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  • Writer's pictureTania

Eat to Thrive Podcast #13: Gut Health

The final episode in the “Eat to Thrive” podcast series is a subject close to my heart.

Well, closer to my digestive system to be more accurate – it’s gut health!

The subject of gut health is certainly being discussed a lot more recently, which is great progress! We have traditionally been a bit shy about gastrointestinal issues, especially bowel habits, and as a country with such a high incidence of bowel cancer, not talking about it isn't doi us any good. In fact, New Zealand has one of the highest rates of bowel cancer in the world. Interestingly, New Zealand also has one of the highest rates of Inflammatory Bowel Disease (IBD) in the world - Crohn's disease and Ulcerative Colitis - as well as a high number of people with Coeliac Disease. Canterbury seems to be quite the hot spot within our country, with even higher rates than the national average of Crohn's and Coeliac Disease.

Although genetic predisposition is a factor to varying degrees in your risk of developing any of these bowel conditions, taking steps to look after the health of your gut can still reduce your risk - especially for bowel cancer. There are even strategies for the prevention of IBD's that may alleviate some of the genetic risk, preventing the development of those diseases.

It’s not just about preventing disease, although that is super important. Looking after your gut health has real benefits for your day-to-day physical and mental health.

How can the gut have such a huge influence?

This next bit is not for the squeamish…

We are home to an enormous population of microbes, and it’s been estimated these cells outnumber our own by as much as 10 to 1, although a study from 2016 I found put the estimate closer to 1 to 1. Nevertheless, somewhere in the region of 1-3% of our body weight is our microbial population, which would account for between 750g and 2.25kg in a 75kg adult. That's a lot of cells that aren't us! The largest proportion of our microbes live in our colon, or large intestine.

This part of our microbe population is known as our gut microbiota, and although around 1/3 of these microbes are common to everyone, the remaining 2/3 are specific to the individual (kinda like a gut fingerprint I guess!).

Image courtesy of the Centers for Disease Control (CDC) via Unsplash

That’s a lot of bugs.

And most of these critters live in a type of symbiotic relationship with us (their host) called mutualism. This is where both organisms benefit from the relationship.

They benefit from the fibre in the food we eat: we absorb all the nutrients we can from our food as it travels through our small intestine, and the dietary fibre that’s left is food for the gut bugs in our large intestine.

We benefit from the relationship in many ways:

  • our gut bugs produce some vitamins (vitamin K, and vitamins B1, B7, B9 and B12)

  • they keep potentially harmful bacteria in check

  • they produce short-chain fatty acids (SCFA) that have beneficial effects in our gut by keeping the cells lining our gut healthy

  • those same SCFA's benefit our whole body by fighting inflammation, supporting our immune system, lowering our risk of cardiovascular disease, even communicating with our brain!

It seems to me that we get a pretty good deal out of the relationship...

Before we get into the nitty-gritty, I'll cover some helpful definitions.

Dietary fibre:

We’ve covered this in an earlier podcast episode, but just to recap, dietary fibre or "roughage", is a form of carbohydrate that we can’t digest – we don’t have the enzymes to do that. Fibre is only found in plant foods - it’s the structural part of the cell wall of plants. So when we eat foods that contain fibre (fruit and veg, grains, legumes, nuts and seeds), the fibre these foods contain survives the journey through our stomach and small intestine, and arrives in our large intestine pretty much intact.

grainy bread wholegrain
Image courtesy of Monika Grabkowska via Unsplash


Prebiotics are indigestible substances that provide food for selected resident gut microbes, and in turn, this confers a health benefit on the host – that’s you. Now you may have noticed prebiotics are also indigestible, just like dietary fibre. It was thought up until recently that all prebiotics are fibre, but there are actually some non-fibre prebiotics found in plants too. I guess you could sum it up as: not all fibre is prebiotic, but most prebiotics are fibre. Either way, both fibre and prebiotics are indigestible parts of plant foods, and both benefit our health.


Probiotics are defined by the WHO as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host”. So there’s three parts to that definition: they need to be live; they need to be present in adequate amounts; and they need to actually benefit the person consuming them. Probiotics are very much in vogue at the moment, and I’m seeing a lot more packaged foods incorporating probiotics into their formulations. In addition to the traditional yoghurts and milk-based drinks, foods such as cereals, snack bars and juices are coming onto the market, all trumpeting the benefits of their added probiotics. This is a great strategy by food manufacturers to increase their sales, but it also may be a response to growing markets in countries that have high rates of lactose intolerance in their populations, and to the rise in interest in veganism (hence the move away from dairy based foods).

You can also buy probiotic supplements in most pharmacies and health food stores. The advantage here is that you can know exactly which strains of microbes the supplement contains. The challenge is knowing which strain you’re after! There are a lot of probiotic strains available – hundreds of different strains of Lactobacillus alone – and each one can have a different effect, so if you are looking for a strain to help with a specific issue, then you should find the exact strain that has been shown to have a positive effect in clinical trials, and take the same dosage for the same duration. You can find clinical trial information on a couple of sites: the US Probiotic Guide and the Canadian Probiotic Guide. They show products available in the US and Canada – but this can give you the info to find products of the same formulation here in NZ.

