Being asked ‘how old are you?’ used to be a simple question to answer. If you weren't sure, you could always just count the candles on your birthday cake. The candles may no longer tell you the whole story, however.
That’s according to a growing group of scientists who claim that you don’t just have a traditional chronological age, but also a potentially more fluid ‘biological age’. And that biological age could even be wound back… if you know how.
The excitement about this idea began around 2013, with the first DNA tests that could estimate your age to within a few years. The fact that a person’s DNA and chronological ages were usually slightly different raised a question: if the test deemed that you were older than your age in years, was that an error, or could it indicate something about how fast you’re ageing on a biological level?
A decade of intervening research has shown us that people with an older DNA age, known more correctly as an ‘epigenetic age’, do indeed seem to be older biologically, and so they tend to get ill and die sooner than others.
It’s a scientific discovery that demonstrates what many of us have believed all along: people age at different rates. But what does this actually mean, both biologically and practically speaking?
Biologically, we now understand many of the underlying cellular and molecular processes that drive ageing, from damage to the proteins that keep our bodies working, to the ageing of cells themselves. It’s these changes – known collectively as the ‘hallmarks’ of ageing – that are behind wrinkles, grey hair, frailty, memory loss and diseases like cancer, heart disease and dementia, all of which become radically more likely as we get older.
Practically, therefore, if we could slow these hallmarks down – whether through healthy lifestyle choices or, hopefully soon, medical treatments for the ageing process – we could reduce the risk of many or even all of the problems of old age at the same time.
For now, you might want to start by measuring your biological age to find out what you’re working with. Don’t rely on an epigenetic age test – although available from a number of providers, they’re not cheap and results are too inconsistent. Instead, there are quite a few completely free measurements to try in the comfort of your own home to get a rough idea.
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The first is just to gaze in the mirror and check how old you look. One study of Danish twins found those rated as looking older than their chronological age were at greater risk of getting ill or dying than participants who appeared more youthful.
There are physical measurements that can be tested too. Seeing how fast you can walk 10m (32ft) provides a gauge (with speed dropping from 1.4m/second – or 4.6ft/second – in those below 50 to less than 1m/second or 3.2ft/second in the over-80s); or you can try standing on one leg (under-40s can typically manage 45 seconds with their eyes open or 15 with their eyes closed, but that drops to 32 and 4 seconds respectively in 60–69-year-olds).
If these tests ring any alarm bells for you, there’s some good news: science tells us that our rate of ageing isn’t simply determined by genes. Studies ranging from comparisons of lifespan in identical twins, to massive number-crunching exercises on gigantic databases of family trees suggest somewhere between 75 and 95 per cent of lifespan is down to lifestyle and luck,a huge chunk of which we can control.
So, where should you start on your journey to delay – and possibly reverse – age-related decline? Science furnishes us with a range of suggestions, from the obvious to the obscure.
Maintain your muscle
Doctors joke that if exercise were a drug everyone would be queuing up to take it. Alas, getting fit is harder than simply popping a pill and many of us don’t get enough of this miracle treatment – even though it seems to be able to slow the ageing process.
Most of us know that we should be getting 150 minutes of moderate activity (such as brisk walking), or 75 minutes of vigorous exercise, per week. What’s often overlooked is strength training. Resistance exercise can help preserve both bone density and muscle mass, which are really important as we age, for a variety of reasons. Muscle even helps to regulate your blood sugar levels after meals, which our bodies often get worse at as we age.
We lose roughly 5 per cent of our muscle and 10 per cent of our strength every decade after the age of 30. But resistance exercise can delay or even reverse this decline. This doesn’t need to be pumping iron at the gym: plenty of exercises can be done at home using your bodyweight, from press-ups to squats. It’s never too late to start, either. One particularly inspiring study gave 90-somethings a two-month resistance training programme and nearly doubled their muscle strength in the process.
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Ignore the fad diets
You could spend a lifespan just trying every diet put forward as the best way to increase health and longevity. Fortunately, the big picture is fairly straightforward: most of us would benefit from less meat and more vegetables, fruit, legumes, nuts and whole grains.
