The cost of food staples such as cheddar cheese, sliced white bread and porridge oats are up to 80% more expensive than a year ago.
Cheddar cheese prices increased by an average 28.3% across all the supermarkets compared to the three months to March 2022, consumer body Which? said.
The biggest increase in Which?’s basket, Dragon Welsh Mature Cheddar 180g at Asda, went from £1 to £1.80, a rise of 80% year on year.
The cost of porridge oats went up by an average of 35.5% across the eight biggest UK supermarkets compared to the same time last year.
At Ocado (OCDO.L) Quaker Oat So Simple Protein Porridge Pot Original 49g went from 94p to £1.56 — an increase of 65.5%.
The price of large loaf of sliced white bread went up 22.8% on average. The Bakery at Asda Soft White Medium Sliced Bread 800g, went from 56p to 94p — an increase of 67%, according to Which?'s research.
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Average inflation of white potatoes was around 14% across the supermarkets. At Morrisons a four pack of baking potatoes went from 40p to 66p — a 63.5% rise.
Inflation in the price of pork sausages across the eight supermarkets was 26.8% on average.
The budget range item at Asda, Just Essentials by Asda 8 Pork Sausages 454g, went from 81p to £1.40 — a 73.5% increase. The value version at Tesco (TSCO.L), Woodside Farms 8 Pork Sausages 454g, went from 80p to £1.39 — up by 73.3%.
Sue Davies, Which? head of food policy, said: “Our latest supermarket food and drink tracker paints a bleak picture for the millions of households already skipping meals of how inflation is impacting prices on supermarket shelves, with the poorest once again feeling the brunt of the cost of living crisis.
“While the whole food chain affects prices, supermarkets have the power to do more to support people who are struggling, including ensuring everyone has easy access to basic, affordable food ranges at a store near them, particularly in areas where people are most in need.
“Supermarkets must also provide transparent pricing so people can easily work out which products offer the best value.”
The consumer group analysed inflation on more than 26,000 food and drink products at the eight supermarkets.
The figures showed that it continues to be the cheapest products which are being the hardest hit by inflation in percentage terms.
Which?’s tracker shows supermarket own-label budget items — which are still the cheapest overall — were up 24.8% in March compared with the same time last year.
This was higher than the 20.5% increase seen on standard supermarket own brands and the 13.8% on branded and premium own brand ranges.
The consumer body warned that even value foods, despite remaining a cheaper option, were at risk of becoming too expensive for those on the tightest budgets.