DnaNudge: The wristband that tells you what to eat based on your DNA

Your wristband syncs to a phone app where the data of thousands of types of food is stored and coded red (for high risk), amber (medium) and green (low). Photo / 123rf

Could a new wristband that offers bespoke dietary advice also solve the obesity crisis? Victoria Lambert gives the DnaNudge a whirl.

Red, green, red, green, red, red, red… The light emitting from my new black wristband keeps changing as I hold my wrist up to the foods in our fridge, letting me know whether I can eat them (green) or not (red). Hellman's mayonnaise: red. Greek yoghurt: red. Tomato sauce: green.

Let's move over to the pantry, shall we? Mince pies? Red. No surprises there. But look, arborio rice: green. Pickled onions: green. Peanut butter, coffee, manuka honey – green, green, green. Glenfiddich: green. Yes! And Bisto Best Vegetable Gravy granules: red.

Wait, what? Forget the traffic lights in UK supermarkets that reveal the nutrient value of foods in general. My new DnaNudge wristband – which will be available in some UK supermarkets from Monday - is telling me in no uncertain terms what is healthy specifically for me, according to my DNA profile. In particular, it's on the lookout for foods high in salt – which, I am to learn, are absolutely verboten for this Lambert – a possibility I had never considered before agreeing to take the latest weapon in the battle to stay healthy: the DnaNudge test.

The DnaNudge, which costs $239.16, offers a level of personalised health that is almost impossible to beat and, claims its inventor Chris Toumazou, regius professor of engineering at the Institute of Biomedical Engineering at Imperial College, London, it could hold the key to solving the obesity crisis for everyone. Toumazou, who has already chalked up some remarkable inventions including cochlear implants for born-deaf children and an artificial pancreas for type 1 diabetics, created the wristband and its accompanying technology, which uses your genome as a way of personalising health, not healthcare.

Of course, buying DNA tests is not new. There has been a boom in the advent of services such as 23andMe, which test your genes and reveal a huge array of potential health risks and traits. These range from whether you have a higher chance of cancer to the likelihood of you inheriting (and passing on) a unibrow. But until now, no DNA service has explored the idea of using the information it finds about the risk of developing conditions such as heart disease or type 2 diabetes with real-time information designed to overhaul your actual lifestyle. This is where DnaNudge comes in. It harvests your genetic code and mashes it up with the best scientific evidence on what nutrients (sugar, fat and salt, for example) you need to avoid or eat depending on those conditions – such as obesity – that nature may have in store.

Your personal prescription is then fitted on a microchip in a capsule that sits inside a wristband (the same size as any other tracker); it syncs to a phone app where the data of thousands of types of food is stored. Look on the app and you can see your personal DNA report, condensed into eight areas: caffeine metabolism, calories, carbohydrate, fat, obesity risk, salt, saturated fat and sugar. These are coded red (for high risk), amber (medium) and green (low). And they reveal how much at risk you are from different types of nutrient and obesity in general. The capsule also contains a barcode reader. Flash it at any food with a barcode and you'll get an instant decision: green for go, red for oh no.

I sign up and the process is simple. A saliva swab yields cells from your cheek that are transferred to a small processing device. It takes about an hour for the DNA to be decoded and transferred on to your chip. After harvesting, the DNA device is destroyed; the company does not keep your genome. Then it loads on to the wristband and syncs to the app and you're good to go shopping. When my DNA downloads, the news could be worse. I am at medium risk for most things: my health will be moderately affected by eating too much fat or carbohydrate. So far, no surprises. But where the chart goes red is salt and caffeine – both of which are likely to affect my health in a negative way. Goodbye double espressos and salted pretzels. I feel quite depressed. Whatever I thought of salty food, and I do think of it quite often, such as rich French cheeses and salmon sushi dunked in soy (sigh), I always believed a black coffee was safe to enjoy.

The DnaNudge will nudge shoppers towards healthier choices by indicating red or green, when they scan the product barcode.

At least I can check individual Starbucks on the device to see if any of them are okay, plus products from Pret a Manger and other food chains are due to be uploaded soon. And thousands of foods from different suppliers with most major supermarkets can be checked, though not Marks & Spencer until next year.

