NAHA, Okinawa Pref. -- Legend holds that an ancient Chinese emperor dispatched a mission of explorers to find Horai, a heavenly island believed to exist in the ocean, with orders to find the elixir of life and bring it to him.

The mission of 3,000 people, however, never returned, and it is believed the earthly paradise proved too tempting for them to leave. Could "the island of eternal life" have been today's Okinawa? The idea is not too far-fetched, according to one health researcher.

Japan's southernmost prefecture of 1.3 million people has the most healthy and longest-living population of elderly in the entire country. According to the latest available data, there were 365 people aged 100 and over in Okinawa in 1998.

In a nation known around the world for its longevity records, the number of centenarians comes to 28.86 per 100,000 in Okinawa, which is strikingly high compared with the national average of 8.97.

While many scholars suggest that Okinawa's warm climate and generally carefree mentality are behind the long life spans, Makoto Suzuki, head of the Okinawa Research Center for Longevity Science, maintains that food is what makes Okinawa the island of long life.

According to Suzuki, a former professor of medicine at the University of Ryukyus, many indigenous ingredients used in Okinawan cuisine are rich with nutritive substances.

One local vegetable famous for its high nutrition content is the bitter gourd, which is known as a "goya" in the local dialect. Goya are packed with vitamin B and vitamins C and E, which are antioxidants that help fight harmful chemicals known as free radicals, which contribute to the aging process, he said.

Locals are also known to eat a lot of tofu, and some statistics rank the prefecture as top in the country for consumption of the soybean product.

While the health benefits of tofu are internationally recognized, the Okinawan variety, which is firmer and larger than mainland one, is especially rich in a protein believed to bolster the immune system.

Okinawan tofu contains a large amount of phytoestrogen, a hormone found in female plants, Suzuki said. Phytoestrogen helps to slow aging but is also effective in preventing breast, prostate and intestinal cancers, he said.

Okinawans have long consumed these and other healthy foods in dishes called "champuru," a traditional and widely popular family dish made with fried ingredients.

The word champuru, which means "to mix," is said to date back to the 15th century when Okinawa, then an independent kingdom, thrived on extensive trade with neighboring Asian countries.

Champuru is an easy way to take in vegetables, and people can take two thirds of the daily recommended vegetable intake in one dish.

Locals say a champuru dish made with goya and tofu is indispensable for surviving the hot summers here.

According to Yaeko Nishio, a local food expert, champuru was originally a simple fried dish of tofu and seasoned vegetables flavored with salt. It later grew to include pork, Spam, a kind of spiced processed ham, and canned tuna.

"It is almost as if the dish reflects the transition of Okinawan society from a period of heavy influence from China, which consumes a lot of pork, to the U.S., with Spam, and then to Japan, with canned tuna," she said.

Okinawa had a close relationship with China around the middle of 14th century. After being annexed by Japan in 1889, the island came under the rule of the United States in 1945, during World War II. In 1972, it was returned to Japan.

"I think champuru therefore symbolizes strength and generosity of Okinawans in embracing external influences and using them in their lives," she said.

The dish has recently become recognized in Japan and is often used as shorthand to describe Okinawa's culture.

Eating pork, which is no less dominant in Okinawa's culinary scene, is believed to have begun in late 14th century, when livestock was imported from China. But while Okinawa exceeds other parts of Japan in its consumption, the people's partiality to pig extends to almost all other parts of the animal.

Facial skin and ears are cut up and dressed with peanut butter and vinegar. "Tebichi," or pig paws, are rich in collagen and served in soup with "konbu," or kelp, which is known for its high nutritive qualities.

Even pigs' blood is used for frying. Okinawans' exploitation of the pig is so thorough that it is said they eat everything but their oinks.

Although high pork consumption usually raises of fat-related health problems, Nishio said Okinawans avoid the problem by boiling the meat before cooking, which reduces fat content considerably.

The other healthy aspect of an Okinawan diet is its lower salt intake, which is 10.8 grams, against the national average of 12.8 grams.

Instead of relying on salt or soy sauce, locals use a thick soup taken from dried bonito chips, or water used in boiling pork. These are used to add flavor to certain dishes.

In addition, Okinawans have not formed the habit of eating salted pickles that is popular in northern Japan, because the warm climate makes fresh vegetables available year round. The same can be said of dried fish, which is preserved with large amounts of salt.

Nishio said that for Okinawans, diet and medicine are inseparable, a concept reflected in the local phrase "nuchi-gusui." Locals use nuchi-gusui instead of "gochisoo-sama" to give thanks for their meals.

"They say (the meal) was nuchi-gusui, which means 'the life medicine.' It is an attitude among locals toward food. We eat to support our body," Nishio said.