What is the secret to exceptional longevity? Scientists studying people who live beyond the age of 110 believe they may now have an answer: an immune system that appears to be biologically reprogrammed to resist aging.

Brazil is at the center of this research, as it is home to an unusually large number of supercentenarians—people aged 110 and older. According to researchers, these rare individuals do not simply survive to extreme old age; many remain physically healthy, mentally sharp, and more independent than much younger people.

An Immune System That Behaves Like a Younger One

At the heart of their longevity appears to be an immune system that functions more like that of a much younger person. It efficiently renews cells and removes biological damage that would normally accumulate with age and lead to disease.

Researchers from the University of São Paulo suggest that Brazil’s unique history may help explain this phenomenon. Centuries of population mixing since the 16th century have created one of the most genetically diverse populations in the world—an important factor believed to enhance disease resistance.

Studying the World’s Oldest People

The research team analyzed data from an ongoing study involving more than 140 centenarians and 20 supercentenarians from across Brazil. Among them was Sister Inah, a Catholic nun who was the world’s oldest living woman until her death in April 2025 at the age of 116. The study also included the former world’s oldest man, who died at 112, as well as his 113-year-old successor.

What impressed scientists most was not how long these individuals lived, but how well they lived.
“If there is a source of longevity,” said lead researcher Dr. Mayana Zatz, professor of human and medical genetics, “it is probably somewhere in Brazil.”

Immune Cells That Defy Aging

Detailed single-cell analyses revealed that the immune systems of Brazilian supercentenarians behave very differently from those of the general population.

Their immune cells showed highly efficient mechanisms for protein recycling and cellular ‘cleanup’, preventing the buildup of damaged proteins and harmful mutations linked to heart disease, cancer, and dementia. Remarkably, these mechanisms resemble those typically found in much younger individuals.

Researchers also identified an unusual immune pattern: CD4+ “helper” T cells, which normally coordinate immune responses, behaved more like CD8+ “killer” T cells, which directly destroy infected or abnormal cells. This hybrid behavior is rare—even in younger people—and may offer enhanced protection against disease.

Surviving COVID-19 Without Vaccines

The strength of these immune systems became especially clear during the COVID-19 pandemic. Supercentenarians in the study rapidly produced neutralizing antibodies and activated early antiviral defense proteins.

Three participants survived COVID-19 infections in 2020—before vaccines were available—highlighting the adaptability and resilience of their immune responses.

In a paper published by Genomic Press, researchers concluded that immune aging in supercentenarians follows a unique form of biological adaptation that preserves immune function well into extreme old age.

Not Just Surviving Disease — Avoiding It

The findings support earlier research suggesting that long-lived individuals do not merely endure disease for longer periods, but often avoid serious illness altogether.

Large population studies in Sweden have shown that centenarians develop major health problems later in life and are far less likely to suffer from age-related diseases such as heart attacks, strokes, and dementia. A long-term study tracking more than 170,000 people over four decades found that those who eventually lived past 100 had significantly lower rates of cardiovascular disease—even in their mid-80s.

The immune adaptations observed in Brazilian supercentenarians may help explain this pattern, challenging the long-held belief that longer life necessarily comes with poorer health.

No Special Diet — Just Exceptional Biology

Interestingly, unlike other long-lived populations around the world, Brazilian supercentenarians do not appear to follow a specific longevity-linked diet, such as the Mediterranean diet. Instead, biology—particularly immune system resilience—seems to play the dominant role.

The research team is now developing cellular models to identify the unique protective mechanisms at work. Their long-term goal is ambitious: to determine whether the biological secrets of extreme longevity could one day be used to extend healthy aging across the wider population.

For now, the message is clear: longevity may be less about slowing aging itself and more about redefining how the body defends itself from the very beginning.