Processed foods - convenient or catastrophic?
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Hello and welcome to Zoe Shorts, the Bite Size podcast where we discuss one topic around science and nutrition. I'm Jonathan Wolf and as always I'm joined by Dr. Sarah Berry and today's subject is processed foods. So Jonathan, the word processed has become associated with the unhealthy, with the mainstream media encouraging us to detox from processed food or giving us, you know, 10 easy ways to stop eating it.

But actually, everything that we consume has undergone some type of processing. So Sarah, if most of what we eat is processed, can it really all be unhealthy for us? Well, shall we dive into this, Jonathan? Let's do it.

So first off, Sarah, I think we better start off by understanding what a processed food actually is. Yeah, so if I can give you a kind of formal definition according to the Department of Agriculture, processed foods are any raw agricultural commodities that have been washed, cleaned, milled, cut, chopped, heated, pasteurised, blanched, cooked, canned, frozen, dried, dehydrated, mixed, packaged, or had anything done to them that basically alters their natural state. My gosh, that was a mouthful.

Yeah, I was going to say, try saying that three times fast. So basically, that's anything that you haven't actually picked off a tree. Is that right? Do you know what? Pretty much, yes. Now, there is an important subcategory to highlight as well, right? Ultra processed foods. And these usually have lots of added ingredients like sugar and fat. They can contain additives like artificial colors and flavors or stabilizers. Think ready meals, soft drinks, hot dogs, fast foods, cookies, cakes, etc.

We're going to dive sort of deep into ultra processed foods in another episode. So let's not really focus on that right now and stick to processing in general. And even here, there's an official sliding scale, isn't there? So you go from minimally processed, like freezing your raspberries to make them last longer through adding ingredients that enhance flavor or things like cold pressing olive oil to more moderately processed foods like bread or canned fish.

Yeah, so I think for simplicity, Jonathan, when we talk about food processing, I think we should think about it as any process that's either changed the original structure of the food, which we call the food matrix,

or the addition of extra ingredients. Now, sometimes changing the structure of the food or even adding in additional ingredients or chemicals can actually make the food healthier and sometimes it can make it less healthy. So should we first start by looking at what happens when we break down the food matrix? And I'd love to use oats as an example of this, just from my own research that I've done.

So if you take whole large oats, for example, we know that these are quite favourable in terms of lots of health outcomes. If we break these down further, so we ruin the kind of matrix, the structure, and we finally grind them,

then what happens is it changes the way our body metabolizes them. And suddenly you get this really big increase in circulating blood glucose, blood sugar. And why does that happen, Sarah? Why is it that when you've chopped this up more finely, because I might have thought it all goes in my stomach, it's all going to get like...

like, mished around? Why does it make any difference? - So what happens is, is we metabolize it more quickly. So I often use the term of changing a slow food, which is what we would ideally want, into a fast food, which ideally we wouldn't want. So we are able to process it in our stomachs, in our small intestine more rapidly. So you get this very rapid increase in circulating blood sugar and a rapid drop that often can cause a blood sugar dip and subsequent effects on hunger and all sorts of things.

So is that a bit like, you know, if I think about, you know, you're trying to dissolve something in water, right? And when it comes in a powder, it's really fast. But if it's a big block, you might be sort of like turning it round and round and round for half an hour before it all disappears. And is that a sort of analogy to what's going on here? That is a fabulous analogy. And I think it's important to say, you know, on the back of

pack labeling, those two foods would look identical, but how they're processed is totally different. And that's purely due to the structure, purely due to one's ground and one's not. And this is one of those reasons that the oatmeal that I used to eat for breakfast all the time just spiked my blood sugar through the roof, but people talk about oats as being this healthy food. It's just nothing like the sort of pre-prepared oats that we tend to get from the supermarket or the grocery store.

Correct. Now, there are some examples, right, where changing this matrix, as you put it, can actually be beneficial, right? So dairy is a good example where milk is not a particularly healthful food, but there are some dairy products such as cheese, which have favorable health effects, despite, again, having very similar sort of nutrient composition. And in this case, changing the food matrix has actually made it better because of fermentation, isn't it, Sarah?

Yeah, and it's not just dairy. There's other fermented foods like kimchi and sauerkraut, which I know these are rather specialist foods, but it's important to mention that have also been shown to have similar benefits helping with a healthy gut microbiome.

And so fermentation is sort of the key thing here. Once again, we see bacteria, this time not in our gut, but outside, doing all of this magic to create all of these very complicated sort of new chemicals that suddenly makes this much richer for us than the, they're sort of turning lead into gold in a way in terms of food.

Yeah, absolutely. And I think this brings us nicely onto another benefit of processed foods, which is that it's a great way of storing food from frozen to tinned. Tinned pulses like chickpeas, broad beans, red kidney beans can last ages without going off or losing their nutritional value.

