Every person has two ages: a chronological age, which tells us how old we are relative to the time on the calendar, and a biological age, which tells us how our body is functioning compared to our average fitness or health level.
"Chronological age does not mean we are old. Chronological age is simply the number of times the earth has gone around the sun," says Professor David Sinclair, co-director of the Paul F. Glenn Center for the Biology of Ageing at Harvard Medical School.
"Everyone's biological age is different because it depends on our genes, what we eat, what supplements we take, how much we exercise and what toxins we are exposed to," adds Sinclair.
Study on 1,000 New Zealanders
Biological age researchers at Duke University in Durham, N.C., led by Maxwell Elliott, agree. They conducted a study related to the biological age of humans on more than 1000 New Zealanders, following them from birth in the 1970s to the age of 45 (the study was published two years ago, in 2021, in the journal Nature Aging).
They paid particular attention to the period from the age of 26 onwards. At that time, the participants' biological ageing rate was intensively monitored using various measures (body fat, heart fitness, lung capacity, blood inflammation markers, and dental health).
They found that participants varied widely in their biological ageing.
The study data show that the slowest ageing participant gained only 0.4 'biological years' for each chronological year in age, while the fastest ageing participant gained almost 2.5 biological years for each chronological year.
What does this mean?
The fast biological ageing group showed some health indicators not normally associated with age as early as 45. Compared to their peers, they moved more slowly and had more problems with balance, vision and hearing. The researchers also found differences in mental sharpness.
The rapidly ageing group scored lower on average on memory performance tests, and they reported forgetfulness in everyday life.
Using magnetic resonance imaging, Duke University researchers found that these participants showed more signs of thinning brain tissue.
Ageing does not "magically begin at 60"
Dr Sofiya Milman, Director of Longevity Studies at the Albert Einstein College of Medicine's Institute for Aging Research in New York City, agrees with the findings of PhD student Maxwell Elliott and his research team and warns that ageing does not "magically begin at 60".
"Ageing is a continuum," said Milman, who reviewed the findings. "And it probably starts even earlier than we have known."
What determines the rate of biological ageing in an individual?
Dr Milman agrees with Professor David Sinclair that environment and genes play an important role in body function and longevity. She says that certain "longevity genes" (more than fifty genes that organize proteins and recruit enzymes that repair broken DNA) can help protect people from environmental stressors.
It is, therefore, important to take care of both - longevity genes and healthy habits (eating a healthy diet, exercising regularly, keeping a healthy body weight, not drinking too much alcohol, not smoking etc.).
What activates longevity genes?
One way to increase longevity genes is to take supplements, which significantly increase NAD. NAD is a key coenzyme in every living cell and is needed for energy production, DNA repair, chromosome stability, and regulation of immune and inflammatory processes. It also plays an essential role as a neurotransmitter. Unfortunately, our bodies produce less and less NAD+ as we age.
Healthy Gut for life
Regular exercise, a healthy diet, enough sleep and smoking cessation also reduce the risk of various diseases and increase longevity.
Research from Brigham Young University shows that intense exercise (HIIT, cycling, walking briskly uphill or running for 30 minutes) five days a week reduces biological age compared to a sedentary lifestyle.
It is never too late to change your lifestyle and slow down the biological ageing of your body.
Maxwell Elliott, PhD student, department of psychology and neuroscience, Duke University, Durham, N.C.; Sofiya Milman, MD, MS, associate professor, medicine, and director, human longevity studies, Institute for Aging Research, Albert Einstein College of Medicine, Bronx, N.Y.; Nature Aging, March 15, 2021, online, LiveScience, MyHealth.