What are the secrets to living a long and healthy life? Most people realise that to reach a healthy old age you need to do regular exercise, keep to a reasonable weight, get enough sleep and manage stress.
But you can now add to that list something much more surprising: get infected by the right viruses.
That, at least, was the conclusion of a recent study of centenarians from Japan and Sardinia.
The Japanese are famously long lived, while the small Italian island of Sardinia claims to have one of the highest proportions of people who live to 100 or beyond.
The assumption has always been that this is mainly to do with food and lifestyle, but it now seems that harbouring the right viruses in your gut can also make a difference.
The assumption has always been that this is mainly to do with food and lifestyle, but it now seems that harbouring the right viruses in your gut can also make a difference
In a study published in the journal Nature Microbiology earlier this month, researchers at the Massachusetts Institute of Technology and Harvard University in the U.S. studied poo samples collected from nearly 200 centenarians from these two areas.
The scientists used these to analyse the participants’ gut microbiomes — the community of trillions of microbes that live in our guts and have profound effects on our health — for clues to their longevity.
What they found was that, compared to people in their 60s, the centenarians had both a greater range of ‘good’ bacteria — and also more ‘good’ viruses.
It might surprise you to learn that there are plenty of viruses and fungi living in our guts, alongside the bacteria we’ve all read so much about recently.
While we normally think of viruses as being bad for us — and they do indeed cause a range of nasty illnesses — most do nothing bad and some seem to be beneficial.
V iruses are tiny, around 100 times smaller than bacteria and partly because of their size they are difficult to study, which is why until now the ones that are living in our guts have received a lot less attention than bigger, more prominent bacteria.
So what, you might wonder, are the viruses in the guts of centenarians doing that’s helping them keep healthy?
Some of the viruses, at least, are attacking and killing off ‘bad’ bacteria, the type that can cause inflammation and nasty infections of the gut.
These particular viruses, known as bacteriophages, are very common and are increasingly being used in medical settings as an alternative to antibiotics, particularly when it comes to treating drug-resistant skin and gut infections.
That’s because, unlike with antibiotics, bacteria don’t seem to be able to develop resistance against bacteriophages.
The researchers think that as well as killing harmful microbes, some of the viruses in the centenarians’ guts are also good at creating the gas hydrogen sulphide.
On the face of it that doesn’t sound like a good thing because hydrogen sulphide smells like rotten eggs and is one of the reasons why some people produce such noxious fumes when they break wind.
But surprisingly, although hydrogen sulphide smells dreadful out in the open, when it’s being generated in the gut it has lots of potential benefits. One of the most important is that it helps maintain the lining of your gut, a barrier of tightly packed cells which lets your body absorb nutrients, but which also prevents bacteria and toxins escaping into your blood.
And if the bad stuff gets out, it can lead to chronic inflammation, which in turn is one of the main drivers of the diseases of ageing, such as arthritis, heart disease, dementia and cancer.
Hydrogen sulphide also has its own direct, powerful anti-inflammatory and antioxidant effects, which could explain why studies have shown that it plays an important role in preserving the health of our brain, heart, liver and other organs.
In small doses, hydrogen sulphide has also been shown to improve the efficiency of mitochondria, the ‘batteries’ in our cells, which in turn suggests it contributes to improved energy and cell health.
The thinking is that faecal samples from centenarians might one day be used to cultivate the beneficial viruses — which would then be given to people who aren’t ageing so well, either as a pill or a faecal transplant.
If you don’t fancy that then your best bet is to do the sort of things that have already been shown to benefit your overall health, as well as that of your microbiome.
This means eating plenty of fruit, veg and fibre-rich legumes, including lots of sulphur-rich greens, such as broccoli, cauliflower, cabbage, kale and radish, which will help boost your internal production of hydrogen sulphide.
Another great way to cultivate your good gut microbes is gardening, as it brings you in closer contact with soil, which is rich in bugs. This could be one reason, along with exercise and spending time outdoors, why gardeners tend to live longer. Spending more time hanging around with your loved ones is another way proven to help you live to a ripe old age.
A study of 117 people, published in Nature in 2019, found that those who were happily married, or who had plenty of close friends, had richer, more diverse microbiomes than those who lived alone or were socially isolated.
So it seems that keeping in close touch with friends is also a good way to keep your microbial friends, whether they’re bacteria or viruses, happy.
I hate the sound of traffic so much that many years ago I persuaded my wife, Clare, that we should move to a quiet, leafy lane.
Even now, I take ear plugs and noise-cancelling headphones when travelling.
Clare thinks I’m being overly sensitive, so I was delighted to show her the results of a recent Swedish study that found playing people the sound of traffic, even at volumes as low as 40dB (similar to talking quietly in a library) had a significant impact on their ability to focus and get work done.
Why faking a smile is good for your marriage
Social isolation and mask wearing during the pandemic means some of us may have got out of the habit of producing a smile.
That seems to be true of Japan at least, where there’s been a recent boom in classes to teach people how to do it.
Although I wouldn’t want to spend time and money on this, there’s a surprising amount of evidence for the beneficial impact of a smile.
In a 2001 study by the University of California, researchers analysed pictures of women taken in their 20s and found that, decades later, those judged to have smiled most naturally were happier and far more likely to have married and stayed happily married than those who didn’t.
This is possibly because ‘smiling people attract other happier people, and the combination may lead to a greater likelihood of a long-lasting marriage’, the researchers said.
Social isolation and mask wearing during the pandemic means some of us may have got out of the habit of producing a smile
But if you don’t feel like smiling, faking it in a particular way may be beneficial. New research in the journal Human Behaviour, involving more than 3,800 people, showed that mimicking the smiling faces of actors in photos made people feel happier — as did making the corners of their mouths turn upwards using facial muscles.
But the ‘pen-in-mouth’ technique — where you grip a pen between your teeth, to make your facial muscles curl up in a simulated smile shape — didn’t make much difference.
So why should faking a smile make you feel more cheerful? One theory is that it stimulates the amygdala — the emotional centre of your brain — to release chemicals that make us feel more cheerful.
Whatever the explanation, there seems to be truth in that old saying: ‘Smile and the world smiles with you, cry and you cry alone’.