Scientists Explain How Cold Could Boost Heart Health

The changes were massive. 17 out of 17 involved in the effects of THC more resilient to this metabolic challenge. What if a simple plunge into icy water could unlock a cascade of health benefits, including improved heart health and reduced inflammation? That's the tantalizing question explored in a groundbreaking study on cold exposure and its effects on omega-6 and omega-3 fats—key players in your body's metabolic orchestra. So let's plunge in. But before I get to the study, permit me just a few seconds to say what honestly inspired my deeper dive into this topic of cold plunging. I recently got myself a plunge despite my absolute abhorrence—genuine abhorrence—of cold water. But I forced myself to do it, and I've been chilling myself daily for 3 weeks. And I've noticed improvements in my mood. I actually feel a natural high, and I'll give some insight into that later in this video, and improvements in my sleep. If this is something that interests you, you can check out the link below and use a discount code to get your own Plunge, or if you live in Boston like me, you can also go out in the winter and just sit in some snow. But anyway, now on to the free metabolic health learning. In this study, they exposed 64 adults to 2 hours of cold exposure near their shivering thresholds, and they measured levels of different signaling lipids, basically fat-based hormones, in their blood. The changes were tremendous, and they included large shifts in derivatives of omega-6 and omega-3 fatty acids, and also changes in endocannabinoid signaling, and much more. I'm not going to go through all the lipid changes—there were a ton—but rather highlight a few that I found particularly interesting. First, changes in something called oxylipins, which are derived from the oxidation of omega-6 and omega-3 polyunsaturated fats in the body. Now, you may think of oxidation, like inflammation, as bad, but that's not necessarily the case. In response to a short-term stressor, like cold or heat, or exercise, the body can have a challenge response that triggers adaptation that makes us overall stronger and healthier. This is the concept behind hormesis— maybe that's a term you've heard— or the metabolic equivalent of what doesn't kill you makes you stronger. So let's first chat about the omega-6 oxylipins, derivatives of omega-6 fatty acids like linoleic acid. Cold exposure increased levels of one oxylipid called 12,13-dihydroxy-9Z octadecanoic acid, I know, or 12,13-DHOMI for short. Maybe it's DIHOMI. It increased it by 39%, and this 12,13-DHOMI has been shown to increase the uptake of fatty acids by brown fat, which produces heat, and skeletal muscle. This is presumably a very good, healthy adaptive response. But what's even more impressive than the omega-6 response was the omega-3 response. 17 out of 17 omega-3 fats and their derivatives increased in the blood after and during cold exposure by an average of 77%. That's pretty tremendous. And the most prominent change, with an increase of 155%, was a molecule called 14-hydroxydocosahexaenoic acid, or 14-HDOHE for short, which has been shown to inhibit the activation of platelets involved in blood clots and increase blood flow and inhibit inflammation. And there were increases noted in something called resolvin D5, a powerful anti-inflammatory compound that inhibits the production of inflammatory molecules like interleukin-6, reduces pain, and protects various organs from inflammatory damage. And there were changes in endocannabinoids, like increases in something called anandamide, which binds to the CB1 receptor, a key receptor involved in the effects of THC. Yes, THC, that THC. I'll let you put two and two together on that. I'm not saying that a cold plunge will make you high per se, but it's an interesting mechanistic overlap and one that also overlaps with some people's experiences. I could go on, but the fact is this was an exploratory study meant to discover what changes in the cold. And bottom line, the changes were massive. And my interpretation overall is that they likely reflect a challenge response of the body where various organs around the body were systemically releasing fat signaling molecules to promote healthy resolution —of inflammation and further adaptations to make the body more resilient to this metabolic challenge. And of note, in a subgroup analysis, the overall response was actually impaired somewhat in people with overweight or obesity. In other words, these changes were larger in those who were lean and generally metabolically healthy. And to me, the most likely interpretation is that cold, just like exercise, is a metabolic challenge, and how the body responds to this metabolic challenge is akin to a metabolic litmus test of good health. Kind of like a stress test at the doctor's office. But also, it could mean, now extrapolating, that being metabolically healthy helps you extract more benefit from cold exposure. There are actually other examples like this in the literature, like different gene expression patterns after exercise in those who are insulin resistant versus those who are insulin sensitive. Now, what this means is that basically being metabolically healthy can help set up a positive feedback loop whereby you get more bang for your buck when you engage in metabolic health challenges like exercise or cold exposure. Being metabolically healthy helps you get even more metabolically healthy. Pretty cool, right? So, in summary, do I recommend cold exposure and cold challenge from a metabolic health perspective? Well, yes. For more on why I do, you can also see this video where I talk about effects on mental health and more on inflammation. But in general, I see cold exposure like I see exercise—a healthy metabolic challenge that promotes a whole-body systemic response that that also likely improves cardiometabolic health, in part through these lipid signaling molecules. For this video, we were also lucky enough to have an exclusive clip right from the first author. Here's what he had to say.

Hi Nick, thank you for choosing our research to share our findings with your audience, and we are happy because we believe that our results are exciting because they show that acute cold exposure can modulate the levels of certain lipid molecules such as omega-6 and omega-3 oxylipids. But what are these oxylipids? These oxylipids are lipids derived from the oxidation of polyunsaturated fatty acids and are believed to play a key role in regulating inflammation and metabolism in the organism. Traditionally, it has been thought that brown adipose tissue, an— an adipogenic adipose tissue, releases certain molecules in response to cold, also known as batokines. However, our data show that these changes in lipid levels were independent of brown adipose tissue volume and activity, suggesting that other mechanisms might be responsible for these beneficial effects. Eh, interestingly, we observed greater increases in oxylipins derived from polysaturated fatty acids in individuals with normal weight compared to those individuals who were overweight or obese. Moreover, These changes were linked to lower levels of body fat, improved glucose metabolism, better lipid profiles, and healthier liver function. These findings are intriguing because they suggest that individuals with higher adiposity and cardiometabolic risk factors have an impaired ability to produce and secrete these lipids in response to acute cold exposure. Additionally, our data allow us to observe how the metabolic and inflammatory response to cold differs depending on the participants' health status. Previous studies have shown that short-term cold exposure improves cardiometabolic health in individuals with overweight, obesity, or diabetes type 2. Specifically, interventions ranging from 7 to 10 days and includes improvements in insulin resistance, lipid metabolism, and even blood pressure. Based on our results, together with this prior evidence, we we could speculate that, um, these molecules, oxylipins, might play a role in the metabolic benefits associated with coal exposure. In addition, since we have previously observed that elevated levels of omega-6 oxylipins and decreased levels of omega-3 oxylipins are associated with poorer cardiometabolic health, we can speculate that cold exposure might exert its beneficial effects in part through the regulation of these lipids. Therefore, our findings on cold exposure open the door to future research exploring whether the improvements in cardiometabolic health observed in previous studies could be due, at least in part, to the regulation of these molecules. And future studies should also examine prolonged cold exposure to assess whether acute effects that we observed in our study lead to sustained benefits over time. Additionally, we need to investigate whether individuals with compromised cardiometabolic health benefit more from these interventions, given that their typical metabolic and typical inflammatory responses are already altered. Thank you again for your interest in our research, and goodbye!

What are your thoughts? Do you cold plunge? Are you going to start cold plunging? And of course, as always, stay curious, and I look forward to your questions and comments.