Ultra processed foods and gut health: what you need to know

Curious about the potential impact of ultra-processed foods (UPFs) on your body, including your gut? I share the latest research and explain how to eat less UPFs.

There’s a lot of talk about ultra-processed foods (UPFs), and for good reason. A growing number of research studies report that they may impact our long-term health, including gut health. A major new study from the USA suggests that women who eat a lot of UPFs are at risk of abnormal growths that can lead to bowel cancer.

What are ultra-processed foods?

You might be surprised by how many UPFs you eat. Even if you work hard to stay healthy, they can be hard to avoid. Many everyday foods are ultra-processed. This includes supermarket sliced bread, jarred sauces, deli meat, bacon (including plant-based alternatives), and ready-to-eat meals. Even foods that seem like good choices, like flavoured yoghurt, protein bars, cereal, and baby foods, can contain additives and emulsifiers.

Ultra-processed foods and gut health: What the study found

Researchers followed more than 29,000 women over 30 years as part of the US Nurses' Health Study II. By the time the women turned 50, data showed that those who ate the most UPFs (about 9 serves a day – a notably high amount) had almost double the risk of developing bowel polyps compared to those who ate the least (about 3 serves a day).

This research doesn't prove that UPFs cause bowel polyps or cancer, but it may help scientists better understand why bowel cancer is increasing, especially among younger adults. Australia has the highest rates of bowel cancer in under-50s in the world.

Australians eat more UPFs than people in many other countries

In the meantime, a new series on ultra-processed foods has been published in the world-leading medical journal The Lancet. It reports that UPFs are increasingly replacing healthy whole foods in our meals and snacks. This trend is a major driver of obesity, type 2 diabetes, and heart disease. Australians eat more UPFs than people in many other countries – we're up there with the Americans and the Brits.

Health policies and processes influence the foods we buy. The Australian government is considering making it compulsory for food manufacturers to put a Health Star Rating on packaged foods to help us compare products. However, there are ways for the industry to game the system. For example, they might replace sugar with ultra-processed alternatives that aren't identified on the front of the pack.

How UPFs affect your gut health

UPFs are often high in additives, sugar, salt, and refined ingredients. There are many ways that scientists think the ingredients or processing of UPFs might affect our gut. These include inflammation, changes to our gut microbiota, or damage to the gut lining.

UPFs also tend to be low in fibre, which is important for bowel health. It can be hard to find out how much fibre is in a product, as it's not essential to include this information on the front of packs or on the Nutrition Information Panel on the back. Look for food products with more than 3g of fibre per serve. If fibre isn't listed on the Nutrition Information Panel, the product is unlikely to contain much, or any at all.

Avoid UPFs - Here's what you can buy and eat instead

• Try to cut back on buying the most heavily processed products. If a product has more than five ingredients or contains ingredients you don't recognise, avoid it.

• Build your meals around whole or minimally processed foods where possible. Want examples? Porridge for breakfast, egg salad on bakery sourdough for lunch, and roast chicken, sweet potato, broccoli, and a side salad for dinner. Aim to get your 2&5 a day – that's two pieces of fruit and five serves of veg (a small bowl of salad or ½ cup of cooked or raw veg).

  
  

• The more diverse your diet is in plant-based foods, the better chance you're giving your gut microbiota to look after you. Fruit and veg, whole grains, nuts and seeds, beans and pulses, herbs, and spices all count.

  
  

• Too busy to meal prep, or don't like cooking? Don't worry – choosing whole food snacks like fruit and raw almonds and simply prepared meals like a pre-roasted chicken and bagged salad will get you ahead.

  
  

The Importance of Mindful Eating

Mindful eating is an essential practice that can help you reconnect with food. It encourages you to pay attention to what you eat and how it makes you feel. By being more aware of your food choices, you can make better decisions for your gut health.

When you focus on the experience of eating, you might find that you enjoy your meals more. This can lead to healthier choices over time. It’s not just about what you eat, but also how you eat. Take your time, savour each bite, and listen to your body’s hunger cues.

The Role of Hydration

Hydration plays a crucial role in digestive health. Drinking enough water helps to keep your gut functioning well. It aids in the digestion of food and helps prevent constipation. Aim to drink plenty of water throughout the day. Herbal teas can also be a great way to stay hydrated while enjoying a warm beverage.

The Benefits of Probiotics

Incorporating probiotics into your diet can be beneficial for gut health. Probiotics are live bacteria that can help balance your gut microbiome. You can find them in fermented foods like yogurt, kefir, sauerkraut, and kimchi. These foods can support your digestive health and may help reduce the impact of UPFs on your gut.

Conclusion

Research into UPFs and ill health continues to grow at a steady pace. You can be proactive about your bowel and wider health by trying to buy fewer foods with ingredients you don't recognise. Replace them with fibre- and antioxidant-rich foods where you can (check out my recipes for inspiration).

By making small changes to your diet and being mindful of what you eat, you can support your gut health and overall well-being. Remember, every step you take towards healthier eating is a step in the right direction.

Studies:

DOI: 10.1001/jamaoncol.2025.4777

DOI: 10.1016/S0140-6736(25)01565-X