How Alcohol Affects Nutrition, Vitamin Levels, and Metabolism in the Human Body

My social connections are Sunday night, jazz; Tuesday night, jazz; Thursday night, trivia. All at bars so some alcohol is involved and since preventing dementia is vastly more important that this problem which doesn't exist for me.

My diet quality is pretty decent now with meals from Home Chef.

How Alcohol Affects Nutrition, Vitamin Levels, and Metabolism in the Human Body

By Hugo Francisco de SouzaReviewed by Benedette Cuffari, M.Sc.

Introduction
Alcohol and micronutrient absorption and status
Effects of alcohol on metabolic pathways
AUD and diet quality
Clinical and public health implications
Research gaps and future directions
Conclusions
References
Further reading

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Chronic alcohol consumption disrupts nutrient absorption, metabolism, and dietary quality, contributing to widespread micronutrient deficiencies and metabolic dysfunction. These nutritional disturbances exacerbate liver disease, neurological damage, and recovery challenges in individuals with alcohol use disorder.

 Image Credit: Valentyn Volkov / Shutterstock.com

Introduction

This article explores the intersection between drinking and nutrition to reveal how alcohol-induced malnutrition can perpetuate a cycle of craving and relapse.

Alcohol use disorder (AUD) is strongly associated with disturbances in nutritional status arising from both reduced dietary intake and alcohol-mediated disruptions in nutrient absorption, metabolism, storage, and utilization. These disturbances contribute to systemic complications, including liver disease, neurological dysfunction, immune impairment, and metabolic dysregulation. Alcohol-derived calories frequently displace nutrient-dense foods, while chronic exposure alters gastrointestinal, hepatic, and endocrine processes required for maintaining nutritional homeostasis.1,3,4

Alcohol and micronutrient absorption and status

The most severe nutritional consequence of chronic alcohol consumption is the depletion of micronutrients that occurs due to impaired intestinal absorption and increased renal excretion.1 Specifically, ethanol acts as a molecular disruptor of the brush border membrane (BBM) by targeting specific transporters required for the uptake of water-soluble vitamins.

Chronic ethanol consumption has been directly implicated in vitamin B1 deficiency by inhibiting the activity of SLC19A2, a transporter protein for thiamine. Similar inhibitory effects on the absorption of vitamins C and B12, riboflavin, biotin, and folate have been clinically observed.

Alcohol can also impair sodium-dependent and carrier-mediated nutrient transport systems located on intestinal epithelial cells, including transporters involved in glucose, amino acid, and micronutrient uptake. Disruption of these brush-border transport processes alters the function of intestinal enterocytes and contributes to malabsorption of essential nutrients in the small intestine.2

Alcohol consumption also alters the absorption and systemic concentrations of several macroelements and trace elements, including magnesium, potassium, sodium, calcium, selenium, zinc, chromium, and phosphorus. These disturbances may result from gastrointestinal malabsorption, increased urinary losses caused by alcohol’s diuretic effects, and impaired hepatic storage or metabolic regulation.7

Ethanol intake also reduces intestinal absorption of calcium, zinc, iron, and magnesium, in addition to interfering with dietary fat absorption in a dose-dependent manner. Drinking alcohol, even in moderate amounts, also reduces glucose absorption by reducing its maximal rate of uptake to limit its active transport into the bloodstream, rather than through its interactions with a specific transporter.

In addition to water-soluble vitamins, chronic alcohol use may also contribute to deficiencies in fat-soluble vitamins (A, D, E, and K), particularly in individuals with liver disease, steatorrhea, or impaired lipid digestion. These vitamins play essential roles in immune function, bone metabolism, antioxidant defense, and blood coagulation, and their depletion may exacerbate complications associated with chronic alcohol use.6

Ethanol possesses a high caloric density despite being entirely devoid of essential vitamins, minerals, and macronutrients.1 Thus, in addition to the direct effects of ethanol intake on nutrient absorption, primary malnutrition also arises due to the substitution of dietary carbohydrate, protein, and fat intake with alcoholic calories.

