One nutrient stands out among the rest for its low intake in Western countries, and it’s not something you can really get enough of from supplements.
Introduction
Over 80% of Irish adults do not eat enough of this important nutrient (1), and this figure is over 90% in the USA (2). What’s more, this nutrient has been classified as a nutrient of public health concern (3), making these inadequate intakes rather alarming from a public health point of view. This nutrient is not a vitamin or a mineral, meaning that its intake is almost completely dependent on eating foods rich in this nutrient, so taking a supplement isn’t a panacea for this issue.
If you haven’t guessed what it is yet, you’re not alone—consumer research in the USA indicates that less than 30% of people are aware of the widespread prevalence of inadequate intakes of this nutrient (4). The mystery nutrient is… fibre! After reading the following paragraphs, you’ll know what fibre is, why it’s crucial for good health, and how to incorporate more fibre into your diet.
PS. The European Food Safety Authority have set the minimum recommendation for daily fibre intake at 25 grams per day (5).
Note: ‘fiber’ is the US spelling, whereas ‘fibre’ is the UK spelling.
What is Fibre?
Fibre is a type of carbohydrate that the body cannot fully digest, and is found in plant-source foods. Unlike other carbs, fibre passes through the digestive system largely intact. Fibre is the main source of food for our gut microbiome (i.e., all the bugs in our digestive system). This is one of the reasons why fibre is so beneficial for our health—these gut bugs produce healthful compounds for our body when they’re well fed with fibre.
Traditionally, fibre was classified as soluble fibre—the type that dissolves in water to form a gel-like substance (e.g., beta glucan, the main type in oats)—and insoluble fibre—which is also often referred to as ‘roughage’, and which adds bulk to stool and promotes regular bowel movements. This classification was primarily based on the fact that soluble fibre was traditionally considered more beneficial to health than insoluble fibre. However, solubility doesn’t always predict beneficial health effects, so this terminology has been proposed to be phased out (5).
If you’re well-versed in nutrition, you might be thinking that fibre is not an essential nutrient; that is, fibre doesn’t necessarily have to be eaten in order to sustain life. While fibre isn’t technically essential in the manner that vitamins and minerals are, it’s absolutely essential to achieve optimal health.
Beneficial health impacts of a healthy gut microbiome. Image source: Liu et al. (2023).
Health Benefits of Fibre
Fibre packs a punch for health in a variety of ways.
Heart Health
Higher fibre intake is linked to a reduced risk of heart disease, according to a comprehensive meta-analysis of 22 studies (6). This is likely due to fibre’s ability to improve risk factors for heart disease such as LDL cholesterol, blood pressure, blood sugar, insulin, insulin resistance, and body weight (7,8).
Colorectal Cancer
High compared to low fibre intake was associated with a 26% reduced risk of colorectal cancer in another meta-analysis including 25 studies (9). This may be due to the presence of cancer-fighting compounds in fibre-rich foods (e.g., polyphenols), as well as the fact that fibre helps to prevent waste building up in the colon (which if left build up can lead to inflammation and the formation of harmful compounds that may increase the risk of cancer (10)).
Gut Health and Inflammation
High-fibre intakes promote the growth of beneficial microorganisms in our gut which, in turn, produce compounds that provide health benefits to us (e.g., short-chain fatty acids). These compounds may reduce our ability to produce cholesterol, reduce appetite, and help to lower inflammation in the body (11,12).
There are other benefits of fibre, such as a reduced risk of type 2 diabetes and obesity (8,13), and very little downsides. Therefore, let’s shift focus to how to get more of this important nutrient into our diet.
PS. Check out our Technical Terms at the end of this article to read definitions of all words highlighted in orange throughout this article!
Oats are a great source of beta-glucan—a heart-healthy type of fibre.
How to Eat More Fibre
Eating more fibre doesn’t have to be complicated—it’s all about making simple swaps and adding more plant-source foods to your meals. High-fibre foods include whole grains like wholemeal bread, oats, and brown rice, as well as beans, lentils, nuts, seeds, fruits, and vegetables.
