ZOE Science & Nutrition - Recap: How to start fermenting at home | Sandor Katz

Episode Date: August 12, 2025

Today, we’re diving into fermentation. If you’re a regular ZOE listener, you’ve probably heard that fermented foods are some of the best things you can eat for your gut health. Packed with beneficial microbes, they’ve been shown to boost everything from digestion to immune function. Still, the idea of at home fermentation - cultivating bacteria and microorganisms in your fridge - can feel a little daunting. More like a science experiment than a culinary adventure. That’s where Sandor Katz comes in. He’s a fermentation revivalist, bestselling author, and the driving force behind a global fermentation movement. So if you're a total beginner or just sauerkraut-curious, this episode will give you the tools, the confidence, and maybe even the craving to get fermenting at home. 🥑 Unwrap the truth about your food 👉 ⁠Get the ZOE app 🌱 Try our new plant based wholefood supplement - Daily30+ *Naturally high in copper which contributes to normal energy yielding metabolism and the normal function of the immune system 📚 Books from our ZOE Scientists:The Food For Life Cookbook by Prof. Tim Spector Food For Life by Prof. Tim Spector Every Body Should Know This by Dr Federica Amati Free resources from ZOE: Live Healthier: Top 10 Tips From ZOE Science & Nutrition  Gut Guide - for a healthier microbiome in weeks Have feedback or a topic you'd like us to cover? Let us know here Listen to the full episode here

Hello and welcome to Zoe Recap, where each week we find the best bits from one of our podcast episodes to help you improve your health. Today we're diving into fermentation. If you're a regular Zoe listener, you've probably heard that fermented foods are some of the best things you can eat for your gut health. Packed with beneficial microbes, they've been shown to boost everything from digestion to immune function. Still, the idea of at-home fermentation, cultivating bacteria and microorganisms in your very fridge, can feel a little daunting, more like a science experiment than a culinary adventure. That's where Sander Katz comes in. He's a fermentation revivalist, best-selling author, and the driving force behind a global fermentation movement. So if you're a total beginner, or just kimchi curious, this episode will give you the tools,

the confidence, and maybe even the craving to get fermenting at home. fermentation has been an integral part of how people in every part of the world make effective use of whatever food resources are available to them it's part of our cultural legacy everywhere and yet over the past several generations fewer and fewer people have been practicing fermentation and so when I talk about myself as a fermentation revivalist is really trying to you know, revive interest in these ancient practices and basically help people feel confident to bring them into their home kitchens. The easiest way to ferment vegetables of all is what I would describe as the sauerkraut method, dry salting the vegetables. All you do is you shred

vegetables, create surface area, lightly salt them. There's no magic number about how much salt. You've salted lightly, mix it up, taste it, add more salt if desired. Add seasonings, if you like, caraway seeds or garlic or chili peppers or anything. Squeeze the vegetables for a few minutes and that helps get them juicy. Once they're juicy and you like the balance of flavors, pack them into a vessel so they are submerged under their own juices and then wait some days or some weeks. And that's the whole process. For making kimchi, There's an additional step to the process, and that is that I shred the vegetables and I submerge them under a saltwater brine solution. I don't measure the salt, but I taste it, and I'm going for the flavor of the sea.

I want it to be somewhere around 5 or 6 percent salt. Pretty salty. Pretty salty. And then you just leave that for 24 hours. And then the next day, you go ahead and you make a little spice paste. Typically, people add some sort of more concentrated carbohydrates. That could be grain-based, like my rice paste. It could be fruit-based.

Sometimes people will use pears or apples or other fruit. Sometimes people just add a spoonful of sugar or honey. There's various ways to achieve that. But just by adding some more concentrated carbohydrate element just makes for a more vigorous faster fermentation. And, Sandra, one of the things I find amazing, and again, I think this shows you how, I guess, medicalized, I am, is that you didn't say you go and add the particular correct bacteria

into your kimchi, right? In fact, you didn't even mention anything about the bacteria. They just sort of magically appeared. Could you help us to understand and why don't we have to be really careful about this step? Sure. The reason why we don't have to add some specific pure culture starter that's been propagated in a laboratory is that, you know, we have a clear understanding that all plants are host to lactic acid bacteria. I mean, there's a broad consensus among microbiologists and botanists that all plants growing out of soil on planet earth are host to lactic acid bacteria. And so if we create the conditions in which the lactic acid bacteria can thrive, they are always there to do so. Now, I mean, you could certainly

