Using the sauna is one of my all-time favorite therapeutic modalities and for good reason. Not only does it confer innumerable health benefits I’ll discuss, but there’s something to say about getting in a good workout and then going in the sauna and leaving a hot, sweaty mess.
Sauna bathing is a form of whole-body thermotherapy that has been used in various forms (radiant heat, sweat lodges, etc.) for thousands of years in many parts of the world for hygiene, health, social, and spiritual purposes (1). We can thank the Finns for this widely used healing tool as the first documented reports of sauna use were in Finland.
*Sauna use may not be appropriate for everyone, so as always consult a licensed healthcare professional before participating*
Increased excretion of toxicants:
We are constantly inundated with environmental toxicities from all areas of our life that we don’t always think about. A vast majority of these toxicants are fat-soluble and are sequestered into adipose tissue as a biological compensatory measure to protect vital organs from the deleterious effects these have on our bodies.
Environmental toxins encompass a vast range of compounds and elements including heavy metals. Heavy metals like arsenic, cadmium, lead, and mercury are ubiquitous and serve no physiological benefits, yet yield various profound negative health risks.
Common sources of these toxins:
Arsenic- Groundwater, chicken, rice, public, and private water supplies (2). Mining, smelting of non-ferrous metals and burning of fossil fuels are the major anthropogenic sources of arsenic contamination of air, water, and soil (primarily in the form of arsenic trioxide). The historical use of arsenic-containing pesticides has left large tracts of agricultural land contaminated. The use of arsenic in the preservation of timber has also led to contamination of the environment (3).
Cadmium- Cadmium enters the environments through natural and various anthropogenic sources. However, the accumulation of Cd in the soil-plant environment mainly through anthropogenic activities such as application of phosphate fertilizers, wastewater, sewage sludge, and manures (4).
Lead- Lead-based paint, lead-contaminated air, soil, dust, drinking water got through lead soldered pipes, food stored in lead soldered cans, traditional medicines, cosmetic, and artisan ceramics. Lead may be introduced into food inadvertently during harvesting, processing, packaging or preparation. The main sources of contamination of food are soil, industrial pollution, agricultural technology, and food processing (5).
Mercury- Dental amalgam, thermometers, sphygmomanometer, barometers, fossil fuel emissions, incandescent lights, batteries, ritualistic practices using mercury, certain va((ines, fish and shellfish, and the incineration of medical waste (6).
All four elements are confirmed or probable carcinogens and they exhibit wide-ranging toxic effects on many bodily
systems, including the nervous, endocrine, renal, musculoskeletal, immunological, and cardiovascular systems (7).
As you can see these dangerous elements are impossible to completely avoid as the Industrial Age and anthropogenic (originating in human activity) measures have made their presence everywhere from the food we eat to the air we breathe.
This leads many to be discouraged, but there are measures we can take to help with the excretion of these toxicants like frequent sauna use.
In a systemic review in the Journal of Environmental Health, sweating (via sauna or exercise) was shown to augment the excretion of those heavy metals through sweat (8).
In another study, 20 adults had measurements of the presence of various compounds done before and after sweating and the results showed that markedly higher excretion of aluminum (3.75-fold), cadmium (25-fold), cobalt (7-fold), and lead (17-fold) was observed in sweat versus urine (9).
In another study, “Blood, urine, and sweat were collected from 20 individuals (10 healthy participants and 10 participants with assorted health problems) and analyzed for various environmental toxicants including BPA. Results. BPA was found to differing degrees in each of the 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” (10).
An estimated 17.9 million people died from Cardiovascular Diseases in 2016, representing 31% of all global deaths according to The World Health Organization.
Cardiovascular disease is largely preventable with lifestyle factors like frequent sauna use.
In Eastern Finland, large prospective studies on sauna bathing investigated the association of frequency and duration of sauna bathing with the risk of sudden cardiac death (SCD), fatal coronary heart disease (CHD), fatal cardiovascular disease (CVD), and all-cause mortality (11).
The study found that compared to the men who never use the sauna:
Sauna use 2-3 times per week reduced the likelihood of death from cardiovascular-related causes by 27%
Sauna use 4-7 times per week reduced the likelihood of death from cardiovascular-related causes by 50%
Frequent sauna use (4-7x per week) also reduced all-cause premature mortality by 40% regardless of age, activity levels, and lifestyle factors.
In another prospective cohort study, 1628 adult men and women were followed for 15 years to assess the association between frequency of sauna bathing and risk of future stroke found (12):
Having regular sauna baths (4-7 sessions/wk) compared with 1 sauna session/wk was associated with an approximately 62% reduced risk of incident stroke.
It is said that inflammation is not only accompanied by disease, but also at the root of all disease etiology. There are various pro-inflammatory and anti-inflammatory markers of inflammation that can be used to measure the efficacy of an intervention on inflammation.
One of these pro-inflammatory markers is C-reactive protein.
C-reactive protein is a surrogate biomarker for inflammation in the body. CRP is secreted by the liver in response to a variety of inflammatory cytokines. Levels of CRP increase very rapidly in response to trauma, inflammation, and infection and decrease just as rapidly with the resolution of the condition.
Thus, the measurement of CRP is widely used to monitor various inflammatory states (13).
In a study consisting of 2084 men (42-60 years), it was found that there was a significant inverse association between the frequency of sauna bathing and the level of C-reactive protein (14).
Meaning the more frequent the use of sauna therapy, the lower the level of C-reactive protein (those who used the sauna 4-7x per week had the lowest mean serum CRP compared to the 2-3x per week group).
Neurogenesis or the creating of new neurons is largely due to a protein called brain-derived neurotrophic factor or BDNF. This protein promotes the survival of nerve cells (neurons) by playing a role in the growth, maturation (differentiation), and maintenance of these cells (15).
It is active in the hippocampus, cortex, cerebellum, and basal forebrain. These areas are involved in long term memory, learning, and executive function.
Heat stress (and exercise) has been shown to increase the expression of BDNF (16).
Although the cause behind Alzheimer’s and Dementia is still debated/remains to be unknown, a further driver in the progression of Alzheimer’s is the buildup of amyloid-beta plaque in the brain.
Amyloid plaques are the sticky buildup of proteins that accumulate outside nerve cells. In the Alzheimer’s brain, abnormal levels of this naturally occurring protein clump together to form plaques that collect between neurons and disrupt cell function (17).
A study in Finland involving 2,315 healthy middle-aged Finnish men with a median follow-up of 20.7 years assessed weekly ‘sauna bathing’ habits. Study participants were divided into three groups: those who took about a 15-minute sauna 4-7 times a week, those using a sauna 2-3 times a week, and those who only used a sauna once a week (18). The results showed that:
Using the sauna 2-3 times per week was associated with a 22% lower risk of dementia
Using the sauna 4-7 times per week was associated with a 66% lower risk of dementia
Using the sauna 2-3 times per week was associated with a 20% lower risk of Alzheimer’s
Using the sauna 4-7 times per week was associated with a 65% lower risk of Alzheimer’s
Although the mechanism behind these findings weren’t established, the clearance of amyloid-beta plaque due to improved cardiovascular health may be a cause.
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