Hormesis, a Controversy
Lance Kennedy (August 1, 2019)
Growing old is a bummer. At age 70, I am supposed to have gained more wisdom, but I really cannot say I have noticed. But there are certain physical attributes that are definitely not as good as when I was 20. Among them is healing. Once, cuts and abrasions would be gone in a week. No more. Sometimes it takes a month or more. Bummer!
But recently I noticed a change. Several months ago, I began a project to clear a whole load of weed shrubs approaching the house. This work was not only hard, but also led to a whole lot of extra cuts and abrasions. Each time I put in an hour or two of work, I would return with new slices and dicings of my all too tender flesh. Strangely, over that time, the small injuries appeared to be healing more quickly. Is it possible that my body gets more practiced at the business of fighting infection and healing?
Then my wife and I decided to go and explore Koutu, a part of the Hokianga Harbour with massive concretions. These are round boulders like those at Moeraki, only bigger. This part of the harbour is mud flats with oyster covered rocks. Unwisely I walked barefoot through the shallow water. Sure enough, stupidity was rewarded when I slipped, and my foot came down on razor sharp oysters. Three cuts, all deep. There was no first aid available, and no clean water to wash my cuts. Just dirty, muddy salt water. It was six hours later before I could apply antiseptic. I was certain it would be infected, and take forever to heal. Yet three days later, it was restored enough, without infection, for me to walk outside in bare foot. It healed totally, cleanly, and quickly.
Hormesis dose
Is this hormesis? This is a concept that is very controversial. Hormesis is defined as a biphasic dose response to an environmental stressor. Or more simply, it is the idea that minor stress makes you stronger. The suggestion is that low level stress stimulates biological protective mechanisms, such as boosting my ability to heal from minor cuts and scrapes. In some ways, this is not open to question. Exercise stress certainly makes muscles stronger and the body fitter. Perhaps the same is true for healing, and even resistance to cancer? This is unproven, and a matter for debate at this point in time. But there are many other forms of stress, and ways hormesis may operate.
Please note, though, that hormesis is quite different to homeopathy. The levels of stress cited in hormesis are potent enough to be easily measured. They are not the ridiculously diluted toxins in a homeopathic remedy.
Of course, major stress is quite different and may be very damaging. Even exercise, if overdone, is not good. We all know of the aches and pains that come if an unfit person works out too much. Taken to an extreme, this may have serious consequences. The legend of the first marathon is that of a messenger who ran the 43 kilometers and died at the end. This is not hormesis. Hormesis involves only minor stress and suggests that the end result is beneficial.
We make use of minor stress to improve the immune system, using vaccines. I get my flu vaccine every year, and I rarely suffer this nasty illness. A vaccine can be called a challenge or a stress to the body, and thus a stimulus to the immune system. It may even assist with unrelated ills. Some researchers several decades back uncovered a negative correlation between receiving the smallpox or tuberculosis vaccine and chances of contracting melanoma.
This may suggest the stress of the Mycobacterium infection strengthens the immune system so that it is better able to deal with incipient melanoma.
I am a blood donor. This is a very good thing, for me as well as for others. Blood donors live longer and are healthier on average than non-donors.
But why? Several reasons have been suggested, such as the need to periodically reduce our blood iron levels. But maybe it is another example of hormesis in action. Giving blood involves creating a minor stress on our bodies, requiring repair. Could this strengthen those repair faculties? Could that strengthening improve other bodily repair mechanisms, and help us live longer?
Radiation hormesis is an unpopular idea. Many people view nuclear radiation as inevitably harmful, and the suggestion that low-level radiation may help is seen as offensive. But science is not about emotion, and numerous test results show low levels of nuclear radiation have beneficial effects. Surprisingly, since strong radiation is a cause of cancer, low levels appear to provide a degree of protection against this horribly feared disease. But is this correct? Dr. Harriet Hall, who writes for the American version of Skeptic magazine, is skeptical. I am less so, since a few Google searches appear to uncover a number of academic references to radiation hormesis, and protection against cancer.
Chemical hormesis is another idea that stimulates opposition. We know that the dose of a substance determines its effect on the human body. There are clear cases of toxic materials with beneficial effects at low dose. Paracetamol is lethal at high dose, and causes liver damage at medium doses, but at lower doses is a useful pain killer. Could poisons at low dose have a hormesis effect? Many researchers think they might. In fact, some believe that the health-giving properties of green leafy vegetables depends to a degree on the hormesis effects of the natural pesticides found in those leaves. Alcohol is a toxin. Yet many research findings indicate that small doses, like one glass of wine per day, may be healthy. Chemo-hormesis?
Even emotional stress at low levels may be healthy, even though high levels may be very harmful.
Emotional stress may prove to be a valuable stimulant, assisting in brain work. Despite substantial research and positive results by many respected scientists, hormesis is still treated as a suspect idea by a lot of academics. We are still not at a point where this phenomenon is likely to be used therapeutically. Healing my foot quickly and cleanly as a result of hormesis is problematic.
Here is my opinion. Like all individual opinion, it needs to be treated skeptically, but for what it is worth, here goes. My view is that hormesis is a mechanism that is fully compatible with what we would expect from a few billion years of evolution, leading to the development of that which is adaptively advantageous, contributing to survival of the fittest. Damage from stress is healed. But to make the mechanism delivering that healing more effective, at need, appears to be advantageous, and therefore something that evolution would develop. In other words, yes. Perhaps I should finish with that phrase that ends so many research papers. More research is needed.
References
ncbi.nlm.nih.gov: Inverse association between melanoma and previous vaccinations against tuberculosis and smallpox
Sciencenordic.com: Frequent blood donors live longer
ncbi.nlm.nih.gov: Smoking and Hormesis as Confounding Factors in Radiation Pulmonary Carcinogenesis
Journals.sagepub.com: The Dose Determines the Stimulation (and Poison): Development of A Chemical Hormesis Database
Health.com: 5 Weird Ways Stress Can Actually Be Good for You