Claim: Sweating can release a useful amount of toxins/toxicants from the body

[Rory]

This is an age old claim that most of us will have heard, many of us will assume to be true on some level, and some will have looked into.

Whatever the outcome here I don't think there's any dispute that sweating - saunas, steam rooms, strenuous activity, etc - can feel really, really good, and I'm sure have some sort of health benefits. But as for the specific claim of whether it can remove toxicants - especially heavy metals - I think a deeper look is required.

First off, a cursory google seems to indicate that "it small amount of toxins are released through sweating, but it's insignificant in the grand scheme of things and compared to what the liver and kidneys can do." For example:

The body does appear to sweat out toxic materials — heavy metals and bisphenol A (BPA), a chemical found in plastics, for instance, have been detected in sweat. But there's no evidence that sweating out such toxins improves health.

The concentration of metals detected in sweat are extremely low. Sweat is 99 percent water. The liver and kidneys remove far more toxins than sweat glands.

So does it matter that people excrete small amounts of toxins in their sweat? "The fact is, nobody really knows," Dr. [Joe] Schwarcz [a professor of chemistry at McGill University in Montreal] said.

https://www.nytimes.com/2017/08/18/well/live/can-you-sweat-out-toxins.html

Humans sweat to cool ourselves, not to excrete waste products or clear toxic substances. That's what our kidneys and liver are for. Of course, there's usually some grain of truth at the heart of a myth, and toxic sweat is no exception.

"You always have to ask how much," says chemist Joe Schwarcz. "When you look at sweat, you can find many substances, [but] the presence of a chemical cannot be equated to the presence of risk."

At most [...] a typical person doing 45 minutes of high-intensity exercise a day could sweat a total of two liters a day—normal background perspiration included—and all that sweat would contain less than one-tenth of a nanogram of [the] pollutants that are stored in body fat [(including pesticides, flame retardants, and now-banned polychlorinated biphenyls, or PCBs, which are still found in the environment].

To put that in perspective, "the amount in sweat is 0.02 percent of what you ingest every day on a typical diet," [Pascal] Imbeault [an exercise physiologist at the University of Ottawa in Canada] says. If you really pushed it on your exercise regime, you might release up to 0.04 percent of your average daily intake of pollutants.

What that means is that there's no way you could sweat enough to get rid of even one percent of what you'll eat in your food that day.

Back to that grain of truth: small amounts of heavy metals and BPA from plastics do make their way into sweat, because these pollutants dissolve more readily in water. But there are more effective ways to remove high levels of metals from the blood, such as chelation therapy. And you pass more BPA out of your body in urine than in sweat. The best way to reduce your BPA exposure is to avoid eating and drinking out of containers made with it.

https://www.nationalgeographic.com/...ns-myth-detox-facts-saunas-pollutants-science

This article in the Atlantic is a long look at infrared saunas, which are claimed to be "more effective in moving toxins through the skin than steam saunas because in the far-infrared thermal system only 80 to 85 percent of the sweat is water with the non-water portion being principly [sic] cholesterol, fat-soluable [sic] toxins, toxic heavy metals, sulfuric acid, sodium, ammonia and uric acid."

The writer searches for a citation or source for this claim and eventually traces it back to vague links to a textbook called Vander's Human Physiology: The Mechanisms of Body Function, written by Eric P. Widmaier; Hershel Raff, Ph.D.; and Kevin T. Strang. She then searches the book and contacts the authors, but can find nothing to even remotely support the claim.

https://www.theatlantic.com/health/...as-will-not-detoxify-you-toxins-sweat/528813/

So that's three mainstream articles - including nods to university research (as well as the sometimes unimpressive but ubiquitous Harriet Hall) - that poopoo the idea (as do many others, all basically saying the same thing).

What about the other side of the story? Here's a website that claims:

Heavy metals such as mercury, lead, cadmium and arsenic are abundant in our environment and endocrine disruptors such as phthalates and bisphenol A can be found in our blood and urine. What does the science say about removing these risks to our health through our sweat pores?

1. Sweating can help eliminate phthalates.

Researchers in Canada examined blood, urine and sweat concentrations of various phthalates in 20 people. They found that the concentration of these chemicals was twice as high in sweat as in urine.

