WIM HOF, also known as The Iceman, is a Dutch motivational speaker and extreme athlete noted for his ability to withstand low temperatures. He has a Guinness World Record for swimming under ice and a record for a barefoot half marathon on ice and snow.
While Hof says his method benefits various health conditions, there is little scientific basis for these claims.
Much of the Wim Hof Method is based on natural vagus nerve stimulation. The vagus nerve is the body’s longest nerve, stretching from the brain to the abdomen. It is the critical player in the parasympathetic nervous system, the ‘rest and digest’ system that calms the body during times of low stress.
“If you are relaxed, if you are sleeping, if you are in a restorative phase, it’s the vagus nerve dominating,” Prof Gregor Hasler, a psychiatrist with an interest in the gut-brain connection at the University of Fribourg in Switzerland, told Scientific American in 2023.
Natural stimulation of the vagus nerve occurs after exposure to acute cold conditions such as taking a cold shower or jumping into the Irish sea. While the body adjusts to the cold, sympathetic nerve activity drops and parasympathetic (vagus) nerve activity increases.
Deep breathing activates specific neurons that detect blood pressure. When these neurons signal that blood pressure is becoming too high, the vagus nerve responds by lowering the heart rate.
Meditation helps to stimulate the vagus nerve by signalling there is no need for a fight-or-flight response, thereby increasing vagal tone.
A new field of medical research is emerging — bioelectronic medicine — that moves beyond natural stimulation to electrical stimulation of nerves.
In 1997, the Food and Drug Administration approved vagus nerve stimulation (VNS) to supplement epilepsy treatment in the US. Doctors subsequently noticed that the treatment appeared to improve mood, regardless of whether it improved seizures. Further clinical trials in Europe, Canada, and the US led to VNS receiving FDA approval for treatment-resistant depression in 2005.
More recent research is investigating the impact of VNS on the immune system, the complex interlinked network that works around the clock to protect us from infection. But sometimes, these systems go haywire, attacking our bodies instead and causing damage. Cell damage leads to inflammation. Autoimmune diseases such as rheumatoid arthritis, Crohn’s disease and multiple sclerosis are painful, debilitating diseases usually treated with a combination of drugs, often with by painful side effects.
Neurosurgeon Kevin Tracey at New York’s Feinstein Institute has spent decades exploring the impact of one of these inflammatory molecules: Tumour Necrosis Factor (TNF). Tracey and his team discovered that the nervous system carried signals controlling the production of TNF.
Their first paper, ‘The Inflammatory Reflex’, published in Nature in 2002, tested the theory by stimulating the vagus nerve in animal studies. It opened the gates to a revolution in bioelectronic medicine — merging the fields of neuroscience, molecular medicine and bioengineering to harness brain and neural signals to treat insult or injury using devices targeting nerves to stop inflammation.
This breakthrough led to the development of the first ‘bioelectronic’ medical device in California. It was designed to be implanted alongside the vagus nerve in the neck, which connects the brain to the major organs, including the lungs, heart, gut, and spleen, where TNF is produced.
In a 2016 study, researcher Dr Frieda Koopman conducted the first trial of this implant on patients with rheumatoid arthritis in Amsterdam. The device was implanted into the patients’ chest and connected to an electrode that coiled around the critical groups of fibres in the vagus nerve. The patients controlled the stimulation of the device daily.
Most patients in the trial saw improvements in symptoms and a reduction in TNF. However, during one phase of the trial, all were asked to stop using the device, and during this time, the majority saw their symptoms worsen and TNF levels rise.
Researchers in Sheffield Teaching Hospital, NHS Foundation Trust, are commencing a new clinical trial, the Triceps study, over the next 18 months. Stroke patients will be recruited to assess whether VNS therapy can help promote recovery. This trail follows evidence that VNS following induced stroke in animal studies mitigated the amount of lasting brain damage.
As we continue to learn more about the links between the nervous system and the immune system, bioelectronics has the potential to be used for minor ailments such as migraine via devices applied to the skin of the neck, as well as a major player in the armoury of treatments for diseases characterised by devastating inflammation.
- Dr Catherine Conlon is a public health doctor and former director of human health and nutrition at safefood
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