You may remember in my previous article (MM Feb 3), I briefly discussed how fibre (prebiotics) feeds our gut bacteria. There wasn’t enough room there to delve into all the fabulous effects that fibre has, so I am now going to tell you a little more about it.
Fibre is the portion of vegetables, fruits, grains, nuts and seeds that is resistant to digestion and absorption in the stomach and small intestine. However, some can be digested and fermented by the bacteria in our large intestine.
There are two types of dietary fibre – soluble and insoluble; with plant foods usually containing both in varying amounts.
Soluble fibre – dissolves in water and forms a gel. Examples include oats, legumes, broccoli, Brussel sprouts, potato, apples, citrus, pears, berries, almonds, chia, and onions.
Insoluble fibre – does not dissolve in water. Examples include wholemeal/grainy breads, wholegrain cereals, brown rice, legumes, corn, green beans, courgette and celery.
Dietary fibre directly affects the way we absorb nutrients and chemicals from our food, as well as indirectly affecting our body through the chemical by-products of fermentation produced by our gut bacteria.
The gel formed from soluble fibre binds fats and glucose, altering their absorption rate, which is important for reducing cholesterol and aiding type-2 diabetes management.
Another way it can reduce cholesterol is by binding and removing bile from the body. Bile is made from cholesterol, so when bile is excreted the body uses cholesterol from the blood to make more bile.
Even though insoluble fibre doesn’t dissolve in water, it does attract water, therefore making your stool softer and easier to pass. Combining this softening with the bulking that insoluble fibre provides, promotes bowel health and regularity, reducing the risk of constipation.
Some of the dietary fibre fermented by gut bacteria produces chemicals called short-chain fatty acids. These short-chain fatty acids have been shown to have a number of beneficial effects, such as:
• Nourishing the cells that make up the large intestine lining, reducing
irritation and inflammation.
• Increasing the acidity of the colon, which increases the absorption of minerals
and protects the lining.
• Stimulates immune cell production.
Because fibre either binds water or turns to gel, you need to ensure that you are drinking plenty of water to keep it all in balance. Especially as you increase your fibre intake to hit the daily target of 25 to 30g per day. Be sure to add in high fibre foods gradually because you may notice side effects, such as wind and bloating, as your digestive system and gut bacteria get used to all that fabulous fibre.
Nicole Wilson, Registered nutritionist