The truth behind the wellness industry’s dubious promises: From the watch that could do

Doctor and broadcaster XAND VAN TULLEKEN yesterday revealed how faddy multivitamins make little difference to our health. Today, continuing his excoriating denunciation of the wellness industry, he explains why eternal youth is a dangerous (and expensive) myth… 

There is a fundamental difficulty facing anyone who wants to increase human lifespan. It is that our bodies aren’t built to last. Whereas healthcare has limited ambitions – it wants to stop us falling through the floor – the wellness industry is about raising the ceiling. And since the idea of being dead is hard to wrap our heads around, longevity is an easy sell.

Having trained as a doctor and worked as a broadcaster for 20 years, my new book is part of an attempt to understand the wellness industry – by exploring in-depth supplements, wearable tech and testing.

Longevity is such an attractive concept for marketing, and simultaneously extremely difficult to evaluate in studies, that it is hard to know how to assess any claims made about it.

In 2022, American model Hailey Bieber (wife of singer Justin) said about a vitamin infusion containing the molecule nicotinamide adenine dinucleotide (NAD): ‘I’m going to NAD for the rest of my life and never going to age.’

NAD and its close relative, nicotinamide mononucleotide (NMN), are the world’s most popular longevity supplements. NAD is a molecule made from vitamin B3. It is present in every living cell and helps extract energy from food. Without NAD, pretty much every chemical reaction in our body would stop instantly. But NAD doesn’t just help with energy production. It gets longevity scientists excited because it also supports DNA repair.

Unfortunately you can’t eat NAD as the molecule is too large and fragile to survive digestion. So you eat a precursor, a molecule your body converts into NAD once absorbed. The best precursor is NMN. One man, more than anyone, is responsible for their fame. In 2003, David Sinclair, who runs an anti-ageing lab at Harvard, reported that resveratrol (found in grape skin, particularly pinot noir) could activate a gene that can trigger a delay in cellular ageing.

He promoted resveratrol, calling it ‘as close to a miraculous molecule as you can find’. Resveratrol made countless headlines. A lot of supplements were sold and red wine sales got a bump, too. During tests, the tiny turquoise killifish (chosen for its nine-week lifespan) survived 56 per cent longer when resveratrol was added to its water. But to get the same dose that helped the killifish, you’d need to drink 30 bottles of pinot noir a day.

Then clinical trials started failing – and a molecule went from being ‘miraculous’ to worthless in five years. No serious research examines resveratrol now.

Meanwhile, Sinclair was investigating NMN as a potential drug and experimenting with mice. The case seemed compelling.

In 2019, he published Lifespan: Why We Age – And Why We Don’t Have To, in which he revealed he took 1g of NMN every morning, mixed into yogurt. His public self-experimentation, combined with claims that his own blood tests for ageing resembled those of a man a decade younger, was incredible marketing for NMN.

However, while it has apparently improved Sinclair’s life, longevity research has yet to produce a serious, well-powered study showing that any drug or supplement extends life in healthy humans.

One of the first companies to manufacture NAD was a small Shanghai firm called SyncoZymes. Dr Wei Zhu, the SyncoZymes CEO and a gifted organic chemist who still actively participates in his company’s research, had developed a process to make NAD purely as an industrial ingredient – nobody was thinking about longevity or supplements.

‘After the paper published by Dr Sinclair about the anti-ageing effect of NMN on mice, more and more customers from the USA searched NAD,’ Wei tells me. ‘They found us and they asked, “Can you supply?”.’

SyncoZymes did not rush into the supplement space. Instead they downloaded every paper published on NMN and anti-ageing since 2000. Wei found the literature persuasive and he understood the biochemistry: The DNA repair enzymes that decline with age need NAD to function.

If you could top up NAD levels, maybe you could restore the repair machinery. Convinced by what he had read, Wei started taking NMN himself. ‘We were using ourselves as a rat!’ he laughs.