Exactly how much this could roll back your biological clock isn’t clear, though. Diet studies are challenging, considering that the biggest ones are ‘observational’ – you can’t enforce a diet on thousands of people over decades, so scientists make do with watching what people eat and observing what happens to their health.
The aforementioned recommendations do have the backing of shorter-term studies that closely prescribe a diet to participants and then use the likes of blood tests to monitor their key health markers. But what about when to eat? And how much? While there’s solid evidence that maintaining a healthy weight is important for longevity, it’s far less clear whether practices like fasting or long-term calorie restriction will be of benefit.
Calorie restriction works well in many organisms, like single-celled yeast, worms, flies and mice, but results in monkeys (the closest animals to humans we’ve yet tried it in) are more ambiguous. The evidence is thinner when it comes to fasting. Some human studies suggest it may result in weight loss, but disproportionately by loss of muscle rather than fat, which, given the importance of muscle at older ages, may well be a net negative for your biological age.
Brush your teeth
One of the most surprising connections in ageing biology is that between good oral hygiene and living longer. The first hints of this came with studies noting that people with less tooth decay and gum disease seemed to have fewer heart attacks than those with worse oral health.
The exact link was unclear – there could have been an unrelated factor behind this correlation, or it might be that more health-conscious people spend more time brushing their teeth and engaging in other behaviours like eating well – but further studies have solidified the link. What's more, they suggested what the connection could be: chronic inflammation.
Inflammation, a normal immune response to an infection or injury, is usually short-lived. As we get older, however, our immune systems become a little paranoid, entering a state of constant low alert – inflammation that’s chronic – and scientists think this can accelerate the ageing process.
A neverending battle with bacteria on your teeth or gums provides a source of exactly this kind of low-grade and long-lasting inflammation, providing a mechanism by which the cleanliness of your teeth is connected to general health.
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Get enough sleep. But not too much
You’ve heard it before: studies suggest that the sweet spot for sleep is around 7-8 hours per night on average. But what you may not have heard as much is that having too much sleep can have a detrimental effect on your health. Regularly getting over nine hours of shuteye a night is associated with a higher risk of death than getting as little as four hours.
There are a variety of possible causes here: it could be that people who are unwell in other ways are more tired and so sleep for longer. Or it may be down to more complex biology, like more time in bed changing immune system behaviour for the worse. Currently, scientists aren’t sure.
Though sleep remains one of the most mysterious aspects of our physiology, longevity science is uncovering mechanisms to explain how a good slumber can lengthen your lifespan. For example, while we sleep, our brains do a spring-clean, literally flushing out toxins, like the amyloid deposits associated with Alzheimer’s disease, via a recently discovered network of pipes in our skulls, known as the glymphatic system.
Given that the accumulation of toxic proteins is one of the hallmarks of ageing, this could slow down brain ageing – hopefully making the well-worn advice to get enough shut-eye a bit more compelling.
Wear sunglasses more
It’s not only your skin that you need to keep safe from the Sun: looking after your eyes is just as important – and the effects of shielding them could include preventing dementia. That’s because the damage that can be done by ultraviolet light has consequences that stretch beyond vision loss.
For example, the proteins in the lenses of your eyes are normally transparent, but UV damage may cause clouding and yellowing, which, if it gets severe enough, is known as a cataract.
UV light can also do damage to the light-sensitive cells on the back of the eye, accelerating the disease, age-related macular degeneration (AMD), which can blur your vision. Both cataracts and AMD seem to increase the risk of dementia. One theory to explain this is that by cloudiness or blurriness reducing the amount of visual stimulation received by the brain, cognitive decline with ageing accelerates, so protecting your eyes from UV light can slow down these processes and, in turn, could well reduce dementia risk.
The good news for those of you who wear glasses or contact lenses is that the majority of these come with built-in UV protection. For the rest of us, sunglasses – especially those that wrap around to prevent UV light from sneaking in at the sides – and a wide-brimmed hat are worth considering. These will not only help to maintain sight as you go into older age, but also brain function too.
