Sauna and Its Effects on Aging and the Brain

By Rhonda Patrick, PhD

A longer and healthier life is inextricably linked to the prevention or delay of aging, a complex, multi-functional process involving biological, physiological and behavioral changes. Aging has wide-ranging effects on many body systems, even at the cellular and molecular level. However, aging is a dynamic process, which means that it can not only be prevented, but even reversed.

Soaking in a sauna is an ancient practice with anti-aging benefits. In the sauna, the body is exposed to high heat, which causes certain stress. The effects of heat stress on longevity have been observed in both flies and worms , with lifespans extended by 15%. Large-scale, observational human studies have found a strong link between sauna use and a lower risk of age-related conditions such as cardiovascular disease, cognitive decline, and premature death.

For example, the Kuopio Ischemic Heart Disease Risk Factor (KIHD) population-based study of more than 2,300 middle-aged men from eastern Finland found that men who used saunas two to three times a week were 27% less likely to die from age-related disorders , such as cardiovascular disease, than men who did not use the sauna. This benefit was also found to be dose-dependent: men who used the sauna twice as often, from about 4 to 7 times a week, experienced about twice the benefit— a 50% lower chance of dying from cardiovascular causes .

KIHD research also found that frequent sauna use reduced the risk of two age-related cognitive disorders, dementia and Alzheimer's disease, again in a dose- dependent manner . Men who used a sauna 4 to 7 times a week had a 66% lower risk of developing dementia and a 65% lower risk of developing Alzheimer's disease compared to men who only used a sauna once a week.

The KIHD findings also showed that frequent sauna visitors have a 40% lower chance of dying from any cause of premature death . These findings held true even after adjusting for age, activity level, and lifestyle factors that may have influenced men's health.

Here's how it works - while in the sauna, your body is exposed to extreme heat, causing a sudden and strong reaction:

• The temperature of the skin and body rises noticeably, you begin to sweat.
  
  
• Cardiac output, a measure of the work your heart does in response to your body's need for oxygen, increases by 60 to 70 percent. and your heart rate (beats per minute) increases .

• Blood flow is diverted from your core to your skin (about 50%-70%) to help you sweat more easily . The average person loses about 0.5 kilograms of sweat when using a sauna.

• Plasma volume (the liquid component of your blood) increases, providing a backup source of fluids for sweating and preventing your body temperature from rising too quickly, thereby promoting hyperthermic hardening (a form of heat tolerance).

• If you exercise regularly, you've probably noticed that the physiological response to a sauna is very similar to the body's response to moderate-to-vigorous exercise . For example, during a sauna session at moderate temperatures, your heart rate can increase to 100 beats per minute. And when the temperature is raised, the heart rate can increase to 150 beats per minute, similar to moderate to vigorous exercise.

• But these are just some of the visible signs of heat stress. The "invisible" response to heat stress occurs at the cellular and molecular level, most likely through a physiological phenomenon known as hormesis. Hormesis is a defensive reaction of the body that occurs when experiencing mild stress . Interestingly, the hormetic response to stress is generally disproportionate to the magnitude of the stressor. The end result is that your body activates a series of protective responses that promote long-term adaptation, repair cellular damage, and provide protection against potentially greater stressors in the future.

The sauna and the aging heart

The World Health Organization estimates that almost 18 million people die from cardiovascular diseases every year , which is about one third of all deaths in the world. Cardiovascular disease can often be prevented by adopting a certain lifestyle, such as using a sauna. People who regularly use saunas tend to improve several aspects of their cardiovascular health:

• Decreased blood pressure
• Endothelial (cells that make up the inner layer of blood vessels) function is improved
• Improved left ventricular function
• Decreased markers of inflammation

It is interesting that people who cannot engage in physical activity due to chronic diseases or other physical limitations are offered the use of saunas or other forms of heat therapy as an alternative to exercise.

The sauna and the aging brain

Your brain is particularly vulnerable to the damaging effects of aging. The ever- increasing effects of oxidative stress , poor dietary habits , and daily energy metabolism work against our long-term cognitive function. However, heat-induced responses can protect the brain, including:

• Increased expression of brain-derived neurotrophic factor (BDNF) , a protein that affects central and peripheral nervous system neurons, stimulating the growth of new neurons.

• Improved blood flow in your brain, which facilitates the clearance of amyloid-beta (the protein associated with Alzheimer's disease).

• Reduction and/or prevention of depressive symptoms

• The body's production of beta-endorphins (which are part of our body's natural pain-relieving system) is greatly increased.

• Increased norepinephrine production , which improves concentration and attention , and prolactin production , which is needed to repair nerve cell damage.

Sauna and molecular mechanisms

Studies have identified various heat-stress-induced molecular mechanisms that modulate aging and cognitive decline, such as those that reduce protein damage and aggregation or activate endogenous antioxidant, repair, and degradation processes.

Some of these mechanisms include increased expression of the body's protective factors:

• Heat shock proteins , a large family of proteins that play important roles in many cellular processes, including immune function, cell signaling, and cell cycle regulation. Genetic variants of some heat shock proteins are associated with longer lifespan .

• Nrf2 , a transcription factor that regulates a vast network of genes with cytoprotective, antioxidant and anti-inflammatory functions. Activation of Nrf2 confers protection against oxidative stress, electrophilic stress, and chronic inflammation, the underlying causes of many chronic diseases.

• FOXO3 , a transcriptional regulator that plays an important role in human lifespan and healthy aging. FOXO3 is involved in autophagy, but when autophagic mechanisms are impaired, FOXO3 sensitizes cells to apoptosis, programmed cell death. More information - FOXO

• Interleukin-6 (IL-6), a pro-inflammatory cytokine, and interleukin-10 (IL-10) , an anti-inflammatory cytokine, are two proteins that modulate the body's inflammatory response. Heat stress increases circulating IL-6 and, possibly, the reciprocating release of IL-10.

Conclusions and how to's:

A growing body of evidence from observational, clinical and mechanistic studies suggests that sauna bathing is associated with numerous health benefits and can be used as a means of preventing the effects of aging. KIHD studies describe appropriate dosages that can help you create protocols for how to best incorporate sauna use into your life.

To get the most benefits, healthy adults should use the sauna according to the following recommendations:

• Frequency: 4 to 7 sessions per week
• Duration: approximately 20 minutes per session
• Temperature: minimum 78.9°C , optimal - from 80°C to 90°C

💧 And get ready to sweat!

Read more about the health benefits of sauna in this Found My Fitness article - https://www.foundmyfitness.com/topics/sauna

This summary is translated from English. and originally available to all new subscribers to the Found My Fitness newsletter.