lipopolysaccharide- or Tumor Necrosis Factor α-Stimulated Endothelial Cells via Activation of GPR41/43 and Inhibition of HDACs. Front Pharmacol. 2018 May 23;9:533. 

10. Dempsey, L.A. Acetate enhances IgA. Nat Immunol 22, 1071 (2021).

11. Takeuchi, T., Miyauchi, E., Kanaya, T. et al. Acetate differentially regulates IgA reactivity to commensal bacteria. Nature 595, 560–564 (2021).

12.Jeong, S. C., Koyyalamudi, S. R., & Pang, G. (2012). Dietary intake of Agaricus bisporus white button mushroom accelerates salivary immunoglobulin A secretion in healthy volunteers. Nutrition, 28(5), 527-531.