People who eat too much processed foods should consider a new diet – due to processed foods’ links with cancer and autoimmune diseases. 

That’s according to immunologist Professor Luke O’Neill, who said studies suggest the more “manipulated” food is, the bigger the health risk. 

While most foods are processed to preserve or enhance them, ultra-processed foods are those with more oil, flavouring or colouring than normally added to them. 

Prof O’Neill told Show Me the Science this food has become more popular due to its convenience – but too much convenience comes at a cost. 

For example, he explained a study in France found too many microwave meals or fast food can wreak havoc on your gut. 

“This ultra-processed food, the chemicals it contains, is damaging the gut, and in particular, it's damaging the microbiome,” he said. 

“Trillions of bacteria are living in your gut, in your colon, in your intestines, and they're very important for our health – if they get disturbed, it can damage the gut.” 

Ultra-processed foods can damage the microbiome, changing the gut composition. 

These changes to the gut composition of bacteria can impact all areas of health, according to Prof O’Neill. 

“The beneficial effects of these bacteria is they're making natural chemicals that protect the gut,” he said. 

“They stop your gut being leaky and stop leaking into your blood, they suppress inflammation. 

“They can also limit the risk of colon cancer and tumours growing there – so you can if you take ultra-processed foods too much, and you're changing the microbiome, then you could get into trouble.” 

Processed foods in the immune system

Too much processed foods can also damage the immune system, according to Prof O’Neill. 

A study by Professor Vijay Kuchroo in the US found that increased salt – a staple of processed foods – stimulates cells in the immune system. 

“It turns out the salt can give them a kick,” he said. “You're activating t-cells to become too active, and those that your own t-cells begin to turn on your own body and provoke autoimmune responses.” 

Your gut is also harmed by too much salt, according to Prof O’Neill - as short-chain fatty acids can “turn off” the inflammatory part of an immune response, limiting its strength. 

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