Starting in April, all manufacturers of prepackaged food will have to clarify substances that can cause allergies, according to a national regulation for food labels.

The new standard will be compulsory nationwide, and is the first time that the country has included allergens in food safety regulations, according to Fan Yongxiang, an official with the National Institute of Nutrition and Food Safety under the Chinese Center for Disease Control and Prevention.

Approximately 1 to 2 percent of adults and around 5 percent of infants and young children in the country suffer from food allergies, according to Sun Jianqin, director of the nutrition department at Shanghai-based Huadong Hospital affiliated to Fudan University.

China does not have statistics to show how life threatening food allergies are, but figures from the United States government revealed that each year roughly 30,000 individuals require emergency treatment, and 150 individuals die because of allergic reactions to food.

A food allergy is an adverse immune response to food protein. Sufferers usually show acute responses, including vomiting, diarrhea and bronchial asthma.

"It may cause death in severe cases," Sun said.

"Some people are allergic to certain foods in childhood, and improve when they grow older. But it may last a life time for others, so they'd better avoid the food," said Chen Yuzhi, a professor at the Clinical and Education Center for Asthma under the Capital Institute of Pediatrics.

She added that there is no cure for food allergies at present.

Eight major foods or food groups - wheat bran cereals, shellfish, fish, eggs, peanuts, soybeans, milk and tree nuts - account for most food allergies, and they are all included in the mandatory regulation.

"Different food products may be produced on the same production line, so it's possible that a very small amount of ingredients of one product may be brought to another even after the production line is cleaned," said Dong Jinshi, executive vice-president of the International Food Packaging Association.

"It could also be caused when two food materials, say chicken and fish, share one storage house," he said.

Shen Wei, father of a 7-year-old child who is allergic to fish, said such regulations may better protect children and other consumers who have food allergies.

"My son grows blotches and lumps on the skin and suffers a headache whenever he eats fish," said the 35-year-old Shanghai resident. "I think it's a big step forward to safeguard consumers' health and rights to be informed - if food businesses really follow the rule."

However, Chinese consumers and even market watchdogs at present are not familiar with labels about food allergies.

In August, Knorr Stock Pot, a bouillon product by consumer product giant Unilever, was removed from shelves in Guiyang and Changsha because of a message on its package reading: "This product may contain wheat, soybeans, eggs, dairy products and fish" was accused of being unclear and confusing.

"So it's important that the public know something about food packaging labels," Dong said. "And it will be more understandable to consumers if food companies rewrite the alert as 'people allergic to fish should be cautious about eating this'."