Updated: Aug 20, 2020
If you’re interested in gut health, immunity, losing weight, balancing hunger hormones and protecting your health from chronic diseases. Then you might want to consider making the ever-so-modest and under celebrated fibre, your new best friend.
Yes, there is indeed one thing that has all of these amazing health benefits, and more! And I'm going to tell you (perhaps borderline inspire you?!) all about it in this article where I have distilled my top 7 reasons why you could benefit from eating more fibre.
So what is fibre exactly? Fibre is made from complex carbohydrate structures found in plant foods such as beans, rice, pasta, oats, fruits, vegetables, nuts and seeds - all plants! There is soluble fibre, which dissolves with water to form a gel like mass whilst it passes through the stomach and small intestine. Whilst insoluble fibre remains intact, helping to bulk up your poop and make it easier to exit. All plant foods contain a mixture of both soluble and insoluble fibre, so there’s no need to wonder how to get each of them, simply focus on eating fibrous foods in general. The recommended amount for adults in the UK is 30g per day, but really it’s more the better!
Fibre has a really important impact on digestive health and the gut microbiome. In the last decade, a huge amount of research (1) has made exciting discoveries on the role of the gut microbiome (where all the trillions of friendly bacteria live in the colon) and its strong influence on critical organs and overall health (2).
Of the trillions of bacteria that call the gut home, there are over a 1,000 different species (3). The gut’s composition is strongly shaped by the diet, everything we eat has an effect on the gut microbiome. In particular, dietary fibre feeds the gut bacteria by process of fermentation of certain fibre compounds, also known as prebiotics. Prebiotic fibre helps the good bacteria to thrive by stimulating growth and activity, fuelling it to produce short chain fatty acids which act not only as an important fuel source, but also as chemical messengers, similar to how hormones behave. Short chain fatty acids help maintain gut pH balance, fights inflammation, strengthens immunity, regulates appetite, protects the brain and helps prevent diseases (4).
The gut and the immune system have a symbiotic relationship, this means they exist to work hand in hand. In fact, 70% of the body’s immune cells live inside the gut (5). From the moment people are born, the gut begins to train the immune system, educating it on the differences between good and bad bacteria that invade the body through the food we eat and the air we breathe. This functional guidance by the gut is therefore pivotal in the balance and operation of the immune system (6), and can be compromised if the gut microbiome is not working properly. A healthy gut means our immune system functions to protect the body against bad bacteria, viruses and other foreign microorganisms that may cause diseases such as inflammatory bowel disease (IBD) and cancer (7).
The gut and the brain are intimately linked, in fact, they are constantly talking with each other. Hence, the saying ‘gut instinct’ and why you feel butterflies in the stomach when you’re nervous. There are many different pathways in which communication signals are sent. One of which is via those fibre derived short chain fatty acids (8), which is believed to play a very important role in brain health. Short chain fatty acids either directly or indirectly influence emotion, cognition and certain brain disorders such as depression, Alzheimer's, Parkinson's diseases and autism (9).
Fibrous foods, in particular fruits and vegetables tend to be high in volume and have fewer calories. This means there is a whole lot more food to eat and chew which can slow down the rate of eating. When the volume of food stretches the walls of the stomach it triggers fullness signals to the brain leading to improved satiety (10), something that liquids and smaller but more energy dense foods lack. Satiety is further enhanced by soluble fibre when it forms a gel like mass in the stomach, it slows down gastric emptying, a slower rate of digestion means you are feeling fuller for longer. Whereas fibre depleted food such as cake or white pasta passes through the digestive system much faster (11).
Short chain fatty acids produced in the gut help contribute to the production of a hunger suppressing hormone called Leptin (12). To regulate weight, leptin is produced when the level of body fat increases which creates a loss of appetite, although slowly and over a longer period of time. However, short chain fatty acids also contribute to appetite suppressants that work on a short-term basis. Soon after eating fibre rich foods, short chain fatty acids release hormones into the bloodstream that turn down cravings (13).
And if that wasn’t enough to curb appetite, when undigested food is detected in the final stages of the small intestine - the ileum, the body reacts by curbing appetite immediately (14). Undigested food only occurs with fibre present, carrying macronutrients in its gel-like mass towards the colon.
When fibre forms its gel-like mass it grabs hold of food, diluting and blocking absorption whilst it travels through the digestive tract and out the other end. This means, eating fibre rich foods at each meal could reduce the level of calories the body absorbs (15, 16).
Fibre also increases metabolic rate (17), that is the amount of energy the body burns. This is because fibre stimulates the gut, which are highly metabolically active tissues. So, if you want to burn more calories without doing any extra exercise, eat more fibre ;)
There is a direct correlation between high fibre diets and reduced risk of cardiovascular disease (18). As well as blocking the absorption of calories, soluble fibre also reduces the absorption of LDL cholesterol. LDL cholesterol is also known as bad cholesterol because it can increase the risk of heart disease and stroke. Similarly, the slower rate of digestion helps to reduce blood sugar levels supporting those suffering from diabetes, and also helps to prevent type 2 diabetes (19). Increased dietary fibre has also been strongly associated with cancer prevention, in particular bowel cancer and breast cancer (20, 21).
Eating fibre rich foods is highly recommended to help achieve optimal nutrition and health. In particular, fibre and its prebiotic qualities has huge benefits on gut health leading to better health overall. Fibre rich diets also supports healthy weight management, food satiety, energy and blood sugar balance. The average UK adult only consumes 17g for women, and 20g for men so there's some work to be done to start eating more fibre.
Fortunately, fibre is incredibly accessible and inexpensive. Fibre can be found in lots of different whole plant foods, here is a non-exhaustive list that you can use as a starter. Choose foods that are unrefined, unprocessed and eat a variety and you’ll be sure to be getting lots of fibre. So, next time you are shopping for groceries, grab some more fibre rich foods, your gut will thank you for it.
VEGETABLES
Leafy and green vegetables - broccoli, spinach, kale, swiss chard, peas, brussel sprouts, green beans, asparagus, cabbage
Other vegetables - carrots, artichoke, butternut squash, pumpkin, parsnips, sweet potatoes, potatoes, turnips, sweet corn, fennel, aubergine, tomatoes
FRUIT
Avocado, strawberries, raspberries, blueberries, pears, kiwi, passion fruit, oranges, bananas, cherries, apricots, apples, mango, grapefruit, peaches, pineapple, grapes, watermelon
WHOLE WHEAT & WHOLE GRAINS
Oats, whole wheat pasta, whole wheat bread, brown rice, barley, quinoa, rye, couscous, bulgur, buckwheat, bran
BEANS & LEGUMES
Lentils, chickpeas, black beans, kidney beans, white beans, black eyed beans, soybeans, pinto beans, split peas
NUTS & SEEDS
Chia seeds, flax seeds, sesame seeds, pumpkin seeds, almonds, dried coconut, pine nuts, pistachios, hazelnuts, pecans, macadamia, sunflower seeds, peanuts
Note: if you are currently on a very low fibre diet, it is advised to increase fibre intake slowly as it may cause bloating and discomfort until your body becomes accustomed to it. Always seek professional medical advice if you have issues with your digestive process or gut health problems before changing your diet or fibre intake drastically.