The newspaper, which reaches more than five-million readers with its Saturday edition, conducted a "special investigation" involving laboratory screening of 120 supermarket-bought British lettuces for E. coli and Listeria monocytogenes.
It found traces of E. coli in three samples but no listeria. The highest levels of E. coli, found in a Waitrose lettuce, "could causes sickness or an upset stomach", according to Society for Applied Microbiology chief executive Phil Wheat, quoted in the article, headlined: "Attack of the poisoned lettuces! The dangers lurking in pre-packaged salad leaves" - although no pre-packed salads were tested.
British Leafy Salads Association (BLSA) chairman Colin Bloomfield said: "The arguments in the piece didn't justify the headline. The levels of contamination were within acceptable limits. It's natural for fresh products to have some bacteria on them.
"Most people are reassured by the fact that British produce is backed up by Red Tractor and other assurance schemes. If this was a matter of substance like the E. coli outbreak we would be concerned, but one-off reports don't do lasting damage."
BLSA technical director David Norman added: "It was typical Daily Mail scaremongering and not helpful. Eating leafy salads will do you far more good than harm."