How Sauna Use May Boost Longevity & Prevent Alzheimer’s
In my video on the topic of sauna use, I suggested that hyperthermic conditioning might:
* Improve Athletic Endurance
* Prevent Muscle Atrophy
* Improve Insulin Sensitivity
* Increase Neurogenesis (The Growth Of New Brain Cells)
* Improve Learning/Memory
* Possibly Increase Longevity
In this article, I’m going to pick up where we just left off: Longevity.
A recent study (April 2015) was published in the Journal JAMA Internal Medicine, which showed that sauna use was in fact associated with longevity. The study recruited over 2000 middle-aged men in Finland and compared frequency of sauna use with sudden cardiac death, fatal coronary heart disease, fatal cardiovascular disease, and all-cause mortality including cancer over the course of 20 years.
The study found that fatal cardiovascular disease was 27% lower for men who used the sauna 2 to 3 times a week and 50% lower for men who used the sauna 4 to 7 times a week compared with men who just used the sauna once per week.
Moreover, they found that using the sauna 2-3 times per week was associated with 24% lower all-cause mortality and 4-7 times per week 40%.
Before we get started…
Temperature is a very important parameter to discuss since there may be a lot of variation from one sauna to the next. The average temperature of the dry sauna used in this study was 79º C or 174º F (that is hot!), often with a splash of water poured over rocks to increase the humidity and for a duration up to or exceeding 20 minutes. This means the results may not be directly applicable to steam rooms, hot tubs, and some other types of saunas, like infrared, which can operate at lower temperatures. That doesn’t mean something that steam rooms, hot tubs, and infrared saunas have no merit, but it does mean that there are some subtle differences if you’re comparing them to these types of hot Finnish saunas used in the study.
Some of the positive benefits of the sauna on heart health may have to do with similar benefits seen with regular physical exercise. Heart rate may increase up to 100 beats per minute during moderate sauna bathing sessions and up to 150 beats per minute during more intense warm sauna use, which is pretty fast, and in the latter case corresponds to moderate-intensity physical exercise. It is not surprising that long-term sauna use has been shown to generally improve blood pressure, endothelial function, and left ventricular function.
Frequent Sauna Use Associated with Lower Alzheimer’s Disease Risk
Using the same population of men, another study published in Dec. 2016 found that using the sauna 4-7 times per week lowered the risk of dementia by 66% and Alzheimer’s disease by 65% compared to men that used the sauna once a week. This study included over 2,000 middle-aged men that were followed for 20 years. The results were adjusted for many possible confounding factors including baseline age, alcohol consumption, BMI, physical exercise, socioeconomic status, systolic blood pressure, smoking status, type 2 diabetes, previous heart attack, resting heart rate and serum low-density lipoprotein cholesterol.
Sauna Reduces Mortality and Alzheimer’s Disease: Role of Heat Shock Proteins
I think there are a couple of good molecular explanations for how sauna use may influence longevity and decrease Alzheimer’s disease risk. First, we’ll turn to a topic we discussed previously: heat shock proteins (also known as HSPs). Heat stress like sauna use or even or even exercise (to a lesser extent) activates genes that make more HSPs.
Heat shock proteins have many important functions inside the cell. One very important function is to make sure proteins, which do all of the biological work in the cell, keep their proper 3-dimensional structure in the cell when under stress, whether we’re talking about stress from heat or other stressors like exposure to ultra-violet radiation from the sun, cell injury, or even the aging process, in general. Maintenance of protein structure is critical for each protein’s ability to do its specific function, and it is also important for the longevity of the protein.
Normal metabolism and normal immune function, in other words, “just being alive,” create reactive byproducts (called reactive oxygen and nitration species), which damage proteins and disrupt their structure. This not only interrupts the function of those proteins, preventing them from doing their work but also can lead to protein aggregation. The damage from these reactive byproducts accumulates with age and contributes to the normal aging process.
Protein aggregation is associated with cardiac diseases including heart failure, cardiomyopathy, and atherosclerosis as well as with neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. Increased expression of heat shock proteins has been shown to prevent protein aggregation because HSPs help repair proteins that have been damaged. HSPs have also been shown to protect against neurodegenerative diseases including Alzheimer’s Disease.
It has been shown that being acclimated to the heat, such as from regular sauna use, results in more heat shock proteins under normal conditions and even more under stressful conditions such as cell and tissue injury. This is good because as we age we make fewer HSPs so anything to boost them is beneficial.
