SEOUL — One might call it the chicken soup of Korea.
For years, Koreans have clung to the notion that kimchi, the pungent fermented cabbage that is synonymous with their culture, has mystical properties that ward off disease. But what was once little more than an old wives' tale has become the subject of serious research, as South Korean scientists put kimchi under their microscopes.
Last month, scientists at the Korea Atomic Energy Research Institute unveiled a kimchi especially developed for astronauts to prevent them from getting constipated in space. A researcher at Ewha Woman's University in Seoul reported that kimchi lowered the stress levels of caged mice by 30%.
At the Kimchi Research Institute in Busan, hairless mice fed kimchi were reported to develop fewer wrinkles. With a government grant of $500,000, the institute is developing a special anti-aging kimchi that will be marketed this year. Other new products are anti-cancer and anti-obesity kimchi.
"We are proud that we can use scientific methods to confirm the health benefits of our traditional food," said Park Kun-young, who heads the institute.
Kimchi specialists abound here. The library of a kimchi museum in Seoul holds more than 2,000 books about kimchi and thousands more dissertations. ("A Kinetic Model for Lactic Acid Production in Kimchi" was among the recent titles.) New theses are being added at the rate of 300 per year.
Kimchi is a matter of great national pride, and much of the research has been government-funded.
"I think kimchi practically defines Korean-ness," said Park Chae-lin, curator of the museum.
Understandably, perhaps, dissenters on the topic of its healing power are circumspect.
"I'm sorry. I can't talk about the health risks of kimchi in the media. Kimchi is our national food," said a researcher at Seoul National University, who begged not to be quoted by name.
Among the papers not to be found in the vast library of the kimchi museum is one published in June 2005 in the Beijing-based World Journal of Gastroenterology titled "Kimchi and Soybean Pastes Are Risk Factors of Gastric Cancer."
The researchers, all South Korean, report that kimchi and other spicy and fermented foods could be linked to the most common cancer among Koreans. Rates of gastric cancer among Koreans and Japanese are 10 times higher than in the United States.
"We found that if you were a very, very heavy eater of kimchi, you had a 50% higher risk of getting stomach cancer," said Kim Heon of the department of preventive medicine at Chungbuk National University and one of the authors. "It is not that kimchi is not a healthy food -- it is a healthy food, but in excessive quantities there are risk factors."
Kim said he tried to publicize the study but a friend who is a science reporter, told him, "This will never be published in Korea."
Other studies have suggested that the heavy concentration of salt in some kimchi and the fish sauce used for flavoring could be problematic, but they too have received comparatively little attention.
Even the most ardent proponents say that at times, kimchi might be too much of a good thing.
Nutritionist Park, who in addition to the Kimchi Research Institute heads the Korea Kimchi Assn. and the Korean Society for Cancer Prevention, said that traditionally, kimchi contained a great deal of salt, which could combine with red pepper to form a carcinogen.
Nowadays, with refrigeration, less salt is needed, Park said. Instead of preserving kimchi by burying it in earthenware jars in the garden, many Koreans own specially designed refrigerators to keep it at ideal temperatures.
The beneficial power of kimchi comes from the lactic acid bacteria (also found in yogurt and other fermented foods) that helps in digestion and, according to some researchers, boosts immunity. In addition, the vegetables are excellent sources of vitamin C and antioxidants, which are believed to protect cells from carcinogens. The high fiber content aids bowel function.
Although the most recognizable kind of kimchi is made with Chinese cabbage, other variants are made with radish, garlic stalks, eggplant and mustard leaf, among other ingredients. In all, there are about 200 types of kimchi -- plastic models of which are on display at the kimchi museum in Seoul.
Korean pride swelled when the U.S. magazine Health listed kimchi in its March issue as one of the world's five most healthful foods. (The others are yogurt, olive oil, lentils and soy.)
In fact, interest in kimchi's curative properties has risen proportionally with fears related to diseases such as severe acute respiratory syndrome and avian flu.
During the 2003 panic over SARS, people started remarking that Korea seemed curiously immune, and speculation revolved around kimchi.
In March, LG Electronics put out a new line of air conditioners that have an enzyme extracted from kimchi (called leuconostoc) in the filters.
Healthful or not, the kimchi industry is booming, abroad and at home. South Koreans consume 77 pounds of it per capita annually, and many people eat it with every meal, according to industry statistics. Koreans traveling abroad seem to take it with them everywhere.
And that will soon include outer space.
"Koreans can't go anywhere without kimchi," said Byun Myung-woo, head of a team of scientists who developed a specially sterilized form of kimchi for astronauts.
The idea came about because taste and smell are greatly diminished in low-gravity conditions, giving astronauts a preference for strongly spiced foods. And astronauts often suffer from digestive problems.
"The kimchi will prevent constipation and enhance their digestive functions," Byun said.
Space kimchi is expected to make its debut in 2008, when the first South Korean astronauts are scheduled to travel on the Russian spacecraft Soyuz.
Jinna Park of The Times' Seoul Bureau contributed to this report.