Cancer risk from meat will be harder to prove in humans

Researchers at the University of California in San Diego, USA, have been investigating the possible tumour-forming role of the molecule as a way of explaining why people who eat a lot of red meat are at a higher risk of getting certain cancers.

Neu5Gc naturally occurs in most mammals, with the exception of humans. A study published in the Proceedings of the National Academy of Sciences​ revealed that scientists feeding this molecule to mice, that had been engineered to be deficient in the sugar – mimicking humans – "significantly promoted spontaneous cancers".​

Principal investigator Ajit Varki, MD, distinguished professor of medicine and cellular and molecular medicine and member of the UC San Diego Moores Cancer Centre, said: "Until now, all of our evidence linking Neu5Gc to cancer was circumstantial or indirectly predicted from somewhat artificial experimental set-ups. This is the first time we have directly shown that mimicking the exact situation in humans – feeding non-human Neu5Gc and inducing anti-Neu5Gc antibodies – increases spontaneous cancers in mice."​

Varki’s team found that red meats were rich in Neu5Gc. The researchers hypothesised that eating red meat could lead to inflammation if the body’s immune system was constantly generating antibodies against consumed animal Neu5Gc – something that is known to promote tumour formation.

However Varki admitted that to get "final proof in humans will be much harder to come by".​

"Of course, moderate amounts of red meat can be a source of good nutrition for young people. We hope that our work will eventually lead the way to practical solutions for this catch-22,"​ he added.

Commenting on a previous study on the link between cancer and red meat, Dr Emma Derbyshire of UK organisation the Meat Advisory Panel, noted that the causes of cancer were complex, involving a combination of both our genes and our lifestyles.

She said that dietary methods used in studies to assess meat intakes can be limited, often leading to inaccurate estimates of meat intakes and failing to separate out processed and lean meats.

Interestingly, another study by John Hopkins University in Baltimore, US, published in the journal Science​ recently, claimed that most cancers could be put down to bad luck, rather than risk factors such as smoking or an unhealthy lifestyle.