Also, in addition to being put in a tin or a jar, which is a form of processing, they also have to be cooked, which is another process for us to actually be able to consume them. So if we don't process pulses, so if we don't cook them in some way, they can actually cause really serious health problems.

either food poisoning and also in some extreme cases they can even cause death. So I think we would all agree that processing in this case is a good idea. It's vital and by us processing these pulses then Jonathan we're opening up a whole new food source, a nutritious food source to us

which is a great source of protein, fiber, and other micronutrients like potassium and zinc, which are really important as part of a healthy functioning body, important for our microbiome, from the fiber, and a great source of protein as well. What you're saying is rather than just taking away from this raw ingredient, actually, it's suddenly making this thing not only safe for us, but actually much more nutritious and

We've evolved with cooking, I guess, for a long time. So it's not surprising to hear that this can often be beneficial rather than harmful. Yeah, and if we think about this in the context of the staple foods that most of us consume, whether it be pasta, rice, potato, bread,

If all of these have undergone some sort of processing, now I know that there's lots of controversy about how they might impact our blood sugar levels, but actually they're staples across many different populations and a really important part of our diet that if we didn't process the original grain or cook the potato, they would not be a form of food that we could actually consume.

That's right. So you actually just can't digest, right? Potato is another example, isn't it? Where until it's cooked, you can't eat it. So clearly, some processing is good for you because if you don't process it, you get sick. What about tinning? So I think lots of people will listen to this and feel like, well, tinned food, that's not really very good for you, right? Like it's been in this tin, it sits in your cupboard for a year. It can't really be very nutritious anymore. I think they'll be a bit surprised to have just heard you sound quite positive. So...

How do we feel about tinny? I think it depends what else is in the tin. So sometimes with tinned food, they might just be preserved in water, for example, in which case, you know, it's a great way of providing cheap, accessible food that's readily available for people like a lot of the tinned pulses, for example.

And so those still have the nutrients that you would get if you were buying them fresh, like this is still a high quality way to get these plants? So it depends on the plants, but certainly for pulses, absolutely it does, yes.

Amazing. So another example, processing is not all bad. You're saying for a whole bunch of these things, this is your beans and your chickpeas and all the rest of it. It's just fine. Now, not all preservation techniques are healthy, right? I think back, my grandmother used to always make jam. So she had various fruit and she would turn all of this into jam as a way to preserve it. How do we feel about jam?

Okay, that's a good point. And I think it's an important point about how processing can also add unhealthy ingredients. So often processing may add, and the example of jam is a great one, an unhealthy ingredient, in this case sugar, to a healthy ingredient, in this case strawberries.

So it makes it taste nicer. But a byproduct of that is we're consuming unhealthy ingredients, so the sugar. And also often we're also consuming a food that is hyperpalatable. So it encourages us to overeat. It's more energy dense.

And this, again, in turn may contribute to the increased risk of lots of chronic diseases like obesity and diabetes. Another example as well is if you add salt or sugar to nuts, you're changing a really healthy snack to one that I think you should be cautious about overeating. Adding butter and syrup to oats to make flapjacks, again, changes quite a healthy ingredient to a really energy-dense and sugar-fuelled snack. And...

I think it's important to mention that ingredients are also often added to confer better functionality as well as preserve the food. And something we haven't touched on yet is emulsifiers. So these are a great example of this. The emulsifiers are extensively used by the food industry and they allow water and oil to kind of blend together. And so this enables the food industry to create a whole host of different products.

such as mayonnaise is a great example. But we know that emulsifiers unfavourably affect our gut microbiome and some other metabolic processes. So again, this is an example of where an ingredient or additive such as emulsifiers is great for creating a new food, but actually isn't the best for us in terms of our health.

Got it. And also, I guess, an example of processing with something that you don't tend to find in your own kitchen. And I think this is often a good test, right? I rarely reach for the emulsifier. And I think as a handy tip that I've been told by a lot of nutritional scientists, if you don't recognize a lot of these ingredients, then

this is often a sign that this is the sort of processing that you're not feeling really good about. Just before we move sort of off that, I wanted to bring up freezing. We had a lot of questions around freezing as a process. And so we looked a little bit at the studies. And this is, for example, a study of fresh versus frozen fruit and vegetables that showed that

vitamins like vitamin C and vitamin E remained at the same or higher levels in frozen food as they did in fresh food. And I think for many people, including me, that was quite counterintuitive. Again, it's frozen, that feels like that can't really be as good as fresh. Is that something that in general you would feel very positively about frozen vegetables as a processing that actually really sort of secures a lot of the benefits of these plants?

