W*****B
发帖数: 4796 | 1 I Gory Details I
Fact or Fiction: Can You Really Sweat Out Toxins?
There are plenty of good reasons to work up a sweat. Detoxifying your body
isn’t one of them.
Sweating is a bodily function that used to be taboo, with women in
particular being told they don’t sweat, they glow. But look at any fashion
magazine or beauty blog today, and you’ll find that sweat is in style. From
infrared saunas to hot yoga, towel-soaking activities are being touted not
only as relaxation tools, but also as ways to stay healthy by flushing out
toxins.
Too bad you can’t sweat away toxins any more than you can sweat actual
bullets. Recently published calculations back up what scientists have been
screaming into their pillows for years: Sweating out toxins is a myth.
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. While sweat is made up mostly of water and minerals, it can
contain trace amounts of various toxic substances.
But the new findings, published in the journal Environment International,
show that even when we do excrete environmental pollutants through our pores
, the amounts we can sweat out are minuscule.
“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.”
Is Sweat Toxic?
Schwarcz directs McGill University’s Office for Science and Society, which
debunks science myths, and he says the group is inundated with questions
about medical scams and quackery, including many that promise to “detoxify
” the body.
So, what are the levels of harmful substances in sweat?
For most pollutants, they’re so low that they’re essentially meaningless,
says Pascal Imbeault, who led the new study. Imbeault is an exercise
physiologist at the University of Ottawa in Canada who’s studying
pollutants that are stored in body fat. Known as persistent organic
pollutants, these include pesticides, flame retardants, and now-banned
polychlorinated biphenyls, or PCBs, which are still found in the environment.
These are the kinds of chemicals that many people think of as “toxins” in
our food and environment. (Imbeault adds that we’re actually using the
wrong word—they’re toxicants. Toxins are natural substances made by plants
and animals.)
Because these chemicals are attracted to fat, they don’t dissolve well in
sweat, which is mostly made of water.
At most, Imbeault and his colleagues found, 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 these pollutants.
To put that in perspective, “the amount in sweat is 0.02 percent of what
you ingest every day on a typical diet,” Imbeault 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.
Keep in mind, the levels of pesticides and other pollutants in most people’
s bodies are also extremely low to begin with. It’s a testament to
analytical chemists that we can detect a compound down to parts per trillion
, Schwarcz says, but that doesn’t mean it’s harming you or that
incrementally decreasing it will have any health effect.
Sweating It Out
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, according to the National Institute of Environmental Health
Sciences.
Of course, none of this has stopped a growing sweat-detox industry. The
latest fad is infrared saunas, which use infrared lights as a heat source
instead of electric heaters or steam. When a writer at The Atlantic looked
into the detoxification claims made for these saunas, it quickly became
apparent they weren’t based on any actual science.
Yet spas and sauna makers continue to assert their detox benefits. Fire
departments in Texas and Indiana have even bought infrared saunas on the
premise that firefighters will sweat out chemicals they’re exposed to in
smoke, and that this will prevent cancer. While saunas may be soothing and
have other benefits, the cancer-prevention claim has not been proven.
Taken too far, sweat therapy can even be deadly.
A 35-year-old women in Quebec died after a detoxification spa treatment
plastered her with mud, then wrapped her in plastic and put a cardboard box
over her head. She lay under blankets for nine hours, sweating. Hours after
the treatment, she was dead from extreme overheating.
“It’s the old story of wanting to provide a simple solution to a complex
problem,” Schwarcz says. “Hope is so precious, but some people use hope
for selling crazy stuff to people who are vulnerable.”
_ | m**c
发帖数: 7349 | 2 我觉得可以，每次大汗淋漓之后就是爽。科学家的话不能全信 | w*********r
发帖数: 42116 | 3 这得看毒怎么定义了。按Toxins字面意思，出汗当然不排毒。但出汗能局部代谢产生得
尿素、乳酸、脂肪酸排出体外，这就是为什么流汗后要立刻把皮肤擦干净。
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【在 W*****B 的大作中提到】
: I Gory Details I
: Fact or Fiction: Can You Really Sweat Out Toxins?
: There are plenty of good reasons to work up a sweat. Detoxifying your body
: isn’t one of them.
: Sweating is a bodily function that used to be taboo, with women in
: particular being told they don’t sweat, they glow. But look at any fashion
: magazine or beauty blog today, and you’ll find that sweat is in style. From
: infrared saunas to hot yoga, towel-soaking activities are being touted not
: only as relaxation tools, but also as ways to stay healthy by flushing out
: toxins.
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