find on the internet a packet of white powder of lactobacillus plantarium, which people will be happy to sell you as a starter for making sauerkraut or kimchi or other kinds of fermented vegetables. But, you know, I would consider that to be an exploitative product because the lactic acid bacteria are already present on vegetables, and you don't need to add a starter. That's amazing. So you're saying, because I thought maybe it was in the air, you're saying actually the plants themselves, they come pre-packaged with their own bacteria. You literally just have to add the salt, put them in the jar, and you're away. I mean, they're growing out of the soil. And the soil is this just incredible, complex system that we're only beginning

to develop tools to be able to appreciate the level of complexity of it, but the seedling is emerging, you know, partly with the help of microorganisms in the soil. The plant is able to grow and flourish with the assistance of microorganisms in the soil. And so, you know, the soil is the source of all of this. And the organisms that enable the animals that we raise for our food, that are grazing on plants, you know, it's the soil organisms that are feeding their gut bacteria as well. So, I mean, I would say the microbial system really begins and ends in the soil, and that's the source of the constant renewal of life, really. There's a sort of beautiful connectivity as you talk about this, right?

Where actually, you know, through the food and the bacteria, you're connected back to the soil and the world, and that's obviously very different from the interaction with food that most of us have now in the West, where everything comes in a packaged, plastic-wrapped solution, and the more that it has been separated and sterilized, the better. And I do think that it's amazing that just as we've been discovering how important these microbes are inside our gut for our health, we also see equally well that we always used to have this very interactive back and forth connection with the bacteria outside us. And I guess, you know, what I'm hearing is that fermentation is one of these ways that you can start to maybe pull this back together

again. Absolutely. And I mean, I think beyond fermentation, I mean, we really have an imperative to reconnect to the sources of our food and reclaim our food. You know, food is not a commodity like every other commodity. I mean, you know, food is what enables us to continue to exist. Food comes from plants and animals. The pursuit of food connects every kind of organism in the world with its environment. And, you know, human beings in the name of our sort of supposed progress have really sort of severed that connection. And, you know, I think we need to become reconnected to the sources of our food and reclaim our food as a product of our environment that, you know, we interact with. What would be your five tips for trying fermentation yourself?

Okay. Number one, do not be afraid. Do not project all of the anxiety you've ever had about bacteria onto the process of fermentation. Understand that these are ancient practices that have been tested by time and that they are extremely safe. Okay, number two, fermentation is all about manipulating environmental conditions so as to encourage the growth of certain organisms and simultaneously discourage the growth of others. Understand what the conditions you're trying to create are. In the case of fermenting vegetables, it's simply getting the vegetables submerged, which protects them from the flow of air with oxygen. And that's what supports the flourishing of the lactic acid bacteria

rather than, say, spores of molds. So, you know, understand the condition you're trying to create. A third would I'll say that's a little bit different is, you know, don't overthink it. Don't try to imagine everything that could theoretically go wrong and make yourself crazy. You know, these are simple processes. like accept the simplicity of them.

Number four, don't be afraid to experiment. It's the process that's important. You know, if you add a different kind of vegetable or a different kind of seasoning, that's great. Kimchi is not one thing. You know, kimchi is the name for this, you know, incredibly diverse tradition. And there's a lot of regional variation,

but there's also just family recipes. And, you know, every grandma who has her own secret something that she adds into it. So don't be afraid to experiment. Don't be afraid to play. Number five, be creative about how you incorporate these foods into your diet. I think for a lot of people who aren't accustomed to them, that's the hard part. And just experiment.

Like, I love it with eggs. I love it as a condiment on a sandwich. You know, there's endless applications. I love to use the extra juice of the sauerkraut or the pickles in salad dressings. But, you know, be creative. I'll end this episode with something I think you'll like, a free Zoe gut health guide. If you're a regular listener, you know just how important it is to take care of your gut. Your gut microbiome is the gateway to better health, better sleep, energy and mood.

The list just goes on. But many of us aren't sure how to best support our gut. I wasn't sure before doing Zoe, which is why we've developed an easy-to-follow gut health guide. It's completely free and offers five, six. simple steps to improve your gut health. You'll get tips from Professor Tim Specter, Zoe's scientific co-founder and one of the world's most cited scientists, plus recipes and shopping lists straight to your inbox. We'll also send you ongoing gut health and nutrition insights, including how Zoe can help. To get your free Zoe gut health guide, head on over to

zoie.com slash gut guide. Thanks for tuning in and see you next time. You know,