Could your favourite bag of Doritos be dulling your brain? A growing pile of scientific research suggests the answer for heavily processed snacks may be uncomfortable. One 2026 study found that eating the equivalent of just one extra packet of crisps a day was linked to a measurable drop in people’s ability to focus.
No study has tested Doritos on their own. But Doritos, like most flavoured crisps and tortilla chips, are classed as an ultra-processed food, and that is the group of foods scientists are increasingly linking to poorer brain health.
The study: one packet of crisps a day
Researchers from Monash University, the University of São Paulo and Deakin University looked at the diets and brain health of more than 2,100 adults aged 40 to 70. The study was published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring in April 2026.
They found that every 10% increase in ultra-processed food in a person’s diet was linked to lower scores on tests of attention and mental processing speed, and to a higher score on a tool that predicts dementia risk, Monash University said. Lead author Dr Barbara Cardoso said that 10% increase was roughly the same as adding a standard packet of chips to your daily diet.
Worryingly, the link held up even among people who otherwise ate a healthy, Mediterranean-style diet, ScienceDaily reports.
Not just one study
It is part of a wider pattern. A 2026 systematic review of 14 studies found that most reported a significant link between eating more ultra-processed food and worse memory, thinking and overall cognition. A separate study published in January found that a 10% rise in ultra-processed food intake was linked to a 16% higher risk of cognitive impairment, CNN reported.
Research on artificial sweeteners, which turn up in many processed snacks and drinks, has raised similar concerns. A study of nearly 13,000 adults in the journal Neurology linked the highest sweetener intake to memory and thinking decline equal to about 1.6 extra years of brain ageing, the American Academy of Neurology said.
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What’s actually in a bag of Doritos?
Doritos sold in Ireland and the UK are made from corn and rapeseed oil, coated in a flavour mix. The Tangy Cheese flavour sold by Tesco lists ingredients including:
- Monosodium glutamate (MSG) – a flavour enhancer that boosts savoury taste
- Potassium chloride and salt
- Dextrose and sugar
- Buttermilk powder, milk protein and cheese flavourings
- Acidity regulators (lactic acid, citric acid) and colours (paprika extract, annatto, plain caramel)
Other flavours, such as Cool Original, add a second flavour enhancer, disodium 5′-ribonucleotides. Open Food Facts lists Doritos as ultra-processed.
MSG often gets the blame, but food safety regulators, including the European Food Safety Authority, consider it safe at normal levels. Scientists think the bigger problem with ultra-processed foods is the overall package: high salt, refined starch and additives, eaten often, and pushing whole foods like vegetables, beans and fish off the plate.
So are Doritos making you dumber?
The honest answer: nobody has proven it. Most of these studies show a link, not cause and effect. People who eat lots of processed snacks may also sleep less, exercise less or have other health problems that affect the brain. One Dutch study of older adults published in 2026 found no link at all between ultra-processed food and cognitive decline.
But the weight of evidence is building, and the message from researchers is consistent. A packet of Doritos now and then will not hurt your brain. Making ultra-processed snacks a daily habit might.
Sources
- Monash University: Ultra-processed foods damage your focus even if you eat healthy (April 2026)
- ScienceDaily: Ultra-processed foods may be stealing your focus (June 2026)
- CNN: Even small amounts of ultraprocessed foods increase risk for dementia (April 2026)
- American Academy of Neurology: Some sugar substitutes linked to faster cognitive decline
- European Journal of Nutrition: Ultra-processed food intake and cognitive decline in older adults (2026)
- Tesco: Doritos Tangy Cheese ingredients
Featured image: Bowl of tortilla chips by Bananasoldier, CC BY-SA 3.0, via Wikimedia Commons.
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