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Inside Our Food

What Are Prebiotics | Foods and Supplements?

In the last few years, evidence has emerged on the importance of gut health to our overall well-being. So, how do prebiotic foods and supplements affect a healthy gut?

Our bodies host ~10 trillion tiny organisms (bacteria, fungi and other microbes) that live mostly in our digestive tract, outnumbering our human cells 10 to 1.1 This is what we call our microbiota. Our bodies have a symbiotic relationship with these microorganisms that not only help aid in our digestion process but also regulate our mood and hormones. 

With most of our immune system located in our gut,2 our microbiota is also heavily involved with how stress affects our body. When operating optimally, this immune-microbial alliance allows our body to arm itself with immunities necessary for it to thrive.

What are prebiotics? 

Our digestive systems rely on the presence of ‘good’ bacteria in our guts and are thrown off balance by the presence of ‘bad’ bacteria. Prebiotics are essentially ‘food’ for the healthy bacteria (like bifidobacterium) in our gut, allowing them to grow in numbers.

In technical terms, prebiotics are non-digestible fibrous substances (mostly fermentable carbohydrates). Since we can’t digest these carbs, they pass through into our lower digestive tract, becoming a food source for healthy bacteria and acting like fertilizer to help them grow.3 So, with the right amount of prebiotics in our system, we optimize the work of the healthy bacteria that promotes good gut health. 

Read more about the role of prebiotics in supporting good gut health.

Then, what is prebiotic fibre?

You’ve likely heard of fibre before. Think of your favourite cereal box: “packed with fibre”! Fibre is the name we give to carbohydrates that our bodies cannot break down into sugar. These digestion-resistant carbohydrates help regulate the body’s use of sugars, keeping our blood sugar and hunger in check. Although prebiotics are a type of fibre, not all fibre can be classified as prebiotic. 

Different types of prebiotics

The most common prebiotics are Fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS). FOS can be taken from plants or synthesized, while GOS is synthetic. Both prebiotics have beneficial effects on human health. 

Other types of prebiotics include certain resistant starches, pectic oligosaccharides (POS), and Non-Carbohydrate Oligosaccharides.6 The names are daunting, but simply put, they have a specific chemical compound that helps them move through the upper GI tract without being absorbed, thus becoming nutrients for our colon. 

Recognising prebiotics on the ingredients list 

If you’re searching for prebiotics on an ingredient list, you’ll often see them listed as inulin (a type of FOS), any of the long daunting prebiotic names listed above, or simply prebiotics.

Prebiotics foods

Chances are you are already including prebiotic foods in your diet.

Well-known prebiotic foods include:

  • Chicory root: contains almost 50% inulin. It is often used to relieve digestion issues. 
  • Jerusalem Artichoke: provides about 2g of dietary fibre per 100g, around three-quarters of which comes from inulin. 
  • Garlic: about 11% of garlic's fibre content comes from inulin and 6% from FOS
  • Bananas: high in resistant starch and full of fibre, they help promote the growth of healthy gut bacteria. 
  • Flaxseeds: full of fibre, which is 20-40% prebiotic soluble fibre. 8

At the moment, there are no official dietary recommendations for “adequate intake” or a “recommended daily allowance” for prebiotics or probiotics, but researchers do recommend eating at least 3g to 5g of prebiotics per day to see some benefit and more generally to eat 28g of fibre per day (based on a diet of 2000 kcal per day).7

However, since low quantities of FOS and GOS naturally exist in foods, we can seek to incorporate them through various sources (e.g. prebiotic breakfast or protein bars, or prebiotic supplements).5

Prebiotic supplements

Although it’s best to include prebiotics in your diet,  you can increase your intake with prebiotic supplements. Be careful, some “prebiotic” supplements actually contain mainly non-prebiotic forms of fibre, so be sure to check the ingredients contain fermentable insoluble fibres such as inulin and oligofructose. Lastly, be cautious when buying supplements that contain only a few milligrams of prebiotics, as this is likely not sufficient to offer any substantial benefit.9

Learn more about prebiotics and probiotics in our 'ask the expert'.

Overall, prebiotics are necessary for those healthy gut bacteria to thrive. Having a healthy digestive system can improve your mood positively, improve your immune system, or even influence cognitive and behavioural functions.

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