(file image) Photo: Unsplash / John Moeses Bauan
Our bodies aren't gradually changing over time, but there are bursts of dramatic changes we go through in our mid-40s and early 60s, according to a US study.
The Stanford University researchers, who looked at data from 108 people from age 25 to 75 over several years, expected to see a health decline as people head into their 60s, considering our immune levels drop and risk of age-related diseases rises. But they were surprised to also see some big bodily changes happening in the 40s.
Specifically, the scientists tracked age-related changes in more than 135,000 different molecules (things like water, fats, carbohydrates, and protein) and microbes (such as bacteria and fungi).
Although these are constantly changing, the research found key molecules decreased and "bad" ones increased more at certain ages than other times.
"As we hit your 40s, we discovered that your lipid shifts quite a bit and those are your fats, things like your bad cholesterol, LDL, you've heard about - your fat deposition we know shifts quite a bit as people hit their 40s," co-author and geneticist Michael Snyder told Nine to Noon.
"We saw changes in muscle and skin and we also saw those as people hit their 60s - again, we expected that in the 60s and in fact visually you can see that; people's skin changes as they hit their 60s and their muscle declines, that's well known.
"In the 40s, we saw alcohol metabolism shift, caffeine metabolism shift - in the 60s, we did see your immune system decline, including your ability to fight a viral infection shifted quite a bit. We saw that your carbohydrate metabolism shifts, your kidney function shifts."
Those changes in turn affect microbiome changes which were also observed during the study.
"Some of your most important microbes are the microbes in your gut. Your gut microbiome, because it breaks down your food and makes essential vitamins. And I think that's very tied in once again to your metabolism and both your lipid and your carbohydrates especially," Snyder said.
These biological changes are likely to affect our health, as the researchers explained 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.
While the researchers want to dive deeper into the causes of these changes, they say it is possible some could be driven by lifestyle or behavioural factors that cluster at these age groups, such as increased alcohol intake in stressful periods of life as we age or increased risk of injury and falls.
"It's known genetics accounts for about 60 percent of your lifespan. The rest is due to your lifestyle and environmental exposures. So we think that keeping yourself healthy may help, you know, through exercise, that would be especially important for keeping your muscle mass up," Snyder said.
"But I would also argue nutrients, eating the right foods.
"Keeping your physical health up is very, very important for keeping your mental health up and your happiness and such. It's very, very clear. These are all super related … people who exercise regularly generally are more happy and healthier. And so it's all tied together absolutely."
*A paper describing these findings was published in the journal Nature Aging on 14 August. The study was funded by the National Institutes of Health and the Stanford Data Science Initiative. 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.