Furthermore, alcohol consumption can disrupt iron homeostasis through alterations in the hepatic hormone hepcidin, which regulates intestinal iron absorption and systemic iron distribution. Experimental evidence suggests that alcohol exposure can suppress hepatic hepcidin expression while modifying ferroportin activity and other iron-regulatory proteins.  These alterations may lead to abnormal iron distribution and contribute to oxidative stress and liver injury in alcohol-related liver disease.8

The nutritional deficiencies observed in individuals with alcohol use disorder (AUD) contribute not only to physiological impairments such as alcohol-related liver disease but also to the core symptoms of alcoholism, such as cognitive dysfunction and increased negative affect, thereby contributing to the vicious cycle of alcoholism and comorbidity.1”

Effects of alcohol on metabolic pathways

Hepatic ethanol metabolism primarily occurs through the alcohol dehydrogenase (ADH) pathway, which generates acetaldehyde, a highly reactive toxin that forms DNA and protein adducts.1 This process further reduces nicotinamide adenine dinucleotide (NAD+) to NADH, which significantly increases the NADH/NAD+ ratio. The subsequent inhibition of fatty acid oxidation while promoting triglyceride synthesis directly leads to hepatic steatosis.2

Additional metabolic pathways involved in ethanol metabolism include the microsomal ethanol-oxidizing system (MEOS), largely mediated by cytochrome P450 2E1 (CYP2E1), and catalase-mediated oxidation in peroxisomes. Activation of these pathways promotes the generation of reactive oxygen species (ROS), contributing to oxidative stress, lipid peroxidation, mitochondrial dysfunction, and inflammatory signaling.7

Ethanol also acts as a metabolic toxin by inhibiting the mammalian target of rapamycin (mTOR) pathway, a central regulator of muscle protein synthesis. Furthermore, alcohol reduces the phosphorylation of downstream targets such as ribosomal protein S6 kinase beta-1 (S6K1) and eukaryotic translation initiation factor 4E-binding protein 4EBP1, thereby preventing protein synthesis.4

These alterations contribute to skeletal muscle wasting, metabolic dysfunction, and impaired energy homeostasis.9 Chronic inflammation and oxidative stress further suppress anabolic signaling pathways involved in tissue repair and metabolic regulation.7,9

AUD and diet quality

Diet quality in individuals with AUD can vary greatly during periods of active use and post-cessation recovery. During active drinking, diet quality is generally poor, with patients scoring an average of 42.9 on the Healthy Eating Index-2015 (HEI-2015), compared with 54.3 in healthy controls.4 Using the Nova classification system, ultra-processed foods accounted for approximately 51.8% of total energy intake among individuals with active AUD.4

Despite apparently adequate caloric intake in some individuals with AUD, micronutrient deficiencies remain common because alcohol interferes with nutrient absorption, metabolism, and biological utilization.4

Thrombectomy limitations laid bare

So what? The GOAL IS 100% RECIOVERY! Thrombectomy is only the first step, leaders would deliver 100% recovery protocols regardless of failure of intermediate steps! But there are NO LEADERS IN STROKE! You're screwed if you have a stroke!

Thrombectomy limitations laid bare

John Watson, Associate Director for the Stroke Association in Scotland

by John Watson, Stroke Association

Tuesday 10th March 2026

Around one in 10 people who have a stroke will benefit from thrombectomy, a procedure to remove blood clots from their brain which, if undertaken within six hours, can reduce the risk of long-term paralysis, blindness and speech problems. But across most of the country, says John Watson, Associate Director for the Stroke Association in Scotland, unless you manage to get to a specialist centre during weekday working hours, the intervention is not an option.

(This is whining rather than stepping up and delivering recovery. 

Wonder if he will be singing the same tune after he becomes the 1 in 4 per WHO that has a stroke, will he be satisfied with not getting recovered? Leaders deliver step by step plans to get to 100% recovery! Are you a leader or a mouse?)

