Reaching 100 has long fascinated societies. The century mark is regarded as an almost supernatural seal of hardiness and good health.

Centenarians are regularly celebrated in the media. Upon your 100th birthday in Britain you can expect a letter from The Queen, and in the United States, some get birthday greetings from The White House. Japanese centenarians receive a silver cup and a certificate from the Prime Minister, honoring them for their longevity.

For global longevity, the Japanese still have a firm grip on the crown. In fact, in 2004 Japanese women set a new record for life expectancy at 85.59 years, while the average Japanese man (No. 2 in the longevity stakes) can expect to live 78.64 years (Japan also boasts a robust number of centenarians and a number of super-centenarians (someone who's reached the ripe old age of 110 years or more). Super-centenarian status is something only achieved by one in a thousand centenarians.

According to Japan's Ministry of Health, Labor and Welfare, as of 2004, there were over 25,000 Japanese men and women who had celebrated their hundredth birthdays. And it's the women in Japan who accounted for a staggering 84 percent of all centenarians. In fact, the number of centenarians here has soared over recent years, and new statistics show a dramatic 15 percent rise in the group of people living to 100 and beyond.

Japan also has the highest median age in the world: 41.3 (which is closely followed by Italy, Switzerland, Germany and Sweden), and more than 20 percent of the population in Japan is over the age of 65.

Add it all up, and you get a very high concentration of gray hair.

Island life

Japan's most celebrated centenarians are from Okinawa and the island's legendary longevity, attributed to the local diet and lifestyle, has spawned a number of books and research. These include the best-selling "The Okinawa Way: How to Improve Your Health and Longevity Dramatically" (2001) by Drs. Bradley and Craig Willcox, and Dr. Makoto Suzuki; "The Okinawa Diet Plan: Get Leaner, Live Longer and Never Feel Hungry" (2005).

Okinawa has enjoyed a lot of fame, but not far away, on the Amami Islands, which lie between Kyushu and Okinawa, there is a comparably high number of record-breaking centenarians. One of the Amami Islands was home to the world's oldest woman until October 2003.

Kamato Hongo was born on a small island in the southern Amami Islands called Tokushima in 1887, when Japan was still in the throes of its conversion from an isolated pre-industrial feudal country to a modern democracy. She had seven children, 27 grandchildren, 57 great-grandchildren and 11 great-great-grandchildren when she passed way at age 116. She practiced teodori (a type of traditional slow dance that uses hand movements), ate a fairly traditional diet of fish, local vegetables and soy products, and drank green tea. She never smoked but counted drinking a glass of local shochu liquor as one of her favorite things. The island Tokunoshima has also produced the oldest man ever on record, Shigechiyo Izumi, who died at the age of 120 in 1986.

While the Amami islands are part of Kagoshima Prefecture in Kyushu, like Okinawa, the culture of the islands has been influenced just as much by other Asian countries as it has been by mainland Japan. Eight of the Amami Islands are populated, with a total population of 132,315, according to 2000 figures. The sea around the islands is blessed with clear water, brightly colored coral reefs and tropical fish, and it is known as a fantastic diving spot. The Amami island hills are covered in subtropical forests, and its amazing diversity has earned the islands the nickname "Japanese Galapagos."

Don't rust away

Apart from their untouched natural beauty and slow-paced life, the Amami Islands seem to boast an ideal environment for nurturing long life. Locals eat a daily average of 97.1 grams of seafood, higher than the national average of 92 grams. Fish, especially deep-sea fish like mackerel, sardines and salmon are rich in omega-3 fatty acids, which act as a strong anti-inflammatory and protect against heart disease. They may also reduce the risk for diabetes, stroke, rheumatoid arthritis, asthma, some cancers and mental decline.

Another key ingredient in the local diet are vegetables such as peppers, broccoli, purple sweet potato and goya. A green, bumpy skinned vegetable, goya is a member of the gourd family and a distant relative of the watermelon. According to Okinawa Living Magazine (May 2002), at least three different components of goya have been clinically demonstrated to reduce blood sugar levels. Strongly colored vegetables contain potent compounds called phytonutrients that function as powerful anti-oxidants. Everyday living -- breathing, eating, metabolizing -- normally creates oxidants, agents that metaphorically "rust" the body from inside. If this rust isn't taken cleared away, it can clog arteries, promote the growth of cancer and cause a number of age-related disorders. Antioxidants help slow down the aging process, and research suggests that certain antioxidants may also help prevent Alzheimer's and the complications of diabetes.

While we're on the subject of oxidation, free radicals are produced whenever you digest and metabolize food. And this is what's interesting: The number of calories you consume affects your level of free radical production. Inhabitants of Okinawa and the neighboring islands of Amami consume a diet that is 20 percent lower in calories than those in the rest of Japan. Most practice a dietary philosophy known as "hara hachi bu" (eight parts out of 10), which means to eat until you are 80 percent full. Research in animals has proven the calorie restriction (CR) theory time and time again -- fewer calories means lower levels of free radicals, and therefore protection from a number of age-related diseases.

This, in combination with a low-calorie diet, plus lots of fish oils, has a powerful ability to subdue internal inflammation. Inflammation is believed to be a major culprit in many age-related disorders, particularly cardiovascular disease. According to the results of an new study published in the journal Life Sciences (Vol. 78), a low-calorie diet, rich in fish oil, was found to reduce the condition by as much as 90 percent in female mice.

Along with fish, plant and soy foods, the islanders also eat a lot of seaweed (especially konbu) and unrefined brown sugar, both of which are rich in minerals, accompanied by green tea and a little of their brown-sugar shochu, which is believed to be effective in reducing blood clots.

Then there's the water, which reportedly has a very high mineral content compared to the rest of Japan. And because of Amami's relative isolation, residents have retained their traditional diet and lifestyle. And naturally there are very few toxins, pollution and relatively little of the stress associated with urban living.

Losing traction

You only need to look to the neighboring island of Okinawa to see that longevity rates are eroding rapidly with the introduction of Western fare, particularly fast food. In a Time magazine special on longevity published Aug. 30, 2004, Dr. Makoto Suzuki, a leader of research in Okinawan elderly and coauthor of "The Okinawa Way," said "Okinawan male life expectancy used to be No. 1 in Japan. It started to decline at least 10 years ago and hit 26th out of 47 prefectures in the 2000 census. I expect it to decline even further in the next census."

The invasion of fast-food franchises unfortunately has started to pack the pounds onto the younger generation in Okinawa, so there's an expanding gap between the young and old generations. While the diets of elderly Okinawans are exemplary, the more "Western" diet and lifestyle are shortening the healthy life spans of young Okinawans.

Will this trend extend to the neighboring islands of Amami? Time and generations will only tell. Considering the number of Amami residents that still practice healthy habits, it would be no surprise if these islands produced further record breakers in the years ahead. And it's great to know, at the ripe age of 114, Hongo still didn't lose her taste for life's little pleasures including raw fish, green tea and a drop of shochu. It gives us all a little hope.