2. Sweating can help eliminate BPA.

The same group of Canadian researchers found BPA in the sweat of 80% of subjects tested. Some of these people had no detectable levels in their blood or urine, which suggests that sweat was the best way to excrete stored bisphenol A.

3. Sweating can help eliminate heavy metals.

Studies show sweat can concentrate arsenic up to 10 times more than blood, cadmium up to 25 times more than blood, lead up to 300 times more than blood, and mercury somewhat more than blood, leading to effective elimination.

https://www.mindbodygreen.com/0-15166/why-sweating-is-the-best-way-to-get-rid-of-toxins.html

So not purely an opinion piece but claims based on apparent studies. These studies, in order, state:

Blood, urine, and sweat were collected from 20 individuals and analyzed for parent phthalate compounds as well as phthalate metabolites. All patients had MEHP (mono(2-ethylhexyl) phthalate) in their blood, sweat, and urine samples. In several individuals, DEHP (di (2-ethylhexl) phthalate) was found in sweat but not in serum, suggesting the possibility of phthalate retention and bioaccumulation. On average, MEHP concentration in sweat was more than twice as high as urine levels.

Conclusions: Induced perspiration may be useful to facilitate elimination of some potentially toxic phthalate compounds including DEHP and MEHP. Sweat analysis may be helpful in establishing the existence of accrued DEHP in the human body.

[Study from the Faculty of Medicine, University of Alberta]

https://pubmed.ncbi.nlm.nih.gov/23213291/

Blood, urine, and sweat were collected from 20 individuals and analyzed for various environmental toxicants including BPA. BPA was found to differing degrees in each of blood, urine, and sweat. In 16 of 20 participants, BPA was identified in sweat, even in some individuals with no BPA detected in their serum or urine samples.

Conclusions: Biomonitoring of BPA through blood and/or urine testing may underestimate the total body burden of this potential toxicant. Sweat analysis should be considered as an additional method for monitoring bioaccumulation of BPA in humans. Induced sweating appears to be a potential method for elimination of BPA.

[Same writers as above, presumably same 20 subjects]

https://pubmed.ncbi.nlm.nih.gov/22253637/

Sweat is an acknowledged excretory route for toxic metals. For instance, it is recommended to sample hair close to the scalp because content of toxic elements may be elevated along the shaft, from either environmental contamination or excreted toxins in sweat and sebum [32, 42].



Arsenic accumulates highly in the skin, and causes characteristic skin lesions, but little information is available on levels in sweat. On average, arsenic was 1.5-fold (in males) to 3-fold (in females) higher in sweat than in blood plasma; however, arsenic was excreted at [much] lower concentrations in sweat than in urine [- on average, less than one tenth].

Cadmium in sweat was examined in six studies [3, 22, 28, 30–33]. Stauber and Florence concluded that sweat may be an important route for excretion of cadmium when an individual is exposed to high levels [22, 28], a finding that was confirmed by observing that the total daily excretion of cadmium was greater in sweat than in urine [3, 32].

Lead was examined in eleven studies [3, 22, 26–28, 33–38]. In two males, 36% and 50% of sweat lead was of molecular weight >30,000, as measured by ultrafiltration, suggesting excretion of organic complexes rather than simple ions [22]. Haber et al. found that prolonged endurance workouts (rowing) ameliorated elevated blood lead levels in exposed workers but did not alter levels in control subjects and did not affect urine levels [26]. They suggested that the elimination route was not urine, but potentially sweat or/and bile. The English abstract of a 1991 case report in Russian indicated that sauna increased excretion of toxic elements and resulted in clinical improvements [27].

Mercury. In 1973, Lovejoy et al. noted that exposure to mercury does not always correlate with urine mercury levels and that elimination by other routes such as sweat may be an explanation [41]. They suggested, "sweating should be the initial and preferred treatment of patients with elevated mercury urine levels." Robinson measured mercury in sweat repeatedly in two volunteers, observing sweat to urine concentration ratios ranging from less than 0.1 to greater than 5. Sweat mercury concentrations varied widely from day to day, and there was no correlation with urine levels. Sweat mercury levels of 1.5 μg/L were observed by Genuis et al. [3] and 1.4 μg/L by Robinson and Skelly [39].

