From the BBC World Service, this is The Global Story.

Ready meals, chocolate, biscuits, sausages, fizzy drinks.

We know that processed food is bad for us.

But recent research shows that in many countries around the world, the majority of calories most of us consume are from products known as ultra-processed foods.

These foods are being blamed for an increase in ill health, including heart attacks, strokes, obesity, type 2 diabetes and even anxiety.

So, how harmful are ultra-processed foods for our health?

And given how common they are, is it even possible to avoid them?

With me today is BBC health correspondent Philippa Roxby and Ruth Alexander, a presenter of the BBC programme The Food Chain.

Good to have you both with us, hi.

Thanks, hi Lucy.

Hello.

Ruth, I think we need to start with the basics here.

What exactly are ultra-processed foods?

It's industrially made food that's designed to be delicious.

Often the companies making them have really kind of hacked what it is that we crave in terms of taste and they've put those tastes in as additives.

And often food that's marketed at you.

You don't often see adverts for potatoes or eggs.

They're not ultra-processed, of course.

But food that's packaged, displayed prominently, particularly to appeal to children, say, marketed and advertised at you.

Ruth, I'm now just mentally running through a checklist of everything that's in my cupboards, in my fridge and freezer and I'm a little bit worried about what you're about to tell us.

So, I know you've also been going through your cupboards.

What have you found?

I mostly cook from scratch, so I didn't think I would find much.

But I found plenty.

Wholemeal bread, you know, the sliced package variety that you find in supermarkets.

Nutritionally good for you, but ultra-processed.

Fish fingers, which I think of as a sort of quick but healthy, you know, dinnertime thing and I thought, well, that can't be ultra-processed.

It's just fish and breadcrumbs, isn't it?

It was ultra-processed.

Mayonnaise.

I'd had a little bit with my lunch when I was going around my kitchen checking things.

Ultra-processed.

Mustard.

Ultra-processed.

But the one that probably surprised me most of all was stock cubes.

I looked at them and they are ultra-processed.

So, that means that all those home-cooked stews I did, all that cooking from scratch I did, actually was kind of undone.

If we start at the beginning of the day then, what about Philippa?

Cereal.

So many kids start the day with a bowl of cereal with some whole milk.

Is that okay?

It can be, depending on the type of cereal you choose.

There's a lot of cereals that are sweetened, so lots of sugar is added to them.

And actually, you've got some here.

They look a little bit chocolatey.

There's definitely added sugar in there.

But then there's a lot of cereals that are whole grain and have fibre in them and are good for you.

So, this is the slight issue with the definition of ultra-processed foods is that you tend to think that everything in your cupboard cannot be eaten.

But actually, there are some that do contain the good stuff you need.

It's just sorting the good ones out from the bad ones.

I mean, I think one of the things with cereal is that they're marketed as being healthy for you and a really good start to the day, particularly for kids.

And this is where scientists are really concerned, aren't they?

Because they say, actually, the driving force behind multiple diet-related illnesses can be in something as simple as your breakfast cereal.

Yeah, that's right.

I mean, there's evidence that the majority of children's diets, particularly in the Western world, are made up of ultra-processed foods.

So, everything from, you know, the bread they eat to the cereals to maybe the drinks they have at breakfast.

And that's a real worry because these kids are growing up.

And what will this do to their health later on?

I mean, there's lots of research, growing evidence that ultra-processed foods aren't particularly good for us.

But scientists are still not sure exactly what it is about those foods that's causing the problem.

Is it the way they're made, the way they're processed?

Or is it the fact that they just contain lots of sugar and lots of fat, as we can see here?

I mean, we've got a table in front of us full of ultra-processed foods.

And just looking at them, some, you could say, they're high in saturated fats, salt, sugar.

But there's some pretty innocent-looking bread there as well.

I guess these are processed to last longer.

They're probably, they look like sort of long-life rolls.

So you want them to stay OK in your cupboard so you can eat them for, say, several days.

And that's why in the food industry, they do process things to preserve them and keep them for longer.

So there's some reasons why processing is a good thing.

There are other reasons why processing might not be such a good thing.

Yeah, and I see, Ruth, that scientists have done a big review, the largest review of some of the evidence to date.

And they say there are 32 harmful health effects from some of these foods that are out there.

But looking at the table of food in front of us, or even thinking about what's in our cupboards, is there any nutritional value or is there some hope there with some of these foods, Ruth?

Well, that's the thing.

And as Philippa was saying, it's not known why ultra-processed food might be causing harm.

And it could be that there are some foods that are ultra-processed that are absolutely fine for you.

Like my wholemeal sliced bread, you know, it's got sort of lots of goodness in it.

It's got fibre, it's got added vitamins.

It's not necessarily that everything ultra-processed will definitely be bad for you.

And also, I mean, there's another category just down from ultra-processed, which is processed food, and that's not being criticised.

But when I was looking in my cupboards, the dark chocolate, that I would like to say is an occasional treat.

Actually, it's probably quite a frequent treat if I'm honest.

You and me both, Ruth, I have to say.

Keeps you going, doesn't it?

It gets you through.

But that was processed, not ultra-processed.

Is it good for me in the quantities I eat it?

I'm not so sure.

Also, potato crisps, another of my weaknesses, is another good one to look at.

Because if they've got added flavour, they tend to be ultra-processed.

But the plain salted varieties are not considered ultra-processed.

Are they good for me?

Well, they're full of saturated fat and have high levels of salt.

Probably not, actually.

So it's not clear-cut.

