“No Ifs or Butties—Bacon is safe to eat after all,” said the headline in The Sun. The latest of summary meta-analysis reports was published in the Annals of Internal Medicine last week on the evidence for the effects of eating meat eating. The Canadian authors conclude that we have grossly over-estimated the harmful effects of both red meat and processed meat on cancer and mortality and that we should not alter our current habits. This comes soon after a succession of other high-profile reports which reached the opposite conclusion, with some even suggesting that eating bacon was as dangerous as smoking cigarettes. Current NHS and US guidelines are that we should modestly reduce intakes of meat to less than 70 grams a day, which is equivalent to a rasher of bacon. No wonder the public is confused, not to mention the health professionals who are trying to advise them.

An important clarification here is that there are no new data being considered. The publication is from health service researchers who applied a stringent set of evaluation criteria (called GRADE) they created at McMaster University to the existing studies. The criteria are well suited to studies of pharmaceuticals when there are randomized, double-blind, placebo-controlled trials available, but not for studies of meat, eggs, vegetables or any specific food.