Cold is the new hot in spa circles, but sceptics question whether the benefits of such practices are proven.

Two separate studies published in August and September, however, suggest there are still avenues to explore.

Boosting ‘good’ fat

In a review of multiple scientific papers, researchers from Norway say there’s evidence that an icy swim may increase ‘good’ body fat and reduce the risk of diabetes.

The review, published in the International Journal of Circumpolar Health*, analysed 104 studies looking at the health benefits of cold water swimming, paying attention to sample size and other limitations.

Themes covered by studies that were eligible for review included inflammation, adipose tissue, blood circulation, immune system and oxidative stress. Some of these provided evidence that cardiovascular risk factors are improved in swimmers who have adapted to the cold. Yet others suggest the workload on the heart is still increased.

The authors did, however, highlight the positive links between cold water swimming and brown adipose tissue (BAT), a type of ‘good’ body fat that’s activated by cold.

BAT burns calories to maintain body temperature unlike ‘bad’ white fat which stores energy.

According to the review, cold exposure in water – or air – appears also to increase the production of adiponectin, a protein which plays a key role in protecting against insulin resistance, diabetes and other diseases.

In conclusion, the researchers said that more evidence was needed to identify risks associated with cold water immersion.

Spa Business’ most recent issue takes a deep dive into cold water immersion and asks scientists, cold water therapy specialists and retreat leaders about how spa and wellness operators can offer the experience in the safest way possible.

Check out the feature here.

Tumour suppression Another separate study by Swedish scientists at the Karolinska Institute** has found that low temperatures make it more difficult for cancer cells to grow.

Published in the journal Nature, the paper compared tumour growth and survival rates in mice with various types of cancer, when exposed to cold versus warm living conditions.

Mice acclimatised to temperatures of 4˚C had significantly slower tumour growth and lived nearly twice as long compared with mice in rooms of 30˚C.

The theory is that turning down the thermostat activates heat-producing brown fat that consumes the sugars that tumours need to thrive.

Corresponding author professor Yihai Cao says: “We found that cold-activated brown adipose tissue [BAT] competes against tumours for glucose and can help inhibit tumour growth in mice.

“Our findings suggest that cold exposure could be a promising novel approach to cancer therapy, although this needs to be validated in larger clinical studies.”

*Source. Mercer, JB et al. Health effects of voluntary exposure to cold water – a continuing debate. International Journal of Circumpolar Health. September 2022

**Source: Cao, Y et al. Brown-fat-mediated tumour suppression by cold-altered global metabolism. Nature. August 2022