“Imagine your house is on fire. It’s 4pm. You dial 999. The call handler says: ”We’ll be there first thing tomorrow morning.” How do you feel about that?

Now imagine your brain is on fire. Same time - 4pm. You dial 999 and the call handler says the same thing. Except by then, you could be dead or left profoundly disabled.

None of us would accept the fire brigade scenario. So, why do we accept it when it comes to stroke? It happens every day in Scotland to eligible thrombectomy patients.

Until we have a national 24/7 thrombectomy service, Scotland’s stroke clinicians will continue to be placed in the terrible position of not being able to treat patients they could potentially help. They have a procedure which could get the stroke patient walking, talking, back to work and living independently. They might be able to administer thrombolysis, a clot-busting drug, but the patient will likely have a poorer outcome.

Thrombectomy removes the large blood clot, which causes stroke, from the brain. It is considered the basic standard of care for those who are clinically suitable.

In terms of numbers of patients treated, Scotland sits at 2.2% of eligible patients -around 10% of patients who have an ischaemic stroke could benefit from a thrombectomy This means Scotland’s thrombectomy rate is less than half that of the rest of the UK.

It’s a procedure available only at Ninewells Hospital in Dundee, the Royal Infirmary of Edinburgh (RIE) and Queen Elizabeth University Hospital (QEUH) in Glasgow. Eligible patients are transferred by ambulance from hospitals across the country to their nearest thrombectomy centre.

Ninewells, which serves the north of Scotland for thrombectomy, and the QEUH, which serves the west of Scotland, both provide the procedure Monday to Friday, 8am to 8pm.

RIE is the only thrombectomy centre which operates seven days a week 8am to 8pm – for RIE patients. The service is truncated to Monday to Friday, 8am to 8pm for patients referred from eastern NHS hospitals. 

Cochrane review questions cognitive benefits of ginkgo biloba for early memory problems

 With this new knowledge, what is your competent? doctor's EXACT PROTOCOL FOR MEMORY post stroke? Oh NO, INCOMPETENT BECAUSE THERE IS NONE!

• memory (248 posts to March 2011)
• memory decline (14 posts to January 2017)
• memory enhancement (8 posts to October 2014)
• memory rehabilitation (7 posts to June 2018)

Cochrane review questions cognitive benefits of ginkgo biloba for early memory problems

A large systematic review of randomised controlled trials (RCTs) suggests the herbal supplement Ginkgo biloba may offer modest benefits for people with established dementia but provides little or no benefit for those with earlier cognitive decline. 

However, the findings, published in Cochrane Database of Systematic Reviews, highlight the limited and variable evidence supporting Ginkgo use and underscore the need for more rigorous studies to clarify its role in managing MCI and dementia.

“As the population ages and rates of cognitive impairment and dementia continue to rise, rigorous evaluation of widely marketed and commonly used supplements such as Ginkgo biloba is essential to guide informed decisions,” said Lisa S. Wieland, PhD, Georgetown University Medical Center, Washington, DC. 

The researchers analysed 82 RCTs involving 10,613 participants to evaluate the benefits and harms of the herbal supplement Ginkgo biloba in people with cognitive complaints, MCI, or dementia. Databases, including MEDLINE and Embase, were searched through November 2024, and 72 trials with 9,783 participants contributed extractable data. Investigators assessed outcomes such as global clinical status, cognitive performance, activities of daily living, and adverse events at roughly 6 months, pooling results using random-effects meta-analysis when appropriate.

Across 12 trials involving 1,913 participants with MCI, ginkgo showed little or no benefit versus placebo for global clinical status (mean difference [MD], -0.03 on the Clinical Dementia Rating scale), cognition measured by the Alzheimer’s Disease Assessment Scale-Cognition (MD, -0.07), or daily functioning at 6 months.

