Health Benefits of Fermented Foods

Fermentation produces lots of delicious foods, so how do they measure up when it comes to our health?
10 May 2021

Interview with 

John Leech, University College Cork


Fermented food and beverages


Fermentation produces lots of delicious food, but how do fermented foods measure up when it comes to our health? Eva Higginbotham spoke with John Leech, a PhD student at University College Cork where he studies the health impacts of fermented foods...

John - It's a tough question to answer. I guess it's early days for a lot of this research, but there are quite a few foods that are emerging as good for our health. There are about 5,000 different types from around the world and the ones I think we're focusing on mostly at the moment, the ones that will contain live microorganisms like bacteria needs at the point of eating. And so at the moment, I guess, yes, it's looking good for a lot of them.

Eva - That's a good point. Isn't it? Because there are some foods that are made by fermentation. Like we've been hearing the cheese or the corn, and there are other foods like my sauerkraut sitting gently on the table across from me that are made in such a way that they still contain the microbes, the lactic acid bacteria that went into them. In order, when I consume it, I'll be consuming that bacteria. What kind of benefits might we get from eating those sorts of microbes? Do we know?

John - Not entirely yet, no. The microbiome itself, which in human terms is the collection of microorganisms that live on or within our body. That's very important for human health and these fermented foods that contain these microorganisms could potentially be a great source of some diversity into our gut, which is a good thing for health. And there's a little bit of early evidence so far showing that fermented foods are potentially a source of this, but the research has really yet to tease that apart.

Eva - So the idea there would be that we've eaten some good bacteria that goes into our gut and helps populate it with more good bacteria. What sort of studies can you do to try and understand this?

John - Well, it is difficult to study, but giving people these light fermented foods will be the first step at the dire problems with that too. Because when any of these fermented foods, particularly the spontaneous ones, such as sauerkraut, spontaneous meaning you don't add any bacteria or yeast to it to get it started. It's all there in the cabbage or the environment already. So unfortunately this changes quite often from batch to batch. So it's very difficult to have a controlled, scientific experiment when you're giving a population the same thing again and again.

Eva - And that's about the guts, but is there any evidence of the benefits or potential benefits of fermented foods for other parts of our body?

John - So the gut microbiome seems to have a large role to play in health all over the body. So there is evidence showing that consumption of fermented foods can be good for other things outside of the gut, such as mental health and for muscle soreness after training. So as a way for athletes to recover after intense training sessions. But again, there's only a handful of foods like milk kefir, sauerkraut and kimchi that have really been looked into in detail that's three foods out of the potentially 5,000 that are out there.

Eva - What sort of link might there be between eating sauerkraut or kimchi and feeling better in terms of your mental health? Is it just eat more vegetables, feel better?

John - It could be. And that's another reason why it can be hard to study these foods. You have to find the right controls, the right things to compare them to. Sauerkraut and kimchi, I'm not aware of them being studied for health. Yes, it's mostly fermented milk, yogurts and kefir. And there is good evidence for kefir, for improving the symptoms of some depressive illnesses.

Eva - Is there, when we think about yogurt and we think about kefir in these things, is this because they act similarly to the probiotics you might buy in the grocery? I'm thinking of things like Yakult, are they sort of similar cultures that might be good for us?

John - Yeah. There will be quite a lot of overlap between the type of bacteria that are used for probiotics. In fact, some of them are sourced from fermented foods. A probiotic is a very specific strain, like a specific breed of a dog. So when you make milk kefir, you make it at home. You might not know what's in it. So it's really difficult to say for sure, if the particular kefir you're drinking is going to have those benefits or not.

Eva - And I know that you like to ferment some of your own stuff. Tell me about what you fermented and iIf it's good for you while I get my sauerkraut ready for my taste test!

John - I'm looking forward to you trying the sauerkraut. Um, so I've made a lot of sauerkraut. I've made kimchi. I make milk kefir everyday. Kombucha is another good one. I love the taste of kombucha and I've tried a lot of tepache, which is a fermented drink from Mexico. You just use the rinds of pineapples after you have eaten the fruit inside. I've made fermented salsa, and ... it's a big list. I've been making these now for four years. So I've dipped my toes into quite a few different foods.

Eva - All right. It's time. Pray for me. I hope I'm not about to poison myself. Here we go. It's tangy. It's very crunchy. It still tastes very salty. It doesn't taste like what I'd expect cabbage to taste like. Does that sound normal?

John - Yeah, the salts definitely there, that won't go away and it should be crunchy. Should stay crunchy if it doesn't I wouldn't eat it. And the sourness, it will get sour and sour the longer you leave it. But the fact that it's sour now that's a good sign too.

Eva - Well. That's excellent. Maybe I need to do what Ljiliana said and mix in some garlic and some pepper. What do you normally eat it with?

John - I would eat it with burgers or with hotdogs, salads. I went through a phase of putting it with absolutely everything because I had so much of it. And, but then I got a bit fed up with it, mostly burgers and hot dogs.



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