To boost your fibre intake, you could start your day with a bowl of porridge topped with berries and seeds, or swap white bread and pasta for wholemeal versions. Adding a handful of beans or lentils to soups, stews, and curries is another easy way to increase your fibre intake without much effort. Snack on nuts, fruit, or wholegrain crackers with hummus and aim to fill half your plate with vegetables at lunch and dinner. Even eating your spuds with the skin on can help!
It’s important to gradually increase your fibre intake as this allows your digestive system to adjust to the increased intake without causing discomfort. Fibre, especially in larger amounts, can initially lead to bloating, gas, or even constipation if introduced too quickly. However, this lessens as your gut microbiome becomes richer in the beneficial gut bugs that break fibre down.
PS. As an athlete, it’s best to avoid high-fibre foods a few hours before exercise to avoid any gastrointestinal discomfort.
Table 1. Examples of fibre-rich foods (from BDA Fibre Fact Sheet/McCance and Widdowson’s Composition of Foods)
Foods | Total fibre per 100 grams |
Shredded Wheat or bran cereals | 13.0–24.5 grams |
Peanuts | 7.6 grams |
Almonds | 7.4 grams |
Lentils | 7.4 grams |
Chickpeas | 7.1 grams |
Wholemeal bread (2 slices) | 7.0 grams |
Kidney beans | 6.8 grams |
Peas | 5.6 grams |
Baked beans (in tomato sauce) | 4.9 grams |
Wholemeal spaghetti | 4.2 grams |
Strawberries | 3.8 grams |
Summary
All in all, there’s so many reasons to focus on increasing your fibre intake this Fibre February. If you follow the tips in this article, you’ll be well on your way to improved health and wellbeing.
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Thanks so much for reading!
Patrick Elliott, BSc, MPH
Health and Nutrition Science Communication Officer at Training121
Instagram: @just.health.info
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References
(1) Bannon S, Walton J, Flynn A. The National Adult Nutrition Survey: dietary fibre intake of Irish adults. Proc Nutr Soc. 2011;e113. Available at: https://www.cambridge.org/core/journals/proceedings-of-the-nutrition-society/article/national-adult-nutrition-survey-dietary-fibre-intake-of-irish-adults/AC9A013E538718485E9F4B1565109B80
(2) Clemens R, Kranz S, Mobley AR, Nicklas TA, Raimondi MP, Rodriguez JC, Slavin JL, Warshaw H. Filling America's fiber intake gap: summary of a roundtable to probe realistic solutions with a focus on grain-based foods. J Nutr. 2012;142(7):1390S–401S. Available at: https://www.sciencedirect.com/science/article/pii/S0022316622027614
(3) Bailey RL, Ard JD, Davis TA, Naimi TS, Schneeman BO, Stang JS, Dewey KG, Donovan SM, Novotny R, Snetselaar LG, de Jesus J, Casavale KO, Pannucci T, Stoody EE. A Proposed Framework for Identifying Nutrients and Food Components of Public Health Relevance in the Dietary Guidelines for Americans. J Nutr. 2021;151(5):1197–204. Available at: https://www.sciencedirect.com/science/article/pii/S0022316622001535
(4) Gustafson CR, Rose DJ. Consideration of nutrients of public health concern highlighted in the Dietary Guidelines for Americans 2020-2025 among a large sample of US primary shoppers. Appetite. 2023;181:106399. Available at: https://www.sciencedirect.com/science/article/pii/S0195666322004901
(5) EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA). Scientific Opinion on Dietary Reference Values for carbohydrates and dietary fibre. EFSA J. 2010;8(3):1462. Available at: https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2010.1462
(6) Threapleton DE, Greenwood DC, Evans CE, Cleghorn CL, Nykjaer C, Woodhead C, Cade JE, Gale CP, Burley VJ. Dietary fibre intake and risk of cardiovascular disease: systematic review and meta-analysis. BMJ. 2013;347:f6879. Available at: https://www.bmj.com/content/347/bmj.f6879.long
(7) Reynolds AN, Akerman A, Kumar S, Diep Pham HT, Coffey S, Mann J. Dietary fibre in hypertension and cardiovascular disease management: systematic review and meta-analyses. BMC Med. 2022;20(1):139. Available at: https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-022-02328-x