[This is a meta-analysis of around 50 studies, including the Canadian ones cited above. Lead writer was Dr Margaret "Meg" E. Sears, Adjunct Investigator at the Children's Hospital of Eastern Ontario Research Institute]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3312275/

I suppose all that leads me to some questions:

1. What is the quality of the meta-analysis conducted by Sears, et al?
2. Are the cited studies represented accurately?
3. If, as it appears when taking Sears' paper at face value, sweating does significantly aid the elimination of heavy metals, why has it been reported that this isn't the case?
4. Are the levels reported significant? Dangerous? Abnormal?
5. Is the mainstream missing something here?

All questions I suppose I'll get into when I next have the time. But, until then, over to you...

(And placeholding this link here as a reminder of another paper to look at when I get a mo.)

 

[Mendel]

Wikipedia cites a dermatology textbook for information on how eccrine seeat glands work.

Two more names of experts via an LA Times article:

Article:

Sweat does contain trace amounts of toxins, says Dr. Dee Anna Glaser, a professor of dermatology at St. Louis University and founding member of the International Hyperhidrosis Society, a medical group dedicated to the study and treatment of heavy sweating.

But, Glaser, adds, in the big picture, sweat has only one function: Cooling you down when you overheat. "Sweating for the sake of sweating has no benefits," she says. "Sweating heavily is not going to release a lot of toxins."

In fact, Glaser says, heavy sweating can impair your body's natural detoxification system. As she explains, the liver and kidneys -- not the sweat glands -- are the organs we count on to filter toxins from our blood. If you don't drink enough water to compensate for a good sweat, dehydration could stress the kidneys and keep them from doing their job. "If you're not careful, heavy sweating can be a bad thing," she says.

Sweating definitely won't help clear the body of mercury or other metals, says Donald Smith, a professor of environmental toxicology at UC Santa Cruz, who studies treatments for metal poisoning. Almost all toxic metals in the body are excreted through urine or feces, he says. And less than 1% are lost through sweat. In other words, you'll do far more detoxifying in the bathroom than you ever could in a sauna.

Prescription-strength chelation drugs such as EDTA are the only products proven to remove significant amounts of metals from the body, Smith adds.

Source: https://www.google.com/amp/s/www.latimes.com/health/la-xpm-2008-jan-28-la-he-skeptic28jan28-story.html%3f_amp=true

My thoughts:
• The reasoning sounds like sympathetic thinking, both the thought that sweating detoxes like urine, and that more is better, but it's not grounded in a theory of how the body actually detoxes (magical thinking)
• "more is better" is not true for urine after a certain point, why should it be better for sweat?
• if it's true, people who suffer from hyperhydrosis should be healthier than others, are they?
• is there a study that evaluates people's health, then gives them access to a sauna for some months, and then evaluates their health again?

 

[deirdre]

I suppose all that leads me to some questions:

is exercise sweat the same as sauna sweat?
how do they know the toxins they're measuring come from sweat, vs from the exterior skin?

 

[Rory]

My thoughts:
• The reasoning sounds like sympathetic thinking, both the thought that sweating detoxes like urine, and that more is better, but it's not grounded in a theory of how the body actually detoxes (magical thinking)
• "more is better" is not true for urine after a certain point, why should it be better for sweat?
• if it's true, people who suffer from hyperhydrosis should be healthier than others, are they?
• is there a study that evaluates people's health, then gives them access to a sauna for some months, and then evaluates their health again?

The "magical thinking reasoning" I'm sure is true for some, but that doesn't seem to be the case for Sears and Genius. Plus, they're not saying "more is better".

The fourth question is a good one though. I presume there are examples of this - or things similar to this - in the papers cited by Sears.

is exercise sweat the same as sauna sweat?

I think so.

how do they know the toxins they're measuring come from sweat, vs from the exterior skin?

One would hope, as scientists, that they would have controlled for that. But good control is definitely something that should be looked for upon deeper analysis.

 

[Mendel]

they're not saying "more is better".

then there would be no health gain from induced sweating?
some "more is better" has to apply here, or you can't sell health with this

 

[Rory]

then there would be no health gain from induced sweating?
some "more is better" has to apply here, or you can't sell health with this

Ah, you mean "more than nothing/little/a normal amount".

Well, sure.

I thought you meant "one hour sauna better than no sauna therefore two or three hour sauna even better".

 

[deirdre]

it's possible sweating, if exercise induced, might get rid of more toxins faster than normal or no-sweat exercise.. not through sweat but just because our blood is pumping and bodies are working better?

i realize that isn't really what you are asking. but does it really matter if the toxins are IN the sweat or just gone through some other means?

