Biological vs. chronological age and what it means for longevity
How old are you? And how old are you really? The number of candles you blew out on your last birthday cake might have nothing to do with the age of your cells. That’s because our biological age (the rate at which our bodies show signs of aging) can be completely different to our chronological age. Here’s everything you need to know about how old your body is, and what you can do to keep it younger and healthier for longer.
What is chronological age?
Your chronological age is the number of years you’ve been alive. Chronological age is the primary risk factor associated with age-related diseases and impairments. For example you’re likely to lose some hearing or eyesight as you get older, and most cancers are considered age-related diseases. Chronological age plays an important role in how our bodies respond to stressors and diseases.
What is biological age?
While chronological age is the primary factor associated with many conditions, it doesn’t tell the whole story. Why are some people fit and healthy into their eighties and nineties, when others show signs of old-age when barely past middle age? Gerontologists (people who study the aging process) have long believed that chronological age isn’t the only risk factor we need to consider.
Your biological age refers to how fast your body has aged at a cellular level, relative to a chronological baseline. For example if you’re 50 years old but you’re fit and healthy, you might have a biological of 35. Equally if you’re a 25 year old who smokes two packs a day, doesn’t exercise, and eats a high fat diet, you might have a biological age of a 40 year old.
What are the risks of having a high biological age?
The process our bodies undertake at a cellular level play an important role in how well we age, and what diseases are likely to affect us. Our bodies are incredible machines, and they perform millions of chemical reactions each day. Each time a reaction occurs, it has a chance of going wrong. Over time, it becomes almost certain that some cells will break down or mutate in ways that are dangerous to us.
A high biological age indicates that this process has been accelerated, increasing the chances of dangerous mutations earlier in our lives. A 40 year old with a biological age of 60 can expect to experience the same age-related diseases and impairments of someone 20 years their senior. A recent study of COVID-19 patients found that COVID-19 severity is predicted by earlier evidence of accelerated aging. Patients with a high biological age were more likely to contract COVID-19. They also experienced worse symptoms, up to and including death.
In fact, biological age has been shown to accurately predict longevity and mortality rates. The study authors noted that, “The death rate significantly increased as biological age became larger than chronological age.” The authors concluded, “Biological age could be used to predict future risk of death.”
Another study found a link between high biological age and breast cancer. The research showed that for every five-year increase between biological and chronological age, the probability of a patient developing breast cancer increased by 15 percent. (Note this is relative to the baseline risk level for women to develop breast cancer. A woman with matching biological and chronological ages has a 12.5 percent chance of developing breast cancer. If a woman has a biological age five years higher than her chronological age, that risk increases to 14.3 percent, and so on.)
While the science in this area is still new, it seems clear that gerontologists were right when they said that how we live affects how we age. A high biological age increasingly looks to be a risk factor in any number of age-related conditions.
What causes accelerated biological aging?
There are many factors that contribute to how our bodies age. Some of them are out of our control, such as our genetics. The environment we live in can also make us age faster. While it’s almost impossible to completely escape the effects of air pollutants, living in the heart of a crowded, smoggy city will age you faster than living in rural countryside. Finally our medical histories could also play a role in aging our bodies. If you contract a serious illness that does long-term damage, that can continue to affect you for years to come.
However some causes of accelerated aging are under our control — and they’re exactly what you think they are. What we eat and drink, and whether or not we smoke or exercise, all play an important role in aging or rejuvenating our bodies. Sticking to a healthy diet, getting plenty of exercise, and cutting out cigarettes can all help keep us fit and youthful for longer.
Getting enough sleep is also critical to supporting a healthy aging process. Our bodies need downtime to heal and undo all the damage we sustain each day at a cellular level. Without enough sleep, the damage begins to accumulate. On our skin this shows in the appearance of fine lines and wrinkles, while internally, it speeds up our biological clocks.
How is biological age determined?
Because so many factors affect how we grow older, science hasn’t yet developed one definitive test to reveal our biological age. The two most common methods are studying telomeres and methylation. Both show a link between biological and chronological ages.
Telomeres are like little caps at the end of DNA strands. Every time a cell replicates, the DNA inside it has a tiny piece shaved off the end. This is bad, because DNA with pieces missing can lead to mutations, cell death, and diseases. Telomeres prevent this by providing a buffer for DNA — instead of the DNA being shaved off with each replication, part of the telomere is instead. Eventually the telomeres get removed and then the cell stops replicating or begins mutating the DNA.
