Children should not be given ham sandwiches because they could pose a danger to their health, a charity has warned.
The World Cancer Research Fund claimed there is "convincing evidence" that eating processed meat increases the risk of bowel cancer.
Youngsters need to avoid foods like ham and salami, and they should not be included in packed lunches, it said.
The WCRF said sandwich-fillers like chicken, fish or cheese were preferable.
There is no specific research on eating the meats in childhood but the evidence in adults was too strong to ignore, the charity went on.
Both the American Cancer Society and the U.S. government-run National Cancer Institute warn that adults who eat diets high in red and processed meats increase their risk of certain cancers including colorectal cancer, as well as bowel, liver, lung and esophageal cancer.
The WCRF is also urging parents to avoid lunchbox fillers that are high in fat and calories, such as sugary drinks.
Marni Craze, children's education manager for the WCRF, said: "It is better if children learn to view processed meat as an occasional treat if it is eaten at all."