Taking a dip in ice-cold water can reduce bad body fat in men and reduce the risk of conditions such as diabetes, a new study suggests.
Researchers looked at 104 studies and found that many reported significant effects from cold water swimming, including on good fats that help burn calories.
They suggest that this may protect against obesity and cardiovascular disease.
But the review was overall uncertain about the health benefits of cold water bathing, an activity that is becoming increasingly popular.
From this review, it is clear that there is growing scientific support that voluntary exposure to cold water can have some beneficial health effects
James Mercer, UiT
It is unclear whether winter bathers are naturally healthier or not, says the research team from UiT Norway’s Arctic University and the University Hospital of Northern Norway.
Lead author James Mercer, from UiT, said: “From this review, it is clear that there is increasing scientific support that voluntary exposure to cold water can have some beneficial health effects.
“Many of the studies showed significant effects of immersion in cold water on various physiological and biochemical parameters.
“But the question of whether these are beneficial or not for health is difficult to assess.
“Based on the results of this review, many of the health benefits claimed from common cold exposure may not be causal.
“Instead, they can be explained by other factors, including an active lifestyle, trained stress management, social interactions, as well as a positive mindset.
“Without further conclusive studies, the topic will continue to be a matter of debate.”
The review indicated a positive association between swimming in cold water and brown adipose tissue (BAT), a type of good body fat that is activated by cold.
BAT burns calories to maintain body temperature, unlike “bad” white fat that stores energy.
The study found that cold exposure in water – or air – also appears to increase the production of the protein adiponectin in adipose tissue.
This protein plays a key role in protecting against insulin resistance, diabetes and other diseases.
According to the findings, repeated immersion in cold water during the winter months significantly increased insulin sensitivity and decreased insulin concentration.
Much of the available research involved small numbers of people, often of the same sex, and with different water temperatures and salinity levels.
The new study reports that weight loss, better mental health and increased libido are among many health and wellness claims made by proponents of regular cold water immersion or arising from anecdotal cases.
It can take many forms such as swimming in cold water in winter, and is the subject of increasing interest worldwide.
The main aim of the review was to find out whether voluntary exposure to cold water has health effects in humans.
Researchers excluded studies where people wore wetsuits, accidental immersion in cold water and water temperatures above 20 degrees Celsius.
However, they say that education is also needed about the health risks associated with taking a dip in freezing water.
These include the consequences of hypothermia and heart and lung problems that are often related to the shock of cold.
The findings are published in the International Journal of Circumpolar Health.