DR MICHAEL MOSLEY: Walk in the rain to perk yourself up… and backwards to boost memory

Do you like drinking tea or taking a stroll in the rain? Did you know that walking backwards can help your memory – or that stopping yourself from being a mouth breather is good for your oral health?

This might sound like a bad mash-up of the ‘pina colada song’, but in fact these are all subjects (and more) that I’m covering in the new series of my podcast, Just One Thing (which launches next week).

As a reminder, in each episode of this series I take a close look at a different ‘thing’, something simple that could improve your mental and physical wellbeing in surprising ways. Here’s a preview of what I discovered…

Have a cup of tea 

We’ve become a nation of coffee drinkers, a recent survey found, with more Britons now drinking coffee than tea.

But has the pendulum swung too far – is it time to start drinking more tea?

The most popular tea in the UK is ‘black’ tea, which comes from Camellia sinensis, an evergreen shrub native to East Asia. The leaves are exposed to the air to darken, which, among other things, increases their caffeine content.

They’re also packed full of plant compounds called polyphenols that have multiple health benefits, including being good for our bones.

One study in Australia, which monitored more than 1,000 women aged over 75 for more than ten years, showed that those who drank more than three cups of tea daily were 30 per cent less likely to suffer a fracture due to osteoporosis, compared with those who drank one cup or less per week. (I’m particularly interested in this, as I have a family history of osteoporosis.)

On top of that, you will not be surprised to hear that drinking tea is a great way to relax. But not, as you might expect, simply down to the ritual; you stop work, put the kettle on, perhaps have a chat.

In fact, there’s a substance in tea, L-theanine, which studies show increases the activity of alpha brainwaves, which are associated with being calm and creative.

Stroll backwards

And after your cup of tea, why not put on your walking shoes and go for a stroll? Backwards. This might sound eccentric, but it’s a technique that’s been used in physiotherapy for decades to rehabilitate lower leg injuries.

It can improve your gait, balance and mobility, plus a study by Roehampton University in 2018 showed that walking backwards can sharpen your memory.

The scientists behind this experiment think that when you walk backwards physically, this helps you ‘walk back’ mentally, retrieving memories from something you did earlier. So if you’re wondering where you put those keys, perhaps a short stroll backwards will jog your memory.

When I first heard about this I was intrigued that something so simple and, frankly, weird could have such an effect.

It can be done on a treadmill, but with care you can do it safely in your own home or outside.

If you fancy giving it a go then start slowly, doing a few steps, then build up. Try it with a partner: the idea is that you face each other, holding hands, so while you are walking backwards they are walking forwards. Then you swap.

0r when it rains 

If walking backwards isn’t your thing, go for a conventional walk – but in the rain.

For starters, if you’re looking for fresh air, there’s no better time to go for a walk than a rainy day, because rain improves air quality.

A recent study in Japan found that as the rain falls, the droplets attract and wash away tens of thousands of polluting particles from the air. These particles, which are generated by traffic, are very harmful because they are small enough to penetrate deep into our lungs when we inhale them.

And then there’s that wonderful, earthy smell just after it’s rained.

It’s got a great name: petrichor, from the Greek word ‘petra’, meaning stone, and ‘ichor’, the fluid that in Greek mythology flowed through the veins of the immortals. That earthy smell occurs as water hits dusty or clay soils, releasing tiny air bubbles that scent the air.

The main component of petrichor is a chemical called geosmin, which is made by bacteria in the soil. There’s evidence that inhaling geosmin can make us feel good.

In a 2022 study in the International Journal of Environmental Research and Public Health, researchers asked 30 adults to handle soil that contained geosmin, and soil that didn’t.

After just five minutes’ exposure to geosmin, the volunteers had higher levels of the mood-boosting chemical serotonin in their blood and reduced levels of C-reactive protein, a marker for inflammation that’s linked to depression (though why this happens isn’t yet clear).

Try to breathe through your nose 

I’d always dismissed claims that breathing in through your nose is healthier than through your mouth – after all, it still ends up in the same place (your lungs). But as I’ve discovered, being a mouth breather has considerable downsides, including reducing the amount of saliva you produce, making your mouth drier and increasing the risk of tooth decay and inflamed gums.

And nose breathing could also give your brain a boost. In a recent study, volunteers were given a memory test while in a brain scanner: when they breathed through their noses they performed better, and the scans revealed their brains were working more efficiently.

Studies at the Karolinska Institute in Sweden have shown that nose breathing boosts levels of nitric oxide, a chemical that fights off infection in your sinuses and increases the blood flow in your lungs, raising oxygen levels in your blood and presumably your brain.

Listen to Just One Thing on BBC Radio 4 every Wednesday from September 20 at 9.30am – when you can also download the whole series on BBC Sounds.

Early nights may protect brain 

Trying to function after a bad night’s sleep is difficult: you feel tired, irritable and, if you are like me, you also feel an insane desire to eat something sweet.

While one restless night isn’t going to do much damage, night after night of poor sleep can raise the risk of dementia.

One theory is that if you don’t get enough sleep, especially restorative deep sleep, you get a build-up of toxins in the brain that can lead to brain damage.

That’s because when you are in deep sleep, a network of channels in your brain, known as the glymphatic system, opens up and washes away any toxic waste from the day.

Sadly, as we get older, we tend to get less deep sleep, which means that our brains aren’t as good at washing away the toxins. Indeed, young people typically have a couple of hours’ deep sleep a night, but when you get to my age (66), you’re lucky to get 30 minutes.

But the good news is that researchers at Binzhou Medical University in China have now identified a protein, pleiotrophin, that can – at least in mice – protect brain cells from damage by toxins. When mice were deprived of sleep, their pleiotrophin levels drop.

The hope is that we will find some way to pump up pleiotrophin levels. Until then, get an early night to try to maximise the amount of deep sleep you get.

Eat green bananas for healthy liver 

In last week’s column, I mentioned that cooking, cooling and reheating pasta turned the carbs in it into resistant starch, which isn’t readily broken down in the gut but acts more like fibre.

So not only do you get less of a blood sugar spike after eating it (because less of it is absorbed), but it also feeds the friendly bacteria in your gut. They, in turn, convert the resistant starch into a fatty acid called butyrate, which has many benefits for the gut, including reducing the risk of developing colon cancer.

Now a study has shown that consuming more resistant starch helps your liver, too. Researchers at Shanghai Sixth People’s Hospital in China recruited 200 people with non-alcoholic fatty liver disease (NAFLD), a build-up of fat in the liver – one in three Britons has early signs of this condition, which is associated with a raised risk of heart attack, stroke and liver damage.

Patients in the study were given a resistant starch powder made from maize or corn to have twice a day, for four months. When compared with a control group, they had 40 per cent less fat in their livers.

They also had reduced levels of liver enzymes and inflammatory factors associated with NAFLD. The good news is you can easily increase your consumption of resistant starch by eating oats, legumes and green bananas. Or by cooking, cooling and reheating rice, pasta or potatoes.