So since we know that HSPs are awesome because they help us resist stress of both the exceptional variety such as in injury, as well as the everyday variety that is associated with aging, perhaps you won’t be surprised that the effects of heat stress on longevity have been shown in flies and worms to increase their lifespan by up to 15%. The mechanism of lifespan extension was also teased out in these organisms and shown to be specifically dependent on heat shock proteins. Heat shock proteins have also been linked to human longevity. Humans with a gene polymorphism associated with producing more of a certain heat shock protein is associated with being a centenarian.
Figure 1: Heat Shock Proteins Repair Damaged Proteins
The same damage that damages DNA also damages proteins. This damage disrupts their 3D structure and leads to protein aggregation, which can lead to neurodegenerative diseases. Heat Stress induces the production of more heat shock proteins, which repair damage that is inflicted on proteins inside the cells and prevent protein aggregation.
Sauna Reduces Mortality: Role of FOXO3
In addition to HSPs, FOXO3 is another molecular pathway that may explain how using the sauna could improve longevity. Foxo3 is a gene that is associated with longevity, and, indeed, heat stress (such as from using the sauna) activates FOXO3. Humans with a polymorphism that makes more of foxo3 have up to a 2.7-fold increased chance of living to be a centenarian and In mice, having more of their homologous version of this gene can extend their lifespan by up to 30%!
The mechanism by which FOXO3 increases longevity has to do with the fact that it is a master regulator of many different genes. When it is on, it increases the expression of several genes that make you more resilient various types of stress that occur with aging. Many of the genes that FOXO3 increases happen to decrease with age, so it is good to boost their expression.
One particularly important type of stress that FOXO3 protects against is DNA damage. The same type of reactive byproducts (from normal metabolism and immune function) that damage proteins in the cell also damage DNA. DNA damage can lead to mutations and a damaged cell with a mutation may then replicate to form cancer. Foxo3 increases the expression of DNA repair genes that repair that damage to DNA so that a mutation never occurs. It also increases the expression of genes that kill cell damaged cells so that they do not become cancer cell.
FOXO3 also makes cells more resilient to damage by increasing the expression of genes that combat this damage including antioxidant genes (which are much more potent than dietary antioxidants) and prevent the damage from reaching the cell.
When a cell becomes damaged or its telomeres become critically short, the cell can become senescent (which means the cell does not die but it is not alive either) and it just sits around causing more damage because a senescent cell releases pro-inflammatory cytokines and other factors that damage more cells. Well, foxo3 increases genes involved in autophagy, which means the cell will eat itself up so that it is not secreting inflammatory molecules that damage more cells.
FOXO3 also increases the expression genes involved in immune function (which declines with age) so that your immune cells can fight off bacteria, viruses and cancer cells better. FOXO3 also regulates genes involved in metabolism and stem cell function just to name a few!
Figure 2: FOXO3 Increases DNA Repair
DNA damage occurs everyday and can lead to breaks in both DNA strands (called double-strand breaks). This type of DNA damage is very dangerous because it is the most difficult to repair and leads to mutation that are known to cause cancer. Heat stress activates FOXO3, which increases the production of genes that produce DNA repair enzymes to repair this damage so a cancer-causing mutation does not occur.
What About Duration, Frequency, And Timing Of The Sauna?
If the sauna is a traditional dry or wet sauna that is somewhere between 170 180 F (77- 82 C) then a duration of 20-25 minutes is what most studies have shown to be beneficial. I typically stay in for this amount of time.
As for frequency, I mentioned the dose-dependent effect on all-cause mortality 4-7 times per week was better than 2-3 times per week. The 66% reduction in Alzheimer’s risk was found in men that used the sauna 4-7 times per week.
In terms of timing, either before or after a workout, most studies I have read were done either after a workout or on days with no workout. I tend to do both of these. Practically speaking doing the sauna immediately before a workout seems awful. Who wants to be drenched in sweat and exhausted before the start of a workout.
Different Sauna Types
Dry Sauna, Wet Sauna, Infrared Sauna, Far Infrared Sauna
A dry sauna typically refers to a wood-paneled room with wooden benches and a heater that heats up the air anywhere between 70 and 90°C (158-194°F). In a wet sauna (or Finnish sauna), water is poured onto hot rocks, which produces steam and raises the humidity to about 20%. Dry saunas are essentially the same as Finnish saunas but without the steam.
In both dry and wet saunas, the heat is transferred from the air to the body.