In contrast, among 13 trials including 3,288 participants with dementia, Ginkgo was associated with modest improvements in global clinical status (MD, -0.06), cognitive performance on the Syndrom-Kurztest (MD, -1.86), and activities of daily living (MD, -0.19). 

Rates of adverse events were similar to placebo in most analyses and no meaningful differences were observed for serious adverse events.

“This review provides clarity for clinicians and patients navigating decisions about widely used herbal supplements,” said Hakima Amri, Georgetown University Medical Center. “Future studies in this field should expand to include the emerging novel clinical trial designs in order to answer targeted questions of efficacy and effectiveness. ”

The last Cochrane review on Ginkgo biloba for cognitive impairment and dementia was published in 2009.

Reference: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD013661.pub2/full

SOURCE: Georgetown University Medical Center

SIH Herrin and Memorial Hospitals Earn National Stroke Care Award

 

This is the whole problem in stroke enumerated in one word; 'care'; NOT RECOVERY! 

Our non-existent stroke leadership should be demanding RECOVERY NOT 'CARE'! This is for you to solve: WSO!

My god, anyone in the business world would be fired immediately for managing or caring about something rather than delivering RESULTS. And this is why this is a complete fucking failure! This does nothing to guarantee recovery for survivors!

If your stroke medical 'professional'/hospital is touting 'care' it means they are a failure because they are delivering 'care'; NOT RECOVERY! I would never go to a failed hospital! Anytime I see the word 'care' associated with a stroke hospital; I immediately think fucking failure!

YOU have to get involved and change this failure mindset of 'care' to 100% RECOVERY! Survivors want RECOVERY, NOT 'CARE'!

I see nothing here that states going for 100% recovery! You need to create EXACT PROTOCOLS FOR THAT!

ASK SURVIVORS WHAT THEY WANT, THEY'LL NEVER RESPOND 'CARE'! This tyranny of low expectations has to be completely rooted out of any stroke conversation! I wouldn't go there because of such incompetency as not having 100% recovery protocols!

RECOVERY IS THE ONLY GOAL IN STROKE!

GET THERE!

SIH Herrin and Memorial Hospitals Earn National Stroke Care Award

CARBONDALE, Ill. (WSIL) — SIH Herrin Hospital and SIH Memorial Hospital of Carbondale have earned national recognition for their commitment to providing fast, evidence-based stroke treatment that improves patient outcomes.

Both hospitals recently received the Get With The Guidelines® – Stroke Gold Plus with Target: Stroke Honor Roll award from the American Heart Association and the American Stroke Association. The designation highlights hospitals that consistently deliver high-quality care(NOT RECOVERY!) designed to reduce death and disability caused by stroke.

To qualify for the award, hospitals must meet strict performance standards aimed at shortening the time between a stroke patient’s arrival at the hospital and the start of life-saving treatment, including clot-busting medications.

Stroke remains the fourth leading cause of death in the United States and a major cause of long-term disability. The condition occurs when blood flow to the brain is blocked or a blood vessel ruptures, depriving brain tissue of oxygen and nutrients. Quick treatment is essential to minimizing damage and improving recovery.

“Rapid treatment truly changes what recovery looks like for stroke patients,” said Andrea Loggini, MD, Neurointensivist and Neuroscience Inpatient Medical Director at Southern Illinois Healthcare. “This recognition reflects how consistently our teams follow national guidelines and, just as importantly, how well they work together to deliver time-sensitive treatment that can help patients regain speech, movement and independence.”

The Get With The Guidelines® program is designed to help hospitals align stroke care(NOT RECOVERY!) with the latest medical research. It promotes early detection and standardized treatment methods that can limit long-term damage and speed up recovery.

“For stroke care(NOT RECOVERY!), every minute matters,” Loggini said. “From the moment a patient arrives in the Emergency Department, there is a coordinated response involving emergency physicians, nurses, imaging teams and the neuroscience team. That shared focus allows us to move quickly, reduce delays and give patients the best possible chance for recovery.”

