Researchers found that among 515 Taiwanese children and teenagers with and without acute leukaemia, those who ate cured meats and fish more than once a week had a 74 per cent higher risk of leukaemia than those who rarely ate these foods.

On the other hand, kids who often ate vegetables and soy products, like tofu, had about half the leukaemia risk of their peers who shunned vegetables and soy.

The findings, reported in the online journal BMC Cancer, point to an association between these foods and leukaemia risk – but do not prove cause-and-effect.

Long-term human studies, as well as animal studies, are still needed to see what role, if any, dietary factors have in leukaemia development, explained Dr David C Christiani of the Harvard School of Public Health in Boston, one of the researchers of the group.

However, Christiani told Reuters Health, based on this and previous studies, he and his colleagues recommend that children not eat high amounts of cured meats and fish.

During the curing process, foods are preserved and flavoured by the addition of salt, sugar and chemicals called nitrites; the foods are often smoked as well. Nitrites are precursors to compounds known as nitrosamines, which are potentially cancer-promoting.

In contrast, vegetables and soy contain antioxidants that may help neutralize those same compounds.

Christiani and his colleagues found that among children who regularly ate cured meats and fish, those who also ate vegetables or soy products had a substantially lower leukaemia risk.

The study included 145 children and adolescents, 2 to 20 years old, with acute leukaemia who were each matched with at least two healthy individuals of the same age and sex. The researchers collected detailed information on the participants' diets before their cancer diagnosis or, in the case of the comparison group, before their recruitment into the study.

Cured meats included foods like bacon, ham and hot dogs, as well as traditional Chinese staples like dried salted duck, salted fish and Chinese-style sausage.