Cold Showers are Gettin' Hot

What does the science say about cold exposure therapy?

Top of the morning, ultrahumans. Welcome to Common Sense Medicine, where I try and keep you up to date on the latest and greatest in longevity science.

I know, I know, the ultrahuman cliche might get a little tired, and I recognize that I’m not a self-professed biohacker, but the other word that I was considering was “sapiens.” Reply to this post to let me know which one you might like better.

This week, I’m exploring a topic that has been beaten to death by many bro-science and “normie” scientists alike—does cold exposure therapy, more specifically cold showers, actually do anything to help you physiologically? Or are they just one part of the toolkit which help promote longevity?

Other items on the differential:

• Some longevity tactics and strategies to implement in your life

• Why Vox thinks you should eat less protein (I disagree)

• Elon Musk’s microchip comes to human trials

THE WEEKLY DOSE

I’m starting to warm up to cold exposure therapy

If you’ve been around anyone who is vaguely into the self-improvement space, you’ve definitely heard of cold exposure therapy, cold showering, or ice baths. Essentially, this is just submerging yourself under cold water for some portion of time purportedly to gain better discipline for doing hard things, help with recovery, or plain just masochism (hey, we don’t discriminate here at Common Sense Medicine).

As I’ve been playing with this method of cold exposure, I’ve heard various claims on how it can help you—from improving inflammation to hastening lymphatic flow, there are a couple of things which have been said about cold exposure. I want to systematize how I think about cold exposure and what I’m doing to reap benefits in a low-cost manner, without having to break the bank.

Cold water immersion has three different variables, from what I’ve seen

When people talk about cold water immersion, they largely use three different variables to codify how they prescribe a bout of immersion therapy—time, immersion setting, and temperature

• Time: Usually, this can start off as low as 60 seconds at the end of a warm shower, but it has various levels. From a 60 second immersion stint, the practitioner can then move on to a totally cold shower, without the temperature slide, and increase to a longer cold session. Dr. Andrew Huberman of Huberman Lab fame has described a protocol length of 11 minutes weekly for total time under cold water, but I couldn’t find any source which would suggest that is the minimum therapeutic dose.

• Immersion setting: If you’re economical, like me, this will probably be your shower. People get fancier with their set ups, having dedicated cold plunges outside, or even chest freezers where they are able to lay down and put their head under water. Ice baths are actually pretty different than cold showers, and ice baths generally get colder and provide more of the benefits versus cold showers, according to the studies which I’ve read.

• Temperature: There is no consensus as to which is the best temperature for a cold plunge, having purported different benefits for various maladies, but anything that causes vasoconstriction (not studied unfortunately, but mechanistically sound) is said to increase body temperature, which can help with metabolic effects. Creating this uncomfortableness is based on your particular set-point and how you respond to the temperature.

The Chads are divided amongst this front, and argue that the stress exposure is not worth it

When I was looking up various X threads and looking up different websites to get a biohacker, or broscience perspective on cold showers, it was widely divergent—there were some people who lauded the idea of cold showers, and mentioned that they were a godsend. They mentioned how they increased their testosterone, increase dopamine for greater motivation, and decreased inflammation.

In my research, I revisted the work of Wim Hof, who has also picked up steam as the self-reported “Iceman” who loves exposing himself to the cold. He’s mentioned cold showers as one of the ways to expose himself to the elements, and works with breathing and meditation as his trifecta to a healthier, happier life.

However, there was another camp which mentioned that cold showers were putting stress on the body which constituted undue harm on the body. They mention that cold exposure therapy has been widely overstated, and that the benefits that have been described are baloney. I tend to agree with this, because cortisol levels spike when we first wake up, adding another stressor to make us even more awake and alert may decrease the benefits that we get via the “immunity-promoting” factors. In fact, the people who are more likely to do cold showers are also those who are more prone to other health behaviors, so it might just be self-selecting for those who care for their health already rather than the cold shower promoting that health.

Trads have a lot to learn in this space, but mention the basics

Because the Trad Health model lags behind the Chad Health experimenters, it’s hard to say whether it’s a miracle cure or not. To their credit, various health system and outlets have been putting out science-based communication on what physicians and other health professionals know about cold exposure therapy. Furthermore, there’s been a lot more research (7% compound annual growth rate in terms of publications published) in explaining how cold water immersion can (1) help recovery, (2) lead to more disciplined workers, and (3) stave off mental health issues, among more.

According to trad health enthusiasts, the publications which social media health gurus like Dr. Andrew Huberman cite can be inaccurate. One commenter, Stuart Ritchie, took the time to dismantle one of the studies which Huberman was using for promoting cold exposure therapy and found that it was p-hacking, or using multiple comparisons to find one association which showed clinical significance (p=0.05) largely because of randomness (see: multiple hypothesis testing).

Also, the metabolic effects are largely overstated because the cold exposure that it takes for thermogenin to kick in, according to one study, is 2 hours (!). So that 10 minute shower may not be helping your case when you’re getting ready in the morning, although it may make you feel like a savage.

