Potato chips, cheese-flavoured crackers, chocolate spreads, white bread, lollies and soft drinks were once everyday favourites in Australian school lunchboxes, especially for children growing up through the 1980s and 1990s.
But Australian researchers now say there is compelling evidence that ultra-processed foods are linked to weight gain, obesity and a wide range of serious health problems, including type 2 diabetes, heart disease, certain cancers, chronic inflammation and depression.
A major study published in The Lancet in 2025 found that diets high in ultra-processed foods can have harmful effects across multiple parts of the body, with the gut, heart and brain among the areas most affected.
‘We evaluated all of the evidence we had on how ultra-processed foods are impacting on human health. There’s a diversity of evidence and all of that is pointing towards ultra-processed food in the diet,’ Dr Phillip Baker told SBS Insight.
Dr Baker, an Associate Professor at The University of Sydney, said many ultra-processed products began appearing widely on supermarket shelves during the 1980s and 1990s.
‘They are made in factories and contain ingredients that you would never use in your kitchen: emulsifiers, gums, flavourings, colourings, modified starches and protein isolates,’ Dr Baker explained.
He said the concern is not only the additives found in these supermarket foods, but also the industrial processing methods used to create them, often relying on ingredients typically found only in products made by major food corporations.
‘When you ultra-process a product, you’re doing a lot of things to it. First of all, you’re dehydrating the product, they tend to be lower in water content,’ he said.
Dr Phillip Baker co-led the 2025 Lancet study on Ultra-processed Foods and Human Health
‘You’re putting in more sugar, fat and modified starches but we also know that these products are designed to make them irresistible.
‘The colourings, flavourings, emulsifiers, gums and non-sugar sweeteners – these are all about engineering the products to make us eat more of the food.’
Dr Baker said the researchers found a ‘cocktail of additives’ that have ‘quite well-known impacts on the human body’.
‘There’s a lot of emerging science here. For example, emulsifiers could be scrubbing our gut like a detergent, degrading the lining of our gut, disrupting the microflora, contributing to leaky gut and inflammation,’ he said.
‘And inflammation is a big reason for why they might be harmful.’
He said humans have not evolved to eat large amounts of these highly processed foods because they are different from the foods our bodies have traditionally adapted to consume.
‘It’s affecting all of our body organ systems – gastrointestinal, cardiovascular and neurological and brain systems,’ he said.
‘We as humans are poorly adapted to consuming these foods and the ingredients that they contain. In evolutionary terms, we are not adapted to these diets.’
Dr Baker said Australians are among the world’s highest consumers of ultra-processed foods due to intense branding and marketing.
‘We’re eating somewhere between 40 and 50 per cent of our calories from ultra-processed foods so if this were the Olympic Games of ultra-processed foods, we’d be right up there on the podium with the US, Canada and the UK,’ he said.
‘The highest consuming Australians are typically teenage boys or girls, with 70 to 80 per cent of their diet coming from ultra-processed foods. This is something we’re really concerned about.’
Aussie mum Danni Duncan believed her childhood exposure to ultra-processed foods may have contributed to her cancer diagnosis
He said ultra-processed foods are now everywhere, not just the ‘obvious’ products like potato chips, sugary drinks and confectionery chocolate bars.
‘Ultra-processed foods are much broader than that category. We used to have processed pies; now we have ultra-processed pies. We used to have bread, yoghurt and tofu; now we have ultra-processed bread, yoghurt and tofu,’ he said.
‘The list goes on. And that’s because it’s more profitable to make the product ultra-processed than just to make it processed or minimally processed.’
Dr Baker appeared on SBS Insight’s episode titled Processed Food Fight, where host Kumi Taguchi spoke to Aussie mum Danni Duncan, who believed her childhood exposure to ultra-processed foods may have contributed to her cancer diagnosis.
At 39, the ‘super fit and healthy’ mum began experiencing extreme fatigue that made no sense to her shortly after giving birth to her fourth child in September 2024.
It began with tiredness and bloating – symptoms she simply put down to having a newborn baby, along with juggling a young family and two businesses.
But the star marathon runner knew something was seriously wrong when she suddenly struggled to get through a workout at the gym.
The fitness and nutrition coach said she felt ‘my life flash before my eyes’ when she was told she had bowel cancer, despite having no family history of the disease.