Yeah, absolutely. I think there's multiple benefits. So one is that they do retain more particularly of their water soluble vitamins. So the ones that you've mentioned, such as vitamin C, but also it makes the food more accessible to people. You know, it's easy to have a bag of frozen peas in your freezer. They're also a lot cheaper than buying fresh often. And that's really important because we need to think very pragmatically as well about, you know,

the accessibility of food, the affordability of food and the ease of the meals that we're cooking. You can now actually buy frozen fruit and a lot of people are using this as a way of getting lots of fruit in their diet but actually using it in their Nutribullet or their blender. So making a smoothie basically out of this, right? Yeah, and this is where I want to add, caveat this with a note of caution around the frozen fruit or rather even taking fresh fruit and mashing it up.

Do you remember a few minutes ago I used the oats as an example of when you break down the food structure, so the matrix. What we're doing when we take either fresh or frozen fruits and we blend it, we're doing exactly the same as what we did with the oats. We're changing the original structure and we're changing it from a slow food to a fast food. So if we take some strawberries and some different fruits and put them in a blender,

What you're doing is then you're changing that original structure, you're changing all the cell wall structure and the rate at which you metabolize it, just in the way that I talked about those ground oats, also happens. So you metabolize and process the fruit in its original structure quite slowly. As soon as you blend it, then you metabolize it more quickly. Again, back

Pack labeling show it's two identical foods nutritionally, but the effect it has on your health is not quite the same. So my wife was doing Zoe just a few weeks ago. And so she was measuring her blood sugar all the time, trying out various things that she has quite often. She has very good blood sugar control. So unlike me, it's like really low, it's really stable. So I was a bit jealous of that. She had a smoothie from a chain that I won't mention that she viewed as like really healthy.

it spiked her blood sugar more than anything she ate that entire week, like through the roof and then collapsed afterwards. And she was shocked because she was thinking, well, this is like super healthy, right? I've got all this fruit and I got vegetables in it. And I think it's a great example, right, of the processing. So if that hadn't all been smashed up into millions of pieces, then her blood sugar would probably only have moved much less. We just said this was great.

but it said basically she'd lost a lot of the fiber, she'd got tons of sugar and it was almost like injecting blood sugar directly into her veins, which I don't think you would recommend, right Sarah? Absolutely, I would not. And I think it also raises a really important point here around

how there's this perception of processing being not only associated with the term unhealthy, but being associated with animal-based foods, you know, processed meats, for example, you know, processed pies. But actually, a high proportion of the kind of processed foods that we consume that I think have unfavorable effects are

actually come from plant origin. And there's this real explosion in the consumption of plant-based processed foods where, you know, marketeers are really capitalising on this increased awareness around the health benefits of plant-based foods, as well as obviously, you know, people's ethical reasons for not consuming animal-based foods.

But there's a lot of very processed plant-based foods out there that are being marketed as being incredibly healthy because they're plant-based. But just because it's plant-based, if it's also processed, it's equally as unhealthy as well as whether it's an animal processed food. I think it's a brilliant point. And I think it'd be fun maybe just come back and do a whole podcast looking at all of these vegan products that have been promoted where some of them I think we see are

just as unhealthy as the worst sort of ultra processed foods. So if I wrap all of this up together, Sarah, what's our verdict on processed foods? Good? Bad?

So my verdict, as always, Jonathan, is it's more complicated than just saying it's good or bad. I think there's very clear evidence, and we're going to follow up on this, that ultra processed foods are bad for us. I think that the technique of processing is fabulous in many instances and makes entire food groups available for us to consume. But I think we need to be cautious about where it

over destroys the original structure of the food and adds in far too many additives and other ingredients that we wouldn't normally consume if we were cooking that kind of particular food at home.

So conclusion is there's nothing necessarily wrong with food processing and we need to move away from this idea of like it's processed, it's bad, it's unprocessed, it's good. Need to think about in a slightly more complex way. And the more that it is still close to the original food, in general, you're in a good place. And often like a moderate amount of processing might actually make it better, right? Whether that was your potato or cooking your beans or any of the rest of it, if you go too far,

And you've ground it up into tiny little pieces, which I think is one of the key messages many people take away. You're probably not in such a good place. And of course, we all know that if you add loads of sugar and salt, then it tastes great, but it's probably not got any better for you. I absolutely agree with you, Jonathan, on all of that.

Wonderful. We'll post links to all the sources we've cited, which you can find at joinzoe.com slash podcast. If you'd like to try Zoe's personalized nutrition program yourself, it starts with an at-home test kit and then follows with a program to help you improve your health and manage your weight. You can find that at the same link and get 10% off. I'm Sarah Berry. I'm Jonathan Wolfe. And join us next week for another Zoe podcast.