(8) Reynolds AN, Akerman AP, Mann J. Dietary fibre and whole grains in diabetes management: Systematic review and meta-analyses. PLoS Med. 2020;17(3):e1003053. Available at: https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003053
(9) Gianfredi V, Salvatori T, Villarini M, Moretti M, Nucci D, Realdon S. Is dietary fibre truly protective against colon cancer? A systematic review and meta-analysis. Int J Food Sci Nutr. 2018;69(8):904–15. Available at: https://www.tandfonline.com/doi/10.1080/09637486.2018.1446917
(10) Celiberto F, Aloisio A, Girardi B, Pricci M, Iannone A, Russo F, Riezzo G, D'Attoma B, Ierardi E, Losurdo G, Di Leo A. Fibres and Colorectal Cancer: Clinical and Molecular Evidence. Int J Mol Sci. 2023;24(17):13501. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC10488173/
(11) Gunness P, Gidley MJ. Mechanisms underlying the cholesterol-lowering properties of soluble dietary fibre polysaccharides. Food Funct. 2010;1:149–55. Available at: https://pubs.rsc.org/en/content/articlehtml/2010/fo/c0fo00080a
(12) Barber TM, Kabisch S, Pfeiffer AFH, Weickert MO. The Health Benefits of Dietary Fibre. Nutrients. 2020;12(10):3209. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC7589116/
(13) Howarth NC, Saltzman E, Roberts SB. Dietary fiber and weight regulation. Nutr Rev. 2001;59(5):129–39. Available at: https://academic.oup.com/nutritionreviews/article/59/5/129/1875096
Technical Terms
Gut microbiome: The gut microbiome is the community of trillions of tiny bacteria and other microorganisms living in your digestive system. These microbes help break down food, produce essential nutrients, and support overall health, including digestion and immunity.
Soluble fibre: This type of fibre dissolves in water and forms a gel-like substance in the gut. It helps slow digestion, regulate blood sugar, and lower cholesterol. Foods like oats, beans, and apples are rich in soluble fibre.
Insoluble fibre: This type of fibre does not dissolve in water and adds bulk to stool, helping to keep digestion regular and prevent constipation. It’s found in foods like whole grains, nuts, and vegetables.
Essential nutrient: An essential nutrient is something your body cannot make on its own and that is essential for sustaining life, so you must get it from food. Examples include vitamins, minerals, essential fatty acids, and certain amino acids.
Meta-analysis: A meta-analysis is like a big study of studies. Instead of just looking at one study, it combines the results of multiple studies on the same topic to see if there are any overall patterns or trends. By doing this, researchers can make more reliable conclusions about the topic they're studying—but only if the meta-analysis is well done.
LDL cholesterol: LDL (low-density lipoprotein) cholesterol is a measure of the amount of cholesterol in all LDL particles that circulate in the bloodstream. This measure is causally associated with heart disease because the more LDL particles there are in circulation, the greater the risk they will get stuck inside the walls of arteries and lead to plaque formation. This process begins in childhood and, after many decades, can cause a heart attack. Therefore, it is wise to keep LDL cholesterol as low as possible throughout our lifespan.
Insulin resistance: This is when the body’s cells stop responding properly to insulin, a hormone that helps move sugar (glucose) from the blood into cells for energy. As a result, the body needs to produce more insulin to keep blood sugar levels under control. Over time, this can lead to higher blood sugar levels and increase the risk of developing conditions like prediabetes or type 2 diabetes.
Polyphenols: These are a group of phytochemicals—or plant nutrients—that act as antioxidants and improve our health. Health benefits from polyphenol intake include reductions in LDL cholesterol, improved cognition, and other metabolic improvements.
Short-chain fatty acids: These are a type of fat produced when the beneficial bacteria in your gut break down certain types of fibre. Short-chain fatty acids are important for gut health as they help nourish the cells lining the intestines, reduce inflammation, and improve digestion. Foods rich in fibre, such as fruits, vegetables, and whole grains, encourage the production of these beneficial fats.