Hospital officials said that coordination often begins even before the patient reaches the emergency room.

“This recognition is a direct reflection of teamwork — not just in the Emergency Department, but starting with emergency medical services in the field,” said Jonatan Hornik, MD, Neurointensivist with Southern Illinois Healthcare. “Early identification, rapid communication and seamless handoff between EMS and our ED teams set everything in motion. Stroke care(NOT RECOVERY!) succeeds when every link in the chain works together with urgency and precision.”

Hornik said the Target: Stroke Honor Roll distinction recognizes how collaboration helps teams deliver treatment quickly while maintaining high standards of care(NOT RECOVERY!).

“When EMS, emergency clinicians, radiology and neuroscience teams are aligned, we can move efficiently while maintaining high standards of care(NOT RECOVERY!),” he said. “That collective effort is what allows patients to receive timely treatment and what ultimately drives better outcomes.”

According to Steven Messe, MD, volunteer chair of the American Heart Association Stroke System of Care Advisory Group, hospitals that participate in the Get With The Guidelines program often see measurable improvements in patient outcomes.

“We are incredibly pleased to recognize SIH Herrin Hospital and SIH Memorial Hospital of Carbondale for their commitment to caring for patients with stroke,” Messe said. “Participation in Get With The Guidelines is associated with improved patient outcomes, fewer readmissions and lower mortality rates — a win for health care(NOT RECOVERY!) systems, families and communities.”

Marijuana compound may help prevent dementia when paired with common drug

 Will your competent? doctor put 2 and 2 together and see if this could prevent your increased risk of dementia post stroke? Or is your doctor so incompetent that knowledge of this doesn't even exist?

Didn't this from November 2013 already lead the way?

OTC painkiller may blunt memory loss from puffing pot November 2013

Your risk of dementia, has your doctor told you of this?  Your doctor is responsible for preventing this! Is s/he willing to try this on you?

1. A documented 33% dementia chance post-stroke from an Australian study?   May 2012.

2. Then this study came out and seems to have a range from 17-66%. December 2013.`    

3. A 20% chance in this research.   July 2013.

4. Dementia Risk Doubled in Patients Following Stroke September 2018 

The latest here:

Marijuana compound may help prevent dementia when paired with common drug

THC shown to keep Alzheimer's at bay when combined with pain medication

As marijuana's potential health benefits are under debate, new research has found that THC could have a powerful and positive effect on the brain.

Researchers at the University of Texas (UT) at San Antonio, Long School of Medicine, recently discovered that THC (tetrahydrocannabinol, the main psychoactive compound in marijuana) could prevent the development of Alzheimer’s disease – but only when paired with an anti-inflammatory drug called celecoxib.

Celecoxib is a selective COX-2 inhibitor that is commonly prescribed for arthritis and pain.

ALZHEIMER’S DECLINE COULD SLOW DRAMATICALLY WITH ONE SIMPLE DAILY HABIT, STUDY FINDS

While THC has previously been shown to have anti-inflammatory and neuroprotective properties, it’s also been linked to negative effects on the brain, particularly in learning and memory, according to a UT Health press release.

Combining THC with an anti-inflammatory drug, however, could provide the same benefits with fewer negative side effects.

THC could be powerful against cognitive decline when combined with an anti-inflammatory, a new study suggests. (iStock)

The study, which was published in the journal Aging and Disease, paired low-dose THC extract with celecoxib, which was administered to mice daily for 30 days.

The mice received the treatments before the development of memory symptoms to measure the impact on preventing or delaying Alzheimer’s.

The results showed improved cognition, learning and memory, as well as decreased markers of neuroinflammation and reduced Alzheimer’s-related brain pathology, the release stated.

Although THC alone had the same results, it also increased inflammatory signals, while the combination dosage did not.

"What really mattered was behavior. If cognition is not improved, then the treatment doesn’t matter. And that’s where the combination clearly worked better than THC alone," noted lead study author Chu Chen, Ph.D., professor in the Department of Cellular and Integrative Physiology.

