Researchers from Queen’s University, Belfast have questioned the World Health Organisation’s (WHO) blanket classification of processed meat as carcinogenic, after finding ‘significant evidence’ gaps between processed meat treated with nitrites and nitrite-free processed meat.

Researchers at the University looked back at more than 60 studies into the link between processed meats and cancer and found the results were inconclusive, with only half of the papers finding any type of relationship.

Dr Brian Green, Dr William Crowe and Professor Chris Elliott OBE, all from the Institute for Global Food Security (IGFS) at Queen’s, reviewed existing peer-reviewed literature on the relationship between processed meat and the development of bowel, colon and rectal cancers

In 2015 the WHO labelled processed meats, such as bacon, sausages and ham as carcinogenic, and warned that 50g a day increased the risk of developing colorectal cancer by 18 per cent.

Not all processed meat, however, contains nitrites. British and Irish sausages, for example, are not processed with nitrites even though many Continental and US sausage equivalents – like frankfurters, pepperoni and chorizo – are. Some newer types of bacon and ham, which are processed without nitrites, are also appearing on the market.

In its 2015 statement, the WHO did not distinguish between processed meats containing nitrites and those without them. Based on the results of its meta-study, the IGFS researchers now believe there is a need to define the health risk of both types of processed meat – separately.

Co-author Professor Chris Elliott OBE, who carried out the UK Government’s inquiry into food safety after the horsemeat scandal, said that this latest research brought more clarity to what has been a confusing area for the food industry and the public.

He added: “Because there have been conflicting claims in the scientific community and the media about which types of meat may be carcinogenic, this study couldn’t have come at a better time. It brings much-needed rigour and clarity and points the way for further research in this area.”

Study lead author, Dr Brian Green commented: “It’s important we eat a healthy, balanced diet in line with the government’s ‘Eatwell Guide’. The current Department of Health guidance advises the public to consume no more than 70g of red or processed meat per day. That remains the guidance, but we hope that future research investigating the link between diet and CRC will consider each type of meat individually rather than grouping them together.”