The Power of Fibre

26 Oct

The Power of Fibre

Over many years, research has been growing around the profound impacts that nutrition and diet have on the health of the human body. Dietary fibre has been recognised as a nutritionally important, health-promoting food ingredient for many years (1). ‘Fibre’ is a word which often appears on food labels and may be described as being a good nutrient to include in one’s diet, however, many may not know why this nutrient is so remarkable and important for health.

Let’s discuss what fibre is, what it does in the body, why it is important for health, how much fibre to consume, and how to include more of it in the diet.

What is fibre?

Dietary fibre is a nutrient contained in plant-based carbohydrates which cannot be digested or absorbed in the body (1). Instead, fibre passes through the stomach and small intestine relatively unchanged, and then makes its way into the large intestine. It is at this point where fibre may be metabolised and have its greatest effects on the body, as it is fermented by certain species of gut bacteria (1).

What does fibre do in the body?

When fibre passes through the gastrointestinal tract (the gut), it is fermented by gut bacteria (1). Once fermented, short chain fatty acids (SCFAs) are produced, providing the bacteria with energy to thrive on (2). SCFA production is known to positively regulate sugar and fat metabolism, as well as exert other beneficial effects (3).

Although these terms are not officially used to define fibre, fibre is commonly classified as ‘soluble’ or ‘insoluble,’ which refers to its ability to dissolve in water (4). Soluble fibre dissolves in water to form a material which is gel-like, and may help lower blood cholesterol and glucose levels (4). Foods containing soluble fibre may include psyllium, oats, beans, apples and carrots. Insoluble fibre does not dissolve in water and instead promotes the movement of material through the digestive system, increasing stool bulk (4). Some good sources of insoluble fibre may include vegetables such as cauliflower and green beans, nuts, and wholegrains. The amount of soluble and insoluble fibre present in plant foods is different, which is why eating a wide variety of fibre-containing foods is important in order to achieve an optimal intake of fibre, and to experience its various health benefits.

Health benefits of fibre

  • Regulates blood sugar levels: fibre helps to decrease the absorption of glucose/sugar from food, allowing for a more controlled rise in blood sugar and insulin, which is important for supporting healthy weight and reducing risks of developing type-2 diabetes or obesity (5).
  • Regulates hunger hormones and promotes satiety: fibre helps regulate the release of insulin, which is the hormone responsible for determining whether food is used for fuel or stored as fat. It also promotes the secretion of Glucagon-Like Peptide-1, Cholecystokinin, Leptin and Peptide YY, which are hormones involved in signalling to the brain that the body is full and satiated (6).
  • Supports gut health: an individual’s diet may significantly influence the make-up of the gut microbiome, which is the community of bacteria in the gut which may influence the overall health of an individual (2). Dietary fibre may play a fundamental role in gut health due to its interaction with gut bacteria. It may also alter the composition of the gut microbiome, as well as increase bacterial diversity (2).
  • Reduces inflammation: through its effects on the gut microbiome and the production of SCFAs which may inhibit inflammatory processes in the body (7).
  • Reduces risks of developing certain diseases: such as type 2 diabetes, heart disease, colorectal cancer, constipation and diverticular disease (8,9).

How much fibre should I consume?

In the UK, it is recommended that adults consume 30g of fibre per day. As there are different types of fibre, consuming a range of fibre-rich food sources may help to ensure an optimal fibre intake. To give an indication of how consuming 30g fibre/daily may be achieved through main meals:

  • Breakfast: ½ cup cooked porridge oats (2g), with ½ cup raspberries (4g), and a tablespoon of chia seeds (5.5g). Total: 11.5g fibre
  • Lunch: 2 slices of wholemeal/wholegrain toast (4g), with ½ an avocado (5g) and a side salad with 100g baby spinach (2.2g) and a sliced tomato (1.5g). Total: 12.7g fibre
  • Dinner: A portion of meat with ½ cup of cooked, cubed sweet potato (2g), 1 cup steamed broccoli (5.1g) and 1 cup cooked cauliflower (2g). Total: 9.1g fibre
    Total: 33.3g fibre

Currently, the average intake of dietary fibre for adults in the UK is about 20g a day (10), which is below the recommended intake. Modern dietary habits have shown a decrease in overall fibre consumption, and this may be due to food processing and the emergence of “western diets” (1). Nowadays, western diets include more processed and refined foods. In the refining process, fibre is often extracted to improve the taste or texture of the food, potentially contributing to less fibre being consumed in the diet. With the emergence of low-fibre western diets, links have been found between these diets and an increased occurrence of diseases including type-2 diabetes mellitus, obesity, metabolic syndrome and inflammatory bowel disease (1).