Years of research led Chen to connect the dots on how THC can manipulate the brain and why it’s difficult to use safely for neurological conditions, according to UT Health.

"When THC is given, it unexpectedly increases COX-2 in the brain. That increase is closely associated with learning and memory impairment," Chen said.

Both THC and celecoxib are FDA-approved for use in humans, which could provide a "real advantage" in moving along to clinical trials, according to UT Health.

"What really mattered was behavior. If cognition is not improved, then the treatment doesn’t matter."

Future studies will investigate whether the drug combination can slow disease progression or reverse deficits after symptoms have appeared.

Negative social ties as emerging risk factors for accelerated aging, inflammation, and multimorbidity

 

Well, at age 50 I had my stroke and the result of that is making me happy for the rest of my life.  Got divorced at age 58, fired at age 56. All leading to moving to Michigan and finding lots of new friendships.

(Life is definitely better as I age, I got divorced enhancing my happiness immeasurably. I'm retired and comfortably well off. And healthy as I can be post stroke. I'm going to live a long time yet.)

Negative social ties as emerging risk factors for accelerated aging, inflammation, and multimorbidity

Byungkyu Lee https://orcid.org/0000-0003-0248-3088 bklee@nyu.edu, Gabriele Ciciurkaite https://orcid.org/0000-0001-8496-4031, Siyun Peng https://orcid.org/0000-0002-4049-4485, +1 , and Brea L. Perry blperry@iu.eduAuthors Info & Affiliations

Edited by James W. Moody, Duke University, Durham, NC; received June 27, 2025; accepted January 22, 2026 by Editorial Board Member Mark Granovetter

February 18, 2026

123 (8) e2515331123

https://doi.org/10.1073/pnas.2515331123

Vol. 123 | No. 8

Social relationships are fundamental to human health, yet research has focused primarily on their supportive dimensions. We investigate the role of “hasslers,” people in one’s close social networks who create problems or make life more difficult, finding that these negative ties are not rare, disproportionately experienced by individuals facing greater social and health vulnerabilities, and consequential for aging. Each additional hassler is associated with faster biological aging, with especially pronounced effects when the hassler is a family member. These findings identify negative social ties as chronic stressors that shape aging trajectories and underscore the need for interventions that reduce harmful social exposures to promote healthier aging.

Abstract

Negative social ties, or “hasslers,” are pervasive yet understudied components of social networks that may accelerate biological aging and morbidity. Using ego-centric network data and DNA methylation-based biological aging clocks (i.e., DunedinPACE and age-accelerated GrimAge2) from saliva from a state representative probability sample in Indiana, we examine how negative social ties are associated with accelerated biological aging and a broad range of health outcomes, including inflammation and multimorbidity. Negative relationships are not rare within close relationships, as nearly 30% of individuals report having at least one hassler in their network. These hasslers tend to occupy peripheral network positions and are more likely to be connected through weak, uniplex ties. Importantly, exposure to negative social ties follows patterns of social and health vulnerability, with women, daily smokers, people in poorer health, and those with adverse childhood experiences more likely to report having hasslers in their networks. Having more hasslers is associated with accelerated biological aging in both rate and cumulative burden: Each additional hassler corresponds to approximately 1.5% faster pace of aging and roughly 9 mo older biological age. Moreover, not all hasslers exert the same influence; kin and nonkin hasslers show detrimental associations, whereas spouse hasslers do not. Finally, a greater number of hasslers is associated with multiple adverse health outcomes beyond epigenetic aging. These findings together highlight the critical role of negative social ties in biological aging as chronic stressors and the need for interventions that reduce harmful social exposures to promote healthier aging trajectories.

Scientists are discovering that sauna's health benefits aren't all hot air

 

Well shit, your competent? doctor knew that a long time ago and made damn sure you had some immediately poststroke! Oh NO, nothing happened because your doctor is so fucking incompetent!