In the UK's National Health Service, the concept is causing lots of interest with trials due to be published next year and interim results promising. One triallist lost 8kg in six months without dieting, simply by eating foods the DnaNudge liked and avoiding those it didn't. Six months on, she had kept the weight off. This is where the nudging comes in. The wristband isn't a diet. It doesn't count calories. Instead, it suggests food swaps that are personalised on an unprecedented level – and it assumes that no one will be surviving on celery and a handful of edamame beans.

For example, you can look at two packets of nuts and check each with the scanner to see which one would be preferable for you. Toumazou demonstrates with two packets of peanuts.

"I love the dry roasted ones, but my scanner shows them up as red. The salted ones are green for me."

Delve a little deeper on the app and it explains the decision. Each product you ever scan and all its nutritional details are listed with a green or red tick next to them. On the dry roasted nuts, there is a red tick by salt (2g per 100g). On the salted nuts, the ticks are all green – there is only 1.3g of salt per 100g. This has shown up on the professor's wristband because his DNA has revealed he is likely to be highly affected by excess dietary salt. He looks sad – he's a big fan of dry roasted but says now he will always choose the salted version instead. Anyway, there's good news when he flashes his wristband at two chocolate bars. A Mars is off the menu, but Snickers – a favourite – is green to go.

You could say that much of what the band highlights red is obvious – no one ever thought eating Mars bars would lead to weight loss. And at $239, it's arguable that those who don't understand nutrition or are shopping on a tight budget while wrangling a bunch of toddlers will be able to afford the DnaNudge anyway. Even though they might benefit from its speedy red/green advice. Moreover, some of us remember that the last great proponent of health nudging was one UK PM David Cameron who set up a "nudge unit" in the Cabinet Office in 2010 – and that didn't shift the dial on the national attitude to food. Yet that's not to say this new piece of kit couldn't be useful. And its inspiration comes from a good place.

Much of what the band highlights red is obvious - no one ever thought eating chocolates would lead to weight loss. Photo / Brett Phibbs

Toumazou developed the DnaNudge after his son Marcus fell ill at the age of 8 in 2000.

"Both his kidneys collapsed suddenly," he explains.

The family learned that Marcus had inherited a genetic predisposition to kidney disease through a renal mutation in his genes.

"We couldn't have prevented it," says Toumazou, "but – if we had known earlier - we could have managed his lifestyle differently to protect his kidneys longer."

Marcus is now well and the recipient of a donor kidney, but the professor remembers well the feeling of confusion when it happened and what it was like to be thrown into a world of acute medicine as they dealt with home dialysis while he waited for an organ donor.

"Our situation inspired the DnaNudge," says Toumazou, "a way to find genetic predispositions and then demystify them for the consumer."

The DnaNudge is not diagnostic, he is at pains to point out. It doesn't reveal whether a user has cancer or heart disease, but their predisposition. "It gives you a chance not to mess your health up," he says. So why should this little wristband work when everything else we have thrown at obesity from gastric bands to five-a-day campaigns has failed to halt the national juggernaut of lard?

"This is about behavioural change," says the professor. "And giving people an informed choice. The best diet is the one you don't know you are following."

He's invented one further twist on the app – a green bar which tracks how sedentary you are.

"We know that long periods of inactivity are bad for you. So this nudges you to get up every so often and move about."

You can set how often you want the band to remind you to take some steps. But forget to be active and the green bar starts to turn amber. This, in turn, starts to affect what foods the tracker says are green or red. "This puts the whole idea of steps into perspective," he says.

My own wristband is now alerting me to get moving. It's only a few short steps to the fridge but my inner me - my DNA - wants me to go further afield and get some proper exercise. It's about half a mile to the shops and there's a double incentive now. Who knows what it will let me eat once we get there?

How it works

A person's saliva is taken at a DnaNudge store.

The DNA is analysed and data loaded on to your personalised microchip.

The microchip sits inside a capsule, which is fitted to a wristband, a colour of your choice.

The user downloads the app, which gives them product recommendations.

The chip syncs to a phone app where the data of thousands of types of food is stored as well as your DNA report, condensed into eight areas: caffeine metabolism, calories, carbohydrate, fat, obesity risk, salt, saturated fat and sugar.

Each is either coded red (for high risk), amber (medium) or green (low).

The capsule also contains a barcode reader which can be flashed at food to get an instant decision: green for go, red for oh no.