As the temperature lingers below the annual average, more people are getting the flu.

According to the Korea Centers for Disease and Control and Prevention, 4.66 of every 1,000 patients visiting the doctor recently were diagnosed with influenza. The authorities blame the cold weather, saying it likely brought down overall immunity.

According to experts, one way to restore or boost immunity is an extra intake of fruit and vegetables. The effect is much more powerful when coupled with exercise. Still, according to the Korea Food and Drug Administration, 84.5 percent of children aged 10 and 11 eat less fruit than government recommendations and about 70 percent do not eat enough vegetables.

Health Family 365, an association of doctors, nutritionists, housewives, consumers, food makers and others, suggest that people eat six or more kinds of vegetables and fruit of five colors three times a day.

“The most important thing is to eat seasonal foods,” the group said in a recent press release.

The organization recommends five spring vegetables and strawberries for refreshment and to boost immunity.

“Spring vegetables have abundant vitamins and minerals that prevent eaters from catching colds and help beat spring doziness and lethargy,” it said.

Wild chives and mugwort have lots of vitamins C and A. Fatsia has lots of saponin, good for blood circulation and fatigue recovery. Water parsley helps the secretion of toxins from the body. Strawberries are known to contain 1.5 times more vitamin C than tangerines and 10 times more than apples. But don’t sprinkle salt or sugar over strawberries. Doing so may destroy the vitamin B they contain.

“Eating seasonal vegetables is sometimes better than taking medicine,” the group said.

However, vegetables need to be carefully cooked. According to Park Sun-hee, an official of the Korea Food and Drug Administration, sometimes eating raw plants could cause excessive intake of alkaloid and colchicine. Vegetables also should be rinsed in cold water to avoid food poisoning.

“Don’t try to eat wild plants alongside market vegetables. They may be dangerous,” Park said.

“In order to enjoy vegetables and keep healthy, one should refrain from adding salt. Instead, use ground sesame seeds. Adding vinegar instead of salt is also recommendable. If you want to store vegetables as fresh as possible and for a longer time, remove earth from the stem and roots, but do not wash them. Store them in a tupperware or plastic bag. Otherwise, they may lose flavor,” she added.

By Bae Ji-sook (baejisook@heraldcorp.com)