According to new research reported in Medical News Today, a hot
bath could have effects that extend way beyond mental
According to the authors, regular hot baths might reduce
inflammation and improve metabolism.
Over recent years, hot baths, saunas, and other so-called
passive heating therapies have received growing attention from
Scientists now believe they offer some potential benefits,
including improved vascular function and sleep.
Because hot baths are low cost and unlikely to cause significant
side effects, understanding any benefits that a hot bath might have
could be a quick win for medical science.
Recently, researchers set out to understand whether hot bath
immersion could have an impact on metabolic disorders, such as
Almost 20 years ago, a paper concluded that hot water immersion
of individuals with type 2 diabetes enhanced insulin sensitivity.
However, it is still unclear how this might occur.
In the most recent study, the researchers dug a little deeper
into the mechanisms at work.
They theorized that the influence of a hot bath over glucose
metabolism might revolve around the inflammatory response.
Inflammation and insulin resistance
There is some evidence that chronic, low-level inflammation
In other words, inflammation reduces a cell's ability to respond
to insulin, potentially contributing to the development of
Conversely, exercise has been shown to reduce inflammation and
improve insulin sensitivity - meaning that the body has better
control over glucose levels.
Although doctors often recommend exercise to reduce the risk of
developing metabolic disorders, not everyone can exercise - perhaps
due to health conditions or physical capacity.
It is, therefore, essential to find alternative ways to improve
insulin sensitivity for these people.
Exercise, as with other physical stressors, sparks a brief
inflammatory response, followed by a more extended
The researchers wanted to see if a different type of physical
stressor - a hot bath - might have a similar effect on the immune
For this study, the researchers investigated the impact of a hot
bath on overweight, mostly sedentary men. The findings were
published recently in the Journal of Applied
Hot bath intervention
Each participant immersed themselves in a water bath set at 39°C
(102°F) for one hour. Scientists took blood just before and after
the bath, and then two hours later.
Also, the researchers charted the participants' blood pressure,
body temperature, and heart rate every 15 minutes.
Over the following two weeks, the participants had a further 10
hot water immersions.
The researchers found that a single hot water immersion
caused a spike of interleukin - a marker of inflammation.
Similarly, there was an increase in nitric oxide (NO)
The spike in NO is important because it causes blood vessels to
relax, lowering blood pressure.
NO also improves glucose intake into tissues, and scientists
think it has anti-inflammatory properties.
As expected, the two-week intervention saw a reduction in
fasting blood glucose and inflammation. In the same way that
exercise influences inflammation, the researchers saw an initial
increase followed by a long-term decrease in inflammation.
The authors conclude:
"[Hot-water immersion may] improve aspects of the
inflammatory profile and enhance glucose metabolism in sedentary,
The researchers also write that it "might have implications for
improving metabolic health in populations unable to meet the
current physical activity recommendations".
It is important to note that the people who took part in the
study did report some discomfort.
This was either due to the length of time that they were
required to stay in the bath or the high temperature.
Future research might investigate whether shorter periods or
lower temperatures might have similar benefits.
Hot baths alone cannot treat metabolic disorders, but they may
be a simple, cost-effective intervention that can run alongside