The major difference between dry or wet saunas and infrared saunas is that a dry or wet sauna heats the air and this heat is transferred from the air to the body whereas an infrared sauna use thermal radiation, which is electromagnetic radiation that is generated by moving particles in matter, and in this case, the matter happens to be our bodies. So infrared saunas heat the body directly without necessarily warming the surrounding air. The air does get heated but not nearly as hot as a traditional dry sauna.
There are two main types of infrared saunas – infrared and far-infrared..I’m not going to go too much into this but infrared saunas use infrared heat lamps which use incandescent bulbs to produce thermal radiation primarily near-infrared wavelengths, with lesser amounts of middle infrared wavelengths.
Far infrared saunas use ceramic or metallic heat elements that mainly emit energy in the far-infrared range (which is similar to the sun).
I’ve seen much more marketing claiming that infrared saunas induce more sweating than actual science…in fact, I’ve personally experienced the opposite effect.
All the benefits that I have discussed today have to do with heat stress and physiological adaptations that occur as a consequence of heat stress.
I think infrared saunas are great, particularly far infrared because there is more science showing some positive effects on cardiovascular disease.
Additionally, for the home, I think infrared saunas pose much less of a fire hazard than a dry sauna…but I still don’t buy into much the sales marketing I’ve read about them.
Use of Sauna and Cold to Increase Net Resilience, Mitochondrial Biogenesis, Mood and Longevity
The presentation above was filmed in Helsinki, Finland where I presented on sauna use and cold stress and talked about how these modalities may be a way to achieve an increase in net resilience and how this can pour into many different areas: possibly increased longevity and mood… and if we look at the molecular evidence, maybe neurodegenerative diseases as well.
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Perciavalle Patrick has a Ph.D. in biomedical science from the University of Tennessee Health Science Center, Memphis TN and St. Jude Children’s Research Hospital, Memphis TN. She also has a Bachelor’s of Science degree in biochemistry/chemistry from the University of California, San Diego. She has done extensive research on aging, cancer, and nutrition. She did her graduate research at St. Jude Children’s Research Hospital where she investigated the link between mitochondrial metabolism, apoptosis, and cancer. Her groundbreaking work discovered that a protein that is critical for cell survival has two distinct mitochondrial localizations with disparate functions, linking its anti-apoptotic role to a previously unrecognized role in mitochondrial respiration and maintenance of mitochondrial structure. Her dissertation findings were published in the 2012 issue of Nature Cell Biology.
Dr. Patrick trained as a postdoctoral fellow at Children’s Hospital Oakland Research Institute with Dr. Bruce Ames. She investigated the effects of micronutrient (vitamins and minerals) inadequacies on metabolism, inflammation, DNA damage, and aging and whether supplementation can reverse the damage. In addition, she also investigated the role of vitamin D in brain function, behavior, and other physiological functions and has published papers in FASEB on how vitamin D regulates serotonin synthesis and how this relates to autism and other neuropsychiatric disorders.
Dr. Patrick has also done research on aging at the Salk Institute for Biological Sciences. At the Salk, she investigated what role insulin signaling played in protein misfolding, which is commonly found in neurodegenerative diseases such as Alzheimer’s disease.
She frequently engages the public on topics including the role micronutrient deficiencies play in diseases of aging, the role of genetics in determining the effects of nutrients on a person’s health status, benefits of exposing the body to hormetic stressors, such as through exercise, fasting, sauna use or heat stress, or various forms of cold exposure, and the importance of mindfulness, stress reduction, and sleep. It is Dr. Patrick’s goal to challenge the status quo and encourage the wider public to think about health and longevity using a proactive, preventative approach.
* Vitamin D and the Omega-3 Fatty Acids Control Serotonin Synthesis and Action, Part 2: Relevance for ADHD, Bipolar, Schizophrenia, and Impulsive Behavior FASEB Journal
* Vitamin D Hormone Regulates Serotonin Synthesis. Part 1: Relevance for Autism FASEB Journal
* Requirement for Anti-Apoptotic MCL-1 in the Survival of BCR-ABL B-Lineage Acute Lymphoblastic Leukemia Blood
* Delving Deeper: MCL-1′s Contribution to Normal and Cancer Biology Trends in Cell Biology
* Anti-Apoptotic MCL-1 Localizes to the Mitochondrial Matrix and Couples Mitochondrial Fusion to Respiration Nature Cell Biology
* Ubiquitin-Independent Degradation of Anti-Apoptotic MCL-1 Molecular and Cellular Biology
* Opposing Activities Protect Against Age-Onset Proteotoxicity Science