When Xand van Tulleken set off on a journey into the wild west of wellness, he didn’t expect to discover anything new about vitamin D. Of all the supplements that line our shelves and social media feeds, it ought to be the least controversial; even the NHS website, which is hardly a wellspring of quackery, advises that everyone should consider taking a daily dose during autumn and winter, when we risk becoming deficient (D is the vitamin we get mostly from sunlight, and which helps keep our bones strong).
The tiggerish TV doctor and twin brother to Chris (he’s the one who wrote Ultra-Processed People about the food industry) qualified at a time of high excitement in vitamin D circles; in the early 2000s, big studies were linking it not just to bone health but cancer, heart disease and dementia. “The range of potential problems to be solved was dizzying,” Van Tulleken writes in Make Me Well.
But – spoiler alert – it turns out evidence even of the benefits of the most medically endorsed supplement shrivels under scrutiny. After immersing himself in decades of trials and speaking to a professor who had devoted his career to what he now views as the false promise of vitamin D, Van Tulleken finds no justification for its routine consumption for all but a tiny proportion of the population who are genuinely deficient.
The vitamin D chapter follows what becomes a familiar and compelling pattern in Van Tulleken’s first proper solo book, in which he combines the rigour of an investigative journalist with medical expertise and the bouncy bedside manner that makes him such a natural broadcaster. He’s also the best kind of science writer, leaning into complexity while making it as easy to digest as a fish oil gummy (another thing you might want to stop forking out for).
As well as vitamin D, he goes deep on collagen, testosterone, multivitamins, turmeric and krill oil supplements, as well as the burgeoning markets for personalised nutrition, glucose monitoring, wearable tech and private blood screening. In each case, he finds a troubling blurring of the lines between wellness and healthcare – and yawning gaps between hype and the evidence. He also uncovers the harm that wellness fads can do to our bodies, our relationship with food and the environment.
In a chapter devoted to collagen, Van Tulleken travels to China to learn how a messy byproduct of the meat industry has been marketed as a modern elixir with a mark-up of as much as 1,000%. Ejiao, a premium kind of donkey-derived collagen, has become such a coveted source of “ingestible beauty” that manufacturers have exhausted Chinese supplies of donkey hides; soon rural communities in countries across Africa were finding that their animals were being slaughtered for export so that their skins could be boiled up and turned into expensive gummies and powders.
He also explores the history and booming business of supplements, from the literal snake oil of the late 19th century to an unwholesome contemporary market driven by podcasts, influencers and a scientific publishing industry that appears to have striking deficiencies of its own: “The more research I do, the more I see the same patterns repeatedly: conflicts of interest, industry-funded trials, industry-owned journals and an entire system designed to exploit people.”
He concludes that, for the generally healthy person, wellness requires things that it’s hard to package and sell to supermarkets or via a subscription: a diet rich in whole foods and fruit and vegetables, for example, and a hobby that involves the achievable yet challenging mastery of some kind of rewarding skill. (The scientific evidence for the health benefits of, say, becoming a potter or learning the piano is far more robust than that for knocking back testosterone or vitamin D.)
“The right people to make you well won’t be health gurus,” Van Tulleken says at the end of a book that deserves to prompt some kind of industry reckoning. “They might be dance instructors or librarians or martial arts teachers or the person who runs your local choir.” While I consider resuming reacquainting myself with my own piano, I have no plans to dust off my bottle of vitamin D pills as the nights draw in.
• Make Me Well: A Quest to Understand the Confusing World of Wellness by Xand van Tulleken is published by Cornerstone (£22). To support the Guardian order your copy at guardianbookshop.com. Delivery charges may apply.
