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  • Health & Medicine

Are ultra-processed foods linked to cancer?

Sophie Wedekind
by Sophie Wedekind | In depth

18 April 2024

1 comment 1 comment

Woman holding a basket in front of cheese aisle

Many of us spend a lot of time thinking about the foods we eat. 

Clearly, not all foods are as nutritious as each other, but it can sometimes be difficult to work out how or why. It seems like everywhere we turn, people are making big claims about which foods are ‘good’ or ‘bad’ for our health. And the phrase on everyone’s lips is ‘ultra-processed foods’. 

The term ‘ultra-processed foods’ has been hard to avoid in recent years. So are the foods themselves: in the UK they make up around half of our consumed calories. But what are they? And do they really impact our health? Let’s take a look at the evidence. 

What are ultra-processed foods?

To understand what ultra-processed foods are, we first need to look at what ‘processed’ means. 

A processed food is any food that has been altered in some way during preparation. This can be as simple as freezing, cooking or canning.  

The term ‘ultra-processed foods’ comes from the NOVA food classification system, developed by researchers at the University of São Paulo, Brazil.  

  • Group 1: Unprocessed and minimally processed 

Unprocessed foods are what we usually consider as whole foods. They have no added ingredients and haven’t been altered from their natural state. Minimally processed foods have only gone through very simple processes like the removal of inedible parts, grinding or freezing. 

For example: Fruit, vegetables, eggs, fresh meat and grains. 

  • Group 2: Processed culinary ingredients 

This includes foods which are added to other foods rather than eaten by themselves. 

For example: Sugar, salt, butter, honey, oils and vinegar. 

  • Group 3: Processed foods 

These are foods that are made by combining foods from groups 1 and 2 to preserve them or make them more palatable. 

For example: Freshly made bread, tinned fruits and vegetables, salted nuts, bacon, canned fish and cheese. 

  • Group 4: Ultra-processed  

These are ready-to-eat or ready-to-heat foods. They generally have a long shelf life and tend to include additives and ingredients that are not typically used in home cooking, such as preservatives, emulsifiers, sweeteners, and artificial colours and flavours. 

For example: Ice cream, sandwich ham, crisps, plant-based meat substitutes, mass-produced bread, breakfast cereals, biscuits, carbonated drinks, fruit-flavoured yogurts and instant soups. 

From the list above, we can see not all processed foods are bad for you. Some foods need processing to make them safe, such as milk, which needs to be pasteurised to remove harmful bacteria. And some foods like yoghurt and high-fibre cereals can be part of a healthy diet.

One of the criticisms of the NOVA method of categorising foods is that foods like these, which can be part of a healthy diet, sit in the same group as less nutritious ultra-processed foods. 

Why do we eat ultra-processed foods?

At the end of your regular grocery shop, chances are that around half of your basket will be made up of ultra-processed foods. That’s because, on average, 54% of the calories consumed in the UK are from these foods.  

While it seems better to have a diet consisting of minimally processed foods, a lot of us don’t have the time or the budget for it. Ultra-processed foods can be cheaper, last longer before expiring and can be easier to prepare. And thanks to clever marketing, they’re often some of the first things that come to mind when we’re hungry. 

cartoon flash light shining onto a blue background showing images of food
Reading food labels can help you work out which ultra-processed foods are high in salt, sugar and saturated fats.

Are they bad for us?

Many ultra-processed foods, like crisps and biscuits, are high in sugar, salt and saturated fats, and it’s clear that eating too many of these types of foods is bad for us. It can result in weight gain and also leaves less room in our diet for more nutrient dense and fibre-rich foods like fruits, vegetables and whole grains. That’s important because a healthy diet isn’t just about calories, it’s also about making sure we are consuming foods with a range of vitamins and minerals which help our body to function. 

So we know that basing our diet with lots of ultra-processed foods high in fat, sugar and salt would be bad for us. But more research is needed to understand whether there’s a specific negative effect from ultra-processing itself.  

Do ultra-processed foods cause cancer?

Recently, some studies have claimed that eating a diet high in ultra-processed foods can raise people’s risk of cancer and other chronic diseases.  

In one recent review, researchers looked at 45 studies on ultra-processed food exposure and health outcomes. When analysed together, these studies suggested there was a very small increased risk of cancer. But most of them only offered very low-quality evidence for their claims. So currently, the evidence that ultra-processed foods cause cancer is still very weak. 

That means we should take big statements about ultra-processed foods with a pinch of salt. 

Overall, it’s very hard to prove direct links between specific foods and health outcomes. That’s because we don’t just eat one type of food. Our diets are made up of many different things, so it’s hard to determine how a certain food or ingredient is impacting our health. 

Even if we can’t find direct links, that doesn’t mean there couldn’t be an indirect link. As mentioned earlier, ultra-processed foods are often high in salt, sugar and saturated fats. Eating too much of those ingredients can lead to weight gain. We know for sure that being overweight and obese increases the risk of 13 different types of cancer.  

So, it could be that any risk from ultra-processed foods comes from the fact they contribute to obesity, which in turn contributes to cancer risk. That could be separate from the way these foods are processed or the preservatives or additives they contain. In fact, some ultra-processed foods – like wholegrain bread, cereals, or low-fat yoghurts – could even have nutritional benefits. 

Why should we be aware of ultra-processed foods?

The low quality of evidence means it’s too early to say we should be cutting out ultra-processed foods. But if you eat a lot of ultra-processed foods that are high in salt, sugar and saturated fats, it’s a good idea to try and cut down. Reading food labels can help you work out which foods these are and make the best choice for you. You could also think about whether you can make any healthier swaps to help balance your diet, like including more fruit and vegetables or planning home cooked meals. 

Remember, when it comes to cancer risk, the most important thing is to aim for a healthy, balanced diet. That will probably always contain the occasional less healthy or ultra-processed food, but as long as you’re eating lots of wholegrains, fruits and vegetables and keeping a healthy weight, there’s no need to worry.   


  • Paul Richmond
    1 May 2024

    A very well thought out bulletin, having had Cancer and recovered, it is good to see your preventative research educating the populace.

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  • Paul Richmond
    1 May 2024

    A very well thought out bulletin, having had Cancer and recovered, it is good to see your preventative research educating the populace.

Tell us what you think

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Read our comment policy.