Sweat do contain some ‘toxins,’ like metals, but it is often nowhere near the toxicity that some massage therapists claim.
Unless you are exposed to high levels of industrial chemicals, such as chloride, arsenic, mercury, and lead, almost everyday in your work or living environment, your sweat hardly have any “toxins.” If you live in an area where there is low contaminants in the air, then your chances of being constantly exposed to deadly levels of toxins is likely to be very low. However, there is a common misconception among massage therapists that massage therapy can “get rid of toxins” or drinking more water help “flush toxins out,” but that isn’t exactly how our body works. Also, it is not our responsibility or business to decide whether a client or patient needs to get “detoxed” or not. Unless you are a qualified toxicologist, this is outside of a therapist’s scope of practice.
Most of the time, the “toxins” therapists talk about rarely have anything to do with actual toxins that medical professions deal with, such as venoms and alcohol overdose. For some reason, these toxins are not identified if someone were to ask what kinds of toxins they are. In fact, the usage of the term is more akin to “miasma” — or “pollution” in Greek — that was a part of medical philosophy of the ancient Greeks and Romans. (1) Of course, thanks to the germ theory of disease, we should discard the outdated model of disease and health that hold no space in modern healthcare — except in the history section.
In the general population, sweat is about 99 percent water with one percent minerals and other compounds. One small study (n=7) found that sweat contains trace amounts of metals, including sodium, potassium, calcium, copper, magnesium, and zinc, after the subjects had completed a long bout of exercise in exposed heat. (2) The amount of these substances also varies among individuals.
A 2004 study on 26 Turkish wrestlers found similar composition with the additional of iron and chromium. But these listed substances are NOT toxins. Within a healthy range, these minerals are essential to maintain normal health. Our body also sweats out water-soluble vitamins, such as vitamin C and riboflavin. (3)
Of course, your body may contain a minute amount of chemicals that we cannot process, but your body excretes these substances out of our sweat glands or urinary tract anyways. Examining the past and current evidence of sweating can help us de-myth some of the beliefs about sweating and “toxins” and have a better understanding how perspiration works.
Toxins do exist in blood and sweat, but under certain conditions
Research in perspiration in the early 20th century had found a number of toxic chemicals that the body excretes, such as chlorine. A review published in 1934 identified two such studies of water poisoning among men who performed hard labor while drinking unclean water. (4) Industrial and environmental workers who were exposed to various hazardous chemicals, such as arsenic and mercury, had significant levels of such metals in their sweat. (5)
In a Canadian systematic review, the authors argue that such population may benefit from sweating while in a sauna or engage in exercise to help rid of such metals. For many who are not exposed to such metals in our environment or handle such materials everyday, there may be no need to worry about this.
Another Canadian study also found that phthalates, a flexible compound that makes up the flexibility and durability of plastic, are found in the sweat samples among their sample of subjects (n=20). Yet this compound was not found in the blood samples, which was hypothesized that sweating is a way the body removes phthalates from the bloodstream. (6)
So should you be concerned about this? Probably not. Without proper training and better understanding of human physiology, it is not a massage therapist’s responsibility to make a pseudo-diagnosis about whether our clients or patients have “toxins” or not. Even if they have, how do therapists know? How would they measure it? Is it within their scope of practice?
Any benefits to sweating?
Despite the benefits of sweating that has a strong likelihood of removing unwanted substances in our body, there are some drawbacks if we sweat too much for too long. Two Taiwanese studies found that excessive sweating during exercise — in these cases, badminton and tennis — can decrease uric acid excretion in urine and increase the level of uric acid in the blood. Not a good thing, especially if you are not rehydrating during exercise. (7,9) Such an increase in uric acid may increase the risks of getting neuropathic disorders among type II diabetics. (8)
Remember that sweating is simply your body’s way of cooling down, and in certain circumstances, it is a way to eliminate true toxins (e.g. heavy metals) among specific populations. Most clients and patients seek massage therapy for pain relief, relaxation, and/or stress relief. Thus, therapists should stick with what they do best and avoid breaching their scope of practice and make toxic claims.
1. Gorski D. Fashionably Toxic. Science-based Medicine. Sept 2014.
4. McSwiney BA. The Composition of Human Perspiration (Samuel Hyde Memorial Lecture): (Section of Physical Medicine). The Composition of Human Perspiration (Samuel Hyde Memorial Lecture): (Section of Physical Medicine). 1934;27(7):839-848.
5. Sears ME, Kerr KJ, Bray RI. Arsenic, Cadmium, Lead, and Mercury in Sweat: A Systematic Review. Journal of Environmental and Public Health. 2012;2012:184745. doi:10.1155/2012/184745.
6. Genuis SJ, Beesoon S, Lobo RA, Birkholz D. Human Elimination of Phthalate Compounds: Blood, Urine, and Sweat (BUS) Study. The Scientific World Journal. 2012;2012:615068. doi:10.1100/2012/615068.
7. Huang LL, Huang CT, Chen ML, Mao IF. Effects of profuse sweating induced by exercise on urinary uric acid excretion in a hot environment. Chin J Physiol. 2010 Aug 31;53(4):254-61.
8. Papanas N, Demetriou M, Katsiki N, et al. Increased Serum Levels of Uric Acid Are Associated with Sudomotor Dysfunction in Subjects with Type 2 Diabetes Mellitus. Experimental Diabetes Research. 2011;2011:346051. doi:10.1155/2011/346051.
9. Huang CT, Chen ML, Huang LL, Mao IF. Uric acid and urea in human sweat. Chin J Physiol. 2002 Sep 30;45(3):109-15.