The effect, for Wei, was immediate. Before NMN, he was sleeping from 10pm until 7am − nine hours – but the quality of his sleep was poor and he would wake frequently. After beginning to take NMN he would sleep from midnight to 6am without waking once – less sleep, but better quality sleep. His energy improved.

Wei has been taking NMN for more than seven years. When I ask his age, I guess, as honestly as I think is polite, 43. He is 51.

He sees me looking impressed. ‘I look young not only because of NMN,’ he says. ‘I have another thing to tell you. It is not food, not material. It is…’ He struggles momentarily for the words and then confidently, but enigmatically, says ‘spirit!’ Only after his self-experimentation did Wei decide that SyncoZymes should develop food-grade NMN.

Although in animals, especially mice, the case for NMN looks compelling, in humans it is far less convincing. The first published human study of NMN supplementation appeared in 2020. Led by Japanese researchers, it focused purely on safety and reported no serious adverse effects.

The best-known randomised controlled trial was published in 2021. In this, postmenopausal women with pre-diabetes who took 250mg per day of NMN for ten weeks had modestly improved insulin sensitivity in skeletal muscle compared with similar women given a placebo.

But NMN did not significantly affect glucose tolerance, body weight, lipid levels or inflammation markers. It was not an anti-ageing miracle; there was just a mild metabolic signal in one group. Other small studies have reported some improvements in subjective fatigue, sleep quality or exercise capacity in people taking NMN.

None of these studies demonstrate reduced mortality, delayed onset of age-related disease or extension of lifespan.

There is, in other words, no good reason to believe that NMN will do you any good at all. And there are reasons for caution. NAD fuels DNA repair, which seems good, but it also may drive cells to divide more rapidly, potentially increasing the risk of cancer.

I ask Wei and he is candid. ‘For healthy people, taking NMN is good,’ he says. ‘But there is less data for illness. If you have cancer, is taking NMN good or not? We just don’t know. If you are pregnant, is NMN good or not? We do not know. So, the Chinese government is more cautious.’

Our anxiety is a large part of why the wellness industry is so successful. Huge swings in medical consensus over 25 years have led to confusion – and we have an understandable desire to do something about the unavoidable fact our bodies are falling apart.

Screening our bodies for all manner of possible things can be the result of such anxiety. It’s a part of the wellness industry that involves high-tech and is indistinguishable from healthcare to almost everyone.

Take prostate cancer, which is hard to spot. It often has no symptoms until the disease is advanced, when it can be difficult to treat.

The Prostate-Specific Antigen (PSA) test, which has been proposed as a tool for screening since the 1980s, measures the level of a protein produced by the prostate gland in the blood. Elevated levels can indicate cancer and could potentially enable tackling the disease at an earlier, treatable stage.

The problem is that many things that raise PSA levels have nothing to do with cancer: Benign enlargement of the prostate, infection, sexual activity – even riding bikes.

So, the test produces false positives – roughly six or seven men in every 100 who don’t have cancer will have raised PSA levels. This still sounds pretty good – 93 per cent accuracy seems very reassuring. But a 93 per cent specificity does not mean that if your PSA comes back high there is a 93 per cent chance you have cancer.

A large Finnish prostate cancer screening trial found almost exactly this: Of all the men who received a positive PSA result, less than 30 per cent had cancer confirmed on biopsy.

Most men who test negative genuinely don’t have the disease but the PSA test does miss some actual cancers, especially the early, slow-growing ones that haven’t yet produced enough of the PSA protein to be detected.

The Prostate Cancer Prevention Trial gave men biopsies regardless of their PSA result and showed that roughly one in seven with a ‘normal’ PSA result had prostate cancer. They had been told they were fine. They weren’t.

So the PSA test achieves two opposite errors simultaneously. It tells many men without cancer that something might be wrong, and it tells many men with cancer that everything is fine.

The trouble is that we don’t know what to do with a lot of prostate cancers. Many grow so slowly that they will never cause pain, disability or death. So, even if after a PSA test, biopsy and scan you’re diagnosed with prostate cancer, you may not receive any treatment. Some men live long lives with prostate cancer and die from something else, unaware they ever had the disease. Cancers that threaten life are often aggressive from the outset: They spread early, grow quickly and may not be caught in time by a PSA test.