• heat shock proteins (6 posts to April 2013)

• sauna (16 posts to January 2015)

Scientists are discovering that sauna's health benefits aren't all hot air

 Saunas have captured the wellness zeitgeist, attracting a new generation of followers eager to tap into the benefits of the age-old practice. The upswell of public interest has fed a growing industry dedicated to offering the sauna experience, and inspired festivals in cities like New York, Minneapolis and Seattle."It is my mental reset – my control, alt, delete," says Ana Hernandez, who launched a mobile sauna business after the pandemic and organized Seattle's first ever sauna festival this past fall.Turnout for the two-day event ended up being three times what they'd anticipated. Attendees milled around a makeshift sauna village, assembled outside the Nordic Museum in Seattle, sampling different styles of sauna, and occasionally dipping in an ice cold tub or shower. "The crowd is very mixed," she says, "People come for their physical and mental wellness."  Sauna challenges the body in ways that are similar to exercise, researchers say. Confronted with the sudden increase in heat, your cardiovascular system is put to the test – blood vessels dilate, heart rate increases and blood gets pushed to your skin, where it can be cooled more easily by sweat.JJ Meston, right, and Chris Shotwell, both from Seattle, exit a sauna after a session during the Seattle Sauna Festival. Heat can boost the cardiovascular system in similar ways to exercise, research finds. "There's very good evidence now that repeated use of heat is healthy for humans," says Christopher Minson, a human physiologist at the University of Oregon who focuses on thermoregulation and health. "We have this incredible ability to adapt to heat that's really helped shape human evolution much more than our ability to adapt to cold," he says. A boost for cardiovascular health The most compelling data come from large population studies out of Finland, a country of about 5 million that famously boasts more than 3 million saunas. A 2015 study, published in JAMA Internal Medicine, that followed more than 2,300 Finnish men for about 20 years has received considerable attention. That showed using a sauna four to seven times per week was associated with a 40% to 60% lower risk of cardiovascular disease and death, compared to those who only went once a week. Subsequent studies have bolstered those findings on cardiovascular health, showing improvements in blood pressure, cholesterol, arterial stiffness and other markers of cardiometabolic health."The evidence is robust, it's consistent," says Dr. Setor Kunutsor, a cardiologist at the University of Manitoba, in Canada, who has been involved in much of the research in Finland. "We know temperature has an effect on disease, but we were surprised by the magnitude of the effect," he says. Amanda Morrow, of Seattle, ladles water onto sauna rocks inside a vintage camper trailer-converted sauna during the festival.Mike Kane for NPR Traditional Finnish saunas are generally kept anywhere from 180 to more than 200 degrees Fahrenheit. Stepping into a room that hot triggers an immediate stress reaction, activating the sympathetic arm of the nervous system, the fight-or-flight response."We see an increase in blood pressure and heart rate" comparable to physical activities like light jogging, says Sascha Ketelhut, an exercise scientist at the University of Bern in Switzerland who has done work in this area.

As with exercise, this "acute stressor" is then followed by improvements in these markers of cardiovascular health and a calming of the nervous system during the recovery period, he says.

The role of inflammation

While cardiovascular health has the most supporting data, large-scale studies have also linked sauna use to lower rates of respiratory illness and even some neurodegenerative conditions like dementia and Alzheimer's.

There are a number of mechanisms that could explain the decreased risk of chronic disease, among them the effects on systemic inflammation and oxidative stress. In a 2018 study, Kunutsor and his colleagues showed that Finns who frequently sauna have lower levels of inflammatory markers. Experiments have revealed that sauna and other forms of heat therapy also cause the secretion of various hormones and boost immune cells, at least in the short-term. The role of heat shock proteins is of particular interest. Sauna enthusiasts sit inside a barrel sauna during the Seattle Sauna Festival. According to Christopher Minson, a human physiologist at the University of Oregon, growing evidence shows that regular sauna use can combat inflammation. Mike Kane for NPR Minson says these help combat harmful molecules called reactive oxygen species that can build up inside of us and trigger a cascade of inflammation.

