The British Retail Consortium said food prices dropped last month for the first time since it started collecting data in December 2006, as a supermarket price war intensified.
The BRC, which represents major retailers, said food prices declined by 0.2% in the year to November, compared with a 0.1% rise in the year to October.
Shop prices for all goods fell by 1.9% in November, the same as October's drop and matching July's record decline.
Britain's official inflation data, which cover a wider range of retailers, have shown falling food prices since July.
"We're seeing the big supermarkets investing in price cuts worth millions of pounds during a hugely competitive period in the food market," said BRC director-general Helen Dickinson.
Established UK retailers such as Tesco, Sainsbury's and Wal-Mart's Asda have cut prices in response to challenges from discounters Aldi and Lidl, who have benefited as slow wage growth makes British consumers more cost-conscious.
The BRC said a fall in oil prices to a five-year low was likely to lead to further reductions in food prices, and predicted strong Christmas trading as wages started to rise.
Bank of England Governor Mark Carney has said that overall consumer price inflation is more likely than not to fall below 1% in the coming months, more than a percentage point below the bank's 2% target.