Always wear sunscreen
For all the potions making promises in the beauty aisle, by far the most effective anti-ageing cream is the humble sunscreen. As well as causing skin cancer, ultraviolet (UV) light emitted by the Sun accelerates the ageing of skin through a few different mechanisms.
Firstly, it damages the collagen and other structural proteins that make our skin strong yet supple in youth, leading to wrinkles and the skin being slower to return to position when pinched. (Incidentally, that's another at-home test of biological age.)
Secondly, the damage to our DNA caused by UV light means that almost all our skin cells are mutated by the time we reach our 50s. We don’t yet know exactly how this contributes to ageing, but these mutations aren’t present in young skin. Slapping on some sunscreen will help you maintain a more youthful mutational profile.
You need to seek out creams with factor 15 or higher and four or five stars for UV-A protection. It’s worth applying sunscreen every morning since UV rays can be strong enough to damage skin on overcast days or through a window. With this regime, it’s probably also worth supplementing vitamin D (10 micrograms a day), which is normally produced when UV light hits our skin.
Don’t waste your savings
Perhaps the most talked-about story in ageing biology of late has been the tale of American entrepreneur Bryan Johnson, who is burning $2 million (£1.6m) of his reported $400m (£326m) fortune every year on dozens of tests, hundreds of daily pills and supplements, and an extreme diet, exercise and sleep regime in the hope of stopping his biological ageing.
For the rest of us, the good news is that there’s no need to spend anywhere near that much. Almost all the bang for that considerable buck is probably coming from eating more vegetables, nuts and legumes; getting plenty of exercise; and consistent sleep patterns.
By contrast, scientific studies show that many common supplements have no effect on life expectancy, or sometimes a slightly negative one. If you’re taking over 100 different pills, it’s likely to reduce life expectancy overall: while some anti-ageing interventions add together, other combinations don’t play nicely.
Biology is complicated and changing dozens of things at once doesn’t make for a safe, controlled experiment, whether or not you’re ultra-wealthy.
Wash your hands
If you heard it once during the pandemic then you heard it 1,000 times: wash your hands for 20 seconds, and be sure to scrub between your fingers and under your nails. We were told it would save lives by reducing the risk of infection, but washing your hands can boost your life expectancy too.
How? Firstly, we know that certain infectious diseases have a direct link to non-infectious ones later in life – from human papillomavirus (HPV) being the leading cause of cervical cancer, to a virus called cytomegalovirus (CMV) that seems to accelerate the ageing of the immune system.
After an initial infection that’s usually comparable to a mild cold, CMV hides away in your cells for the rest of your life. Because it can never quite get shot of CMV, ever more of your immune system ends up specialising in fighting it, leaving less ‘immune memory’ for other threats as we age.
There’s even more general evidence suggesting that infections lead to problems in later life. As hygiene, vaccines and antibiotics gradually reduced the burden of infectious disease in childhood, people who got fewer bugs as kids have been shown to age better as adults. This is probably due to the same chronic inflammatory mechanisms as keeping your teeth clean.
It means that doing everything you can to avoid infections might have a positive impact beyond the short-term desire to avoid the misery of being ill.
Prepare for future super drugs
Perhaps the most important health tip for all of us in the medium term is to learn a bit more about the biology of ageing. That’s because there are drugs on the horizon that could slow down the ageing process and keep more of us healthier for longer.
Some could be drugs already available today, like metformin (a diabetes drug) or rapamycin (given to help transplant patients), which seem to have a broad anti-ageing effect.
Other new treatments could target one or more of the hallmarks of ageing, such as so-called ‘senolytic’ drugs designed to remove certain misbehaving cells, known as ‘senescent’ cells, that accumulate in our bodies as we get older.
The science of longevity offers the promise of treatments far more powerful than the lifestyle tips currently at our disposal.
That’s just another reason to stay as healthy as possible with the tools of today: in order to still be around to be able to benefit from the game-changing therapies of tomorrow.
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