I want to start this month’s article with a question for you…how many plants are you consuming on a daily basis, a weekly basis? By plants here we can include nuts, seeds, legumes, whole grains and of course fruits and vegetables. The current recommended daily fibre requirement for women is 25g and for men 38g. And our fibre needs can increase with age due to slower rates of digestion. Foods considered to be high in fibre are: oats, carrots, apricots, broccoli, lentils, avocados, almonds, cauliflower, walnuts and wholewheat bread, just as a small sample. Maybe you can tick a few items on this sample list, or maybe you can include them all as part of your daily/weekly fibre intake, but it turns out that it is not just about getting enough fibre in your diet but that variety in our fibre sources is incredibly important.
Most of us are familiar with the concept that adding fibre to the diet helps ‘keep you regular’ and aids in preventing constipation. While this is true, it is however both a rather basic and outdated view of the role fibre plays. It is not simply a brush to sweep you clean internally. It plays a vital role in feeding our gut microbes.
Microbes are tiny organisms, invisible to the eye and they are found everywhere on earth – in the soil, the water, the air and on and in animal bodies; microbes include bacteria, fungi and viruses, some beneficial, some harmful. It is estimated we have 39 trillion microbial cells in our human bodies, compared to a total 30 trillion human cells, by that measure we are only about 43 per cent human! Together these 39 trillion microbes form what is known as our microbiome. Research into gut microbiome in the last few decades is changing how we think about biology and what it means to be human.
Our microbiome functions as an ecosystem comprised of diverse communities of microbes all with different needs and functions that are intricately interwoven and interdependent. We are in a symbiotic relationship with our microbiome where we can enjoy a mutually beneficial relationship with our gut bacteria though we may never meet them.
Different plants have different types of fibre and these different types of food will in turn feed different populations of microbes. In all healthy ecosystems, the greater the diversity, the healthier the ecosystem. The greater our microbiome diversity, the greater the potential we have to offset the chronic diseases of the body, as we have so many different communities of microbes that feed on fibre. For instance, there are particular microbe populations resident in the colon that feed on fibre producing Short Chain Fatty Acids (SCFA) as a by-product in their digestion process. These SCFAs have an important role, acting as a source of energy for colon cells, helping maintain the gut barrier function which regulates inflammation in the gut. They also influence metabolic processes and impact the immune system and because they cross the blood-brain barrier they can influence brain function affecting mood, behaviour and cognition.
In recent years, some of the most groundbreaking research on the role of fibre in our gut is in relation to how it impacts cancers, both its onset and outcomes. A recent study carried out on behalf of the World Cancer Research Fund on the impact of dietary fibre on melanoma patients undergoing immunotherapy treatment, found that those patients consuming over 20g of fibre daily had a significantly higher survival rate when undergoing this treatment. When they broke down the research, they discovered that for every 5g the individuals upped their fibre intake by their survival rate increased by 30 per cent. As a caveat here, particularly in relation to melanaoma cancer, physical exercise also proved to be a particularly important factor also in both preventing onset and progression of melanoma.
The good news for your gut health is that just four weeks of increasing your fibre intake will positively impact your microbiome. We should consume soluble and insoluble fibre as well as resistant starch, which though classified as a carbohydrate is treated like fibre by important microbes in the colon. Among sources of soluble fibre are coffee (good news for the coffee drinkers ), oats, apples, bananas, peas, carrots and citrus fruits; insoluble fibre is found in unprocessed grains, green beans, cauliflower, broccoli, sunflower and flax seeds to name but a few and resistant starch is found in cooled potatoes, rice or pasta – the cooled part is important, as it is the cooling that returns the food to a ‘starchier’ state and thereby feeds the specific microbes in the colon that produce the all-important short chain fatty acids. Fermented vegetables are a particularly important source of fibre for the gut microbes, so they should also be included in your fibre intake.
Treat your gut like a garden and tend it well. We don’t want to feed the weeds as it were, which is what happens when we consume overly processed foods and sugars. Fibre is your friend. Like any friendship however, we want to ensure mutual respect and benefit, building it gradually. Friendships are made over time. Don’t throw yourself into consuming buckets of fruit and vegetables overnight, especially if your current fibre consumption is low. Bloating and gas is a real issue with sudden fibre uptake. And remember there are certain conditions which preclude the consumption of fibres so make sure you know if increasing your fibre is right for you. Get to know what your body can handle on the fibre front so you can enjoy the benefits of a healthy and diverse microbiome.
May you be fibre-fit for life.