 

[Rory]

it's possible sweating, if exercise induced, might get rid of more toxins faster than normal or no-sweat exercise.. not through sweat but just because our blood is pumping and bodies are working better?

Right. That's a thing:

Vigorous activity does help the body rid itself of toxins by increasing the circulation of lymph fluid and blood, which are filtered by the lymph nodes and kidneys respectively. (Any toxins filtered out by the lymph nodes are redeposited in the bloodstream and eliminated by the kidneys.)

https://www.britannica.com/story/can-you-really-sweat-out-toxins

But this idea/theory is something different (eg, sweating through saunas, etc).

 

[deirdre]

plus you might end up with more toxins if you sauna with someone else. like if lil me saunas with a big fat guy he will sweat at least 5x more than me just from more surface area.. and then his sweat drops on the floor and i walk through it and then his toxins get absorbed through my feet which may be more toxins then i personally sweated out in the first place.

 

[FatPhil]

I've always worked on the principle that in the sauna I was just pushing through stuff I was going to sweat out anyway, there's no additional extraction or purging process taking place. The *feeling* of cleanness is unmatched, and I definitely smell differently, I'm definitely shedding something, but nothing that wasn't ready for shedding through the sweat glands anyway.

An example from personal experience - after an IPA/DIPA-heavy beer tasting session, a lot of the aromatics in the hops will emerge from my pores in the following 24 hours, it's quite off-putting to be honest - even my hands and forearms can smell hoppy the next day. I can start the next day with a nice long sauna, and for half an hour afterwards everything will be fine, but the humaloids will continue working their way through and it will be as if I'd never had the sauna in the first place before long.

I'm also not sure by what mechanism they think a human responds differently to the heat from an infrared sauna and from a proper one. The reasoning quoted from the Atlantic article seems bunk - I even disagree with the "through the skin" concept, which I interpret as implying some kind of cell-membrane-crossing process - you don't sweat through the skin, you sweat through pores.

 

[Rory]

So I was thinking a way to begin looking at this would be to take one 'toxin' at a time and look at the data for it and see what was what. I thought I might start with a metal but perhaps phthalates are a good place to start since they've been in the news lately and perhaps have more up-to-date data.

First question would be: are phthalates a toxin? (I'mma stick with the colloquial term; I don't see a need to adhere to 'toxicant'.)

Answer: it seems that unequivocally the answer is "yes". Some articles to back that up here:

https://www.theguardian.com/lifeandstyle/2015/feb/10/phthalates-plastics-chemicals-research-analysis
https://en.wikipedia.org/wiki/Phthalate#Health_effects
https://www.webmd.com/a-to-z-guides/features/what-are-phthalates

Second question: is there any evidence to show that phthalates can be eliminated through sweating?

First study, carried out by professors at the University of Alberta in 2012. Twenty volunteers gave samples of blood, urine and sweat. Sweat was obtained by either: infrared sauna (10); steam sauna (7); or exercise (3).

Results: seven "parent compounds" (DMP, DEP, DBP, BBP, DCHP, DEHP, DiNP, and DOP) were tested for in "19 sera and 18 sweat samples". Only DBP (dibutyl phthalate) and DEHP (di (2-ethylhexl)phthalate) were detected.

"DBP was detected in 16/19 sera and 4/18 sweat samples. In 3/4 of the participants where DBP was detected in sweat, this parent phthalate was undetectable in their sera. DEHP was detected in 2 sera and 11 sweat samples, yet out of the 11 individuals who were positive for DEHP in sweat, none had DEHP detected in their serum samples."

Also:

The phthalate metabolites MEP, MiBP, and MEHP were detected in all samples of serum (n = 19), urine (n = 20), and sweat (n = 18). For the 17 participants who had matched serum, urine, and sweat data for MEP, MiBP, and MEHP, we calculated the ratio of their concentrations in sweat to urine (S/U ratio) and found the following median values: MEP: 0.3, MiBP: 1.4, and MEHP: 4.6. This is suggestive of MEHP being more efficiently excreted in sweat, followed by MiBP, and urine being the best pathway of elimination of MEP.

