Probiotics and prebiotics

Good’s nutrition columnist Ben Warren of BePure explains the difference between probiotics and prebiotics and why they are so good for us

Words Ben Warren. Illustration Janelle Barone of Makes MGMT

Kombucha, sauerkraut, coconut yoghurt, probiotics, prebiotics, …There’s a healthy buzz that’s flying around that is going to be here for a while. It’s the world of the human microbiome.

Estimates state we have 10 times more bacterial cells living in our body than human cells, which begs the question, who’s carrying who around? Are we just a block of flats for bacteria?

The truth of the matter is it’s most likely a highly synergistic relationship – we provide a home and resources for the bacteria and in return they make specific chemicals we need, even making vitamins and actually protecting us from more pathogenic species of bacteria. There is a complex interplay between our immune system and the bacteria living in our intestines, plus the bacteria can turn on and off expression of our genes and our genes can control to a degree which bacteria are more likely to be present in our gut. It’s a close interplay, one which we currently have very limited knowledge of.

Research suggests the broader and more diverse the species living in our intestines the better our health associations, and part of the potential negative impact of antibiotics is they reduce this diversity and number.

In recent years there has been a lot of talk around probiotics – and so what are they? Probiotics are bacteria that have a known health benefit to humans when consumed. In the research the benefits of probiotics are incredibly broad – from the obvious, such as assisting with the digestive system and strengthening the immune system, to effects on mood.

The list of known beneficial species of bacteria is growing by the week. You may have heard of some of the common ones like lactobacillus acidophilus – the beneficial bacteria that’s associated with yoghurts. Many fermented foods contain a variety of beneficial bacteria (and yeasts) hence it’s often advantageous to try to consume these foods daily to keep up species numbers and diversity and support a happy, healthy, broad microbiome.

Probiotics, specifically, refer to the bacteria that confer a known health benefit, whereas prebiotics refer to foods that feed the bacteria that live in our intestines. So not only is it important that we have the right strains of bacteria either in or passing through our gut but that they can thrive on their way, meaning we have to be feeding them the right food. 

Many foods confer a prebiotic benefit – garlic, onions, sweetcorn, watermelon, nectarines, millet, cashews – but the powerhouse of prebiotics are legumes; lentils, beans, chickpeas. 

Consuming more prebiotics can often be very beneficial for cases of constipation and the research is clear that for most people they will get a benefit from consuming them. Note, however, as you increase your consumption of prebiotics, excess gas production can be a side effect until your microbiome adjusts to your new diet.

There are also a small group of people who actually benefit from eliminating prebiotic foods. These are often people who have inflammatory bowel issues. There are a number of dietary protocols that restrict foods that feed bacteria, with FODMAPS and FOS-free diets leading the way in the research. Clinically, we’ve found if people respond well to these diets, then often they have pathogenic bacteria in their intestines. 

Like many things, there’s no black and white and the chances are some strains of bacteria are going to be better for an individual than others. The research is still in its infancy relatively speaking. But we know enough to know our systems have co-evolved with these microorganisms and we need them as much as they need us. Therefore I’m a big fan of fermented foods and feeding these essential little guys with prebiotic foods.

Ben Warren is a nutrition and holistic health expert. For more visit bepure.co.nz

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