How to live to a healthy 100

Forget about Generation X and Generation Y. Today, the most intriguing demographic is Generation C. That stands for centenarians – folks age 100 and over. Indeed, living to the ripe old age of 100 – and being aware of it – is a monumental achievement that, in the past, few have achieved.

But today, in advanced countries like the United States, the number of people reaching 100 has become the fastest growing segment of the population. Thanks in part to advanced medical technology and a greater awareness of healthy lifestyles. In fact, the number of centenarians in the US doubled in the 1980s and did so again in the 1990s. The total now exceeds 70,000. By 2050, according to midrange projections, there could be over 800,000 Americans who will celebrate the century mark. Studies show the same trend in other industrialized countries and, recently, in China. Indeed, demographers are now counting the number of supercentenarians, people age 110 and over.

The swelling population of people age 100 and over has given researchers an opportunity to answer some of the most fundamental questions about human health and longevity: What does it take to live a long life? How much do diet, exercise, and other lifestyle factors matter compared with "good" genes? And, perhaps most importantly, what is the quality of life among the "old old"? Does getting older invariably mean getting sicker, or can people remain productive, social, and independent on their 100th birthday and beyond?

Centenarian Studies

There are a dozen or so centenarian studies. A health-advice book has been published based on findings from the centenarian study in Okinawa, where the average life expectancy, 81.2 years, is the highest in the world. There are active centenarian studies in Italy, Sweden, and Denmark. For the most part, results from these studies belie the myth that the oldest old are doddering and dependent. Some harsh demographic selection may come into play. Frail individuals die sooner, leaving only a relatively robust group still alive. In fact, one of the rewards of living a long life is that, for the most part, the "extra" years are healthy years.

Physical activity is a recurring theme: The people in these studies are walkers, bikers, and golfers. In Okinawa, centenarians do tai chi and karate. People, who live to 100 and beyond, exercise their brains, too, by reading, painting, and playing musical instruments. Some continue to work, an indication that our love affair with retirement may be a mixed blessing.

The Gender Gap

Female centenarians outnumber males by a 9:1 ratio. The longest documented life was that of a French woman, Jeanne Calment, who died in 1997 at age 122. And throughout most of the world, women, on average, live longer than men. Some researchers say it is estrogen that gives women the longevity edge. Others theorize that menstruation and systems related to childbirth better equip women to rid their bodies of toxins. Women also tend to be more social than men, and social connections are believed to be critical to weathering old age.

Yet the men who reach their 100th birthday are, on the whole, healthier than women. They are far less likely to have dementia or other serious medical problems. Thomas Perls, head of the New England Centenarian Study, calls these men "aging superstars."

Longevity statistics favoring women suggest that there may be some protective genes lurking on the X chromosome, the sex chromosome that women have two copies of and men only one. Another possibility: Genetics is relatively neutral, but social conditions favor long life for women. But healthy, odds-defying 100-year-old gentlemen hint of healthy aging genes somewhere else in the genome.

Good Genes

> Traits that run in families though are not necessarily genetic. After all, families often share the same eating habits, activity levels, and other so-called environmental factors that influence health. Still, similarities within families are often a good clue of a strong genetic influence, and longevity does seem to run in families. The New England Centenarian Study, for example, has found that its subjects were four times more likely to have a sibling who lived past 90 than people with an average life span.

Now, the search is on for genetic attributes. Researchers have previously identified some forms of a gene called apolipoprotein E that increase the risk of cardiovascular disease and Alzheimer’s disease. Studies have shown that those dangerous variants are rare among centenarians. Scientists have had success building long life into some animals. They’ve genetically engineered worms to live six times longer. Certain mice’s genes have been mutated so the animals live 30 percent longer than normal.

No one has found such mutation in people. But several years ago, scientists believed they got closer by identifying a section of chromosome 4 that may predispose people to long life. They made their discovery by scanning the genes of 137 sets of very old siblings. The siblings shared this distinctive section of chromosome 4.

Health Conditions

But genes aren’t the whole story. Public health advances like sanitation and routine vaccination have greatly improved the odds for long life. Indeed, it may be the intersection of genes with ever-changing health conditions that really determines how long we live. Today’s centenarians may have survived so long partly because they had genes that protected them against infectious diseases prevalent in the early 20th century. Tomorrow’s centenarians may need to have a different kind of genetic advantage attuned to 21st century circumstances.

Medical interventions are starting to make a demographic difference, particularly with respect to mortality from cardiovascular disease. Most centenarians still die of heart disease, but they might have died much sooner without the medications we now have to control cholesterol, hypertension, and diabetes.

Diet And Other Choices

Diet and other health habits play a role, too. Okinawans lose their actuarial edge when they move to Western countries and, presumably, adopt a more Western lifestyle. In his 1999 book, Living to 100, Perls argues that we can make choices that can help us live longer. Some of the important lessons learned from the way the centenarians lived include the following:

• They don’t smoke or drink heavily.

• Those who had smoked didn’t do so for long.

• They gained little or no weight during adulthood. Being overweight makes people more vulnerable to many life-threatening illnesses, heart disease, diabetes, cancer, and stroke.

• They don’t overeat. Okinawan centenarians consume 10 to 20 percent fewer calories per day than typical Americans. And in animal studies, calorie-restricted diets have consistently increased the life span. The old Okinawans consume less fat, too.

• They eat many fruits and vegetables. The Okinawans have an average of seven servings a day.

• They get regular physical activity for as long as they are able.

• They challenge their minds. Stimulating mental activity may help prevent age-related thinking and memory problems by stimulating communication between brain cells.

• They have a positive outlook. Perls says centenarians seem to have personalities that shed stress easily.

• They are friendly and maintain close ties with family and friends.

Many researchers think that people could add up to a decade to their lives if they emulate the centenarians. And, from what we know so far, they aren’t doing anything mysterious. They’re simply following the standard health commandments: Don’t smoke, keep trim, get exercise, manage stress, and avoid social isolation.