Poop Like a Trooper - the benefits of fibre
Fibre is a key component in our diet with many health effects ranging from weight management to cardiovascular disease risk. Most of us in the UK don’t eat enough fibre, with most adults struggling to meet half of the 30g per day recommendation.
We have all heard, ‘fibre is really good for you’, ‘you need to eat more fibre’. We might even know that vegetables contain fibre. But what even is fibre? Is it all good for us? And why should we be eating it?
What is fibre?
Fibre is a group of many different carbohydrates, all with one thing in common: they cannot be digested or absorbed in the stomach or small intestine. This is because we don’t produce the right machinery (enzymes) to break them down. They end up in the large intestine where they have varying effects on our health depending on the type of fibre.
Types of fibre
The human gut is full of different types of bacteria. The balance of good and harmful bacteria in the gut has many health effects. The good gut bacteria, the kind associated with health benefits, is able to break down these kinds of fibre by fermentation and use them for energy.
Eating fermentable fibre increases the amount of good bacteria in the gut and increases the production of short-chain fatty acids (an important byproduct of the fermentation process). These have important and wide reaching effects on health.
The majority of fermentable fibres are also among the other fibres classified as soluble. Soluble fibers can dissolve in water and form a gel like consistency in the gut. Some soluble fibres are known as viscous fibres. These produces very thick gels when they enter the gut, creating volume in the stomach and delaying the rate that the stomach empties.
These fibres do not create gels with water and are generally non-fermentable, meaning that even gut bacteria cannot break them down. They act to increase the size of your poop. This not only plays a role in feeling full, reducing appetite and weight weight management but it also increases the size of your poop, easing transit from the body and reducing the risk of painful conditions such as haemorrhoids.
Where is fibre found?
There are different types of fermentable, soluble and insoluble fibres, with slightly different health effects. And because different fibres are found in varying proportions in different foods, we want to ensure we eat a range of all these fibre containing foods to obtain maximal health benefits.
Adequate fibre intake improves the health of your gut in two ways:
Fermentation of certain fibres (pre-biotics) change the environment in the gut, making it harder for harmful bacteria to survive.
The short-chain-fatty-acids produced from fermentation improves the lining of the gut. This makes it less likely for particles of food or nasty bacteria getting into the body, causing chronic low grade inflammation. While short term inflammation is beneficial as it helps the body to fight off foreign invaders, this long term inflammation is a major problem. It has been shown to play a major role in almost every chronic disease, from metabolic syndrome to Alzheimer’s (REF, REF). Several observational studies have shown that a high fiber intake is linked to lower levels of inflammatory markers in the bloodstream (REF, REF).
The effects of fibre on changing the balance of good and bad bacteria in the gut and the production of short-chain-fatty-acids has been shown to influence the immune system. This has been implicated in reducing severity of inflammatory bowel conditions such as Chron’s disease (R).
The effect of fibre on the balance of bacteria and improving inflammatory conditions appears to be further reaching than just the gut. There is recent evidence that fibre also reduces the severity of conditions such as asthma, eczema and food allergies (R )(R )(R).
Increased fibre intake can help in aiding weight loss and management through a number of mechanisms. By binding with water and creating thick voluminous gels, soluble and viscous fibres, can promote feelings of fullness earlier in a meal, thus reducing calorie intake at the meal. Viscous gels also have a two pronged attack when it comes to keeping us feel fuller for longer. Firstly, they delay how quickly the stomach empties and secondly viscous fibres reduce the rise in Ghrelin (the hormone that triggers hunger) after a meal.
When weight loss is the goal we can take advantage of these effects on appetite because by increasing foods high in fiber such as vegetables, beans and legumes we can reduce energy intake over the day while keeping hunger at bay. Eating more of these foods may also impact by displacing intake of high fat and sugar caloric foods that may contribute to weight gain.
Cardiovascular disease and diabetes
By creating gels, soluble fibres slow the breakdown and absorption of food in our gut and as a result, reduces how quickly and how high our blood sugars rise after a meal. Managing blood sugar levels reduces the risk of developing Type 2 Diabetes.
If you didn’t already know, it's not just blood sugar levels that rise after you eat. If you eat a meal with fat in it, the amount of fat in your blood also increases. If this is too high for a prolonged amount of time it increases the risk of cardiovascular disease. But fibre not only directly reduces the amount of cholesterol in the blood but also reduces increase and amount of fat entering the blood, so lowering your risk of heart attack and stroke!
One type of fibre in particular called beta-glucan has been found to lower cholesterol levels, contributing to the effect of fiber on reducing cardiovascular disease risk.
How to increase your fibre intake
Most people in the UK aren’t reaching the recommended 30g a day of fibre associated with reducing the risk of the health conditions discussed. Here are some tips to help increase your intake:
Eat your veg! Aim for 2-3 fist sized servings of veggies at every main meal and try and sneak some into your snacks too!
Keep your fruit and veg au natural i.e. as a whole food. We want to keep the bulky tough part of the fruit and veg so limit fruit and veg juices to 1 glass a day (as this doesn’t contain any fibre) and eat the rest in their whole form.
Eating your leftovers cold? This may seem a little odd but when you cook starchy carbohydrates (potatoes, pasta, rice) and eat it cold the next day (10 points for meal prepping), it actually increases a certain type of fibre (resistant starch) that is really strongly linked to all these amazing health benefits.
Increase slowly! And drink plenty of water - see why in the next section!
Can you eat too much fibre?
As CrossFitters with more attention to our diets it's likely we have above average intakes, possibly even above the recommended 30g a day. But increasing fibre intakes too high (~70g/day varying for individuals tolerance), or increasing intake too quickly can cause issues!
If you increase fibre in your diet too quickly, this can cause uncomfortable bloating, possible nausea. This is because increasing fibre increases fermentation and that produces gas. It's also key to increase water intake when increasing fibre because fibre needs to bind to water to help it's exit, otherwise it's a little like adding cars to a traffic jam.
Fibre for the CrossFitter
For you CrossFitters, what is just as important as HOW MUCH fibre you eat, is WHEN you have your fibre.
While fibre has a wonderful range of health benefits we want to reduce our intake of fibre directly before and after training for a couple of reasons.
In the hour before training we want to avoid high fibre foods because it can lead to gastrointestinal issues during a workout such as nausea, the urge to go to the toilet, farting and stomach cramps. Not nice for you, not to mention those that may be down wind.
After training is when we want to be taking on board proteins and easily digested and absorbed carbohydrates that can replenish the muscles and help them repair. Fibre slows digestion and absorption of nutrients, not what we want.
This means we want to stick to lower fibre sources of carbohydrates in the 1-2 hours before and after exercise and increase our fibre intake at other meals.