Ask the Doctors: Cold plunge is a form of whole-body cryotherapy

Dear doctors: It’s a tradition in my husband’s family to start the new year with a dip in the ocean. I see on social media that doing a cold plunge is now a craze. Is it true that it’s good for you?

Dear reader: Enthusiasts on TikTok, where cold-plunge videos are amassing millions of views, are advocating a practice that goes back thousands of years. The use of cold as a therapeutic agent is referred to in texts left behind by the ancient Egyptians and cited as beneficial by the ancient Greeks.

How long the dip lasts, how often it is done and how cold the water is varies. The common denominator is that subjecting your body to a sudden and prolonged change in temperature confers physical and mental health benefits.

The cold plunge falls into a treatment category known as whole-body cryotherapy. It involves the application of ice, cold air or cold water.

Proponents cite a varied list of benefits including pain relief, improved exercise recovery, better sleep, sharper focus, improved mood, lower levels of inflammation, enhanced immune function, improved insulin sensitivity, better tolerance of mental and emotional stress and boosted metabolism.

Data definitely support the idea that cold exposure can confer health benefits. But research into the practice is mixed, and cold-plunge skeptics will also find studies to cite.

An intriguing area of inquiry in cryotherapy is its potential effect on what’s called brown fat — a type of fat the body uses to maintain body temperature by breaking down fat and blood glucose, each a welcome metabolic action. Brown fat is activated by cold temperatures.

Anyone who wants to try a cold-water therapy should ease into it. Some enthusiasts say icy showers are a good way to begin. For full-body immersion, start with brief, controlled exposures of 10 to 20 seconds. If longer dips are the goal, get there gradually.

But a cold plunge can have adverse effects. When suddenly immersed in cold water, your body scrambles to preserve core temperature. Blood vessels constrict, the heart races, blood pressure shoots up, and you begin to hyperventilate.

None of this is safe for people with heart conditions, poor circulation and certain other health issues. Also, because water conducts heat from the body far more quickly than air, it doesn’t take long for core body temperature to drop. As the body directs blood flow to protect vital organs, strength and coordination are lost.

So check with your health care provider before giving the cold plunge a shot.

Dr. Eve Glazier and Dr. Elizabeth Ko are UCLA Health internists.