Fermented foods: what to eat to cut inflammation | Prof. Tim Spector

**Jonathan** (0:00)
Welcome to ZOE Science and Nutrition, where world leading scientists explain how their research can improve your health.
What comes to mind when you hear the word fermented food? For many of us, it might be a strong, sour taste, or perhaps even a slight fear. Is it dangerous to leave food out on the counter? Is that jar in the back of my fridge supposed to look like that? For most of human history, fermentation was the primary way that we preserved food. Yet today, especially in the UK and the US, we've become disconnected from this ancient process. But what if this lost art of fermentation could be one of the most powerful tools we have for our health? New science is revealing a stunning connection between fermented foods, our gut microbiome and a reduction in inflammation, a key driver of many chronic diseases. Today I'm joined by my co-founder, Professor Tim Spector, who has literally written the book on this. For the past six years, Tim has been exploring the science behind fermented foods and health. His book, Ferment, explores the latest scientific evidence and provides a wide range of delicious recipes you can try at home. In this episode, he explains the profound benefits of fermented foods on our health. By the end, you will have developed a whole new appreciation for these foods and we will have some simple ways to start incorporating them in your diets today. Tim, what a pleasure, thank you for joining me today.

**Tim Spector** (1:41)
Great to be here.

**Jonathan** (1:42)
So you know the rules, we're gonna start with a rapid fire Q&A from our listeners. Are you ready to go?

**Tim Spector** (1:47)
Hit me.

**Jonathan** (1:49)
Can fermented food support better mental health?

**Tim Spector** (1:52)
Absolutely.

**Jonathan** (1:54)
Is fermenting food at home dangerous?

**Tim Spector** (1:57)
No, but depends on your spouse.

**Jonathan** (2:00)
You throw me off track already. Does fermented food always have a really strong flavor?

**Tim Spector** (2:07)
No, it doesn't.

**Jonathan** (2:08)
Can dead microbes benefit your health?

**Tim Spector** (2:12)
They can.

**Jonathan** (2:14)
Is your wife perpetually annoyed by the state of your fridge?

**Tim Spector** (2:18)
Yes, despite all the things I do.

**Jonathan** (2:23)
I know her and you, so I think she might say something similar. What's the biggest misconception about fermented foods?

**Tim Spector** (2:30)
Probably that they're always smelly and dangerous, and it's highly risky to eat them.

**Jonathan** (2:38)
And that's not true?

**Tim Spector** (2:39)
It's not true.

**Jonathan** (2:40)
So Tim, I think that's a brilliant sort of introduction, and I know you've got a lot to say about the process of fermenting and the wonders of fermented food. After all, you literally just wrote the book on it. So let's just start at the beginning. What is fermenting?

**Tim Spector** (2:57)
Fermenting is the process by which microbes transform food into something better.
And by better, I mean something that preserves it longer before it goes moldy. It also transforms it into something that tastes better and more complex, and it also transforms it into something that is healthier for you than the original. If you look at milk, it's not particularly good for you as an adult, but if you ferment it, it has all these extra properties that are good for you. If you take grapes and you ferment them, you get wine, which has incredible complexities of taste and many other properties and smells. And so generally, you're just increasing the amount of chemicals and benefits of those foods by the power of the microbes.

**Jonathan** (3:47)
And could you maybe help us understand a bit more what's going on? So you gave that example of milk and it turns into something else.

**Tim Spector** (3:54)
You know, like cheese or something, yeah. And I think people do get confused about the difference between fermenting and going moldy because there's similar processes involving bugs, microbes, and by those, we're mainly talking about bacteria and we're talking about yeast. So if you leave some milk out for a couple of weeks, you go on holiday, it comes back, it'll be moldy, it'll be off because randomly microbes are coming from the air around it. Or in the container, and they're starting to eat away at the milk, using it to reproduce, and then they produce funny chemicals and smells. And it's rather random which microbes land on it. So you're not in control of that process. So you'll get a mold eventually growing on it as the acidity and everything changes in that product. So it becomes completely inedible.

**Jonathan** (4:50)
Okay, so that's not the same as fermentation.

**Tim Spector** (4:52)
It's not the same as fermentation. So fermentation is where you are tightly controlling the conditions around that milk. And you're making sure that only the microbes that you want to grow in the milk are growing in the milk. So that's what happens, for example, when you make yogurt, you are heating the milk up, then you're bringing it down to a certain temperature in a very close range, where only certain microbes that you want to favor will grow. And others are killed off. And so if you get the microbes that you want really propagating in that food, they elbow all the other ones out of the way. So by changing the temperature, that allows certain microbes to grow. And in the case of yogurt, they then produce acid, lactic acid and acetic acid, that will lower the pH, that increases the acidity, and that again stops other microbes creeping in and taking over. So you're selecting a really small percentage of all the microbes that could be in that food into this narrow range. It's about like farming or precision gardening. You just want just these microbes that live in these particular conditions to flourish. And when they do that, they make sure nothing else can get in there. So once you've got the acidity, the pH is below 4.5, nothing nasty can grow.