HQ Team
August 21, 2024: Molecules and microorganisms in the human body dramatically rise or fall at an average age of 44 and 60 affecting both the heart and immune functions, according to a Stanford Medicine study on the biology of ageing.
“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,” he said. “I’m a big believer that we should try to adjust our lifestyles while we’re still healthy.”
A molecule is a group of atoms bound together to perform a bodily function. There are thousands of different molecules in the human body, all serving critical tasks.
Molecular cells are composed of water, inorganic ions, and carbon-containing (organic) molecules. Water is the most abundant molecule in cells, accounting for 70% or more of total cell mass.
The organic molecules are the unique constituents of cells. Most of these organic compounds belong to one of four classes of molecules — carbohydrates, lipids, proteins, and nucleic acids.
Ageotypes
The Stanford researchers used data from 108 people to understand the biology of ageing. Past insights from this same group of study volunteers include the discovery of four distinct “ageotypes,” showing that people’s kidneys, livers, metabolism and immune system age at different rates in different people.
They 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.
The researchers found that the abundance of most molecules and microbes does 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,” according to a researchers’ statement from Stanford Medicine.
RNA, proteins
These big changes likely impact one’s health — the number of molecules related to cardiovascular disease showed a significant rise at both time points, and those related to immune function changed in people in their early 60s.
The new study analyzed participants who donated blood and other biological samples every few months over several years.
The scientists tracked many different kinds of molecules in these samples, including RNA, proteins and metabolites, as well as shifts in the participants’ microbiomes.
The researchers tracked age-related changes in more than 135,000 different molecules and microbes, for a total of nearly 250 billion distinct data points.
They found that thousands of molecules and microbes undergo shifts in their abundance, either increasing or decreasing — around 81% of all the molecules they studied showed non-linear fluctuations in number, meaning that they changed more at certain ages than at other times.
Cluster of molecules
When they looked for clusters of molecules with the largest changes in amount, they found these transformations occurred the most in two time periods — when people were in their mid-40s, and when they were in their early 60s.
In people in their 40s, significant changes were seen in the number of molecules related to alcohol, caffeine, lipid metabolism, cardiovascular disease, and skin and muscle.
In those in their 60s, changes were related to carbohydrate and caffeine metabolism, immune regulation, kidney function, cardiovascular disease, and skin and muscle.
Although much research has focused on how different molecules increase or decrease as we age and how biological age may differ from chronological age, very few have looked at the rate of biological ageing.
The large cluster of changes in the mid-40s was somewhat “surprising” to the scientists.
Menopause, perimenopause
At first, they assumed that menopause or perimenopause was driving large changes in the women in their study, skewing the whole group.
When they broke out the study group by sex, they found the shift was happening in men in their mid-40s, too.
“This suggests that while menopause or perimenopause may contribute to the changes observed in women in their mid-40s, there are likely other, more significant factors influencing these changes in both men and women,” said Xiaotao Shen, PhD, a former Stanford Medicine postdoctoral scholar, who is the first author of the study.
“Identifying and studying these factors should be a priority for future research,” Shen said.
The researchers advised making lifestyle changes such as drinking less alcohol and exercising more when nearing the pivotal years of the 40s and 60s.
The findings were published in the journal Nature Aging.
