The current limitations of personalised health

Wellbeing has many contributors and taking potshots at suspicious bystanders will not necessarily fix things

To their credit, long before the phrase ‘generation snowflake’ had crossed anyone’s lips, ‘baby boomers’ were building the foundations of human health as a unique and individual concept. The journey from the discovery of the double helix to the Human Genome Project reimagined humans and their health as long sequences of very personal code. However, these efforts have truly revved up in the past 20 years and made some big promises, both for keeping us well and tackling illness.

The concept is appealing. In wellness, we could take a step beyond the food pyramid and eight glasses of water and instead find the subtle shortcomings (not enough antioxidants, surely?) that were holding us back. In medicine, the rogue mutation in your cancer would be targeted with a molecular sniper rifle, rather than the blunderbuss approach of the past. How has this worked out? It would be fair to say that things have been mixed, at best.

Consider wellness. ‘Zoe’ is likely the best-known personal nutrition app. In return for an upfront fee and subscription, you get to send a stool sample for genetic analysis of the gut microbiome, along with blood tests of fat and sugar. You then receive a personalised plan that emphasises your unique traits to guide diet and achieve your goals, such as weight loss, better glucose control, and successful ageing. Their scientific basis is prominently advertised (‘60+ peer-reviewed papers’).

Look a little closer. These papers explore interesting ideas and early research. But the evidence that this programme makes a material impact on anyone’s life is thin – studies randomise unblinded users to Zoe’s intensive programme or generic and bland dietary advice. In this case, it’s hardly surprising that the motivated trial group lose a little more weight. Equally, the gut microbiome surely has a significant effect on your health, but evidence for altering your diet to influence this does not extend much beyond well-established advice (our old friend, the Mediterranean diet). Intensive glucose monitoring for those who are not diabetic is an elaborate distraction.

On a similar wavelength there are popular podcasts like that of neuroscientist Andrew Huberman, which focus on taking ownership of your health. Look ‘under the hood’ of your body with genetic tests, establish what the problem is, and manage it with a tailored plan of ‘minerals, digestive enzymes, adaptogens, and prebiotics/probiotics’.  These appeal neatly to middle-class ideas of responsibility: If I take rhodiola supplements and do triathlon training, I have created my own wellness. If my neighbour is chronically ill and struggles to lose weight, he has created his own misery. Let’s set that to one side for a moment.

What about in the arena of treatment rather than prevention? Nowhere has this received more attention than in oncology, where genetic sequencing of cancers brought heady new possibilities. Map the genome of every cancer, pinpoint the mutation that has driven its replication out of control, and switch it off with a pill. The use of imatinib, a very effective drug targeted to a specific fusion in leukaemia, has been the poster child for this since the late 1990s.

But progress since then has been more halting. French researchers made a serious effort in 2015 in a trial randomising patients either to a personalised treatment based on their cancer’s mutations or to standard chemotherapy. The targeted therapies made no difference. Too many trials of precision drugs in recent years have had similar results.

What is the lesson from these disappointing findings for personalised fixes in sickness and in health? The most likely reason is that true wellbeing has many contributors and taking potshots at suspicious bystanders will not necessarily fix things. A significant part of our tendency to illness is built in our genes and in our upbringing, and is not easily changed as an adult.

What about the health risk that we can change? Luckily, we don’t need an app for that. A lot of the interventions that we know to truly make a difference, from giving up smoking to reducing alcohol consumption, are already well-known (and are less easily commodified).

The case is comparable in cancer. Some tumours are driven by a single, renegade mutation and targeting it will achieve miraculous results. But most cancers are complex and messy, with 10 drivers at the wheel, and targeting one of them is unlikely to make much difference.

The time will come when we can confidently point to all the factors that contribute to our health and to disease, develop a personalised plan that actually works, and enjoy its benefits. But for now, cast a sceptical eye on these claims and stick to what works.