The evidence base has grown considerably in the last decade. But Kunutsor says there's still a need for large, well-controlled trials, particularly in populations that are "sauna naive," to tease out the effects. He thinks more evidence may lead medical societies to consider incorporating sauna use into official health guidelines.

A mental health boost

For many sauna enthusiasts, the biggest draw is how it makes them feel.

As with the cold plunging craze, saunas increasingly serve as a kind of social lubricant, a place where people can find connection and a brief reprieve from their phones.

However, the link to mental health also has a physiological basis that researchers like Dr. Charles Raison are trying to understand.

"High heat administered for a time-limited period is an antidepressant and a pretty good one," says Raison, a professor of psychiatry and human ecology at the University of Wisconsin-Madison.

This research spans various forms of heat therapy, not just traditional Finnish saunas.

For example, Raison's group uses a special hyperthermia machine so participants can reach a core body temperature of 101.3 Fahrenheit – hotter than you could typically achieve in a sauna. Their heads, cooled with ice packs, stick out of the machine.

The data gathered so far suggest a linear relationship: The hotter a person gets, up to a certain point, the less depressed they feel in the following days and weeks.

"These studies are small, but the signal is pretty clear," he says.

For example, a randomized-controlled trial of about 30 people, published in 2016, found significant reductions in symptoms of depression after just one session of whole body hyperthermia, compared to a group that received a sham treatment.

"The pathways in the brain and body that mediate thermoregulation overlap spectacularly with the pathways that mediate mood, desire, the state of emotions," Raison says.

An intriguing finding from this research relates to an immune-signaling molecule called Interleukin-6, or IL-6. An acute spike in IL-6 following heat exposure appears to correlate with how much depressive symptoms improve.

More broadly, scientists interested in leveraging heat for mental health have noticed a link to body temperature, specifically that people with depression tend to run hotter, according to a 2024 study of more than 20,000 adults.

"What that shows is people with depression may have some thermoregulatory challenges such that they're not able to cool down so well," says Ashley Mason, a researcher at the University of California San Francisco Osher Center for Integrative Health, whose lab published those findings and is running several trials on heat exposure and sauna.

Given that pattern, it may seem counterintuitive to then expose someone to high heat, but in reality, data suggest this can actually improve a person's ability to thermoregulate, she says.

If you try it

If you don't have a sauna available, the researchers who spoke with NPR said the health benefits of sauna bathing extend to other forms of passive heat therapy, including steam rooms and hot tubs, provided they're hot enough.

There aren't large, well-controlled trials that have compared how outcomes differ based on the amount of time you spend in a sauna week-to-week or the precise temperature.

The Finnish data suggest you need at least three to four sauna visits a week, with each session lasting a minimum of 15 minutes to get the "optimal benefits," says Kunutsor at the University of Manitoba.

While it can be a similar stimulus as light exercise, he stresses sauna is by no means a substitute — and his research shows you stand to gain the most by doing both.

Minson, who advises professional athletes on using heat to improve performance, recommends aiming for about 20 to 30 minutes in the sauna immediately after a workout.

"If you're doing that smartly, then you're getting the best benefits of exercise training and potentially increasing some of the oxygen-carrying capacity of your blood," he says.

But proceed with caution, particularly if you're a newcomer or have an underlying health condition. Heat-related illness like heat exhaustion is a risk — symptoms tend to crop up when people are already vulnerable because they're fighting a cold or some underlying infection.

The notion that you can "sweat out the toxins" — whether that's due to a bug or last night's round of shots — is "simply not true," says Minson.

And like exercise, even the experienced sauna-goer can overdo it.

On a scale of 1 to 10 – where 10 feels like you're on the surface of the sun – he suggests aiming for about a 6 or 7.

"You don't want to feel uncomfortably hot," he says, "You can push that for a little while, but if you go for too long, there's no real added benefit."