When researcher, author and explorer Dan Buettner was first developing the concept of the Blue Zones (the five regions in the world where people live the longest), he realized he was missing one thing: a city in the U.S. that made the cut.

Determined to find an American region that met the Blue Zones criteria, Buettner and a team of demographers dug deep into data on Loma Linda, a city in San Bernardino County, California, with a population of roughly 24,000 people.

Touting the tagline “A city focused on health and prosperity,” Loma Linda is home to one of the largest concentrations of Seventh-day Adventists in the world.

It was this religious population that drew Buettner to further investigate the city as a Blue Zone contender.

“I found that Seventh-day Adventists lived between seven and 11 years longer than people in its Northern American counterparts,” Buettner tells NBC News BETTER. “The highest concentration of them is in or around Southern California, specifically Loma Linda. I [qualified] it as a Blue Zone namely because these were verifiably the longest lived Americans, given available data in 2005.”

Like the other Blue Zones Buettner discovered, Loma Linda excelled in several aspects which contribute to longevity in Buettner’s estimation.

“In all five of these zones, the reason they're living long is not because of one special diet or one other thing; they're living longer because of a cluster of mutually supporting factors than enable [residents] to do the right things long enough and avoid doing the wrong things long enough so as to [lower risk] of developing a chronic disease.”

The ‘Garden of Eden’ Diet

Seventh-day Adventists are by and large vegetarians says both Buettner and John Westerdahl, PhD, a registered dietitian nutritionist who graduated from the Loma Linda University School of Public Health and is a member of the Seventh-day Adventist Church.

Westerdahl, who grew up in a different religious environment, was attracted to the Seventh-day Adventist Church, a Protestant Christian denomination, in part because of its strong emphasis on nutrition and health.

The religion promotes what he refers to as a “Garden of Eden” diet.

“In Genesis 129, [it reads] ‘And God said, behold, I have given you every herb bearing seed, which is upon the face of all the earth, and every tree, in the which is the fruit of a tree yielding seed; to you it shall be for meat.’”

“Seventh-day Adventists take the position that this [plant-based diet] is the original diet of man that we were designed to eat,” says Westerdahl. “It also ties into the concept of heaven — that in God’s new kingdom, we will go back to this Garden of Eden diet. There will be only peace and no killing or animal slaughter. There’s a strong association of compassion and being kind to animals.”

Lacto-ovo vegetarianism, and biblically ‘clean’ foods reign supreme

“Around 30 percent of Seventh-day Adventists are vegetarian, and within that group are mostly lacto-ovo vegetarian, meaning they consume no flesh but they do eat dairy and eggs,” Westerdahl says. Those who are not vegetarian tend to follow the Mosaic Law, which identifies pork and shellfish as “unclean”, and should not be eaten.

“The Bible is very specific and says do not eat of these foods,” says Westerdahl. “The ‘clean’ animals are the ones that eat leaves, grass and so forth.”

Westerdahl is vegan, as is his 21-year-old daughter, who lives and studies health in Loma Linda. He’s observed a spike in this stricter type of dieting among fellow Seventh-day Adventists because of the way livestock are commonly mistreated.

“For us with veganism, there’s a health standpoint as well as an aspect of believing in treating animals in a nice way,” he says.

No drinking, no caffeine — and no outside pressure to ‘cheat’

The benefits of a plant-based diet are surely going a long way to help Seventh-day Adventists live longer, but remember that this religious group typically abstains from coffee and alcohol.

“The adherent Seventh-day Adventist doesn’t drink alcohol or caffeine, including caffeinated sodas,” says Westerdahl. “We’ll have tomato juice or sparkling water at a party [hosted by fellow Seventh-day Adventists]. Alcohol isn’t an option. Instead of coffee, it’s common to offer a coffee substitute such as Kaffree Roma, which looks and tastes like coffee but has no caffeine.”

Because the Seventh-day Adventists of Loma Linda have a “very strong social network connected to the Church,” as both Westerdahl and Buettner emphasize, there’s little pressure or even option to stray from your dietary practice.

“The environment is one where healthy choice is often the only choice in their social settings,” says Buettner.

A weekly day of no work, no wi-fi and no worry

In America’s overworked culture, we tend to treasure our days off, but Loma Linda’s Seventh day-Adventists suggests we might want to up our game of relaxation.

“Seventh day-Adventists [observe] their sabbath from sunset Friday through all day Saturday,” says Buettner. “No matter how busy they are or what their parenting schedule dictates, they stop everything and spend the day with family and usually go on a nature hike. There’s no TV, no internet and no work at all.”

Westerdahl says he gets the best sleep of the week on Friday evening, partly because he knows that on Saturday he will completely unplug from the world, and focus solely on “mental, physical and spiritual rest.”

Often one doesn’t even cook during this window of time (certainly they do no shopping), and prepare meals the day before. It’s common for families to hold potlucks after church services on these days, as well as go on nature hikes — a mild exercise that the usually balmy weather of Southern California makes inviting.

“We may also fast that day because it’s a day of rest,” says Westerdahl. “It’s just a day of totally clearing your mind.”

The importance of being there for your friends and community

The Seventh-day Adventists of Loma Linda are perseverant volunteers, a commitment that Buettner says directly correlates with their longevity.

“Volunteers live longer than non-volunteers,” says Buettner. “We also know that loneliness kills. In America, it shaves 8 years off your life expectancy. An adventist in Loma Linda has such a strong face to face social network. You go to church with them, you hike with them, they're there for you and you're there for them. These are subtleties that are enormously powerful but vastly under celebrated because there is no profit in them. If social connectedness and volunteerism were pharmaceuticals, they would be blockbuster drugs.”

We don’t need to be Seventh-day Adventists to bring these aspects of plant-based eating, days of total rest and community celebration and support into our lives. And we don’t need to live in Loma Linda, either; it’s really a matter of making these healthful habits a way of living.

“I live in Thousand Oaks [,California] now and though I visit Loma Linda often, there are times in the ‘outside world’ where there can be challenges,” says Westerdahl, noting occasions when he’s the only vegan or the only non-drinker in the room. “But I’m 64 now and I’ve been doing this since the 1970s. By now, it’s just my lifestyle.”

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