Good friends help us get through life, but according to a new study, they do much more than that. Strong social ties may actually keep our bodies younger and healthier.
The study, published in Brain, Behavior and Immunity – Health journal, found that people with consistent, long-term social connections showed signs of slower biological aging. Conducted by Cornell University, the research involved more than 2,100 participants from across the United States and examined their biological age — how "old" their bodies feel — through advanced DNA testing. The findings revealed that those with stable social relationships throughout life appeared biologically younger and had lower levels of chronic inflammation.
At the same time, a massive 85-year study from Harvard University reinforced the same conclusion: the key to longevity and good health isn’t wealth or diet — but meaningful relationships. Participants who reported being satisfied with their personal connections at age 50 — whether with partners, friends or family — were healthier in old age, lived longer and retained better cognitive function.
What Cornell researchers called a “cumulative social advantage” refers to the depth and breadth of a person’s social network over their lifetime. This measure included four main factors: parental warmth and support in childhood, a sense of belonging in one’s neighborhood or community, religious or spiritual involvement and long-term emotional support from family and friends.
Unlike previous studies that focused on isolated social indicators, such as marital status or number of friends, this research examined the combined impact of early- and later-life social resources. The team found that social bonds built and maintained over time directly influence how the body functions — including the immune system, hormonal balance and even genetic expression.
People with strong lifelong social networks were found to have lower levels of inflammation, including reduced levels of interleukin-6, a compound linked to diseases like diabetes, heart conditions and neurodegenerative disorders. However, no significant effect was observed on short-term stress markers such as cortisol.
“What's striking is the cumulative effect,” said lead researcher Prof. Anthony Ong. “It's not just about having friends today; it's about how your social connections have grown and deepened throughout your life. That accumulation shapes your health trajectory in measurable ways.”