STANFORD, Calif. — Scientists have discovered that humans age at the molecular level in two accelerated phases: first at age 44 and then at age 60.
In a study published in the journal Nature Aging, scientists from Stanford University and Nanyang Technological University in Singapore followed 108 participants for several years to observe aging-related changes in their molecules (participants’ RNA, proteins, and microbiomes).
Scientists have discovered that human aging does not occur in a gradual, linear manner. On the contrary, the majority of molecules studied showed accelerated, nonlinear changes at ages 44 and 60.
Xiaotao Shen, an assistant professor of microbiome medicine at Nanyang Technological University and first author of the study, told CNN that the findings show that “we are not aging gradually.” Certain moments in time are particularly important for our aging and health, he added.
For example, the ability to metabolize caffeine declines dramatically, first around age 40 and then again around age 60. Compounds involved in alcohol metabolism also decline, particularly around age 40, Michael Snyder, chair of Stanford’s genetics department and an author of the study, told CNN, referring to the two waves of aging.
Snyder added that, anecdotally, “people often experience muscle injuries and fat accumulation in their 40s (related to lipid metabolism), and sarcopenia (muscle loss) certainly affects people in their 60s — it’s a very serious problem.”
Both age groups experienced changes in the proteins that hold tissues together, which likely helps explain the skin, muscle and cardiovascular changes, he added.
Disease risks also increase more rapidly, especially after age 60. The study found that people aged 60 and older are more susceptible to cardiovascular disease, kidney problems and type 2 diabetes.
Discovering patterns like these can help in the diagnosis and prevention of disease, according to the study, which also identified “clinically actionable markers” that can be used to improve healthcare management and the well-being of aging populations.
The study included participants, ages 25 to 75, on average, for nearly two years. All participants lived in California, were healthy, and came from diverse ethnic backgrounds. Blood, stool, skin, and nasal and oral swab samples were collected every three to six months.
Since women’s accelerated aging could be attributed to menopause (which typically occurs between ages 45 and 55), the researchers ran analyses on separate data sets for men and women. To their surprise, they found that the results were similar, suggesting that a transition point around age 55 may be a common phenomenon for both sexes.
A previous study by researchers in Germany and the United States found that there was another “wave” of aging around age 75, but the latest research could not confirm those findings due to the limited age range of the trial cohort, Shen told CNN.
As for what to take away from their findings, the researchers advise making lifestyle changes, such as drinking less alcohol and exercising more, as you approach those pivotal years of your 40s and 60s.
Snyder advised people approaching their 60s to watch their carbohydrate intake and drink plenty of water to support kidney function.
“Take extra care of yourself at specific times in your life,” Shen advises.
