Most of us would like to live a long and healthy life, though few would go as far as 45-year-old U.S. tech multi-millionaire Bryan Johnson, who reportedly eats more than 70lb of vegetables a month, plus dark chocolate and lots of supplements to help reverse the effects of ageing.
Is he crazy? Perhaps not. I’ve recently finished making a TV series on the science of ageing, which involved travelling the world, meeting ‘super agers’ — people in their 80s and 90s who look and act like someone decades younger.
Those like Arakaki Toshimitsu, a karate master from Okinawa, an island off the coast of Japan. Aged 80, he is in terrific shape and attributes this to daily workouts and a diet relatively low in calories but packed with vegetables and seaweed.
While making the series, I also spoke to leading scientists who are researching ways to slow, or even reverse, the ageing process.
One of the things they said, which really surprised me, is that genetics plays a relatively small part in how well you age — your lifestyle is far more important.
Most of us would like to live a long and healthy life, though few would go as far as 45-year-old U.S. tech multi-millionaire Bryan Johnson (pictured), who reportedly eats more than 70lb of vegetables a month, writes Dr Michael Mosley
Genetics plays a relatively small part in how well you age — your lifestyle is far more important
We know that what, and how much, you eat play key roles in whether you stay healthy or not — but what seems to be equally important is the impact this food has on your gut microbiome, the mix of bacteria, viruses and fungi, which live in your intestines.
It seems that every few weeks a new study reveals a novel way these microbes impact our bodies and brains.
For example, they play a critical role in regulating your immune system, which is not only central to protecting you from infections, but also in seeking out and destroying cancers.
Now there’s mounting evidence that your microbiome has a big impact on how well you age.
In a study, published earlier this month in the journal Nature Aging, scientists at Guangxi Academy of Sciences in China compared the microbiomes of 1,575 people, ranging in age from 20 to over 100.
They found that the healthy centenarians (those least troubled by age-related disease) had a very diverse mix of bugs in their guts, with particularly high levels of a bacterial species called bacteroidetes. This bug has previously been linked to slimness, and is present in far smaller amounts in the guts of people who are overweight.
Bacteroidetes seem less good at absorbing the fat we consume than other gut bacteria, so people who have more of it tend to remove more calories from their bodies.
Dr Michael Mosley (pictured) spoke to leading scientists who are researching ways to slow, or even reverse, the ageing process
Another advantage of having lots of bacteroidetes is they are very good at converting the fibre in the food we eat into short-chain fatty acids, chemicals that have powerful anti-inflammatory effects throughout the body.
Since chronic inflammation drives a lot of the diseases linked to ageing, such as cancer, heart disease and dementia, it is not surprising this particular bug seems to play an important role in keeping us healthy as we get older.
The best way to boost gut levels of bacteroidetes (and other ‘good’ bacteria) is to eat a largely plant-based, fibre-rich diet, making sure you eat lots of different-coloured fruit and veg.
When you look at the dietary habits of communities around the world with high levels of people living into a healthy old age, this is exactly what you see.
Daily helpings of fermented foods, such as sauerkraut and kimchi, have also been shown to boost your ‘good’ gut bacteria, while sugary foods have the reverse effect.
But interestingly, it seems not everyone has enough of the good bugs in their guts required to benefit from a fibre-rich diet — although there is no easy way to spot if this applies to you.
So what about undergoing faecal microbiota transplantation (FMT) from someone who already has lots of them? To do this doctors collect faeces from a healthy donor, treat it to remove anything potentially harmful — and transplant it into the recipient’s gut (usually via a tube passed through the nose down, or up the rectum).
It can be life-changing. I’ve seen a patient infected with a nasty bug called clostridium difficile, which had caused them years of pain and was resistant to all available antibiotics. Within hours of having FMT, she was cured, thanks to the influx of healthy donor bugs.
But can it impact on ageing? Animal studies certainly suggest so.
In one report by the University of East Anglia last year, poo samples from three-month-old mice were transplanted into ones 24 months old; the equivalent of 80 in humans. They also did the reverse experiment, transplanting gut microbes from old mice into young ones.
Remarkably, the young mice who got the old poo soon showed signs of accelerated ageing, with widespread inflammation in their brains, eyes and nervous systems.
The transfer of young poo into old mice had the opposite effect, boosting levels of beneficial bacteria, calming inflammation and making the older mice appear younger and healthier.
It’s clearly early days, and I doubt if the search for eternal youth will end with faecal transplants — but it shows yet again how important our gut bacteria are, and why you should nurture and respect them.