Hormesis. Benefits of Hot & Cold

Dr. Rhonda Patrick, Ph.D. in biomedical sciences and expert in nutrition, metabolism and ageing. Known primarily for her studies of the mechanistic link between vitamin D and serotonin production.

‘Our bodies are beautifully designed to handle all types of stress; but our genes have to be working; they have to have the right nutrients.’

Most animals have the latent ability to live longer when stressed.  This is called hormesis, a major clue concerning the nature and evolutionary provenance of the ageing process.  The body compensates when stressed and is remarkable in that it overcompensates so that paradoxically, stressors actually lengthen lifespan.

One of the major responses to stress at the cellular level is the role of Heat Shock Proteins. Heat was the stressor that led to the original discovery of HSP, the word heat remained, though it soon became clear that HSP are secreted in response to other kinds of stress, including cold.  HSP are a family of molecules, all of which are highly conserved with the human versions appearing similar to HSP in flies and yeast cells.

HSP protects the delicate biomolecules from damage and act as chaperones to help newly-created proteins to fold, and helping mis-folded proteins to find the correct shape.  HSP protect against muscle-wasting (sarcopenia), responsible for so much frailty. Lab worms with an extra copy of an HSP gene have decreased overall mortality.

(HSF) Heat Shock Factor  is a signal molecule that turns on the full set of HSP genes and which activates a host of other protective proteins at the same time. Calorie restriction and exercise both activate HSP, but protein restriction may attenuate it.  HSP induction in response to HSF declines with age in rodents, but not if their calories are restricted. Pro-biotics and a high-fiber diet can encourage microbiome signaling to increase HSP expression in mice.  Insulin resistance, characteristic of diabetes, suppresses HSP in response to HSF while

high fat diets reduce HSP and garlic in the diet will increase it. HSP acts as neuroprotective when there is potential damage from a stroke or head injury.

Heat

A proven powerful form of human hormesis after calorie restriction, the statistics for saunas ability to suppress cardiovascular disease and especially dementia are profound. Exert from article by Rhonda Patrick about the benefits of saunas;

If you’ve ever run long distances or exercised for endurance, it’s intuitive that increased body temperature will eventually induce strain, attenuate your endurance performance, and accelerating exhaustion. What might not be as intuitive is this: acclimating yourself to heat independent of aerobic physical activity through sauna use induces adaptations that reduce the later strain of your primary aerobic activity. Hyperthermic conditioning improves your performance during endurance training activities by causing adaptations, such as improved cardiovascular and thermoregulatory mechanisms.

I don’t enjoy getting overheated any more than you do, but hey—stress is stressful.  How surprised can we be that heat is a powerful inducer of Heat Shock Protein? Perhaps more interesting is that saunas are associated with increased growth hormone, a far safer and cheaper way to achieve higher HGH levels than injections.  The combination of HGH and HSP help to maintain muscle mass against the erosion that almost always comes with age. Patrick documents that saunas contribute to maintaining (or restoring) insulin sensitivity, and to growth of new brain cells.  Another pathway by which saunas work their magic is norepinephrine=noradrenaline, which is both a neurotransmitter and a hormone, and higher levels are associated with good attention and cognitive performance.

‘The greater the discomfort experienced during your workout or sauna, the better the endorphin high will be afterward.’

Jari Laukkanen is a Finnish cardiologist who followed male middle-aged sauna-bathers and matched controls for 20 years. This study found dramatic decreases in cardiovascular deaths with a 40% drop in all-cause mortality for those reporting sauna use at least 4 times per week for 20 minute sessions.  A prospective study to follow 2,300 men over 20 years is the gold standard for this epideiology. A 40% drop in mortality equals about 3 years of extended life.  An even more impressive number: the Alzheimer’s risk of men taking at least 4 saunas a week was a third the number as those who took 1 sauna per week.  The benefit compared to no saunas at all is likely to be substantially greater.

Cold

HSP is a stress adaptation, not specialised to heat, and can also trigger release of HSP.  Yet

cold and heat are not symmetric- Saunas work by raising the core temperature of the body by several degrees similar to a fever. With cold applied to the skin, the core of the body works harder to keep its temperature close to normal and goes on to use blood flow to protect the organs. The benefit is mediated by cold-sensing nerves in the skin and trigger the release of norepinephrine, similar to heat exposure.  A specific response to cold is a protein called rmb3, which helps to promote neurogenesis.

It’s tempting to take a cold shower or plunge into icy water after you have worked out, with core temperature elevated.  This may actually cause delayed cramping and lessen the benefit from the exercise.  After resistance training is the most beneficial time to take your sauna and yes, the least comfortable.  If you can’t stand a cold shower yet, when your body is already cold, try a warm shower first, studies show a drop in infectious disease rates from hot showers followed by cold.  Wim recommends you take your cold plunge after a course of deep breathing.

One of the most consistent and profound physiological responses to cold exposure is a robust release of norepinephrine into the bloodstream, as well as in the locus coeruleus region of the brain. — Rhonda Patrick

Does the Wim Hof method increase life expectancy

In recent years, Dutch extreme athlete Wim Hof has popularised a training discipline combining breathing exercises, cold immersion, yoga, community and meditation.

Hof is able to suppress immune response to a standard challenge, and is also able to consciously suppress the auto-immune response that contributes to arthritis, and diabetes and AD.  When Hof was studied with metabolic and neurologic sensors, the result indicated he has acquired conscious control over physiological adaptations which, in the rest of us, are automatic and subconscious.

This is a fascinating approach to health though there is little in mainstream literature on the subject. There have long been stories about yogis and ascetic devotees of Eastern religions who culture extraordinary control over their bodies and live to incredible ages. We would love to see such claims subjected to controlled conditions and standardised lab tests.

There is no direct evidence that Wim Hof training affects ageing yet, the fact that it lowers inflammation and releases the neuroprotective RMB3 and norepinephrine which make a large contribution against the diseases of old age, is important.

The Bottom Line

If we believe the Finnish study, then hyperthermia and overheating, is the most powerful mode of hormesis we know of and second only to calorie restriction.  Hyperthermia works by a path independent of insulin and we can hope, there is synergy between saunas or hot yoga and calorie restriction or fasting.  Combining a low calorie with high heat has the potential to yield life extension equivalent to the sum of the two separate measures.  Cold exposure and the full Wim Hof program, including meditation techniques, are further from validation as a life-extending practice yet show real promise.