In studies, scientists have found a correlation between telomere length and chronological age. As we get older, our telomeres get shorter. This makes sense because the older we are, the more times our cells have already replicated, shortening the telomeres. However we don’t all start with telomeres of the same length, and various environmental factors can also make our cells replicate faster or slower. That means that some people in their 40s might have telomeres as long as people in their 20s, or as short as people in their 60s. This explains why some of us seem to age effortlessly, while others suffer age-related infirmities much younger in life.
DNA methylation is a process where new compounds (methyl groups) are added to DNA and help regulate gene expression. This process can change cell behaviors to make them carry out particular functions. High levels of methylation have been observed in fat cells following exercise, and in brain neurons responsible for memory and learning.
Researchers have found a direct link between methylation levels and the age of the surrounding cells. This means methylation can be used to establish a biological age. The older we get, the more methylation is lost, and at a proportional rate. Therefore by measuring the amount of methylation present in our DNA, we can accurately predict what our biological age really is.
What can you do to reduce your biological age?
Prevention is always better than cure when it comes to your health, so the earlier you start looking after your body, the better. However that doesn’t mean all is lost if your biological age is already far ahead of your chronological age. You can slow the rate of advancement, and maybe even lower your biological age by leading a healthy lifestyle. Stop smoking, drink alcohol in moderation, cut back on soda, and follow these guidelines to help you live a healthier, longer life.
The more you move, the healthier you become at a cellular level. A study found a link between physical activity and telomere length, suggesting that the more active you are, the longer your telomeres are likely to be. That means regular exercise can contribute to having a lower biological age, helping you to live longer and age better.
Following a healthy, balanced diet is good for all your cellular functions, and can help reduce your biological age. Researchers found a link between good nutrition and lower biological age, meaning you should do more than simply count calories in order to boost longevity. Some nutrients play a role in DNA methylation, and getting more of them in your diet could help you to age better. These include:
- Folate — found in leafy greens, rice, kidney beans, and fortified breakfast cereals (look for “folic acid” on the label)
- Choline — from whole grains, dairy products, eggs, and soybeans
- Vitamin B12 — in fish, eggs, almonds, and milk
- Vitamin B6 — eat more skin-on potatoes, chicken, avocado, and tuna
You should aim to eat a broad range of fruits, vegetables, fish, meats, whole grains, and legumes in order to get a wide variety of nutrients from food. Try to eat different color fruits and vegetables, stick with lean proteins, and find alternatives to compensate for dietary restrictions. If you can’t get all the nutrients you need from your diet, consider taking a supplement such as Qyral’s Sustain Cellular Health Supplement.
The damage the sun does to us isn’t just limited to painful burns when we’re on vacation. Sunlight is UV light, and it can cause harm at a cellular level, mutating our DNA and speeding up the aging process. One study showed that skin wrinkling after limited sun exposure can be used as a marker of biological age.
Sunlight is good for us in small doses — sunlight helps our bodies make Vitamin D and better absorb minerals like calcium — but try to avoid getting sunburned. We should all wear SPF 15 or higher sunscreen every day, even if it’s cloudy outside. If you regularly wear makeup, choosing a foundation with SPF is the easiest way of incorporating sunscreen into your daily routine.
Get more sleep
Our bodies sustain damage every single day from side-effects of all the tiny chemical reactions going on inside our cells, UV rays, pollution, and free radicals. When we sleep, our cells have time to rest and heal. If we skip sleep too often, that damage starts to accumulate, and eventually overwhelms our systems. Studies have shown that sleep deprivation is linked to the molecular processes associated with biological aging.
Make bedtime part of your routine, and aim to go to sleep at the same time each night. Start to unwind an hour before bedtime, limit your exposure to blue light (put down your phone!), and make your bed a comforting and inviting place. If you have trouble nodding off, try using a white noise machine, sleep with a fan to circulate cool air, or take a melatonin supplement.
While it’s no secret that eating a healthy, balanced diet and exercising regularly can help you live better for longer, science is now finding ways to measure the impact our lifestyles have on how we age. By paying attention to our biological age at a cellular level, we can better understand how to look after our health, improve longevity, and age well.