If the data is correct this suggests that "the potentially toxic metabolite MEHP" - "associated with liver toxicity, testicular atrophy, hormone disruption, and cardiotoxicity in animals" (and banned in some parts of the world) - is better eliminated in sweat than in urine.

This would therefore support the claim that some toxicants can be effectively released from the body by sweating.

Other studies are not easy to come by. This 2012 University of Alberta study states that "this is the first study, to our knowledge, that examines the release of phthalates into sweat." A 2020 paper looking at the risks caused by pthalates in the diet of Mexican schoolchildren states that "the elimination of [phthalic] compounds is through biological fluids mainly by urine, feces and sweat."

Genuis and his team also tested the same twenty volunteers for the presence of the toxicant BPA and found that, on the whole, it was more prevelant in sweat than blood or urine:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255175/

Also interesting to note is that the Science-Based Medicine article quoted in the NYTimes 'debunking' of the claim does actually include the following paragraph:

"The liver and kidneys are the primary organs evolved to remove toxins from the blood. There is one potential exception to this, based on preliminary case-report level evidence – heavy metals like cadmium, lead, mercury, and arsenic. A 2011 review did find case reports of clinically relevant excretion of one or more of these heavy metals in sweat.

https://sciencebasedmedicine.org/infrared-saunas-for-detoxification/

The review pointed to is the one done by Sears, noted above. There is no mention of the work done by Genuis, et al however.

Is the jury out? Or are we leaning towards the notion that some toxicants can be effectively and best eliminated through sweating?

Or maybe it's the middle ground of: yes, they can be eliminated but not to an extent that it would actually make any difference? In which case some more specific stats are required.

Also to hypothesise why it appears some compounds are best eliminated by sweating while skeptics like to repeat the claim that "the liver and kidneys are the primary organs evolved to remove toxins from the blood and remove far more toxins than sweat glands" (NYT/SBM): perhaps that's mostly true. Perhaps for millennia the liver and kidneys have done just fine. But in recent decades we've invented things that the body doesn't innately/yet know how to deal with and has to find new means. Artificial substances. Alien objects. Things akin to metal or wooden splinters that it pushes out through the skin rather than processes through the liver and kidneys.

Just a thought.

 

[Mendel]

Is the jury out? Or are we leaning towards the notion that some toxicants can be effectively and best eliminated through sweating?

The problem with many of these toxins is that they're only toxic when they're "on the move", i.e. when they actually reach organs they can damage. Many of them are simply stored away harmlessly (e.g. in fat cells, until you go on a diet).
If you "wring out" the fat cells under your skin, that may get rid of some these toxins, but not improve your overall health (except by placebo effect), if the toxins you sweat out didn't do anything anyway.

So, the real danger seems to be when the toxins are in the blood; but this study seems to show that sweating doesn't help with that.

We've also cited the argument above that the amount of toxins eliminated via sweating is much less than the toxin intake. (This supports my idea that sweat only detoxes cells near the skin anyway.) It'd probably be a good idea to check the amounts.

 

[Rory]

The problem with many of these toxins is that they're only toxic when they're "on the move", i.e. when they actually reach organs they can damage. Many of them are simply stored away harmlessly.

Support for that idea with regard to phthalates and BPA?

 

[Ann K]

Disclaimer: I'm not a medical professional. But BPA and other fat-soluble toxins might be more readily removed by exercise-sweat (but not by sauna-sweat) simply because the exercise metabolizes the fat and releases the toxin. Am I off base with this?

 

[Rory]

Disclaimer: I'm not a medical professional. But BPA and other fat-soluble toxins might be more readily removed by exercise-sweat (but not by sauna-sweat) simply because the exercise metabolizes the fat and releases the toxin. Am I off base with this?

In the table above the largest sweat-to-urine ratio is from a volunteer who sweated by exercise - but then the other two who exercised has quite low/normal ratios.

I guess more data required.

 

[Rory]

More on this subject in an article at The ZRT Laboratory Blog:

Literature is rather limited on the subject of heavy metal elimination through sweat, but with the advancement of sweat collection and sophisticated instrumentation, recent studies have shown encouraging results on heavy metal detox via sweat.

