From Simon Joller on srf.ch:
More and more people are taking ice water baths since the COVID-19 pandemic, believing it benefits both body and mind. Goodbye flu, farewell winter blues. It’s also believed to aid in weight loss and protect against cardiovascular diseases long-term. While research has had to moderate some of these claims, it also confirms certain effects.
This view is shared by physician and extreme swimmer Beat Knechtle. He says he’s been asked so frequently about the effects of swimming in ice water in recent years that he wrote a review article (https://phc.swisshealthweb.ch/fileadmin/assets/PHC/2023/phc-d.2023.10702/phc-d-2023-10702.pdf) on the studies. His conclusion: there are indications of health benefits. However, similar benefits can be found in jogging, cycling, or swimming in normal water temperatures. This suggests that the benefits are more likely due to physical activity rather than the water temperature.
The full article can be found at the following link: https://www.srf.ch/wissen/mensch/trend-ums-kalte-bad-eisbaden-macht-es-gesuender-oder-ist-alles-nur-einbildung.