How to live well into your nineties, according to science

David Attenborough will turn 99 this week and still seems to be hard at work, with a new documentary due to be released on Thursday.

It’s enough to make you wonder what his secret is – and how the rest of us can maximise our chances of staying productive and healthy in our later years.

It is certainly unusual to reach Attenborough’s age. Life expectancy may have been rising for decades, but the average lifespan in the UK is currently about 79 for men and 83 for women.

Only one in 100 of the population are aged 90 or over while only one in 5,000 make it to the status of centenarians, the term for those who reach the age of 100. And men are less likely to achieve this than women, with males making up just a quarter of UK centenarians, according to the Office for National Statistics.

Medical researchers have long been interested in centenarians of either sex, seeking to understand whether their longevity is chiefly down to healthy lifestyles or their DNA.

Lately there has also been growing public interest in longevity research – triggered partly by online “anti-ageing” influencers like US entrepreneur Bryan Johnson, who says he takes 54 supplements a day and has transfusions of his son’s blood.

The age-old advice

But extreme measures like this are not supported by science, said Dr Saul Newman, a demographer at University College London.

People would be better off following age-old advice from doctors. “Don’t drink, don’t smoke, do some exercise,” he said. “Those have the biggest effects. It’s never really changed.”

Two of those recommendations are supported by the results of a huge study into the relative contributions of lifestyles and genes on our risk of dying, which was published earlier this year.

Based on a long-running project called UK Biobank, this study was notable because unlike much previous research, it did not set out to support any particular theory about longevity, but analysed exposures to many different aspects of the environment – sometimes called the “exposome”.

It found that the two biggest factors linked with earlier death were indeed smoking and lack of exercise.

In this study, alcohol had no significant correlation with death rates. But most other research has found that heavy drinking is bad for us, yet light drinking is better than being teetotal – although that could be because some people become teetotal as a result of health problems.

Watch your weight

A good diet is usually touted as one of the most important things you can do for a long and healthy life.

NHS advice is to have plenty of fruit and vegetables, with starchy carbohydrates in the form of wholegrain or brown versions of bread, rice and pasta, and protein coming from lean meat such as chicken or fish, eggs or beans and other pulses. Any dairy is supposed to be low-fat.

But the evidence supporting this way of eating is not as strong as we are often led to believe. Much of the research consists of “observational” studies, which can be flawed, while randomised trials – the best kind of evidence – have given mixed results about the key principles of avoiding red meat and full-fat dairy products.

But while scientists still debate the healthiest eating pattern, one thing they agree on is that being very overweight shortens lifespan and healthspan. So, whatever kind of diet suits you best, if it’s keeping you within healthy weight guidelines, that’s a boost for your longevity odds.

It’s not only physical factors

As well as physical factors, researchers are increasingly investigating how our mental well-being can affect our health.

Bodies such as Alzheimer’s Research UK advise people to lower their risk of dementia by trying to stay mentally stimulated as they get older, for instance by keeping up hobbies and seeing people socially.

Less well-known is that people can also cut their risk of dementia by getting their ears tested and wearing hearing aids if needed.

A long-standing question is whether it can be better for health to retire from work or continue working, at least part-time, if someone has the choice.

If work is enjoyable, it can provide not only mental stimulations but a sense of purpose, said Dr Mark Cortnage, a public health researcher at Anglia Ruskin University.

Researchers in Japan – where there is more of a cultural belief in the importance of a sense of purpose, known as “ikigai” – have shown that people lacking this feeling were more likely to die from heart disease or external causes over a seven-year period.

It isn’t clear that people should delay retirement, said Dr Cortnage. And many people find meaning through volunteering, caring for grandchildren or hobbies.

“But if you retire and you do nothing, there’s a reasonable chance that you’re going to have a poorer-quality lifestyle than if you have some sort of purpose and challenge ahead of you,” said Dr Cortnage.

What you can’t control

Making it to extreme old age may also be down to your DNA, as a few gene variants are more likely to be found in centenarians than the rest of us.

One gene, for instance, called ApoE, has three different variants, with two of them being more common in centenarians. The third version, linked with shorter lifespan, may be detrimental because it raises risk of heart disease as well as Alzheimer’s disease.

But altogether, genes seem to play only a small role in our chances of reaching 100. According to the Biobank study, genes contributed to just 2 per cent of the variation in age at death, compared with 17 per cent for lifestyle factors.

In fact, a whopping 32 per cent of the variation seemed to be down to random influences, like car accidents. When it comes to our chances of reaching our nineties or even 100, a great deal might be down to plain luck.