A study by Genuis and colleagues looked at serum, urine, and sweat levels of toxic heavy metals and essential elements and found compelling results. The most striking result was the large excretion of lead and cadmium in sweat collected during exercise or in an infrared/steam sauna in comparison to concurrent serum and urine collections. Interestingly, lead and cadmium are elements characterized by long half-lives in the body (20-30 years), miniscule excretion in urine, and serious bioaccumulation. A typical sauna session results in a half-liter of sweat loss, meaning that a significant amount of toxins are potentially being excreted. Other studies have shown similar results. This means that a possible route of detoxing from lead and cadmium may be through sweat.

So are heavy metals excreted through sweat? Possibly.

Even though studies have shown that sweat excretion of heavy metals should not be overlooked, I am somewhat critical of the collection methodologies used in different studies. An investigation into drugs of abuse in sweat showed that blood capillaries and adipose tissue may contribute to secretions from sebaceous and apocrine glands connected to hair follicles. These are different than the eccrine sweat glands which are the main producers of sweat for thermal regulation. Most sweat collection studies involve scraping the skin to collect sweat, which will also pick up fatty sebum excretions (disintegrated epithelial cells).

Most toxins, including heavy metals, are fat-soluble. It is plausible that sebum excretions from the sebaceous gland are a route of heavy metal buildup and excretion that may stick around longer than sweat from the eccrine gland, which quickly evaporates.

At this point it is difficult to tell if heavy metals are excreted through eccrine sweat glands or apocrine sweat glands, or the sebum from sebaceous glands, or all of the above. It is also possible that sweat samples used in the studies mentioned were contaminated by dermal exposure to heavy metals. Future studies monitoring sweat should compare collections from areas where sebaceous glands are present in high concentrations (scalp and face) to areas where only eccrine sweat glands are present (palms and soles).

https://www.zrtlab.com/blog/archive/sweating-heavy-metal-detox/

In a nutshell: studies are few and far between; results for some heavy metals are encouraging; but the writer has concern over possible contamination due to collection methods.

Conclusion: more data required.

 

[Rory]

Also, a terrific video that shows there's nothing clearcut on the subject:


Source: https://www.youtube.com/watch?v=ypkjUy_jghQ

Most interestingly mentions a study where basketball players were measure before and after a strenuous exercise session and were found to have increased levels of lead in their blood (hypothesised as to being due to the environment they were playing in).

 

[Mendel]

In a nutshell: studies are few and far between; results for some heavy metals are encouraging; but the writer has concern over possible contamination due to collection methods.

That study also does not compare intake to excretion.

"detox" suggests an impact on toxin levels in the body, but if it's not enough to matter either way, it'd still be placebo.

 

[Rory]

it's not enough to matter either way

Can you provide figures to back this up please?

 

[Mendel]

Can you provide figures to back this up please?

you overlooked the word "if" and "it'd" (short for "it would"), which makes my statement hypothetical.

Figures that compare intake to excretion would back this up, but a study that merely compares sweat to urine is not helpful in that regard.

 

[Rory]

you overlooked the word "if"

True, I did. That changes things.

and "it'd"

Not so there though.

Anyways, I'm still interested to know if these excretion levels are "enough to matter" or not. That seems a key component of the claim.

 

[Ann K]

Most interestingly mentions a study where basketball players were measure before and after a strenuous exercise session and were found to have increased levels of lead in their blood (hypothesised as to being due to the environment they were playing in).

If the level of lead is expressed as weight per volume, you'd also get a higher level by decreasing the volume, i.e. simple dehydration.

 

[Mendel]

If the level of lead is expressed as weight per volume, you'd also get a higher level by decreasing the volume, i.e. simple dehydration.

or if you hydrate with lead-containing water
(e.g. in Flint)

 

[FatPhil]

This concept will of course never sleep, here's another instance: https://www.thedailybeast.com/best-sauna-blankets-for-weight-loss-and-detox?source=articles&via=rss

I do like the various back-covering wording that's been used, much of it is just self-reporting "feels". But there are some that could be interpreted as testable scientific claims:

According to the brand, one 30-minute session in this far infrared sauna blanket can burn up to 600 calories (for reference a 30-minute jog burns around 300 calories). Plus, the infrared heat is seven times more detoxifying than normal heat.

I can't decide if the 2nd claim there is 100% meaningless (how is infrared heat not normal heat?) or 100% true, as seven times zero is zero.