So, the PSA test can save lives by catching some cancers early but it can also harm men by starting unnecessary treatments.

Over the past decade, the private blood-testing industry has expanded, meeting a demand driven partly by the difficulty of accessing healthcare via the NHS, and partly by relentless marketing on social media.

Healthy people are urged to measure numerous biomarkers – such as salt levels, hormone levels, liver enzymes, immune cells and inflammatory markers.

If you measure enough of these things, you are guaranteed to find an ‘abnormality’. Our bodies constantly change over the course of a day and most of what is measured in the blood reflects these adjustments. We inhale viruses, bacteria and fungi in every breath. A blood test can be ‘abnormal’ without anything being wrong.

Margaret McCartney, who founded the Royal College of General Practitioners’ overdiagnosis group, believes that both public and private healthcare providers must be far more transparent about the risks and limited benefits of many health screening tests.

She says despite a lack of credible evidence, private screening companies routinely make unsubstantiated claims, such as that testing saves thousands of lives.

Consequences of excess screenings – false positives, patient anxiety and unnecessary treatments – often fall back on the NHS.

I have experience of the blood testing industry. Fifteen years ago, I took on promotional work with a private blood testing company and learned how much can be made from endorsements. For a brief advert and a handful of social media posts – a day’s work – I was paid a six-figure sum.

Knowing what I know now, I wish I hadn’t done this work. But it gave me some information that is extremely hard to get: A clear idea of the vast sums doctors are paid to endorse and promote products.

It’s worth bearing in mind the next time you see a doctor advertising wellness: They are likely being paid more than many earn in a year for a small amount of work.

The overlap between health and wellness is increasingly confusing for consumers and perhaps nowhere more so than in the marketing of testosterone, a hormone that has soared in popularity in recent years thanks to the marketing efforts of wellness companies.

NHS Business Services Authority data shows testosterone prescriptions increased by 135 per cent between 2021 and 2024. NHS prescriptions for testosterone preparations also rose nearly 90 per cent between 2001 and 2010, yet the proportion of men with low testosterone was unchanged.

Symptoms of low testosterone are excessive tiredness, weight gain, obesity, depression, poor memory, low libido and difficulty concentrating. It’s difficult for many men to admit they need help with what some regard as the main hormone of masculinity.

Firms selling testosterone say it will improve libido, muscle mass, energy levels, mood and all-round enthusiasm for life. Dr Channa Jayasena, a consultant in reproductive endocrinology and andrology at Hammersmith and St Mary’s hospitals in London, calls the explosion of interest from men a serious challenge to both the health service and society.

It might help with erections but won’t make men live longer, won’t fix weight and will worsen cholesterol and blood pressure slightly. Testosterone drops by 0.4 per cent a year from middle age, but the men whose levels declined most slowly were physically fit. Testosterone fell faster in the sedentary, obese and stressed.

The logic of taking testosterone is appealing, especially when HRT can be so beneficial for women – as I’ll explain in part three of this serialisation tomorrow.

Dr Jayasena points out that testicles, which make testosterone, are different from ovaries in that they don’t age as quickly.

He agrees that taking a mega-dose of testosterone could potentially work, but there are two problems. Though such a high dose would help build muscle and make you feel more vigorous, it would also give you a much higher risk of death from heart disease and could cause many other side-effects like liver cancer, heart problems, acne and rage.

What’s more, if the brain tells the testicles to shut down after repeated large doses of testosterone, they will wither and eventually permanently retire. So, taking testosterone suppresses fertility – in some cases permanently, and you could end up dependent on testosterone pills for the rest of your life.

With millions of men taking tests and initiating testosterone treatment, it’s not inconceivable that the hormone might be shaping the mood in households and workplaces.

You need only a few men taking high doses to dramatically affect the culture in an office. Dr Jayasena emphasises that testosterone therapy genuinely helps men if their bodies aren’t making enough.

