A Global Look at the Oldest-Old and Centenarians: Is It Genes, Diet, Luck or All Combined?

By Gloria M. Gutman

Population aging is occurring around the world. Today there are 31 countries with 15 percent or more of their population ages 65 and older. Japan and Monaco continue to lead, each with 24 percent of their population ages 65 and older, followed by Germany and Italy each with 21 percent. However, with the exception of Japan, Martinique and Puerto Rico (the latter two both with 15 percent of the population ages 65 and older), the majority of the countries with the highest proportion of people ages 65 and older are in Europe.  

The picture is different if one asks, “What countries have the most old people?” In 2000, there were 12 countries with more than 10 million people ages 60 and older, five with more than 20 million: China (129 million), India (77 million), United States (46 million), Japan (30 million) and the former Soviet Union (27 million). By 2050, the Population Division of the United Nations (U.N.) projects that 33 countries will have more than 10 million people ages 60 and older: China (437 million), India (324 million), United States (107 million), Indonesia (70 million) and Brazil (58 million). 

What lessons have we learned from those countries whose population has already reached the 20 percent ages-65-and-older mark? The first is that reaching such a proportion does not automatically mean this age cohort will “break the bank” with their demands for healthcare, housing and income support—the three big issues for elders worldwide. Nor is there evidence of intergenerational warfare. The latter appears to be an American social construction that has never materialized.

Centenarians on the Rise

There are more centenarians living today than ever before. The U.N. estimated there were 343,000 centenarians worldwide in 2012, a figure projected to grow to 3.2 million by 2050. The United States has the most centenarians, with an estimated number of about 80,000. Japan follows, with an estimated 47,700, and is also home to the “official” oldest living person in the world, Yone Minigawa, age 114.

Other countries with a relatively large number of centenarians include England and Wales—12,320 in 2012 and Canada—7,500 in 2011, the year of its latest census. In all countries, women centenarians outnumber their male counterparts. But the gender gap has lessened recently in England and Wales, from eight women to every one man in 2002, to six women to one man by 2012, attributed to relatively greater improvement in male mortality rates. 

Most centenarians have been remarkably healthy over their life course, and experience relatively rapid terminal decline late in life—i.e., demonstrating compression of mortality at the end of life. 

There are several important centenarian studies going on in Okinawa, Japan, Sardinia, Italy and in the United States. While Okinawa and Sardinia are small geographically, they have a disproportionate number of centenarians. Sardinia also stands out because it has a high prevalence of male centenarians.  While the United States did not introduce a birth registry until 1940, raising questions on the validity of self-reported age in census estimates, Okinawa’s family registry system dates back to 1879, so age verification is possible there. 

Researchers on the 36-year-old Okinawa Centenarian Study, which has followed 8,000 Japanese American men in Hawaii, say many centenarians in their sample lived independently well into their 90s, and seem to have avoided onset of the chronic diseases of aging such as Alzheimer’s disease, cardiovascular disease and cancer. 

The New England Centenarian Study, headquartered at Boston University, reports similar findings.  More than 90 percent of centenarians in their sample were still functioning independently at the average age of 93. 

Researchers are trying to determine what exactly contributes to extreme longevity. Genes play a part. The Okinawa researchers have found a gene that if inherited from both parents triples a male’s chances of becoming a centenarian. But the New England Centenarian Study notes that many genes are involved, so in predicting who will be a centenarian many different genes have to be considered rather than relying on only one.

They have found 281 genetic markers that are 61 percent accurate in predicting 100 year olds and even more accurate in predicting super-centenarians, or people who live past age 105, suggesting that genes play an increasingly important role at the extremes of longevity. These markers point to genes that have been shown to play a role in Alzheimer’s disease, diabetes, cancer, high blood pressure and basic biological mechanisms of aging.

Lifestyle is also thought to play an important role in extreme longevity. Much has been said about the largely fish-based diets of the Okinawans, and the benefits of a Mediterranean diet. Centenarians also seem to have been able to avoid fatal injuries and exposure to deadly contagious diseases—perhaps it’s the “good luck” factor centenarian researchers speak about as also being a determinant of having a very long life.

Gloria M. Gutman, Ph.D., is a past president of the International Association of Gerontology, a research associate in and developed the Gerontology Research Centre and is Professor Emeritus in the Gerontology Department, which she also developed, at Simon Fraser University, in Vancouver, Canada.