If you’ve been looking into how to support your gut health, you might be familiar with the terms ‘prebiotics’ and ‘probiotics’. Although they sound the same, prebiotics have an entirely different - but very important - role.
Your gut microbiome is the community of trillions of live bacteria - both good and bad - that reside in your gut. As you probably know, it’s important to nourish and support the good bacteria as they perform essential functions in your body. These functions promote optimal digestion and overall good health, so they need extra love!
It’s thought that an imbalance in the gut microbiome, causing a reduction in good bacteria, could contribute to conditions such as IBS, obesity, and some autoimmune disorders such as coeliac disease. So it makes sense to start with your gut health when looking to improve your overall health.
What’s the difference between Prebiotics and Probiotics?
Prebiotics are essential for gut health, but their importance often gets forgotten about in favour of their more popular sibling, probiotics. Prebiotics and probiotics work hand in hand and are both totally necessary for supporting your gut microbiome. Without prebiotics, probiotics can’t thrive, so eating probiotic foods along with prebiotic fibres makes sure the healthy bacteria gets to your gut safe and sound. It will also give them a food source to convert to many beneficial, health-promoting compounds, supporting your overall health and energy levels.
Prebiotics are mostly found in high fibre foods. Their purpose is to feed the good bacteria (the probiotics!) in the gut, encouraging them to thrive and multiply.
Probiotics generally come from fermented foods. They are beneficial live bacteria that offer support to the gut as they pass through. Some types can even ‘stick’ and colonise the gut, creating a healthier community of microbes.
For your gut microbiota to be healthy, you need to foster the right strains of beneficial bacteria in your gut (aka probiotics), and secondly, it is equally important that you feed those beneficial bacteria with the right foods to keep them in abundance and thriving (aka prebiotics).
What are Prebiotics?
Prebiotics are non-digestible fibre compounds - found mostly in plant foods - that feed certain types of bacteria in the gut and encourage them to multiply. Although they are a type of dietary fibre, not all fibres are classed as prebiotics as there is strict criteria that must be met.
To qualify as a prebiotic, a food must:
Be resistant to stomach acid
Remain undigested until it reaches the colon
Be fermented by the gut microbiota
Change the growth or activity of the gut microbiota
How do Prebiotics work?
Think of prebiotics as food for your good gut bacteria. They act like a fertiliser, feeding and stimulating the growth of beneficial species, including Lactobacillus and Bifidobacterium. These good bacteria have several beneficial effects on health, such as regulating and strengthening the immune system, inhibiting the growth of bad bacteria, improving digestion, producing vitamins and digesting food.
The body isn’t able to break down these prebiotic fibres, so they are passed through the digestive system to the gut microbes in the colon. Here they’re digested by these microbes, and as a result produce various beneficial metabolites, including vitamins and short chain fatty acids (SCFAs).
SCFAs are the end-products of prebiotic fermentation, and play an important role in regulating the intestinal barrier, immune system and inflammatory response.
Types of Prebiotics
The most beneficial prebiotics are inulin, fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS), which can be found in a variety of plant foods. Some examples include:
FOS and inulin:Foods such as Jerusalem artichoke, banana, asparagus, garlic, onions, chicory, leeks, barley, oats, etc.
GOS: Foods like legumes e.g. peas, lentils and beans.
What are the Benefits of Prebiotics?
Prebiotics not only regulate the gut microbiome, but studies are finding potential in them to prevent a number of diseases. These health benefits mostly come down to the increased production of SCFAs.
Effects on the Immune System
Prebiotic fibres work to maintain immune system health by nourishing certain types of good bacteria in the gut, which play a role in strengthening the body’s natural defences against pathogens. SCFAs also help to balance the gut environment, maintaining the immune response and reducing inflammation.
Colorectal Cancer Prevention
Prebiotics may help prevent colorectal cancer due to their ability to modify the gut microbiome. The production of SCFAs and ability to modify the gene expression in cancerous cells are the main mechanisms thought to be responsible for the anticancer effects of prebiotics.
Prevention of Inflammatory Bowel Disease
An imbalanced gut microbiota is the major cause of Inflammatory Bowel Disease (IBD), and prebiotics can bring balance to the gut microbiome.
An imbalanced gut microbiome is also a trigger for constipation. And promoting the growth of good bacteria with the help of prebiotics - as SCFA production stimulates bowel movement - can relieve the issue.
Prevention of Obesity
An imbalance of the microbiome causes low-grade inflammation in the gut, which can disrupt the body’s metabolism of glucose and absorption of fats. And both of these issues are associated with obesity.
Prebiotic fibres work to modulate the gut microbiome, reducing inflammation and in turn helping to improve glucose tolerance. Prebiotics have also been linked to an increased secretion of satiety-promoting hormones, and a decreased production of ghrelin, a hormone which promotes appetite.
Cholesterol and Blood Pressure Lowering Effects
The cholesterol-lowering effects of prebiotics are mainly due to their production of SCFAs. These SCFAs are absorbed into the bloodstream, which allows them to travel around to various organs and take effect.
In the large intestines, they’re involved in the absorption of fats and phospholipids, and have a binding effect on molecules such as cholesterol. This can lead to decreased levels of cholesterol in the bloodstream. A lower level of total cholesterol increases the clearance of LDL cholesterol (bad cholesterol), which can potentially reduce blood pressure.
Improve the Absorption of Several Minerals
Prebiotics improve the absorption of key minerals such as calcium and magnesium, which in turn has a beneficial effect on bone mineralisation. The SCFAs produced by prebiotics help maintain healthy levels of stomach acid, which ensures optimal absorption of minerals.
What Foods contain Prebiotics?
Prebiotics are found in hundreds of plant foods. In fact, you probably already eat many of them each day. Good sources include:
Vegetables: Artichokes, chicory, garlic, onions, leek, shallots, asparagus, beetroot, fennel, green peas, cabbage, potato, sweet potato.
Fruit: Bananas, nectarines, apples, white peaches, watermelon, grapefruit, pomegranate, dried fruit (e.g. dates, figs, mango).
Legumes: Chickpeas, lentils, kidney beans, lima beans, soybeans.
Nuts: Cashews, pistachios.
Grains: Millet, quinoa, rye bread, oats.
Something to note as you increase your consumption of prebiotic foods is that excess gas production can be a side effect until your microbiome composition adjusts to the change. If you’re not used to eating these foods, start small and gradually increase the amount and variety you consume each week.
Good gut health can be achieved by eating a balanced and varied diet, with as many different plants as possible. Switching the composition of bacteria in your gut to a more favourable balance could play an important role in supporting your overall health and taking preventative measures against certain health conditions and diseases.