IN SHORT: Walking barefoot and "being in touch with Mother Nature" might have its benefits. But there is little scientific evidence that the concept of "earthing" can heal various diseases.
"Modern shoes making us sick?" asks the headline of a video circulating on social media in June 2023. The video has been viewed over 14,000 times.
It shows clips from a documentary - The Earthing Movie: The Remarkable Science of Grounding - and was also posted on a Facebook page advertising the film.
Similar posts have appeared on Facebook, while one Twitter user wrote: "Yet another way that the modern world is failing our health is the shoe."
In the video clip, someone holds up a synthetic-soled shoe and claims: "This was the single thing that probably caused the proliferation of inflammation-related health disorders far and above anything else."
The idea relates to "grounding" or "earthing", a practice that centres around supposed health benefits of being in direct contact with the ground. We looked into the evidence surrounding this popular wellness trend.
'Earthing' or 'grounding' theory and physics
According to the Earthing Institute, the practice of earthing can heal disease by transferring electrons from the earth's surface to the human body. The therapy falls under the umbrella of complementary and alternative medicine (CAM). CAMs are treatments that generally do not have a scientific basis, and are either used in addition to or instead of conventional medicine.
CAMs often, but not always, claim to be supported by some theory and evidence. Proponents of earthing suggest the therapy works because direct physical contact with the earth's surface, like when walking barefoot, balances electrical charges in the body.
"It's like taking handfuls of antioxidants, but you're getting it through the feet," a narrator in the clip explains.
Chad Orzel wrote about the physics involved in the practice of earthing back in 2014. He's an associate professor in the physics and astronomy department at Union College in the US.
According to Orzel, the theory of grounding proposes that when we don't have contact with the ground, our bodies "pick up a positive charge relative to the Earth", causing illness. But connection to the ground, like being barefoot, equalises this potential difference.
This is important, according to the Earthing Institute, because this process neutralises the damaging "free radicals", unstable molecules in the body that could damage cells and trigger inflammation, causing a range of illnesses.
But Orzel criticised the physics underlying this idea. He said there was no difference between the electrons that come from the earth and electrons that come from a synthetic material you touch. "Electrons are electrons," he said, and if there was a difference, "chemistry would be a mess".
But proponents have responded to such criticisms by saying that "standard scientific models can't account for the details of this transfer". So maybe science just doesn't yet understand the mechanisms of how it works. What about if it works?
Grounding: concrete evidence?
Scientists have conducted limited research on the effects of grounding on human health, with some positive results. For example, some studies suggested earthing could help balance circadian rhythms, the cyclical 24-hour period of biological activity, or could help thin the blood, which might in turn lower the risk of cardiovascular disease.
But these studies have been small, and were not placebo-controlled or double-blinded. This means that the placebo effect or other factors could explain these results.
Other research has been more rigorous. Some studies with placebo conditions have suggested grounding could have positive effects including body relaxation, enhanced mood, or reduced muscle damage.
But before you ditch the shoes and buy expensive earthing mats and other products, it is important to note that this research might not be all that water-tight.
These studies have also been conducted on very small samples of people, and were largely funded and conducted by earthing companies and people affiliated with them.
For instance, Gaeten Chevalier, director of the Earthing Institute, authored many of the studies available. There is a need for independent studies, to reduce the chances of anything biassing the results.
There have also been mixed results when studies are replicated. Replication is an important part of scientific research - a study that yields the same results when it is repeated is much more trustworthy than a once-off investigation.
But, for example, a 2010 study found large differences in white blood cell count, signalling inflammation, and pain in earthing versus control groups, but a similar 2015 study found no significant differences.
All in all, there needs to be independent, rigorous research with large samples to test the idea before anything can be concluded about the effects of grounding on human health.
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Inflammation, shoes and disease
Inflammation is part of the body's natural immune response to infection or injury. But sometimes inflammation can last for a long time or be triggered when there is no injury or infection. This is when it can be damaging, according to the US-based National Institute of Environmental Health Sciences (NIEHS).
This damaging inflammation is linked to a range of diseases, like asthma, inflammatory bowel diseases, rheumatoid arthritis, cardiovascular disease, type 2 diabetes, as well as some types of mental illnesses and cancers.
Inflammation can have a variety of causes. Chemicals in the environment, as well as diet, stress, exercise, microbiome imbalances and prenatal conditions all have links to inflammation, according to the NIEHS.
But there is no scientific evidence backing the idea that wearing synthetic-soled shoes, and so not being in direct contact with the ground, "caused the proliferation of inflammation-related health disorders", or is making us sick.
As experts have pointed out, there isn't any convincing theoretical basis for the idea either.
