What Cold Showers Really Do for Your Immune System (And Why Your DNA Matters)

Los Angeles Times

23-07-2025

For years, cold showers were the domain of athletes and wellness zealots. But new research in genetics and metabolism suggests that a quick blast of cold water has benefits way beyond mental toughness. Under the chill lies a growing body of science showing that cold exposure can support immunity, reduce inflammation and improve mood and metabolism. And according to Dr. Castel Santana, MD, a longevity and human performance specialist at 10X Health System, these benefits may be especially powerful for people with specific genetic profiles.
Recent genetics research is flipping the old advice on its head. Under the shivering and swearing is real science: cold exposure seems to boost immunity, lower inflammation, and shift your mood and metabolism. Dr. Santana says it's not just about being tough, it's about your DNA. 'We're finding that certain people respond exceptionally well to cold exposure, especially when they have specific genetic traits tied to inflammation or stress response,' says Dr. Santana.
And Daniel Wallerstorfer, PhD, a biotechnologist at 10X Health, says their genetic testing data shows that certain immune-related genotypes (like those that cause overactive immune reactions to infection, sunburn, or exercise) may benefit from cold exposure's dampening effects. 'We haven't studied the direct link between cold and specific genotypes yet, but cold seems to lower pro-inflammatory cytokines and may help modulate an overactive immune system,' he says.
Dr. Santana spends his days in DNA. He's tracking single-nucleotide polymorphisms (SNPs) — tiny genetic quirks that affect how we deal with inflammation, neurotransmitters, and toxins. Some people, especially with certain IL6 or TNF-α variants, have immune systems that love to overreact. Cold showers can help turn down the fire for these folks.
COMT (rs4680) is the gene that decides if your body burns through dopamine and norepinephrine fast or slow. Santana says if someone has the Val/Val genotype, they metabolize those neurotransmitters quickly, so cold exposure would result in a bigger mood and focus boost. Wallerstorfer also notes that 'Cold showers can help with mood and mental clarity as 0 they trigger a rise in dopamine and endorphins.' But for people who break down dopamine slowly, Wallerstorfer says, cold could make things worse, 'for anyone with low dopamine, it's a bigger help.'
That post-shower zing? It's not in your head. Cold spikes dopamine, norepinephrine and beta-endorphins so you're more alert, a little more resilient, maybe even less grumpy. 'It's a fast way to improve alertness, especially for people with genetic inefficiencies in dopamine or serotonin pathways,' says Santana. Have SLC6A4 or TPH2 variants? (That's serotonin genetics.) Cold might help keep your mood steady. Not a miracle, but there's real data.
A Dutch study found that people who finished their showers with cold water missed 29% fewer workdays, even though they weren't actually sick less often. Go figure. 'We believe it's due to the sympathetic nervous system activation,' says Santana. 'It boosts norepinephrine, improves lymphatic circulation and may help regulate inflammatory cytokines.'
If your detox genes are slow (MTHFR, GSTT1, NQO1, cold might help your glutathione enzymes do their job and keep inflammation in check. Wallerstorfer doesn't mince words: 'The body reacts to cold by releasing stress hormones that temporarily activate immune cells and reduce inflammation. While cold showers don't directly improve detoxification, they may ease the burden by lowering inflammation. The effects are short-lived, so regular practice is needed to see lasting benefits.'
Cold cranks up mitochondrial biogenesis, fancy speak for making more energy factories inside your cells. That's the PGC-1α and UCP1 pathway at work. Santana says, 'It's one of the more accessible ways to improve metabolic resilience without needing intense exercise or restrictive diets.' Wallerstorfer adds that short bursts of cold water can improve mitochondrial function and boost metabolic rate. 'The body increases energy output to stay warm, activating brown fat and promoting healthy mitochondria, which is especially helpful for people with slow metabolism.'
Cold isn't for everyone. If you've got thyroid or adrenal issues, tread carefully. With certain DIO2 variants, your thyroid might not handle the cold well and you'll just end up more tired. 'For anyone dealing with adrenal fatigue, introducing cold too aggressively can be more depleting than helpful,' Santana says. 'Start slow, even 30 seconds of cool water at the end of your shower can trigger benefits.'
Wallerstorfer adds that cold exposure isn't ideal for everyone. 'People with underactive thyroids or weak adrenal function might feel worse, because cold increases the body's need for thyroid hormones and a robust stress response. If these systems are already under strain, cold exposure could lead to more fatigue, stress or even blood pressure spikes, especially in those with heart-related genetic tendencies.'
You don't need a fancy cryotherapy chamber. Just end your shower cold. If you love gear, try an adapter or a plunge tub. Santana sums it up: 'You're not trying to suffer, you're training your system to adapt. Resilience builds over time.'
Click here to learn more about 10x Health System