What are prebiotics? Find out the definition of prebiotics.
What are the different types of prebiotic & how do prebiotics work?
Discover why eating a variety of prebiotic fibre is important for helpful gut bacteria.
What does Prebiotic mean? A definition
A prebiotic is food for the helpful bacteria that live in our gut
Prebiotics are the non digestible fibres found in plant foods, that our body can’t break down on its own.
These fibres pass through undigested to the colon (also known as gut / large intestine), where our gut bacteria feed on them.
Gut bacteria break these fibres down into nutrients and chemicals vital to our immune system & health.
What are Prebiotics?
Prebiotics are types of indigestible fibre in food.
They are chemical compounds, made of long chains of sugar molecules (also called complex carbohydrates)
Prebiotic fibres are found mainly in plants (fruit, vegetables, legumes).
Human breast milk also contains prebiotic fibres, which provide food for the first bacteria that colonise a baby’s gut.
Types of Prebiotic Fibre (Fiber)
Prebiotic fibre compounds have complex sounding names.
Some well known types of prebiotic are :-
– Inulin (found in onions, leeks, garlic & other foods)
– Fructo-oligosaccharides or FOS (found in beans, wholegrains and many types of fruit & vegetables)
– Galacto-oligosaccharides or GOS (long chains of sugar found in breast milk)
How do Prebiotics Work?
Leftover parts of our food, which our bodies can’t breakdown & absorb by itself, pass through into the large intestine (or colon).
Here, bacteria in our gut breakdown the indigestible leftover food molecules (mostly fibre) that our body couldn’t digest on its own.
Our body doesn’t produce the enzymes needed to breakdown fibre into useful calories or nutrients.
Gut bacteria can produce up to 6000+ enzymes.
Enzymes are like chemical scissors : used to chemically cut the indigestible fibre into smaller molecules.
The breakdown of fibre particles unlocks vital nutrients from the fibre which the gut bacteria feed on.
And in the process, they produce chemicals (including short chain fatty acids and vitamins) which are vital to our immune system & overall health.
Different Bacteria Prefer Different types of Prebiotic Fibres
Different bacteria live in different parts of our gut and prefer different types of food.
For example, we know bifidobacteria & lactobacilli (which are the main bacteria types in most probiotic supplements) thrive on inulin contained in
– leeks, asparagus, onion, garlic (all from the lily plant or lilaceous family)
– endives, artichokes (from the sunflower plant family)
Other types of bacteria prefer the fibres in bananas, yet others prefer the pectin fibre in apples.
Variety is key to encourage a wide range of helpful bacteria to thrive.
Studies show that eating a diet full of plant based foods (fruit, vegetables, wholegrains) containing lots of different types of fibre, is key to feeding our gut bacteria, increasing the types of helpful bacteria in the gut & the range of vital chemicals they produce.
The Science Bit
The information I share on this site distills the research I’ve read on the microbiome, prebiotics & probiotics.
You’ll find links to the relevant research studies on each page.
I’m not a scientist / dietician / nutritionist. I’m a food lover & home cook, putting microbiome research findings into action in my kitchen.
Find out more about the scientists leading research into the microbiome on the FAQs page