When it comes to health information, who should you trust? 4 ways to spot a dodgy ‘expert’

When it comes to our health, we’re constantly being warned about being taken in by misinformation. Yet for most of us what we believe ultimately comes down to who we trust, including which “experts” we trust.

The problem is that not everyone who presents themselves as an expert is actually an expert. And an expert in one area isn’t necessarily an expert in everything.

The reality is that we often rely on superficial cues to decide who to trust. We’re often swayed by how confidently someone speaks, their perceived authority, or how compelling their story sounds. For some, it’s simply the loudest voice that carries the most weight.

Even if we feel we have some understanding of science, few of us have the time or the capacity to verify every claim made by every so-called “expert”.

So how can we distinguish credible experts from those that are not? Here are four things I look out for.

1. Dodgy experts don’t acknowledge uncertainty

One thing that separates trustworthy experts from dodgy ones, is their humility. They have a healthy respect of the limitations of science, the gaps in the evidence, and even the limitations of their own expertise.

And importantly, they communicate this clearly.

Read more: Uncertain? Many questions but no clear answers? Welcome to the mind of a scientist

In contrast, one of the most common characteristics of the dodgy expert is they are misleadingly certain. They often present issues in overly simplistic, black-and-white terms, and they draw conclusions with misplaced confidence.

This, of course, is part of their appeal. A neat clear-cut message that downplays uncertainty, complexity and nuance can be persuasive – and often even more persuasive than a messy but accurate message.

One of the clearest examples of unfounded certainty was the confident claim by some “experts” early in the pandemic that COVID was no worse than the flu, a conclusion which ignored uncertainties in the emerging data.

2. The dodgy expert doesn’t strive to be objective

Credible experts follow a well-established and disciplined approach when communicating science. They present their understanding clearly, support it with evidence, and endeavour to remove emotion and bias from their thinking.

A core principle of scientific thinking is striving for objectivity – and language reflects this. Experts generally aim to provide high-quality information to assist the public to make informed decisions for themselves, rather than manipulating them to reach specific conclusions.

Dodgy experts often rely on overly emotional language, inject political agendas, or resort to personal attacks against critics in order to elicit strong emotions. This is a powerful tool for manipulating opinions when the evidence is lacking.

One of the most harmful examples of this is the use of emotional testimonials by dodgy experts who claim people have “beaten cancer naturally”, offering false hope and often leading patients to abandon proven treatments.

3. Dodgy experts cherry-pick evidence

Despite what those seeking to mislead you would have you believe, scientists only reach consensus when a large body of high-quality evidence points in the same direction.

So one of the most crucial skills experts possess is the ability to critically evaluate evidence. That means understanding its strengths and weaknesses, assessing its reliability, and synthesising what the full evidence base indicates. This task requires a deep understanding of their area of expertise.

Dodgy experts don’t do this. They tend to dismiss inconvenient evidence that contradicts their narrative and readily embrace flawed, or even discredited, studies. In short: they often cherry-pick evidence to suit their position.

Unfortunately, this tactic can be hard to spot if you don’t have an understanding of the full evidence base, which is something dodgy experts exploit.

A red flag that you are being misled by a dodgy expert is when there is a clear over-reliance on a single study, despite its low quality.

Perhaps the most well-known example of cherry-picking is the way dodgy experts rely on a single, discredited study to push the false claim that the MMR (measles, mumps and rubella) vaccine causes autism, while ignoring the vast body of high-quality evidence that clearly shows no such link.

Read more: Monday's medical myth: the MMR vaccine causes autism

4. Dodgy experts don’t change their mind when the evidence changes

Dodgy experts are often rigidly attached to their beliefs, even when new evidence emerges.

In contrast, genuine experts welcome new evidence and are willing to change their views accordingly. This openness is often unfairly portrayed as weakness, but it reflects an expert’s desire to understand the world accurately.

A striking example of this is the shift in our understanding of stomach ulcers. For years, ulcers were blamed on stress and spicy food, but that changed when Australian gastroenterologist and researcher Barry Marshall, in a bold move, swallowed Helicobacter pylori to demonstrate its potential role.

His self-experiment (which is generally not recommended!) was the first step in a broader body of research that ultimately proved bacteria, not lifestyle, was the primary cause of ulcers. This ultimately led to Marshall and his colleague pathologist and researcher Robin Warren being awarded a Nobel Prize.

As this example highlights, when presented with the evidence, clinicians and scientists acknowledged they’d got the underlying cause of stomach ulcers wrong. Clinical practice subsequently improved, with doctors prescribing antibiotics to kill the ulcer-causing bacteria.

This is how science informs practice so we can continually improve health outcomes.

In a nutshell

True expertise is marked by intellectual humility, a commitment to high-quality evidence, a willingness to engage with nuance and uncertainty, flexibility, and a capacity to respectfully navigate differing opinions.

In contrast, dodgy experts claim to have all the answers, dismiss uncertainty, cherry-pick studies, personally attack those who disagree with them, and rely more on emotion and ideology than evidence.