Bacon, ham and sausages rank alongside cigarettes as a major cause of cancer, the World Health Organisation has said.
Its report says each 50g of processed meat a day – the equivalent of one sausage, or less than two slices of bacon – increases the chance of developing bowel cancer by 18 per cent.
Global health experts listed processed meat as a cancer-causing substance – the highest of five possible rankings, shared with alcohol, asbestos, arsenic and cigarettes.
Fresh red meat was ranked on the next level – as a “probable” carcinogen.
The classifications, by the WHO’s International Agency for Research on Cancer (IARC), mean processed meat is officially regarded as “carcinogenic to humans”.
It follows a meeting of scientists from ten nations, including the UK, who reviewed all available evidence.
Cancer charities welcomed the findings.
They said those eating a lot of processed meats should cut back, while saying the occasional bacon bap would do little harm.
Although processed meats have been classed in the highest risk category, alongside smoking, it does not mean that each are an equal danger, experts stressed.
The classifications describe the strength of the scientific evidence that a substance causes cancer, rather than the level of risk attached to it.
Dr Kurt Straif, from the France-based International Agency for Research on Cancer, said: “For an individual, the risk of developing colorectal (bowel) cancer because of their consumption of processed meat remains small, but this risk increases with the amount of meat consumed.”
Red meat – under which the IARC includes beef, lamb and pork – was classified as a “probable” carcinogen in its group 2A list that also contains glyphosate, the active ingredient in many weedkillers.
The lower classification for fresh red meat reflected “limited evidence” that it causes cancer. The IARC found links mainly with bowel cancer, but also observed associations with pancreatic and prostate cancer.
The World Cancer Research Fund (WCRF) has previously warned of “strong evidence” that consuming a lot of red meat can cause bowel cancer.
In 2009, it recommended eating no more than 2.5oz (70g) processed meat a week – the equivalent of three rashers of bacon – and said children should not have processed meat at all.
Professor Tim Key, from Cancer Research UK, said the links were backed by substantial evidence. He said the ruling should not mean cutting out all meats.
“If you eat lots of it you may want to think about cutting down. You could try having fish for your dinner rather than sausages, or choosing to have a bean salad for lunch over a BLT.
“Eating a bacon bap every once in a while isn’t going to do much harm – having a healthy diet is all about moderation,” he said.
Current NHS advice is to limit intake of all meats to 70g a day, but there is no specific recommended limit for cured and processed meats.
The average person in the UK has 2.5oz (70g) meat a day 3oz (88g) among men, 2oz (52g) among women) but one in three people have more than 3.5oz (100g) a day, research suggests.
The new advice from WHO suggests 50g of processed meat is enough to significantly raise bowel cancer risk, by 18 per cent.
A fry-up including two rashers of bacon and two sausages makes up almost three times that amount, at 130g.