Secrets of centenarians: 4 factors that influence who makes it to 100

What’s the secret formula for living 100 years? 

According to centenarian comedian George Burns, it was 20 cigars and six martinis daily and a distaste for fruits and vegetables. Actor Kirk Douglas, 103 at time of death, relied on more wholesome practices, such as daily activity and time with family. And Queen Elizabeth, who made it to 96, walked her dogs, rode horseback, and strolled the grounds of her estates.

Anecdotal evidence—and questionable lifestyle decisions—aside, what are the scientific facts of longevity? 

Lucky genes

First, let’s get the unfortunate truth out of the way: Some of longevity is a matter of luck. 

Research indicates that genetics^[] determine about 25% of the differences in duration of human life. Certain polymorphisms located on the APOE, FOXO-3, and CETP genes are associated with long life.

Furthermore, if you have a centenarian parent, you’re more likely to be free of age-related disease at 70 than your peers. Siblings of centenarians also tend to live longer and develop age-related disease later in life, compared with their peers.

Don’t have a centenarian first-degree relative? Don’t despair. Not all people who become centenarians have these genetic variations. And despite what George Burns said, lifestyle factors still count toward longevity.

Caloric restriction

Researchers gathered relevant studies of international populations that looked at longevity factors such as nutrition, lifestyle, gender differences, blue zones, aging rate, and various others, in addition to caloric restriction.^[]

After reviewing the evidence, researchers concluded that they cannot definitively say that caloric restriction leads to longevity. Part of the problem is that the data on nutritional habits and caloric intake of centenarians living in longevity blue zones is too inconsistent and/or incomplete to establish a causal link. Still, they believe there is a connection.

Their review contained numerous data points linking longevity to improved glucose handling, insulin sensitivity, and declines in plasma IGF1 levels—all of which are modulated by caloric restriction.

But, before you tell grandma to eat less, proceed with caution, the researchers noted.

“Higher frailty levels and increased anxiety were detected in experimental models of late-onset [caloric restriction] and similarly could happen in older people who are often at risk of undernutrition and sarcopenia, rather than of obesity, and in those who already have an appropriate diet and a normal weight,” researchers wrote.

Fasting

Researchers summarized this evidence in a 2021 review article published in Nature Communications.^[]

For example, the researchers highlighted how four short-term clinical trials have demonstrated that alternate-day fasting produces health benefits that are comparable with caloric restriction. Those benefits include weight loss, better lipid profiles, hypertension reduction, and improved insulin sensitivity. Furthermore, at least two studies have produced evidence that fasting may have cancer-fighting benefits and make cancerous cells more vulnerable to chemotherapy.

Additionally, the research suggests that sleep and eating may be inexorably linked, in terms of their potential impact on health and longevity.

“The timing of food intake relative to the natural increase in melatonin (which marks the beginning of night for each individual) is significantly associated with body fat percentage and body mass index,” the researchers wrote, adding that people with excess weight tend to consume most of their calories 1.1 hours closer to the onset of melatonin, compared with people who do not have excess weight.

However, the researchers concluded that there’s more we don’t know than we know about how fasting affects longevity.

Gut microbiota

The more researchers uncover about gut microflora, the more apparent it becomes that these multitudinous microorganisms may be indispensable for human health. A 2020 review article published in Nutrients indicates that they may have an important role to play in longevity, too.^[]

The researchers included 27 human studies to identify trends in gut microbiota diversity, composition, and functional features that may be associated with aging. 

“What might make the oldest-old adults unique is the ability to maintain (or possibly upregulate) anti-inflammatory activity despite a concomitant uptick of pro-inflammatory activity that occurs in all older adults,” the researchers wrote.

They noted that supporting this hypothesis observations of an increase in health-sustaining taxa that coincides with the production of short-chain fatty acids. Researchers postulated that while gut taxa are influenced by certain genetic factors, environmental factors such as diet also are influential. 

So perhaps encourage patients to lay off the George Burns diet after all.