Shoppers are increasingly turning to supermarket own-brands as they bid to shield their grocery bills from rising prices.
According to industry data from Nielsen, growth in the sale of own-brand goods rose at almost five times the rate of branded products during the 12 weeks to 9 September.
The data also showed discounters continuing to challenge the big four chains on market share.
Mike Watkins, Nielsen’s UK head of retailer and business insight, said: “Own-brand sales are growing across all major food retailers but fastest at the discounters – Aldi and Lidl – and at the Co-operative, Iceland, M&S and Tesco.
“Looking at what shoppers are putting into their baskets suggests food retailers are helping shoppers manage the impact of inflation by offering different ranges of own-label alongside brands across many categories.”
Prices have been rising this year because the weaker pound since the Brexit vote has raised import costs.
But the data also suggested that because of the “very competitive” market, companies are “increasingly reluctant to pass on all of the rising cost of groceries to shoppers”.
A separate study on the grocery market by Kantar Worldpanel measured grocery inflation at 3.2% in the 12 weeks to 10 September.
Price rises are squeezing budgets because wages are only rising by an average 2.1% at the last official measurement.
In a trading statement on Tuesday, the online grocer Ocado reported a 1.2% decline in its average order size.
Group revenue rose by over 14% in the 13 weeks to 27 August.
Its chief executive, Tim Steiner, said: “Our industry-leading technology has continued to set the bar for customer service and satisfaction and we continue to grow sales at a rate significantly in excess of the average for our industry.
“Recent innovations include Ocado becoming the first UK grocer to offer its customers Amazon’s Alexa voice-activated tool, meaning they can verbally modify their online grocery orders.”
Kantar pointed to a slight hit to industry sales in August because of poor weather knocking demand for seasonal products but said that despite the blip the sector was currently enjoying its best run of sales growth for four years.