California, USA: A sugar found in red meat such as beef but absent in humans may cause cancer.
Mice engineered to be Neu5Gc-deficient like us had a fivefold rise in tumours after trying to fight it with antibodies, a study found.
This process in humans could lead to inflammation then cancer, said experts.
Dr Ajit Varki, of the University of California, said: “Until now, all our evidence linking Neu5Gc to cancer was circumstantial.”
“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.
“The final proof in humans will be much harder to come by.
“But on a more general note, this work may also help explain potential connections of red meat consumption to other diseases exacerbated by chronic inflammation, such as atherosclerosis and type 2 diabetes.
“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.”
The study is online in the Proceedings of the National Academy of Sciences.