If stress is bad, why do we feel such a rush of pleasure after successfully facing a challenge? Why does a gruelling examination or giving a public speech lead to a feeling of euphoria when they are over? Some people do best under a deadline. For them, it may be the only time they can function. But what is it that causes us to feel so good after gasping our way through an exercise routine?
Stress is not always bad. Nature has equipped us with the means to overcome stress – a philosophical view of stress might claim that the meaning of life is facing and overcoming challenging circumstances, since this leads to wisdom and understanding, and makes us better equipped to deal with the next onset of problems. This is also true at the molecular level. Exposure to low levels of stress, such as exercise, irradiation or free radicals, leads to a cascade of maintenance and repair. Stress therefore makes our cells better equipped to repair DNA and proteins and to remove toxins. A little bit of stress – psychological or physical – tells our body to activate its anti-oxidant mechanisms and to switch on the defenses against free radicals, which are responsible for molecular ageing. The stress hormone cortisol in small doses can also activate the immune system. Stress therefore makes us stronger by increasing our defence mechanisms; it is an adaptive survival response.
How does this fit into the current trend in stress avoidance techniques? In nature, short-term stressful events are exactly what we are made for – but it is the chronic, unrelenting high-levels of stress that eventually lead to overload, a point at which our body is unable to repair itself following a stressful event, since the stress never goes away. High doses of cortisol suppress the immune system. Healthy ageing therefore must involve stressful situations micro-managed by the organism in such a way that it has the chance not only to repair the damage caused by the emotionally or physically stressful events but even profit from them.
Photo Credit: eflon via Compfight cc
Photo Credit: Victoria Nevland via Compfight cc
Most organisms have a molecular clock which sets the lifespan of cells. The number of times a cell population can divide is called the Hayflick limit, after which the cells undergo “apoptosis” (programmed cell death). Apoptosis is otherwise triggered by the body’s inner and outer environment (stress, UV light, pollution..). People in their 80s and 90s have a Hayflick limit of 20 divisions compared to younger people who have around 50. Telomere shortening in humans eventually makes cell division impossible, and this aging of the cell population appears to correlate with the overall physical aging of the human body. Maximum life span in humans is currently approximately 125 years.
Here are a few reasons why cells deteriorate and die:
When telomeres are depleted after a number of cell divisions.
Proposed solution : The enzyme telomerase contains an RNA template capable of producing new telomeres on the ends of aging cells. Cancer cells, stem cells and sperm and eggs can divide indefinitely because they express telomerase. If telomerase is added to a cell it will replicate beyond the Hayflick limit. TA-65, an (expensive) prescription drug from the astragalus root, adds telomerase to the cell.
When the cell accumulates too much waste.
Proposed solution : Calorie restriction with sufficient nutrients is at the moment the only scientifically proven way of lengthening life in mammals, since it restricts damage caused by metabolising food.
Free radicals, which are negatively charged molecules, break up pairs of molecules to steal their positively charged partners, attacking the cell membrane, collagen and elastin.
Proposed solution : Vitamins and minerals are free radical ‘scavengers’ and can slow aging.
There is a genetic code within our DNA that is programmed to self-destruct after a number of years.
Proposed solution : When scientists silenced a gene called IGF-1 in mice organs life span was extended by up to 33%; calorie intake stimulates IGF-1.
Hormone depletion causes a decline in the body’s ability to repair itself.
Proposed solution : Hormone replacement therapy.
Wear and tear damages cells. Just using our organs wears them out like any machine component and serious abuse will hasten the end.
Proposed solution : Nutrients and clean living.
Biological immortality is not impossible. There are a few creatures, such as the hydra and the turtiopsis dohrii jellyfish, which maintain telomere lengths; lobsters also show no signs of aging, becoming increasingly fertile throughout their lives.
Nature has therefore allowed for a small window of “negligeable senescence”. Keep reading these blogs for more ways of staying ageless.