In 2021, global centenarians numbered approximately 573,000, with United Nations estimates projecting a sharp increase to 3.7 million by 2050.
Reaching the hundredth birthday marks entry into a “special club” of centenarians. While researchers suggest that centenarians were rare before 1900, today this remarkable age is being achieved by many.
So, what factors contribute to reaching the triple-digit milestone—what is the secret? Insights were shared with Medical News Today by six experts who explored the “secret sauce” behind longevity.
Blue Zones: What Are They?
In 2016, a study published by National Geographic Fellow Dan Buettner and his team uncovered key insights into the secrets of longevity.
Referred to as the Blue Zones, Buettner identified five distinct regions worldwide where people consistently reach the age of 100 or beyond. These regions include:
- Sardinia, Italy
- Ikaria, Greece
- Nicoya, Costa Rica
- Loma Linda, California
- Okinawa, Japan
“These are places where human beings have lived manifestly longest. They’ve achieved the health outcomes we want: long lives largely free of chronic disease. Since only 20% of how long we live is dictated by disease, the lifestyles and environments in these areas offer instructions and clues for extending lifespan.”
Dan Buettner
Across these regions, Buettner observed nine shared practices—known as the Power 9—that appear to promote slower aging. These practices include:
- moving naturally
- maintaining a sense of purpose in life
- reducing stress
- following the 80% rule, which involves stopping eating when 80% full
- favoring a plant-based diet
- consuming alcohol moderately
- belonging to a community
- prioritizing family
- cultivating a social circle supportive of healthy behaviors
Loneliness, Buettner noted, is a primary risk factor for shorter life expectancy, making social connectivity essential:
“We know that lonely people are expected to live 8 fewer years than well-connected people, and health behaviors are measurably contagious. People in Blue Zones are embedded in socially connected communities with strong ties, granting them an edge in longevity from the outset.”
Dan Buettner
Adding that longevity has no short-term fixes or supplements, he suggested adopting plant-based meals that appeal personally and cooking at home, while creating a social circle of three to five health-conscious friends who provide support.
“Health behaviors are contagious, and friends tend to be lifelong companions.”
Dan Buettner
The Best Diet for Longevity
Diet is a significant aspect of the Power 9 principles observed in Blue Zones, and Dan Buettner has introduced the Blue Zone Food Guidelines, with 11 recommendations inspired by the dietary patterns of some of the world’s longest-living populations.
“To understand what contributed to a centenarian’s lifespan, it’s essential to consider what they ate throughout life. For The Blue Zones Kitchen, 155 dietary studies from all Blue Zones over the past 80 years were analyzed in collaboration with Harvard.”
Dan Buettner
“It became evident that over 90% of their traditional diets consisted of whole, plant-based foods and about 65% complex carbohydrates. The core elements of every longevity diet include whole grains, nuts, greens, other garden vegetables, tubers, and beans.”
Dan Buettner
Dr. Valter Longo, a gerontology expert at USC, developed the Longevity Diet after extensive research on aging, nutrition, and disease.
“The Longevity Diet, based on five pillars of longevity, includes daily and periodic dietary habits linked to extended lifespan and healthspan.”
Dr. Valter Longo
Key elements of the Longevity Diet:
- a low-protein pescatarian diet until ages 65–70, with moderate protein intake later
- 12-hour fasting each night
- three annual cycles of a fasting-mimicking diet, each lasting 5 days
“Diet, viewed as ‘how and what is eaten’ rather than as a weight-loss method, can influence genes related to aging, as well as those that manage cellular repair and regeneration.”
Dr. Valter Longo
Further evidence points to the Mediterranean diet as beneficial for longevity. A review published in January 2020 found that the Mediterranean diet can help slow the progression of aging and delay frailty in later years. Research from March 2021 further supports that following this diet may add years to life expectancy.
The Importance of Diet for Longevity
When considering diets that support longevity, those like the Blue Zone Diet, Longevity Diet, and Mediterranean diet are often highlighted due to their shared lifestyle components, explained Monique Richard, a registered dietitian nutritionist and spokesperson for the Academy of Nutrition and Dietetics.
“Commonalities seen in these populations include a stronger focus on families and individuals growing and consuming their own food. “Whole foods, as close as possible to their natural state, are emphasized over items sourced from industrial farms or fast-food outlets.”
Monique Richard
“The overall intake and structure of these diets generally limit highly processed foods, which automatically reduces sodium, artificial flavors, colors, preservatives, added fats, and sugars.”
Monique Richard
“These dietary patterns are typically lower in saturated fats, cholesterol, and calories, while being rich in fiber, antioxidants such as vitamins C, E, A, and B, and essential minerals like potassium, magnesium, and iodine.”
Monique Richard
How to Shift Dietary Habits for a Better Quality of Life
“The focus isn’t on restriction or limitations but rather on embracing quality, consistency, and overall health through wholesome, foundational choices.”
