Massive biomolecular shifts occur in our 40s and 60s

If it's ever felt like everything in your body is breaking down at once, that might not be your imagination.

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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 published in the journal Nature Aging.

"We're not just changing gradually over time; there are some really dramatic changes," said Michael Snyder, PhD, professor 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." These big changes likely impact our health - the number of molecules related to cardiovascular disease showed significant changes at both time points, and those related to immune function changed in people in their early 60s.

Abrupt changes in number

Snyder, the Stanford W.