There are two types of healthy fibre: soluble fibre, which feeds your helpful gut bacteria and makes compounds to help you live a healthier life, and insoluble fibre which helps clear waste from the gut. Here are examples of fibre, and benefits.
Dietary fibre – essential for health
Dietary fibre (also called roughage) is the part of your food that cannot be broken down by your own digestive enzymes. It consists of plant-based carbohydrates, such as non-starch polysaccharides – inulins, lignins, pectins, beta-glucans, oligopolysaccharides and dextrins.
The colourful Mediterranean Diet, or Rainbow Diet as we like to call it, is a naturally high fibre diet. That is one of its major qualities. Natural fibre is also a big factor in the health benefits the Rainbow Diet provides – from cardiovascular protection to longevity.
Examples of fibre-rich foods
Legumes or pulses – lentils, red kidney beans, chickpeas, beans
Nuts – walnuts, almonds, pistachio’s
Fruits – berries, apples, pears, peaches, apricots, avocado
Seeds – pumpkin, sunflower, flax, hemp
Vegetables – carrots, broccoli, artichoke, beetroot, greens
Whole grains – oats, barley, rye
What’s the difference between soluble fibre and insoluble fibre?
Soluble fibre mixes with water and gastric juices to form a gel-like substance in the gut. This paste is the favorite food of your commensal (healthy) gut bacteria. From it, they make B vitamins, vitamin K, serotonin, melatonin, and three crucial Short Chain Fatty Acids (SFAs) – butyrate, acetate and propionate, which keep your gut healthy, lower inflammation in the body, kill cancer cells and block cholesterol formation amongst other notable health benefits.
Insoluble fibre helps the essential passage of food through the gut.
In fact many foods contain both types of fibre.
Examples of soluble fibre?
Oats, vegetables (carrots, broccoli), pulses (lentils, peas, beans), nuts (walnuts, almonds) and seeds (sesame, pumpkin and sunflower seeds), psyllium.
Examples of insoluble fibre?
Bran (oat bran and wheat bran), beans (legumes, pulses), vegetables, whole grains.
The Health benefits of fibre
i) Soluble fibre consumption, immune response and inflammation
Your commensal (good) gut bacteria love soluble fibre and feed off it. It helps them grow their numbers. And the more good bacteria there are, in terms of volume and diversity (species – families, and strains – family members) the stronger your adaptive immune system. About 85% of your immune response and immune memory, is produced in response to the bacteria in your microbiome. Who needs pills?
Unsurprisingly, research has shown that people who consume the highest levels of soluble fibre have the strongest immune systems.
The good bacteria in your gut are called ‘Probiotics’ (pro-life).
And the ‘soluble’ fibre, much loved by these commensal bacteria,is called ‘Prebiotics’.
Prebiotics are foods that feed ‘Probiotics’ (your bacteria).
The good news is that you can change the composition of your whole gut microbiome in just 24 hours. Although you might have loved lots of refined white bread and pasta, sugary foods, refined oils plus lots of cows’ dairy in the past resulting in large numbers of bacteria in your gut all producing high levels of inflammatory compounds; all you have to do is switch to a high soluble fibre diet and 24 hours later know that you have made many more commensal bacteria that will be making anti-inflammatory, health-promoting molecules.
That’s life. You are what your gut bacteria eat!
ii) Fibre consumption and cholesterol
Research shows that people who eat higher levels of soluble fibre tend to have lower levels of cholesterol. One of the main reasons is the gut bacteria. The fibre feeds them, they grow and multiply, and they make short-chain fatty acids (SFAs). One of these – propionate – can block the formation of cholesterol in the body. Not surprisingly, people who consume more fibre tend to have less cardiovascular and heart disease.
iii) Soluble fibre consumption and weight loss
Most importantly, soluble fibre bulks up with water and makes you feel full. It also slows down the emptying process, so you feel fuller for longer and eat less – and people who eat high soluble fibre diets tend to lose weight.
One study even found that people who added more fibre to their diets felt fuller and lost more weight that people who went on ‘slimming diets’.
iv) Soluble fibre and glucose levels
A high soluble fibre diet also reduces the level of plasma glucose, and people who indulge in high fibre diets live significantly longer than average. One finding in the Human Microbiome Project was that we actually have a strain of Clostridium in our intestines which binds to fibre and helps clear excess glucose from our bodies. How clever is that; a protective bacterium? Unfortunately 5 days of antibiotics can make it extinct. As can stress, poor diet, parasites, smoking and drugs. A poor microbiome can equal poor sugar control and obesity. This is why the same pathogens (bad bacteria) tend to be found in both obesity and type-2 diabetes.
All types of soluble fibre slow the digestion process, whereas only insoluble fibre helps move the waste through the intestines.
Fibrous cell membranes in vegetables and pulses prevent the rapid release of sugar from the cells but over-cooking destroys these cellulose membranes, which is why (for example) raw carrots have a very low Glycemic Index, but cooked carrots have a high GI – the sugar is much more readily available when the fibrous cell walls have been broken down by cooking.
Moreover, refined food has usually lost the fibre – whole brown rice is good for you but eating refined white rice is like eating neat sugar. Ditto pasta, breakfast cereals and various grains.
Glucose rushes can have disastrous effects, for example high plasma glucose damages the immune system, directly feeds (and even causes) cancer cells and high plasma glucose can heighten insulin levels, which in turn stimulate an enzyme (Cox-2) present throughout the body, causing chronic inflammation.
Dr. Chauncey Crandall and the UK’s Dr. Aseem Malhotra have both argued that without this glucose-insulin-inflammatory effect, arteries would not inflame and fat would not stick to them. And so people would have less vascular disease, less heart attacks and less strokes.
So it’s not merely that soluble fibre helps produce higher levels of gut bacteria making SFAs that reduce cholesterol. Soluble fibre consumption helps stop insulin and inflammation leading to blocked arteries too.
Soluble fibre also seems to be able to bind to fats before they are absorbed, further reducing plasma cholesterol levels.
v) Soluble fibre reduces toxic chemical load
Toxicity in the body from chemicals such as mercury, cadmium and xenoestrogens can be a major health concern. Gut bacteria use fibre to bind the chemicals, heavy metals and hormones to them, and then take them effectively out from the body.
Insoluble fibre comes from plant cellulose and hemicellulose. It does not dissolve in . It does however attract water to it, softening your stool and allowing it to pass with less strain on the bowel. It helps promote regularity.
Insoluble fibre moves through the gut largely unchanged. It cannot be attacked by your digestive enzymes. There is a little evidence that, because this fibre is in cell walls, it slows the release of natural sugars from the plant, reducing insulin sensitivity and even type-2 diabetes risk.
Insoluble fires basic benefit is that it helps push your food remains through the gut.
Many vegetables and fruits contain both soluble and insoluble fibre.