While centenarians are often eager to share theories on they key to longevity, there are certain areas of the world where it's proven that people live the longest—and those residents might hold the true answer. Longevity researcher and author Dan Buettner identified these regions with the healthiest and longest living populations, dubbing them the "Blue Zones." In these places—Okinawa, Japan; Ikaria, Greece; Nicoya, Costa Rica; Loma Linda, California; and Sardinia, Italy—Buettner and his team discovered the "Power Nine" traits that residents share, helping them live to 100 and beyond.
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The first common denominator of the Blue Zones is that people in these areas "move naturally." In a post on the Blue Zones website, Buettner notes that people who live the longest "don't pump iron, run marathons or join gyms." They instead live and grow in environments that "constantly nudge them into moving without thinking about it."
Next, it's important to consider diet in terms of longevity. People in the Blue Zones maintain a diet primarily comprised of beans, whole grains, greens tubers, and nuts, Buettner recently told CNBC. They eat meat sparingly—on average, only five times every month.
To avoid overeating, those in the Blue Zones stop eating when they're 80 percent full, and stay mindful of their environment during meals.
"They don’t have electronics in their kitchens, they eat with their families [and] they tend to frontload their day with calories and taper off by late afternoon or early evening," Buettner told CNBC.
Going hand in hand with this, people who live longest are also mindful of alcohol consumption. Buettner told CNBC that "over 85 percent of people, especially males, making it to 90 or 100" have a drink every day. Most of the time, however, it is homemade wine—and Buettner adds on his website that the trick is to have just one to two glasses each day.
Relationships are key as well, making up three of the Power Nine traits. First and foremost, people in the Blue Zones prioritize family. They commit to life partners—which is said to add roughly three years of life expectancy—invest in children, and also care for their elderly, Buettner explains on the Blue Zones site.
As he told CNBC, "If you keep your aging parent nearby as opposed to putting them in a retirement home, it conveys somewhere between two and six extra years of life expectancy."
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When it comes to relationships outside of family, people in these areas also choose the "right tribe," gravitating toward like-minded people. The Okinawans actually created "moais," which is a word for groups of five friends committed to each other for life, Buettner explains on the Blue Zones site.
Religion plays a part as well, as a majority of centenarians in the Blue Zones belong to a faith-based community.
"People who go to church, temple or a mosque live somewhere between four and 14 years longer than people who have no religion," Buettner told CNBC.
While denomination doesn't matter, religion isn't the only piece of the outlook puzzle. People in the Blue Zones also maintain a sense of purpose—something Okinawans call "ikigai" and Nicoyans call "plan de vida," both of which roughy translate to "why I wake up in the morning," Buettner writes. This direction in life can tack on about eight years to your life, the researcher told CNBC.
Rounding out the Power Nine is how people in the Blue Zones deal with stress. They're not immune to it, but their approach sets them apart. According to Buettner, they have active routines to relieve stress, whether by thanking ancestors, praying, napping, or indulging in a happy hour.
