Beware: that hot spring spa might be full of snake oil

The hot springs industry is reported to be worth $50 billion globally and seems only set to grow as the post-pandemic preoccupation with health and wellness continues.

In Australia, new developments include Victoria's Alba Thermal Springs & Spa, which opened in October 2022, and Metung Hot Springs which launched a month later. Both facilities are part of the Great Victorian Bathing Trail currently under development.

Further north, in outback Queensland, Cunnamulla Hot Springs is set to throw open its doors in June 2023, while across the ditch, Belgravia Leisure is preparing to open Wai Ariki Hot Springs and Spa in August, in Rotorua, New Zealand. It will join the company's Hepburn Bathhouse & Spa in Victoria which has been operating in some form since the 1880s.

Propping up this growth are hot springs operators’ claims that time spent submerged yields a host of health benefits.

But much of the science on which they base these conclusions is either non-existent or methodologically flawed.

Much of the science on which they base these conclusions is either non-existent or methodologically flawed.

Peninsula Hot Springs claims that its geothermal mineral waters can reduce symptoms of arthritis; promote healthy skin; build muscle mass, strengthen bones and boost brain activity; and normalise heart rhythms and reduce high blood pressure.

Its Mornington Peninsula neighbour, Alba Thermal Springs & Spa, reports that its waters alleviate neuralgia, bruising, articular rheumatism, stiff shoulders, fatigue and muscular complaints.

As for the calcium, magnesium, bicarbonate, chloride, sulphate, silica and soluble salts in its waters, Hepburn Bathhouse & Spa blithely states that the combination "has powerful healing properties which are all known for their wellness benefits".

And other operators claim that that these improvements come about due to a combination of the chemical composition and temperature of their artesian waters.

However, there's no evidence to support the notion that these waters have healing properties, according to researchers who undertook the first systematic review aimed at determining the potential health outcomes relating to exposure to Australian or New Zealand spring water.

There's no evidence to support the notion that these waters have healing properties.

The review was undertaken in 2018, and in the intervening years, no new evidence has come to light.

"We simply cannot find any evidence that says exposure X in the water will help your disease Y – that evidence simply does not exist," says Professor Philip Weinstein, a Professorial Research Fellow within The University of Adelaide's School of Public Health.

The study's first author, Dr Jessica Stanhope, a lecturer at The University of Adelaide, says such health claims, when made, typically represent quite a stretch.

They tended to cobble together a kernel of truth – such as the important role that magnesium plays in many bodily processes – with the content of their waters.

"They’re choosing bits that are useful for marketing, but not necessarily reflective of the evidence and the science behind it," she explained in an interview.

"They’re choosing bits that are useful for marketing, but not necessarily reflective of the evidence and the science behind it."

"Is it that you need to drink [the water], or do you bathe in it? Is the dosage right? What ongoing exposure do you need for the benefits, beyond a weekend at the spa? There's that missing bit of the story often."

Weinstein noted that while it was reasonable to expect some health benefits from the experience, "that has nothing whatsoever to do with the ‘snake oil’ claims of healing properties of the chemical or geothermal constituents of the water".

"The warm water does have benefits for arthritis, in the same way that moving to the tropics has benefits for arthritis, with many individuals having cold-sensitive joints," he explains.

"The spa experience may be relaxing, may be a break, and may reduce stress – and stress reduction has the potential to reduce the severity of symptoms, or the perception of their severity, for just about anything."

It was important to disentangle claims about the water from all the other elements present in hot springs getaways, Weinstein added.

"As a package, if you do the spa trail, and you’re with your friends, and you have a glass of wine, and you’re away from work, and it's like a holiday and you feel better… the actual chemical composition of the spring water has absolutely nothing to do with it," he says.

Get an update of science stories delivered straight to your inbox.

"You feel better… the actual chemical composition of the spring water has absolutely nothing to do with it."

Stanhope and Weinstein's paper entitled "Do natural spring waters in Australia and New Zealand affect health? A systematic review", was written with The University of Western Australia's Angus Cook, and published in the Journal of Water and Health in 2018.

Their review started with a search for studies that included terms such as "spring", "mineral", "thermal", "curative" and "artesian".

Only 11 papers met a range of inclusion criteria, which included the use of appropriate comparison groups. Papers also needed to have been subjected to the peer-review process, and concerned only with natural spring water, rather than treated or supplemented water.

"We found no published studies which have reported studies investigating whether treatment with Australian or NZ spring water is effective, when compared with other types of water treatments," the authors wrote.

"This may reflect publication bias, or that studies involving formal comparisons have yet to be conducted.

"Based on this evidence, within an evidence-based practice framework, these therapies should not be recommended by health and medical professionals."

The authors acknowledge that there are some international systematic reviews which suggest that spring water therapies may have some benefits, but even these "failed to exclude studies which did not have a comparison group utilising different types of water".

"It is therefore difficult to determine whether the spring water itself provided the benefit, or whether any other type of water applied in the same manner may have been just as effective," the authors note.

Given that the water quality of individual springs varied, they noted that international studies were not necessarily relevant to the Antipodean environment.

The researchers identified a range of potential adverse health outcomes associated with drinking and bathing in spring waters, including diarrhea, in-water fatal hydrogen sulphide poisoning, drowning and fatal primary amoebic meningoencephalitis (brain-eating amoeba).

Although all identified cases of the latter occurred in one region of NZ, Weinstein points out that the risk is present in any environment where these amoebae thrive.

"Depending on the naturalness of the environment, if soil gets into your warm water, you’re guaranteed to have those parasites in there," he says.

"Depending on the naturalness of the environment, if soil gets into your warm water, you’re guaranteed to have those parasites in there."

Karen Golden, General Manager (Executive) of Tourism and Wellness within Belgravia Leisure, said that while "it was hard to put evidence to" some of the health benefits claimed by the industry, more and more research was emerging as interest in the sector grew.

Belgravia Leisure runs the recently renovated Moree Artesian Aquatic Centre, is behind the soon-to-open Wai Ariki and has, according to Golden, at least two more projects in the pipeline.

"There is some evidence out there, and there's a lot of work being done at the moment on that," she explains.

"But if you’ve been to use them, you know how you feel. Because if you have had those beautiful hot mineral springs experiences, you want more, and that's why the industry is growing – people are realising that there is a benefit."

"That's why the industry is growing – people are realising that there is a benefit."

One paper which Stanhope didn't include in her research – because it was conducted in Italy rather than Australia or New Zealand – was the first double-blind randomized clinical trial to investigate the effect of balneotherapy, or bathing in thermal mineral waters, in patients with fibromyalgia syndrome.

Though the 100-participant study found that the intervention reduced pain and improved function, Stanhope raised a few methodological concerns, such as the absence of true randomisation.

Nevertheless, the study represented a step-up compared to many others in the field.

Originally published by Cosmos as Beware: that hot spring spa might be full of snake oil

Denise Cullen is a Brisbane-based freelance writer who contributes to a range of local and international publications, including The Australian, The Guardian Australia and Narratively. She is also a registered psychologist.