Towards the end of his brilliant new book Make Me Well, Xand van Tulleken, the British medical doctor and broadcaster, finally reaches saturation point in his quest to understand the world of wellness.
Research on the book has taken him across the world, to China, the USA and Europe to meet the makers, marketeers, entrepreneurs, journalists, lobbyists and scientists involved in this highly lucrative but frustratingly opaque, even cynical industry of supplements, hormones, blood testing and longevity.
He’d set out to find “evidence about how much wellness products might help us to achieve the things we want to achieve” with our bodies: more energy, better sleep and a healthier gut. He says he wanted them to work.
But at this late stage of this quest, when he’s approached to help promote a supplement that claims to fix the serious heart rhythm condition, atrial fibrillation, he finally cracks. He’s made his mind up and says he’s no longer open-minded about them.
“To get me interested in a new supplement now would be almost impossible,” he says.
“Out of the thousands on the market, I have identified a handful that have some evidence of effectiveness [creatine, beetroot juice, caffeine]; the rest have led me a merry dance through a blizzard of poor quality and fraudulent science. I think there is a pattern here: the supplements don’t work.”
There are some, such as B12 for vegans, that can help make up a genuine shortfall. But for already healthy people, he argues that there is precious little evidence that supplements will do what their makers say they will do.
And in some cases, the mega doses of supplements such as vitamin D, available on the high street, may actually be harmful.
What does that say about the $146bn a year worldwide supplements business and us as consumers who are all too happy to part with our cash?
Here are some of the ways and reasons we’ve become so hooked and why the supplements industry has gained such runaway momentum, according to van Tulleken.
The industry trades in hope
One of the big reasons why the supplements industry has grown so large is because we, as consumers, desperately want them to work.
A central hook of van Tulleken’s book sees him traipse around an enormous wellness trade show in Barcelona, where he’s overloaded with thousands of companies hawking their wares.
“I knew the evidence suggested that supplements don’t work, but I wanted them to work,” he writes. “It would be great if this cheap stuff that’s perceived to be pretty safe could just pick me up and sort me out.
“Hope is the main product being shipped around the world in barrels by the supplement industry.”
Podcasts and influencers may have filled a doctor-shaped hole
Many of the world’s most popular podcasters – Joe Rogan, Andrew Huberman and Steven Bartlett to name three – are immersed in the wellness and supplements industry, influencing listener behaviour through the guests they interview and the products they advertise (or even sell themselves).
“Two decades ago,” writes van Tulleken, “it would have been unthinkable to most people to spend three hours doing a deep, technical dive into the medical and scientific literature for a general audience.
“But it turns out that this is exactly what huge numbers of people in the USA and UK want, possibly because accessing medical care from our doctors is so difficult.”
Our understanding of a supplement is skewed by ‘publication bias’
One of the most fascinating chapters of the book is dedicated to vitamin D – the ‘sunshine vitamin’.
The vitamin helps to keep bones strong and it's one of the few that the NHS in the UK suggests people take as a supplement: in this case, in the autumn and winter, when we have less exposure to sunlight.
There was once hope that its influence on health went well beyond this, which led to an explosion in research into these apparent game-changing effects. This, as chronicled in the book, subsequently imploded when it came largely to naught.
A major influence on leading researchers up the garden path of vitamin D was the idea of publication bias: the absence of published negative results happens because the lack of a positive finding is seen by a researcher to be a failure.
It can lead to false hope being created, when the truth is hidden away on the laptops of scientists, who are worried it’ll damage their careers.
“Every time I see a doctor on the news talking about a study showing how great supplements are, I ask myself: ‘what wasn’t published?'” writes van Tulleken.
A positivity bias at work in journalism
Similar to the publication bias of scientific papers, van Tulleken writes about how, with the rise of online news, a positive story on a wellness product will generate far more views and dwell time than a negative one.
The obvious result of that is that more positive stories are commissioned at the expense of negative ones, regardless of how compelling the evidence is.
Supplements are the perfect product for influencers to sell online
As the world of online influencing has grown to unprecedented levels, supplements are a common denominator in how many influencers make their money.
“No other product in the world is, or could possibly be, as perfect as supplements for influencers to sell,” writes van Tulleken, and offers several reasons why. They have a great price point – affordable but not too expensive – are easy to store and ship, offer big profit margins, and are quick to make and consumable.
They also enjoy the benefits of association with medicine, but with a far, far lower bar to clear to make it to market.
Industry puts a finger on the scales of biomedical research
Collagen supplements, which proponents say can improve joint health and improve skin health, are big business, and are profiled in a chapter called ‘Turning waste into gold’ (those collagen capsules are coming from the leftover carcasses of the meat industry).
Many positive studies on collagen supplements exist in the literature, so why then aren't they being backed by any “serious medical organisation”, ponders van Tulleken?
He shows how a 2025 review study, when taking industry funding of the studies into account, found no evidence that collagen supplements prevent skin ageing. In other words, always look at who’s funding a study – it’s rarely out of benevolence.
Manipulating study design, publication bias and outright fraud are three ways that this is made possible, he adds.
Data and claims that are hard to decipher
Few people outside of science and journalism spend their time reading scientific papers and studies, but even if you want to, you’ll often be confronted by insurmountable paywalls that make it difficult to scrutinise the claims you’ve seen from influencers on social media.
"If such claims are built on the result of a study designed and conducted by contract research companies who exist to gin up a product, then you’re going to want to know that," writes van Tulleken.
Wellness/supplements and health/medicines are often conflated – but one has a much higher bar to clear to reach market than the other
At one particularly entertaining, if troubling, juncture of the book, van Tulleken – in China learning about the workings of the supplements industry – pretends to be a businessman wanting to create his own supplement.
It's startling how easy he finds it to put anything into a tablet, or onto the box. The only limits appear to be your tolerance for legal jeopardy in the country where it's being sold (which won't be in China).
To get approval for a new medicine, a drugs company has to spend much time and resource proving its effectiveness, including pre-clinical trials, multi-stage human trials and regulatory approval in whatever country or territory they're looking to market it.
For supplements, there's no such high barrier to entry: you don't have to prove it works or is safe, nor back up the claims you're making.