There are loads of multi-strain products available, which to be fair can make for a pretty impressive looking label, but remember one of the three criteria for a probiotic is that it needs to be present in adequate amounts. The typical minimum therapeutic dose to treat an issue is 1 billion CFU's (colony forming units) of a specific strain. Any less than that may be completely ineffective, so while there might be a whole range of strains in a product, if there isn’t enough of any one of them it’s likely not going to make a difference.

So, do I need to take probiotics to have a healthy gut?

Now I know I’ve just spent a bit of time talking about probiotic supplements, but for the average healthy person, probiotic supplements aren’t necessary. As long as you follow a few basic guidelines to look after your gut health (which I’ll list at the end of this post), you don’t need to spend your money. However, if you are experiencing a gut issue like traveller’s diarrhoea, or if you are taking a course of antibiotics, or are experiencing antibiotic-associated diarrhoea, then certain probiotic supplements have been shown to be effective. Ask your GP, Dietitian or Registered Nutritionist, or check out the probiotic guide links above for info.

Likewise, if you have been diagnosed with Irritable Bowel Syndrome (IBS), there are certain strains that have shown benefit in clinical trials. If you have been diagnosed with IBS and want to explore the use of probiotics, best to seek the advice of a Dietitian or Registered Nutritionist who is experienced in the area of gut health, as in some situations taking a probiotic supplement can make symptoms worse. This will also give you the opportunity to include other IBS management strategies like identifying your own personal triggers (those pesky FODMAPs), and relaxation and mindfulness exercises. As a side-note, it's also really important not to jump into the low FODMAP diet without professional guidance. It's a highly restrictive way of eating that is only intended to be followed for a short period of time. You'll need to go through a carefully planned re-introduction phase so you can identify your own individual triggers, and get back to as full and varied a diet as soon as possible, to minimise the risk of nutrient deficiencies.

Reuben sandwich sauerkraut
mmmm, sauerkraut in a tasty sandwich. Image courtesy Jonathan Pielmayer via Unsplash

What about fermented foods?

You also find naturally occurring beneficial microbes in fermented foods, like yoghurt, sauerkraut, kimchi, miso, kefir, and kombucha. However, due to the lack of detailed information about exactly which microbe strains and how many viable cells are present, they are referred to as containing “live cultures” rather than “probiotics”. But just because we can’t be sure these fermented foods contain clinically therapeutic amounts of specific beneficial microbes, doesn’t mean they won’t benefit your health. You can enjoy a degree of immune enhancement through regular consumption of fermented foods – just make sure they are still live. For example, don’t buy the canned sauerkraut off the shelf, as it’s been through the canning process, and the heat will have killed all the microbes. Choose the sauerkraut in the chiller section of the supermarket. Same goes with yoghurts – look for the ones that say they contain live cultures. You can even ferment foods at home – I recently started making my own sauerkraut (it was surprisingly easy), and I’m fermenting milk kefir too, just to add something different to my food repertoire. The great thing about eating fermented foods is that you don’t just benefit from the microbes, you get the nutritional benefits from the foods as well.

However, quaffing probiotic-fortified foods, live-culture fermented foods or probiotic supplements won’t have any impact on your gut health unless you keep them fed with the prebiotics we talked about before. If we introduce beneficial bugs into our gut, and don’t give them any food to live on, we’ve essentially wasted our time and money. It’s like putting a mob of sheep into a bare paddock.

So here are my Top Tips for "Growing your inner garden":

1. Maximise the diversity of plants foods in your diet.

Both type and colour. Eat your 5+ a day (but not the same 5 every day); eat a variety of wholegrains; make sure to include legumes and nuts a few times a week; try new plant foods.

2. Eat fermented foods containing live cultures regularly.

Choose foods you enjoy: yoghurt, sauerkraut, kimchi, kefir, kombucha, miso, kvass… Try making your own!

3. Ensure you eat an adequate amount of fibre.

Choose mostly wholegrain breads and cereals, get that 5+ a day variety, and you’ll be feeding those gut bugs what they need.

4. Try and include 10 minutes of relaxation or mindfulness in your day.

Hard to do, I know. I really struggle with this one myself. I even have a meditation app that reminds me, but I still find this difficult. It’s actually one of my New Year’s resolutions, and very much still a work in progress. However, many gut symptoms can be exacerbated by stress, so it might really help to grab that "me time" when you can.

5. Exercise regularly.

Even if you can only manage a 15 minute walk, it’s better than nothing at all. Regular activity helps keep your gut healthy too.

yoghurt granola blueberries
Having a serve of yoghurt containing live cultures will introduce some beneficial bugs.

As this post marks the end of my "Eat to Thrive" podcast series on Plains FM, I wanted to thank those of you who have come along on the radio journey with me, whether you listened on Plains FM when it was broadcast, via a podcast app, or by reading these podcast blogs - I hope you have enjoyed the programme. I’m very grateful for the opportunity to create a programme that contributed to the fight against pseudoscience and nutrition misinformation out there. It’s a challenging landscape, and one that can be difficult to navigate your way through. If you missed any of the episodes along the way, I'm going to upload them to my website at some stage, so all 13 episodes will eventually be there to play - keep an eye out on my Facebook page for details.

For those who like to dig into the detail, here are links to loads of other resources on gut health you can explore at your leisure:

International Food Information Council Foundation / Food Insight – Gut check series:

Gut Microbiota for Health:

International Science Association for probiotics and prebiotics:

More detailed and clinician-level info:

Some great podcast episodes to listen to:

Great evidence-based websites to check out (for nutrition info in general):

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