Margaret Jennings discovers that the more you exercise, the more your body has the capacity to fight off debilitating illnesses — in spite of inherited disease
WERE exercising, eating well and leading a more stress-free life among your new year resolutions? If your enthusiasm is flagging then keep this in mind: those positive lifestyle changes may have more influence on how you age and your longevity, than the genetic blueprint you inherited from your family tree.
While it can be easy to blame our health problems on our ancestors, buying into the belief that we will inevitably have certain diseases or will die young — genes only explain about 25 percent of the variation in our lifespan, according to James McInerney, former director of the Genetics and Bioinformatics degree course at NUI Maynooth and now chair in Evolutionary Biology at The University of Manchester.
“We know there is a genetic component to longevity but exactly which genes, is still an open question. Identical twins have the same genetic sequence, non-identical twins have different genetic sequences. They are as similar as siblings and, therefore, if we see different outcomes for the two groups, we can, tentatively, attribute the difference to genetics,” says Professor McInerney.
It turns out that identical twins have much more similar life lengths than non-identical twins, which leads to the conclusion that genetics can explain about 25% of how our lifespan is dictated.
“Genetics is not everything in terms of lifespan, but it is significant and people with identical genetics will expect to have more similar lifespans, than non-identical people,” he says.
However, at the same time, many genetic conditions can be easily dealt with through lifestyle choices, he says. “Type 2 diabetes, adult onset, can very often be controlled by diet alone, for instance. So, genetics is not everything and there is no reason for adopting a fatalistic attitude.
Consider that 150 years ago, life expectancy in Ireland was about 40 years old. Public health initiatives such as vaccination, modern medicine and hygiene have all contributed a lot. If people want to live longer, exercise is the single greatest ‘pill’ available to humanity,” he says.
Results of research released last year from the US-based Duke University Centre for Ageing, on 1,000 people studied at three stages of their lives — aged 26, 32 and 38 — found some of the participants were ageing three years per chronological year, while others of their peers were not ageing at all.
Already, before mid-life, individuals who were ageing more rapidly were less physically able, showed cognitive decline and brain ageing, self-reported worse health, and looked older. The researchers concluded that environmental factors, rather than genetic, influenced the ageing process more. Results from the Genome-Wide Association Studies suggest that multiple genes govern longevity, says Professor McInerney. So far there seems to be associations with inflammation — influencing our response to disease and injury for instance; oxidation in cells, and metabolism of fat.
“The human is a complex system. It is responsive to its environment and it can have errors which we call disease. Longevity in general can be thought of as a good response to the environment — how we are able to defeat diseases, to be protected against diseases like cancer and to age more slowly, for instance,” he says.
Inflammation is our body’s natural response to the threat from an injury, infection, or disease; our immune system sends in an army of white cells to fight them off. However, as we age, our bodies seem to be less able to disarm the inflammatory process. Chronic inflammation develops when our body fails to call back the army and the white cells flood our system, causing disease.
So what can we do? Lots of research on inflammation and ageing has already linked the benefits of exercise — which brings us back to our own lifestyle choices.
“Genetically, my inflammation process is about 99.9 percent similar to yours, but these tiny differences might be crucial,” says Professor McInerney.
“A slightly different inflammatory response might result in quicker clearance of infections and might mean a better recovery from disease. It certainly looks like maintaining a good level of overall health will keep your immune system generally healthy.
“At the population level, staying healthy, exercising continuously — yes, even if you are 85 years old — not becoming obese, not smoking, moderating alcohol — these can have a much more important effect than genetics,” he says.
In their book You Staying Young: The Owner’s Manual for Extending Your Warranty, authors Michael Roizen and Mehmet Oz suggest thinking of your genetic inheritance as stored information: “It’s the factory-installed info that comes with your biological system.
You have the power with your behavioural software to alter that information along the way. But if you don’t take any action, then the stored information is what dictates how those genes play out.”
So keep those new year resolutions up for a longer healthier life.
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