My take: cold showers are not a magic pill—they might be better than placebo though

Trad Health incentives largely allow publishing any positive association, in a pay-to-play fashion, so I’m not surprised that bad science gets out, nor am I surprised that biohackers make unhinged claims like boosting testosterone 400% by taking one cold shower. However, I believe that there is some truth to the power of cold showers. My “dry January” was more like a “wet January" as I experimented with a cold shower for 22 days out of the month, with 8 days at the beginning to act as a control.

I found that while I had drier skin (obviously, I was taking 2 showers a day, one cold and one warm post-workout), I didn’t notice a real uptick in discipline. I think it’s just a superficial way to say that you’re “doing something” but not actually doing anything. Largely, I found myself wasting time the days that I didn’t want to go in the cold shower, and that it didn’t really motivate me but rather made me hesitant to start my day, delaying the worst.

There’s a case to be made that it helps for my personal recovery, though. The soreness from past workouts melted away as I went in the cold shower, and I was able to focus more on my morning workouts as I was more awake, thanks to putting my head under cold water. It probably upregulated thermogenesis through the browning of white adipose tissue, but I didn’t find myself losing too much weight during the challenge. In fact, athletes have been using ice baths to recover from strenous exercise, and it’s a known side effect of dunking yourself in freezing water that you probably can’t feel much after you get out (but boy, does it feel nice!).

And let’s talk about mood. It staves off sad feelings probably as much as eating chocolate staves off sad feelings, which is to say—maybe a little? I think that my noticing of a bad mood is largely through something that happens maybe a little more towards the middle of the day, if I’m being honest, so I didn’t find anything to be particularly noticeable in terms of an uplift of mood.

We’ll see how this plays out, but I’m probably not going to be doing a cold shower every day. I’ll use it as a tool to get myself into shape, and wake myself up to reduce caffeine consumption (mine is pretty low already, about once a week I drink 1 cup of coffee or a matcha latte). When and if I get access to a sauna, I’m going to try and alternate the two—I’ve seen pretty compelling evidence that pairing the two might make sense although I have not tried it myself. It would make sense that warming and then cooling yourself is intuitively something that makes sense because it allows you to spend longer in each setting, and modulate the temperature which you’re exposed to, but I’ll have to save that for another issue.

THE PRESCRIPTION

• Eat ya fruits and veggies: Mice undertaking a lifelong high-fat diet with fruit and vegetable supplementation (read: powder, yuck) lived longer than, and had less tumor incidence, than those which did not eat fruits.

• Miracle powder (JK): Astaxanthin (the antioxidant and inflammation modulator which gives salmon its’ pink color) and Meclizine (an antihistamine which gives salmon their pink color) caused mice to live 12% and 8% longer, respectively.

• Back pain, begone: Dr. Peter Attia mentions how strength & stability go hand-in-hand when he discusses the three most common prophylactic exercises for back pain (56 minutes in) with Stuart McGill, PhD.

FIGURE OF THE WEEK

The upshot: Vox notes that American people eat more protein than is recommended by the federal government—getting most of it through animal sources. They argue that this focus on protein is missing the bigger gap of people eating fiber. (source)

My take: Nutrition is one of the hardest things to study, largely because there are so many different variables to control. If we had a sterile environment where I could control every single variable in your body and measure anything that I wanted to, I still might not be able to get causality for any large length of time. A lot of people on Twitter / X were getting mad at this chart because it didn’t explain the larger picture—the fact is, we eat a lot of ultra-processed food in the U.S., most of which also comes with protein.

The fact that we’re eating more calories in general may correspond to why we’re eating more protein, but it’s not only because we’re eating more protein that we’re unhealthy. Also, the fact that we’re not eating enough fiber is an unrelated point, which, while true, doesn’t correspond to the fact that we should be eating less protein due to the guidelines. Based on the current guidance, my recommended daily amount (RDA) of protein is 57 grams (Calculate your own here). In my opinion (and the research), that’s hogwash, especially if you’re taking care of your body and working out multiple times a week (which you should, if you care about longevity). Now, the average American may only need 50 g if they’re not working out, but I would argue that they would probably be a lot healthier if they did increase protein and fiber intake. I think the closer recommendation should be 1.6 - 2.2 g / kg.

JOURNAL CLUB

• Inflammaging: Gut inflammation (as measured by calprotectin due to its’ ability to recruit monocytes) was correlated with a higher distribution of amyloid plaques in Alzheimer Disease patients (n=125) in an observational study.

• uPAR-fect: Targeting an aging-related protein called urokinase plasminogen activation receptor using genetically modified immune cells can reduce signs of metabolic aging.

• Cyborgs Among Us: Elon Musk announced that the first human implant of Neuralink, a brain-computer interface, has been completed. (study brochure)

REMEMBER, IT’S JUST COMMON SENSE.

Thanks so much for reading! If you have a chart, longevity tactic, or paper which you’d like me to check out, respond to this email.

See you next week,

Shree (@shree_nadkarni)

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The information provided here is not medical advice. This does not constitute a doctor patient relationship and this content is intended for entertainment, informational, and educational purposes only. Always consult with a doctor before starting new supplementation protocols.

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