Are ultra processed foods impacting your gut health?

By Sandy Soni

Dr Megan Rossi in a lab looking through a microscope

Ultra processed foods (UPF) have had a lot of negative media attention in the last month. But is it really necessary and feasible to cut them all out? Do we even know what foods are ultra-processed and is there a ‘safe’ amount?

With busy lives it can be easy to rely on UPF to save time and  money, but how are they affecting our gut health?  In this blog we will discuss this controversial  topic and help to guide you on how much UPF we should consume for optimal gut health.

What are UPF?

The term ‘ultra-processed foods’ comes from the NOVA food classification system.

The NOVA system places foods into four categories based on how much they have been processed during their production:

Unprocessed or minimally processed foods: This includes produce such as fruit, vegetables, milk, fish, pulses, eggs, nuts and seeds that have not had their natural state altered or had ingredients added.

Processed ingredients: This includes foods that would be used as an ingredient when cooking, such as salt, butter, sugar and oils.

Processed foods: These are foods that are made by combining foods from groups 1 and 2, which are altered in a way that home cooks could do themselves. They include foods such as jam, pickles, tinned fruit and vegetables, salted meats, homemade breads and cheeses.

Ultra-processed foods: UPF typically have five or more ingredients. They tend to include many additives and ingredients that are not typically used in home cooking, such as preservatives, emulsifiers, sweeteners, and artificial colours and flavours. These foods generally have a long shelf life.

Why are Ultra-processed foods bad for us?

UPF often contain high levels of saturated fat, salt and sugar. Eating a large amount of them leaves little room for the more nutritious, less-processed foods in our diet.. A number of studies have shown that consuming UPF relates to an increased risk of developing chronic diseases such as obesity, metabolic syndrome, diabetes, cardiovascular disease, high blood pressure and cancers. Studies have also found a link between the consumption of UPF and inflammatory bowel disease (IBD) suggesting that high intakes of UPF can change the gut microbiota and lead to inflammation

The scientific bit

UPF tend to undergo industrial physical, chemical or biological processes and contain industrial substances that are not found in domestic kitchens.

This processing typically results in these foods having  poor nutritional values, and they contain potentially toxic substances such as trans fatty acids, additives, (dyes, emulsifiers and artificial sweeteners), modified starches, hydrogenated oils and maltodextrin.

Where to find Ultra-processed foods?

Examples of common ultra-processed foods:

Unprocessed or minimally processed foods: Fruit, vegetables, meat, eggs and grains.

Processed ingredients: Sugar, salt, butter, oils, lard and vinegar.

Processed foods: Freshly made or unpackaged bread, tinned fruits and vegetables, ham, bacon, tinned fish, cheese and salted nuts.

Ultra processed: Ham, sausages, chicken nuggets, crisps, mass-produced bread, breakfast cereals, biscuits, carbonated drinks, fruit-flavoured yogurts, instant soups, ice cream, vegetable/vegan patties (meat substitutes), chocolate and some alcoholic drinks including whisky, gin, and rum.

Are bread, vegan products and cereals considered UPF?

When thinking about UPF most people think of chips, sweets, and colourful sugary drinks, but UPF is not limited to these . Everyday items such as mass-produced or packaged bread and breakfast cereals are considered ultra-processed foods. This is because they tend to have extra ingredients added during production, such as sweeteners, emulsifiers, artificial colours and flavours.

The problem with categorising foods like these with NOVA method is that foods such as bread or cereals, which can be part of a healthy diet, are categorised with less nutritious ultra-processed foods such as chicken nuggets, sweets and pastries.

With the rise of veganism, plant-based products have become popular in recent years, however plant-based meat and cheese substitutes are also considered as ultra-processed foods, and so might not be as healthy as they are marketed to be.  Although placing different foods together as ultra-processed can be confusing, the NOVA classification is helpful in establishing a difference in foods and allows people to make informed  food choices.

Activity suggestion

To help you identify the amount of UPF in your current diet:

Write down everything you ate yesterday and reflect on how much of it comes from ultra-processed foods. Are there any simple changes you could make to swap UPF for less-processed versions?

Scientific Advisory Committee on Nutrition (SACN)

In July 2023 the SACN published their position statement on processed foods including consideration of ultra-processed foods (UPF).

In simple terms, the NOVA classification system for processed foods is currently the gold standard but it does have limitations.  Much of the data for the SACN report was entirely observational, relied on self-reporting dietary choices, and was limited in population diversity which does not paint an accurate picture.

Although some studies currently suggest that a diet high in UPF isn’t great for our guts, or overall health, the research is still in its early stages.

So should I cut out all UPF?

It might sound like we should only eat foods that are unprocessed or minimally processed, but with limited time and budgets, this is challenging for most. The reason food is processed, isn’t with the goal to make it unhealthy, it’s to make it either last longer, remove harmful substances, make it easier to digest or to improve flavour and appearance. For example, milk needs to be pasteurised to remove harmful bacteria.  Instead of trying to completely cut out these foods, it is more important to think about the balance in your diet and try to include more minimally processed foods in your diet alongside UPF.


Overall, the relationship between  ultra-processed foods and gut health is complex. While some studies show a connection between highly processed foods and undesirable changes to our gut microbiome, the research is in preliminary stages and currently limited.

Rather than trying to cut out ultra-processed foods entirely, consider how you can reduce your intake and how they can  be included as part of a balanced diet, which allows for convenience, enjoyment and pleasure as much as nutrition and health.

If you need help in reducing the amount of ultra processed foods in your diet, you can book an appointment with Sandy or another of our specialist dietitians by emailing us at [email protected].

This article is authored by Sandy Soni, gut specialist dietitian at The Gut Health Clinic.
Book an appointment with Sandy.


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