‘I couldn’t believe it. My first thought was, “No this can’t be happening, I’m supposed to live to 100”. I’ve always been fit and healthy. I’m literally one of the healthiest people I know. How has this happened to me?’ Danni previously told Daily Mail.
‘I’m a runner so I was training for a marathon at the time and I was really struggling, I couldn’t even finish a set. I was getting dizzy at home and then one day, I almost fainted making breakfast. My husband said “You need to go to the doctor”.’
Danni with her husband and their three kids before she welcomed their fourth child
Danni said her surgeon told her that childhood exposure to ultra-processed foods – like popular supermarket snacks and fast food – and even household cleaning products ‘most probably’ contributed to her cancer diagnosis.
‘That’s pretty scary,’ she explained.
‘The doctor was talking about things like all the ultra-processed foods and chemicals that we were exposed to through the 90s and the early 2000s.
‘We were active kids who grew up on fruits and vegetables but we also had processed ham and cheese with white sandwich bread. In the ’90s, there was this big influx of ultra-processed food because convenience was a thing.
‘It was the ’90s… Parents were busy (they still are) and as long as we had our meat and three veg and some fruit – the mentality was, “We’d burn it off”.
‘At the time, our parents would have thought the processed foods were great – but without understanding the impact of what they were going to do to us.’
Bowel cancer is the deadliest cancer for Australians aged 25 to 54, with cases diagnosed in people under 50 surging – but the cause of the increase has remained largely a mystery to experts.
Every year, more than 1,800 young Australians are diagnosed with bowel cancer, despite it being considered an ‘old person’s disease’.
In 2025, more than 14,780 Australians were diagnosed with colorectal cancer, while the disease claimed an estimated 5,235 lives.
Why yoghurts labelled ‘Greek’ or ‘Greek style’ are not the same
Dr Karl Kruszelnicki previously pointed out that yoghurts labelled ‘Greek’ or ‘Greek style’ are not the same.
The major difference between the two options comes down to their processing methods. Traditional Greek yoghurt is made by straining to remove whey, resulting in a thicker, protein-rich consistency.
Greek-style alternatives, on the other hand, usually contain additives like thickeners (gelatin), gum and milk solids to mimic the thick, creamy texture of Greek yoghurt without going through the lengthy straining process.
He pointed out that Greek-style yoghurts contain emulsifiers – additives used to keep ingredients blended without separating – which could potentially do more harm than good to our health.
In his podcast Shirtloads of Science, Dr Karl asked Professor Clare Collins, an Australian dietitian and Professor of Nutrition and Dietetics at the University of Newcastle, what emulsifiers in Greek-style yoghurts could do to our bodies.
Breaking down the science behind it, she explained how emulsifiers in some processed foods have been found to affect the gut bacteria, known as microbiota.
‘There’s been an assumption that with these food additives, your body doesn’t absorb them, so what’s the problem?’ she told Dr Karl.
‘But now there’s more recognition that some of these food additives can go through the loops all the way down to the large intestine, get to the very last section of the colon where all the bugs live, and the microbiota can have a field day with them.
‘While the emulsifiers are of concern, they can disrupt the bugs, but they can go straight for the gut wall, break down the mucus layer, and potentially create little holes, which is referred to as a leaky gut.’
When the gut wall becomes ‘leaky’, she said unhealthy bacteria can slip through, potentially leading to symptoms such as allergies, an increased risk of inflammatory bowel conditions or diarrhea.
Professor Clare explained how emulsifiers are like dishwashing liquid. Just like dish soap breaks down grease on a dirty dish, emulsifiers can break down fats and affect the gut wall.
‘You have a dirty baking dish. If you squirt that on, what it does is it can really break down all of those fats, and that’s kind of the same effect on your intestinal wall,’ she said.
‘When the emulsifiers get all the way to the colon, it’s kind of now presented like a dirty dish, so to speak, and can actually attack your colonic wall.’
If you want to avoid emulsifiers, she said the additives may be listed on the label under chemical names – such as ‘soy lecithin’ or ‘polysorbate 80’ – or they may appear as numbers, often in the 400 range.
However, Professor Clare urged shoppers not to worry.
‘Don’t panic,’ she said repeatedly.
‘Go to Food Standards Australia New Zealand (FSANZ) and download the food additives list. I think it’s worth it, save it to your phone, so you know what numbers and words you’re looking for.’