 

[Mendel]

But there are some that could be interpreted as testable scientific claims

Blankets provide contact heat to the user, not radiant heat. (I guess they radiate into the room?)

one 30-minute session in this far infrared sauna blanket can burn up to 600 calories

600 Calories = 600 kcal = 2500 kJ in 30 minutes comes out to 1800W. That's probably about the electric power that the blanket "burns". (It's also 2.4 horsepower.) If your body burned that amount of Calories, it'd be heating the blanket and not the other way around.

Note that the graphic below, used to sell blankets all over the Internet, claims 3000 calories in 10 minutes. This should make you lose almost a pound of body fat, but what you'll actually lose is mostly water. (Also, Yoga is not burning more Calories than jogging.)

Another fun thing is that all 5 of the basic functions are basically "fat loss", with "detoxification" being half of the fifth function.

Up until "promote systemic blood circulation", the graph describes the effect of heat on the body, as does "increase your metabolism" and "sweating".

"Dredge the whole body meridian" refers to a concept from Traditional Chinese Medicine that has so far escaped western science, see https://www.metabunk.org/threads/cl...f-hyaluronic-acid-and-piezoelectricity.11819/ .

"Physiotherapy" is more than sweating, and the "slimming" effect is going to be marginal, unless you count water lost as sweat (which is quickly reconstituted).

A heated blanket is probably a safer wellness treatment than a UV bed, but I doubt it has much of an effect beyond the wellness. It's convenient if you don't have access to a bathtub or hot spring, I guess; the inside of the blanket is definitely going to be moist afterwards.

 

[Leifer]

Saint Paul, MN

Will a sauna help prevent firefighter cancer? A study in St. Paul aims to find out

"What we are hoping to find out, through this study, is if saunas can help reduce the amount of carcinogens that remain in our bodies after being exposed at fires," Mokosso said.

That study is being led by Dr. Zeke McKinney, an occupational and environmental medicine physician with the HealthPartners Institute and the University of Minnesota Medical School.

"Being able to prevent and reduce the risk of cancer in firefighters is, I think, everyone's primary interest," Dr. McKinney said.

Firefighters noted that in the past, saunas seemed to work better at removing smoke and soot odors better than a typical soapy shower.
At this point, it is just a study, along with samples of skin sweat resulting from these infrared saunas.
It's possible they are just trying to demonstrate that surface soot can be removed via sweating.... not carcinogens from "inside" the body.

 

[Mendel]

That study is being led by Dr. Zeke McKinney, an occupational and environmental medicine physician with the HealthPartners Institute and the University of Minnesota Medical School.

Article:

Dr. McKinney's clinical research interests are in preventing work-related illness and injury, improving data-driven decision-making in clinical contexts, environmental toxicology, public safety medicine, managing complex impairment/disability and increasing the health literacy of patients and communities.

Principal investigator, "Firefighter Soot, Sauna, and Sweat Excretion Pilot Study" funded by the City of St. Paul & the St. Paul Fire Department.

Source: https://www.healthpartners.com/knowledgeexchange/display/person-McKinney-Z-J

This looks like a proper study, although it may be quite small. I'd classify it as a preliminary study, which may or may not provide conclusive results; but it should show whether there is an effect worth investigating further. The study was pre-registered, which is good. Excerpts:

Article:

Study Objective(s)

Aim 1. This study aims to demonstrate that sauna use immediately after active-duty firefighting will result in measurable (above the level of detection) PAH biomarkers in sweat.

Aim 2. This study secondarily aims to demonstrate that sauna use immediately after active-duty firefighting will result in significantly different mean levels of PAH biomarkers in urine as compared to no use of a sauna.

There will thus be two comparison groups within the study: 1) active-duty firefighters using a sauna after fire suppression (sauna group); 2) active-duty firefighters not using a sauna after fire suppression (metabolism control).

Inclusion criteria:
1. Willingness to collect urine samples before, during, and/or after work shift
2. Willingness to refrain from eating barbecued or smoked foods during the duration of the study
3. Willingness to use a sauna after active fire suppression and to collect sweat samples at that time

Number Of Subjects
A minimum of 20 people (10 per group) and a maximum of 60 people (30 per group) will be recruited.

Start Date 2021-11-01
Completion Date 2023-02-01
Primary Completion Date 2022-12-01

Source: https://ichgcp.net/clinical-trials-registry/NCT05256966

I take it that they're gathering data up until Dec 1st 2022, and hope to complete the study by Feb 1st 2023.