For sexual dysfunction, the evidence is solid. Also, testosterone is a vital, life-long medication for many who can’t make their own. It’s safer than we used to think: At doses a wellness clinic would prescribe, it doesn’t seem to significantly raise cardiovascular or cancer risk.

But I’d urge you to find a family doctor or endocrinologist who isn’t making a living selling testosterone prescriptions and discuss if you really need it. Also, consider the expense – thousands of pounds for a drug that’s free on the NHS.

Before you sign up to private health testing, it is worth asking if you have fully used screening programmes that already exist.

These include evidence-based national programmes – bowel cancer screening, cervical screening, breast screening – as well as routine dental and eye-checks.

It is worth checking yourself for symptoms: Persistent pain, unexplained weight loss, fatigue, bleeding or a changing mole.

These services might save your life – and are available for free.

Time we knew if an Apple Watch does you more harm than good

Wearable tech is increasingly intruding into the wellness world and turning it into a multi-million-pound industry.

Devices such as the Apple Watch are increasingly presented as medical tools capable of spotting conditions like atrial fibrillation (AF), a heart rhythm disturbance that can lead to stroke, before symptoms appear.

Apple is careful about the language it uses, referring to ‘heart health notifications’ and ‘irregular rhythm alerts’ rather than ‘screening’. But the watch can look for AF, so it is effectively screening millions of largely healthy people.

Again, it seems like such screening should be beneficial: Surely finding a heart condition is a good thing?

The Apple Watch records heart rhythm and analyses it for possible problems. This is the cutting edge of early warnings – a heart monitor permanently strapped to you. As with private blood testing, the technology trades on legitimacy.

In this case, clinical studies and partnerships with cardiology societies give the products a medical gloss that makes them feel like preventive medicine.

The Apple Watch is very good at detecting AF. I know because I had AF and my cardiologist advised me to get an Apple Watch to monitor it. It spotted every episode of AF I had.

Large observational studies have shown that when the device flags an irregular rhythm, a proportion of users do have AF confirmed on follow-up ECG monitoring.

But the question for doctors is what to do with these identified cases. The essential thing to know about any screening programme is whether it prevents disease and saves lives.

Here, the evidence for Apple Watches is far weaker. In my case, I had severe symptoms from my AF, so I had an operation to fix it. But patients who have no symptoms but whose watch flags a problem will face more testing, with hospital equipment, drugs to control their heart rate and rhythm, and blood thinners (that come with a risk of bleeding).

As of now, we don’t know if it’s actually beneficial to detect AF early and begin these treatments.

A major review article in 2022 put it bluntly: No randomised studies have shown that consumer wearable tech that screens for AF reduces the risk of stroke or other complications.

Another overview of these technologies last year showed that wearables increase AF detection and use of anticoagulation medications, but that there is an inconsistent impact on rates of stroke and mortality.

Benefits of detection come with trade-offs, including a risk of internal bleeds. The over-detection of medical problems, combined with the idea that all heart-rhythm disturbances are equally dangerous, is a terrible approach to tackling health issues.

And yet we are increasingly encouraged to monitor our own health, at a time when scientific standards, regulations and traditional health services are all under strain.

The consumer testing market – which, in truth, is the unevidenced screening market – is, to my mind, one of the most insidious manifestations of the wellness industry because it is the part that most closely resembles actual healthcare. It is the part that most effectively exploits our willingness to monitor and scrutinise ourselves, and is often dressed in the language of disease prevention.

I love using the wearable tech to track my fitness and remind me to stay active. But I’m far more cautious about using it to improve my health: There’s no good evidence that it can do this yet and until there is trial data saying it can, it’s worth considering that it might do you more harm than good.

Adapted from Make Me Well by Xand van Tulleken (Cornerstone, £22), to be published September 10. © Xand Van Tulleken 2026. To order a copy for £19.80 (offer valid to 20/09/26; UK P&P free on orders over £25) go to www.mailshop.co.uk/books or call 020 3176 2937.