The Age Code
David Cox
HarperCollins

Every good narrative needs an inciting incident – something to kick-start the protagonist into action. For freelance health journalist David Cox, it arrived in the form of a health scare, which he recounts in his new book, The Age Code: The new science of food and how it can save us.

In his mid-30s, increasingly immersed in the burgeoning field of geroscience, Cox decided to have his biological age measured. He took three tests, which all delivered the same wake-up call: he was getting old before his time.

His biological age – a measure of the amount of age-related damage he had accumulated in his 34 years – was what you would expect in an average 36-year-old. So no cause for panic, but, as he explains, “if I do absolutely nothing, projections suggest that by the time I reach my fifties, I would be at a notably higher risk of developing a chronic illness such as diabetes or cancer, than if I took steps to lower my biological age”. And so begins his absorbing and often demanding quest to do just that.

I will deal with the elephant in the room right away. In principle, the notion of biological age is a sound concept – people age at different rates and there can be large mismatches between an individual’s age in years (their chronological age) and the amount of age-related damage they have accumulated. Biological clocks aim to deal with this mismatch in a simple and easy- to-understand number: your biological age. They also reflect the fact that age-related damage can be arrested or even reversed.

But in practise, they are flawed for many reasons – not least that different clocks produce different numbers. But the fact that Cox took three tests and they all aligned, plus the fact that his goal was to reduce his biological age rather than just take a snapshot, means that we can give him the benefit of the doubt.

Cox quickly discovers that the easiest way to lower his biological age is to change his diet. At the start of his quest, he is a few kilograms overweight and his eating habits leave room for improvement, with too many sugary drinks, chocolate biscuits, desk-bound fast-food lunches and barely a wholegrain or legume in sight. His typical energy intake is 2700 calories a day, higher than the 2500 calories that the NHS recommends for an average adult male.

Through talking to some of geroscience’s leading lights, Cox discovers that this sub-optimal diet is opening him up to multiple drivers of ageing. Ten in all, in fact, starting with the most obvious: too many calories. Some of the others are also familiar, such as too little fibre, too few micronutrients and too much of the wrong sort of fat.

Other drivers he cites, however, are still quite obscure outside the geroscience and nutrition literature. Many of them, such as dietary acid load and advanced glycation end products, have been the subject of New Scientist features. I was impressed with Cox’s grip on the science and how to turn it into actionable self-improvement.

From an initial attempt to reduce his energy intake, Cox works through the drivers and chronicles his attempts to reduce his exposure to them. These feature an impressive number of visits to laboratories to have his body and its various fluids prodded, poked, extracted and measured.

He also, memorably, tries to eat more than 50 grams of fibre a day, which is way over the recommended 25 to 30 grams a day (a trend that is known as “fibremaxxing”, though Cox doesn’t use that term).

I have done that too, and it is very difficult to actually ingest that amount of fibre and even harder to keep a lid on it once you have managed this feat. But all power to him: at every opportunity Cox puts himself, and his quest, at the heart of the book, and it succeeds. He’s an affable and engaging host.

Each chapter works as a standalone, but if I have one big criticism, it is that The Age Code fails to bring everything together. Navigating the myriad, sometimes antagonistic slices of dietary health advice can feel like getting lost in a labyrinth, and even after all the reading I have had to do as a science writer, I could really use some guidance. But it isn’t forthcoming. Many foodstuffs get a namecheck for their supposedly miraculous properties – green tea, pomegranate juice, Iberian ham, blueberries, mustard greens, nuts, potato skins, mushrooms… the list goes on. And on. Ditto for all the supplements and micronutrients. Should I aim to eat them all? Or just focus on a few that will be especially beneficial for me? Cox doesn’t really go there.

On top of that, there’s the problem that some of the ways to evade the dietary drivers of ageing appear to contradict each other. For example, I want to reduce my dietary acid load, which means that I should avoid animal products, but I also want to up my intake of omega-3 fatty acids, which means eating more oily fish. Which to optimise?

Overall, though, there is much to admire in Cox’s journey. New Scientist readers who enjoy our health coverage, especially that covering nutrition and ageing, will find much delicious material to digest here, and helpings of advice on how to eat well and live longer.

At the end of the book, Cox goes back to the labs to have his biological age reassessed – narratives need closure, too. I won’t give the whole game away but, suffice it to say, his quest pays off. And, as he makes abundantly clear, we can all achieve something similar.

Three more great books on living longer, better

Invincible: Defy your genetic destiny to live better, longer
by Florence Comite

Another new book on how to delay or reverse ageing, but with a slightly broader sweep. Comite, a noted endocrinologist, offers advice not just on diet but also on sleep and exercise. A bit self-help for my taste, but full of sound tips.

This Book Could Save Your Life: The science of living longer better
by Graham Lawton

Apologies for the self-promotion, but this book does exactly what it says on the tin. I had wanted to call it This book could postpone your death, but the publisher thought that the title was a bit of a downer.

This Book May Save Your Life: Everyday health hacks to worry less and live better
by Karan Rajan

There’s a bit of a pattern emerging here in the book titles, yes? No matter; Rajan turns his experience to good use in this humorous and useful guide to your bodily functions and how to optimise them.

Graham Lawton is a writer based in York, UK