Fibre is an important nutrient to support health, and there are many food sources of fibre and ways to include it in the diet.

Food sources of fibre

  • Vegetables
  • Fruits
  • Nuts
  • Seeds
  • Beans and Pulses
  • Wholegrains

How to include more fibre in the diet

  • Include a variety of vegetables in every meal (aim for 3-5 different vegetables)
  • Include low sugar fruits such as berries in a meal or as a snack
  • Swap refined white bread or pasta for wholegrain options
  • Sprinkle nuts and seeds on yoghurt, porridge or salads
  • Leave skins on fruits and vegetables
  • Add pulses such as beans, lentils or chickpeas to bulk up meals, or eat as side dishes instead of white rice or other starchy options

Consuming too much fibre too quickly may cause bloating, gas and constipation. When increasing fibre intake in the diet, it is helpful to do so gradually so that there is time for the natural gut bacteria in the digestive system to adjust to the change. It is also important to drink 6-8 glasses of fluid a day, especially when increasing fibre intake, as a diet higher in fibre may work best when water is absorbed (11).

Dietary fibre is a powerful nutrient, and if adequate amounts of it are consumed in the diet, health benefits may be experienced. Fibre plays an important role in maintaining gut health, and in turn, the health of the entire body.

Claudia Ripamonti is about to start her final year of studying Personalised Nutrition. She has an interest in gut health and learning how to support others in their health journeys. To see more of her posts and healthy food creations, she can be found on Instagram as @happy_whole_healthy.

References:

  1. Cronin, P., Joyce, S.A., O’Toole, P.W. and O’Connor, E.M., 2021. Dietary fibre modulates the gut microbiota. Nutrients, 13(5), p.1655.
  2. Zhang, N., Ju, Z. and Zuo, T., 2018. Time for food: The impact of diet on gut microbiota and human health. Nutrition, 51, pp.80-85.
  3. Den Besten, G., Van Eunen, K., Groen, A.K., Venema, K., Reijngoud, D.J. and Bakker, B.M., 2013. The role of short-chain fatty acids in the interplay between diet, gut microbiota, and host energy metabolism. Journal of lipid research, 54(9), pp.2325-2340.
  4. BNF, 2018. Dietary fibre. [online] Available at: <https://archive.nutrition.org.uk/healthyliving/basics/fibre.html?limitstart=0> [Accessed 13 October 2022].
  5. Hasbay, I., 2019. Dietary Fiber and Nutrition. In Dietary Fiber: Properties, Recovery, and Applications (pp. 79-123). Academic Press.
  6. Rao, T.P., 2016. Role of guar fiber in appetite control. Physiology & Behavior, 164, pp.277-283.
  7. Al Bander, Z., Nitert, M.D., Mousa, A. and Naderpoor, N., 2020. The gut microbiota and inflammation: an overview. International journal of environmental research and public health, 17(20), p.7618.
  8. Ma, W., Nguyen, L.H., Song, M., Jovani, M., Liu, P.H., Cao, Y., Tam, I., Wu, K., Giovannucci, E.L., Strate, L.L. and Chan, A.T., 2019. Intake of dietary fiber, fruits, and vegetables, and risk of diverticulitis. The American journal of gastroenterology, 114(9), p.1531.
  9. Harvard T.H Chan, 2022. Fiber. [online] Available at: < https://www.hsph.harvard.edu/nutritionsource/carbohydrates/fiber/> [Accessed 17 October 2022].
  10. NHS, 2022. How to get more fibre into your diet. [online] Available at: <https://www.nhs.uk/live-well/eat-well/digestive-health/how-to-get-more-fibre-into-your-diet/> [Accessed 18 October 2022].
  11. NHS, 2021. Water, drinks and your health. [online] Available at: <https://www.nhs.uk/live-well/eat-well/food-guidelines-and-food-labels/water-drinks-nutrition/#:~:text=The%20Eatwell%20Guide%20says%20we,tea%20and%20coffee%2C%20all%20count.> [Accessed 18 October 2022].
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