Fibre is a carbohydrate that is only found in plant-based foods such as fruits, vegetables, legumes, grains, and nuts. Dietary fibre is beneficial to health and, if consumed in adequate amounts, it can reduce the risk of several chronic diseases.
This article will explain the health benefits of fibre, food that contain fibre and practical tips you can implement to have a thriving fibre friendly diet!
But before we get into specifics, storytime…
Denis Burkitt, a surgeon (1911 to 1993), set his goal as a medical missionary in Africa. While in Uganda, he observed that Africans produced several times more faeces than did westernised people. Also, the stool was more easily produced with minimal discomfort. He stated from his epidemiological studies:
“In Africa, treating people who live largely off the land on vegetables they grow, I hardly ever saw cases of many of the most common diseases in the United States and England – including coronary heart disease, adult-onset diabetes, varicose veins, obesity, diverticulitis, appendicitis, gallstones, dental cavities, haemorrhoids, hiatal hernias and constipation. Western diets are so low on bulk and so dense in calories, that our intestines just don’t pass enough volume to remain healthy.”
He believed that these western disorders had a single causative factor: deficiency of dietary fibre.
What’s the difference between soluble and insoluble fibre?
For many years, the conventional way of classifying dietary fibres has been into soluble and insoluble fibres. Recently, we have come to an understanding that the properties of dietary fibre are much more complex, which can make it difficult to specifically classify.
There is also a lot of overlap between soluble and insoluble fibres as most foods contain both soluble and insoluble fibres. Nonetheless, below is a simple explanation of the two broad categories:
Soluble fibre absorbs water and turns into a gel-like substance as it goes through our digestive systems. This helps slow digestion and softens our stool so it goes through the gastrointestinal tract more easily. Soluble fibre also helps to lower LDL cholesterol, triglycerides, and total cholesterol. It also helps to control your blood pressure and blood sugar levels (1).
Insoluble fibre doesn’t absorb water or dissolve. Instead, it passes through the body in almost the original form it goes in (1). This adds bulk to our stool which helps keep our bowels regular and prevent or relieve constipation.
Foods that are rich in fibre
Legumes + beans (such as chickpeas, lentils and kidney beans)
Vegetables such as artichoke, squash, broccoli, green beans and dark leafy greens
Root vegetables like carrots, potatoes, beets, and radish
Fruits that are rich in pectin, like apples, pears, berries, and bananas
Nuts and seeds
How much fibre do we need?
In 2015, UK Scientific Advisory Committee on Nutrition recommended an increase in dietary fibre intake to 30 g per day (2).
5 reasons why fibre is important for health
1. Lower rates of cardiovascular disease
Greater dietary fibre intake is associated with a lower risk of both cardiovascular disease and coronary heart disease.
Soluble fibre can affect absorption from the small intestine because of the formation of gels that reduces blood glucose and lipid rises (3). In addition, the formation of gels also slows gastric emptying, maintaining levels of satiety and contributing towards less weight gain (4). Soluble fibre and resistant starch molecules are additionally fermented by bacteria in the large intestine, producing short-chain fatty acids, which help reduce circulating cholesterol levels (5).
2. Reduces type 2 diabetes
Dietary fibre intake may reduce insulin resistance and improve the body’s response to glucose (6). In addition, several studies have indicated that risk of type 2 diabetes decreased with total dietary fibre, cereal fibre, fruit fibre and insoluble fibre intake (7, 8, 9).
3. Maintains gut health
Dietary fibre promotes digestive health through its modulation of laxation by increasing faecal bulk, increasing stool frequency, and reducing intestinal transit time (10).
Dietary fibre, particularly those fibres with prebiotic effects such onions, leeks, garlic, wheat, oats, chicory root, and Jerusalem artichoke can modulate the amount and diversity of gut bacteria (10, 11). The friendly gut bacteria process the fibre in your large bowel to produce beneficial short-chain fatty acids such as butyrate. Butyrate plays a key role in maintaining a healthy large bowel as it is the main energy source for cells in the large bowel (colonocytes) and regulates many important processes such as cell growth and cell death. Dietary fibre and butyrate are anti-inflammatory (12).
Inflammation can be one of the contributing factors in several diseases including bowel cancer and people with inflammatory bowel diseases (IBDs) such as ulcerative colitis.
It should be noted, that other compounds in foods containing dietary fibre, such as flavonoids, may also modulate gut bacteria (13).
4. Reduces bowel cancer
The World Cancer Research Fund (WCRF) has reviewed the evidence from research studies for the links between diet, nutrition, physical activity and bowel cancer and concluded that probable evidence exists for a protective effect of foods containing dietary fibre (14).
The evidence demonstrates that dietary fibre from a variety of sources (wholegrains, fruits, vegetables) protect against the development of bowel cancer in a dose-dependent manner (15, 16). Dietary fibre may protect against cancer development through increased faecal bulk and decreased transit time, thereby exposing the bowel to lower concentrations of carcinogens (substances capable of causing cancer) for shorter amounts of time.
In addition, the beneficial short-chain fatty acids such as butyrate (explained above in gut health section) can enhance bowel health by reducing inflammation, thereby can prevent the development of bowel cancer (13).
5. Enhances immune health
The immune system is closely linked with gut microbiota. The development of a health-promoting gut microbiota is thought to start early in life and subsequently affect immune function (17). Dietary fibre intake likely impacts immune function via the gut microbiota, but additional studies are needed to clarify these associations and determine relevant mechanisms.
Potential issues with fibre
Eating too much fibre can cause digestive distress, gas, bloating, diarrhoea and intestinal blockages (18). If you want to include more soluble fibre in your diet, increase your intake gradually. Drastically increasing the amount you eat could create gastrointestinal problems.
4 ways to have a thriving fibre friendly diet
1. Consume a diverse rainbow diet filled with different vegetables, fruit and legumes. For example:
Breakfast – egg omelette with spinach and mushrooms or/ porridge oats with blueberries + nuts and seeds or/ chia seed pudding.
Lunch/dinner – chickpea vegetable stew with brown rice or/quinoa or/lentil dish with vegetables.
Snacks – hummus + carrots sticks or/ apple + nut butter
2. Eat your fruit instead of drinking fruit juice
Juicing removes the fibre from the fruit. For instance, if you drink a glass of pure orange juice, that sugar gets metabolised immediately, causing your blood sugar to spike more quickly. But if you eat a whole orange, which contains soluble fibre, the rate of sugar uptake is more gradual. In juices, you lose fibre’s benefits - especially its important job of regulating digestion and keeping blood sugar from spiking.
3. Consume beans, peas, and lentils in your meals
Legumes are a wonderful and delicious source of fibre (+protein!).
4. Explore different wholegrains options
That does not only include whole wheat bread but also bulgur wheat, pearl barley, quinoa and whole wheat pasta and brown rice.
Fibre is an important nutrient that is an essential part of any well-rounded diet. It helps keep your digestive system regular, stabilises your blood sugar levels, promotes heart health, reduces bowel cancer and may reduce inflammation. Meeting the recommended intake of fibre can be achieved by increasing and diversifying your intake of plant-based foods including vegetables, fruits, legumes, whole grains, nuts and seeds.
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2) Scientific Advisory Committee on Nutrition. 2015. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/445503/SACN_Carbohydrates_and_Health.pdf.
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14) World Cancer Research Fund/American Institute for Cancer Research. Continuous Update Project Expert Report 2018. Diet, nutrition, physical activity and colorectal cancer. Available: www.dietandcancerreport.org
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