Monique Richard
Adjusting dietary habits can contribute not only to longevity but to an improved quality of life, as noted by registered dietitian Monique Richard.
To begin these changes, it can be helpful to:
- review current foods at hand, identifying items to add or reduce
- reassess intake of sugary beverages
- evaluate consumption of animal-based foods and consider plant-based alternatives
- prepare meals at home more frequently
- prioritize in-person grocery shopping over delivery options
- cultivate herbs in small containers on a windowsill or deck if garden space is unavailable
- explore local farmers’ markets
- introduce unfamiliar, nutrient-dense foods
- enhance meals with fresh herbs and spices
- incorporate more greens, beans, lentils, and vegetables daily
- take moments to appreciate and celebrate food
Pausing to savor meals, taking time with each bite, and embracing the process of meal preparation can also support long-lasting, meaningful changes. “Make time to slow down, to enjoy the experience, and to foster these enduring habits”
Monique Richard
Can Positive Thinking Promote Longevity?
The “power of positive thinking” is widely recognized for its benefits to mental health, and research now suggests that a positive outlook may also extend life.
A study from August 2019 found that optimism was linked to an 11-15% increase in life expectancy, with a higher likelihood of living to age 85 or beyond. Another study, published in October 2022, showed that women with a positive outlook across diverse ethnic backgrounds in the United States lived an average of 4.4 years longer than those with less optimistic perspectives.
“Having a positive, optimistic outlook reduces the risk of chronic disease and increases the likelihood of living past 85,” explained Dr. Karen D. Sullivan, a neuropsychologist and founder of I CARE FOR YOUR BRAIN.
“The protective mechanism of optimism is believed to shield against the inflammatory damage associated with stress, while studies show that negative emotions can weaken the immune system.”
Dr. Karen D. Sullivan
Additional insights come from Dr. Karen Miller, a neuropsychologist and senior director at the Brain Wellness and Lifestyle Programs at Pacific Neuroscience Institute. Stress-induced inflammation, Dr. Miller noted, often accelerates aging and increases physical and cognitive challenges.
“When engaging in positive actions such as meditation, yoga, personal spiritual practices, walking, exercise, or simply enjoying fresh air, stress levels and inflammation decrease.”
Dr. Karen Miller
High stress levels, according to Dr. Miller, elevate inflammation, which may lead to cellular damage, especially in the brain.
How Social Activity Supports Longevity
Alongside a positive outlook and stress-reducing activities, maintaining strong social connections has also been linked to extended lifespan.
A September 2019 study found that women with robust social relationships experienced a 10% increase in life expectancy and a 41% higher chance of reaching age 85. Further research from May 2023 revealed that frequent social engagement was strongly correlated with prolonged overall survival in older adults.
“We are social beings with a social brain—wired to belong to a group, with needs for both contributing value and being valued. Those identifying as lonely face a significantly greater risk of early death than those with fulfilling social lives. Chronic loneliness places stress on the immune system, increasing susceptibility to infectious and chronic diseases, particularly cardiovascular disease and cancer.”
Dr. Karen D. Sullivan
Dr. Karen Miller added that active social engagement offers cognitive stimulation, which helps maintain brain health.
“When interacting with others, there’s a dynamic exchange of ideas—like a tennis match. This back-and-forth provides cognitive stimulation, which enhances mental agility or what neuropsychology terms ‘cognitive flexibility.’”
Dr. Karen D. Sullivan
Conversations and social interactions stimulate learning, creativity, and problem-solving, creating what Dr. Miller calls a “whole-brain workout.”
“This kind of social stimulation, is nature’s brain bootcamp, offering an intensive workout for the brain through engagement, unlike the effects of isolation.”
Dr. Karen Miller
Do Exercise and Weight Affect Longevity?
In addition to a balanced diet, stress management, positive thinking, and social engagement, several other lifestyle habits play a key role in supporting longevity.
Avoiding smoking, for example, can add years to life. Non-smoking and maintaining social connections were common factors among centenarians free of chronic diseases.
Maintaining a healthy weight is also essential. Research from 2017 found that a high body mass index (BMI) was linked to significantly shorter healthy, chronic disease-free life expectancy.
Exercise further supports longevity. A study from August 2022 revealed that both light and moderate-to-vigorous physical activity reduced mortality risk in older women, while increased sedentary time heightened it.
“Several studies have shown that physical activity is associated with lower risk of mortality in older adults,” stated Dr. Aladdin Shadyab, associate professor of epidemiology at UC San Diego and senior author of the study.
“Our research was the first to demonstrate that higher levels of physical activity and reduced sedentary time are linked to a decreased risk of mortality, regardless of genetic predisposition for longevity. These findings underscore the importance of a physically active lifestyle in old age.”
Dr. Aladdin Shadyab
“A healthy diet and regular exercise are critical, particularly for older adults. Even light activities, like walking, are vital for supporting a long and healthy life in the aging population.”
Dr. Aladdin Shadyab