Ancient Britons were eating dairy, peas, cabbage and oats, according to gunk trapped in their teeth.
Scientists analysed dental plaque found on the teeth of skeletons from the Iron Age to post-Medieval times.
They found evidence of milk proteins, cereals and plants, as well as an enzyme that aids digestion.
In modern samples, they found proteins that reflect a more cosmopolitan diet, including potatoes, soya and peanuts.
The research gives a picture of what people have been eating through the ages, including food that leaves no trace in the archaeological record.
Lead researcher, Dr Camilla Speller, from the department of archaeology at the University of York, said the technique can distinguish between different crops and show whether people were consuming dairy products, like milk or cheese.
"In the teeth we look at from individuals who lived around the Victorian era, we identified proteins related to plant foods, including oats, peas and vegetables in the cabbage family," she said.
"Occasionally, we find evidence of milk and oats in the same mouth - I like to think it's from eating porridge!"
In the new study, published in the journal Proceedings of the Royal Society of London B, researchers analysed 100 archaeological samples from across England, as well as 14 samples from living dental patients and individuals who have recently died.
Dietary proteins were found in about one third of the analysed samples.
Proteins found in ancient dental plaque have already revealed that humans were drinking milk as far back as 6,500 BC.
Co-researcher Dr Jessica Hendy from the Department of Archaeology at the Max Planck Institute in Germany, added: "While there is still a lot we don't know, this is exciting because it shows that archaeological dental calculus harbours dietary information, including food products that ordinarily do not survive in archaeological sites."