Is there a key to living a long and healthy life?

A popular answer to this question has looked to so-called Blue Zones, a nonscientific term given to geographic regions where people supposedly have higher longevity, according to a 2016 review published in the American Journal of Lifestyle Medicine.

The longevity hotspot concept was first outlined in a 2004 study published in the journal Experimental Gerontology. Researchers identified the Italian island of Sardinia as the region with the highest concentration of male centenarians, or people who live to be 100 or older.

Building on this work, National Geographic fellow Dan Buettner and other researchers identified four more longevity hotspots. Although the regions are geographically and culturally distant from one another, these Blue Zones share a lot of characteristics, which may be the key to understanding why their inhabitants tend to live longer, Buettner proposed in his 2008 book "The Blue Zones: Lessons for Living Longer From the People Who've Lived the Longest."

However, the idea of Blue Zones has been called into question. A 2019 preprint study, which has not yet been peer reviewed, suggested that people in the Blue Zones may not live longer than their counterparts after all. Instead, the high number of recorded supercentenarians, or those older than 110, in these regions might be due to poor record keeping or even pension fraud.

If the notion of Blue Zones is iffy, do any of the factors Buettner identified hold up? Some, it turns out, are based on solid science, while others have much less scientific backing. And much of the research suggesting health or longevity benefits from certain lifestyle factors is based on observational evidence, so it's not possible to prove that these lifestyle factors are truly what cause people in these regions to live longer.

Where are the Blue Zones?

In his book, Buettner described five known Blue Zones:

Icaria: A small Greek island in the Aegean sea Ogliastra, Sardinia: A region of an Italian island in the Mediterranean Okinawa: An island off the coast of Japan Nicoya Peninsula: A peninsula in eastern Costa RicaThe Seventh-day Adventists in Loma Linda: A community in the hilly valleys of California

What do the Blue Zones have in common?

According to Buettner, there are nine common features of Blue Zones:

Physical activity: Blue Zone centenarians maintain high levels of physical activity and frequently engage in manual labor. For example, Sardinia's community of shepherds is known to walk more than 5 miles (8 kilometers) a day.

Purpose: Okinawans call it "ikigai," and Nicoyans call it "plan de vida," both of which convey the idea "why I wake up in the morning." This sense of purpose is deemed to be the source of life satisfaction, which contributes to a longer and happier life.

Sleep: Blue Zones centenarians prioritize rest and sleep. For example, Ikarians are known to take midafternoon naps, while the Loma Linda community recognizes the Sabbath, or a day of rest and worship, once a week.

The 80% rule: People living in Blue Zones do not tend to overeat. The name of the rule stems from an old Okinawan mantra spoken before meals, which reminds people to stop eating when their stomachs are 80% full.

Plant-based diet: The diet of Blue Zone centenarians is based largely on plants.

Moderate alcohol consumption: Buettner believed that moderate alcohol consumption of some Blue Zone centenarians contributed to their long life span.

Sense of community: Strong community ties promote longevity, according to Buettner. For example, Okinawans are known to create secure social networks that provide financial and emotional support to the community members.

Loved ones first: Strong family ties are the cornerstone of Blue Zones communities. For example, the Seventh Day Adventists live in tight-knit communities where children take care of their aging parents.

Social encouragement: Blue Zones centenarians live in social networks that promote healthy behaviors, thus making it easier to stick to a healthy lifestyle, Buettner suggested.

What science says about the Blue Zones

The science suggests people in the Blue Zones don't necessarily live longer. For instance, while people in Japan have the highest longevity of any country in the world, men in Okinawa don't live as long as their counterparts elsewhere in the country, on average, according to a 2012 study in the journal Gerontology.

However, some of Buettner's overall conclusions about what factors may increase longevity still hold up. For instance, he argued that lifestyle factors are more important for human longevity than genetics are — a statement largely supported by evidence. According to a 2018 article published in the journal Genetics, the heritability of human longevity may be as low as 10%, while the National Library of Medicine website MedlinePlus suggests that genes contribute about 25% to differences in lifespan between people.

Physical activity

When it comes to physical activity and risk of mortality, the evidence is fairly unanimous: Highly active people are less likely to die prematurely, according to a 2021 systematic review and meta-analysis published in the journal Preventive Medicine.

Diet

Nutrition has the potential to support healthy longevity, said Annette Creedon, a registered nutritionist and nutrition manager at the British Nutrition Foundation.

"It is estimated that one in five deaths globally is linked to having a poor diet, and an unhealthy dietary pattern is associated with several chronic conditions, such as heart disease, type 2 diabetes, obesity and certain cancers," she told Live Science in an email.

Blue Zones are very consistent in the types of foods they include, Creedon said. Common themes include a high intake of plant foods (including fruits, vegetables and whole grains), protein sources (including plant-based proteins, such as legumes, nuts and seeds), and some seafood, poultry, lean meat, low-fat dairy products and unsaturated oils (such as olive oil).

“Studies have found that healthy plant-rich dietary patterns are associated with reductions in the risk of heart disease, type 2 diabetes and some cancers, as well as death from all causes," Creedon said.

Evidence also supports the claim that calorie restriction may promote longevity, according to a 2020 review published in the journal Ageing Research Reviews. The "80% rule" may improve risk factors involved in the development of type 2 diabetes, cardiovascular diseases, cancer and neurological disorders, the review authors suggested.