New Stanford Research Reveals Humans Age in Two Rapid Bursts: At 44 and 60

Research from Stanford Medicine indicates significant shifts in molecular and microbial levels in the body during the mid-40s and early 60s, which may impact health and the risk of diseases related to aging.

If it’s ever felt like everything in your body is breaking down at once, that might not be your imagination. A new Stanford Medicine study shows that many of our molecules and microorganisms dramatically rise or fall in number during our 40s and 60s.

Researchers assessed many thousands of different molecules in people from age 25 to 75, as well as their microbiomes — the bacteria, viruses, and fungi that live inside us and on our skin — and found that the abundance of most molecules and microbes do not shift in a gradual, chronological fashion. Rather, we undergo two periods of rapid change during our life span, averaging around age 44 and age 60. A paper describing these findings was recently published in the journal Nature Aging.

“We’re not just changing gradually over time; there are some really dramatic changes,” said Michael Snyder, PhD, chair of genetics and the study’s senior author. “It turns out the mid-40s is a time of dramatic change, as is the early 60s. And that’s true no matter what class of molecules you look at.”

Xiaotao Shen, PhD, a former Stanford Medicine postdoctoral scholar, was the first author of the study. Shen is now an assistant professor at Nanyang Technological University Singapore.

These big changes likely impact our health — the number of molecules related to ageotypes,” showing that people’s kidneys, livers, metabolism, and immune system age at different rates in different people.

The new study analyzed participants who donated blood and other biological samples every few months over the span of several years; the scientists tracked many different kinds of molecules in these samples, including DOI: 10.1038/s43587-024-00692-2

The study was funded by the