And it's, as Philippa said, it's not clear-cut what it is about the ultra-processing of food that may be harmful.

Ruth, you and I share these guilty pleasures.

I also love crisps, I have to say, as well as dark chocolate.

So Philippa, I'm standing in the supermarket aisle.

I'm looking at the back of a product.

What exactly should I look for?

In the ingredients list, you're looking for lots of things with very long, unpronounceable names that you would not find anywhere in your kitchen as ingredients.

And those could be emulsifiers and additives and flavourings and colourings.

And they quite often have very long, complicated names.

That's a good indication that it's probably an ultra-processed food.

What else?

It might have added sugars and sweeteners or fake sugars.

And it may say that it's sort of low in sugar or low in fat and make that sort of claim on the packet.

And quite often it will come in a package and not look like the original food, not look like a whole tomato or a whole vegetable.

It will be a sauce that comes in a jar or comes in a tin or comes in a package.

Surely the picture is different depending on which country we're talking about.

And I know in 2010, a group of Brazilian scientists said we should be focusing less on the nutritional content of food and more on the form of processing it undergoes.

And they created this NOVA classification, which categorises foods based on how processed they are.

And Ruth, I know you've spoken to one of the scientists who came up with that system, Professor Jean-Claude Moubarak at the University of Montreal.

Did they give you an idea of just how common UPFs are and how difficult and tricky it is to avoid them?

They did.

I actually asked for some examples of ultra-processed food.

And after about a minute of different foods being listed, I realised it would have been much simpler to ask what isn't ultra-processed actually.

So, you know, think of packaged snacks, sweets, biscuits, pastries, cakes, pizzas, cereals.

I mean, the list just goes on and on and on.

And the sales of this type of food, ultra-processed food, are actually thought to be increasing around the world, particularly in middle-income countries, where the sales are rising.

And then in richer countries, they're already pretty high.

I mean, you know yourself, if you go to the shops, actually, you've got the fruit and veg aisle.

And then beyond that, there are just many, many shelves with lots of different packaged goods.

And if you look at the ingredients on the back, it's often a long, long list of ingredients.

So there is a fair amount of ultra-processed food out there.

Philippa, these Brazilian scientists only came up with the term UPF back in 2010.

That wasn't that long ago.

So how much more is there to find out about the impact that UPFs have on our health?

Well, a lot more.

It's really a fairly recent term.

And there's been an awful lot of research in the last few years into ultra-processed foods and how they affect our health.

And why that might be.

And actually, scientists really haven't come up with an answer to that yet.

And so we really don't know whether it's the processing and these added ingredients that are added into the crisps and the bread and the cereals here.

Is that the problem?

Or is it just that we're going back to too much fat, too much sugar, too many calories in our diet?

Philippa, how much harder is it if you've got a health or dietary issue, which means that you have to have these foods?

I know I have a son who has celiac and a lot of what I go to buy him in the supermarket seems to have a lot of UPFs in it.

And it's because, you know, it doesn't necessarily have the ingredients in it to make the food stick together or to last a long time or it has a lot of sugar in it to make it taste good.

There aren't many other options.

Yeah, that's true.

I mean, a lot of people do rely on processed or ultra-processed foods for their dietary needs.

Celiacs, for example, have to avoid foods that have gluten in them.

So if you go to that particular aisle in the supermarket, you're going to find things that are processed because they need to avoid that ingredient and replace it with something else.

And then there's things like baby formula milk.

That would count as ultra-processed under this classification system.

And yet it's something that's used worldwide by mums trying to feed their babies.

And it comes from cow's milk.

But it has other things added to make it healthy for babies.

There's also vegan foods, plant-based foods.

They would also count as ultra-processed.

And yet they're seen as very healthy alternatives to meat.

I spoke to Jean-Claude Mubarak about the issue of, for example, infant formula and gluten-free foods and said, well, you know, like they're ultra-processed under this NOVA classification system, but people rely on those for health reasons.

And he agreed and said, actually, he said, I view infant formula, for example, as medicine, not as food, but medicine.

I'm a working mum and I'm starting to feel a little bit guilty at the moment about UPFs and what I'm feeding my family.

It's pretty tricky because one of the messages is that we should be cooking from scratch and cooking at home in our own kitchens with food that we know where it's come from.

But this is all really time-consuming at the end of a long day.

Yeah, I mean, it's very difficult, as we discussed, to avoid every single ultra-processed food.

It's extremely difficult.

And if you're a busy working parent, for example, with young children, you don't always feel you have the time to cook from scratch.

That means starting off with the vegetables and making the sauce from scratch, perhaps, and all the different elements of a meal.

And that can be time-consuming.

And for some people, it makes them a little bit nervous and a bit anxious.

And it's much easier, let's face it, to reach for something that's ready-made, ready to go in the oven, ready to go in the microwave.

It's quite often cheaper, too.

And in these constrained times, when we're all thinking about how much money we've got in our pockets, that is an easier option.

Cost must be a big factor for some people when they're considering what to eat.

I think it is.

And also, people are time-poor as well, aren't they?

So even just stopping to examine the ingredients on the back of packets in the shop, you know, that's time that you probably don't have.

When I discovered the stock I was using, I was ultra-processed, thought, right, I'll start making my own stock.

Have I done that?

No, I haven't.

I haven't got the time.

I think, like, as Philippa said...

You haven't got the time to go to the butcher and get the chicken carcass and bring it home and get the vegetables and put it in the pot.

I mean, yes, you're right.