How Physical Activity, Nutrition and Environmental Factors Affect Genetic Risk for Disease
A significant amount of money and effort is dedicated to the study of genetic links to illness and disease. Billions of dollars are invested in searching for genetic causes or associations to cancer, diabetes, obesity and other common illnesses. Remarkably, more than $7 billion was spent on genetics research in 2010 alone.
Yet a wealth of research is growing to support the notion that nutrition, lifestyle and environmental factors have a greater impact on your health than the genes you inherited from your family.4,5,6,9,13 Sorry, you can’t blame mom and dad for everything.
Consider your genes like a light switch. A light switch may have the potential to trigger light when connected to a light bulb and supplied with electricity, but this will not happen without an external force turning the switch on.
Your genes work in a similar manner. While your genetic make-up may create the capacity within you, or susceptibility, to give rise to certain diseases, generally an external factor is required to activate the gene. This external cause is often nutrition, lifestyle or environmental factors.
In an October 2011 study published in the journal Circulation, researchers from the University of Cambridge discovered that diet and environment strongly influence markers of DNA methylation which are associated with heart disease. DNA methylation is a biochemical process which is important to the normal development and the cellular differentiation of higher organisms. It is a crucial process whereby a cell can modify its own DNA and alter gene expression.
Defects in DNA methylation have been linked to several human diseases, such as cancer, cardiovascular disease and diabetes.,, Gene expression is controlled by a number of mechanisms, but methylation of DNA appears to be the cellular communication tool that mediates gene expression through locking genes in the off position.
The study findings suggest that diet and environmental factors exert a considerable influence on gene expression and disease manifestation. Certainly, the research points to external factors that affect health outcomes despite genetic predispositions.
Even leading geneticists are beginning to question the importance of genes in disease research. In 2009, Dr. Steve Jones, a leading geneticist and head of the Biology Department at University College of London, suggested that the belief that genetic research could quickly provide a remedy for diseases was unfounded.
The truth is, while genes play an important role in disease and can increase your susceptibility to certain diseases, most diseases are a result of a combination of nutrition, lifestyle or environmental factors
The National Institutes of Health website states, “…no one gene has the yes/no power to say whether a person has a disease or not. It is likely that more than one mutation is required before the disease is manifest, and a number of genes may each make a subtle contribution to a person’s susceptibility to a disease.”
Cancer is a great example. According to Stanford Medicine’s Cancer Institute – a National Cancer Institute designated cancer center – only a small percentage of cancers involve inherited mutations passed down from your family. Stanford estimates that less than 10 percent of the most common cancers, like breast and colon cancer, are genetically inherited.
On the other hand, a 2011 report by the American Cancer Society concludes that approximately one-third of the annual cancer deaths in the U.S. are attributed to poor nutrition and physical inactivity. The same report states that environmental factors – tobacco use, chemical exposure, and other environmental factors – account for 75 to 80 percent of cancer cases and deaths in the U.S. each year.
If genes are the most important factor in disease, it would be logical to assume identical twins – with essentially the same genetic make-up – would be struck by disease equally. A study of the medical history of more than 44,000 identical twins published in the New England Journal of Medicine confirmed that this is not necessarily the case.
Robert Hoover, M.D., Director of the Epidemiology and Biostatistics Program of the National Cancer Institute, and his colleagues determined only 15 percent of all cancers are due to genetically inherited factors. Cancers with the greatest link to genetics included prostate, colorectal and breast cancer. This suggests that genes play a relatively lesser role in cancer than do lifestyle and behavioral elements.
Scientists have long believed that you can’t modify the genetic risk factors inherited from your family. Two recent studies have found evidence that challenges this long-held belief.
Researchers have identified the 9p21 gene as the gene with the strongest marker for heart disease., Those with the gene are about 30 percent more likely to develop heart disease when compared to those without the gene. Despite this increased risk, scientists discovered that individuals could significantly weaken the affect of the “heart disease” gene by consuming more fruits, berries and raw vegetables.
Remarkably, individuals with the 9p21 gene who followed this prudent diet had similar heart disease risk factors as those who do not have the gene. The scientists published their findings in the October 2011 edition of the peer-reviewed journal PloS Medicine.
The FTO gene has been labeled the “fat gene” because of its strong association with obesity.,, Scientists who examined how physical activity affects the FTO gene observed that physical activity could reduce a person’s risk of becoming obese, despite a genetic predisposition.
The researchers conducted a meta-analysis of studies that included more than 218,000 adults. Extraordinarily, scientists found that those with the FTO gene who were most active decreased their risk of obesity by 27 percent, compared to those who were physically inactive.
Full findings of the study are available in the November 2011 edition of the journal PloS Medicine.
These studies suggest that making lifestyle and dietary changes could modify gene expression and disease manifestation. Too frequently, the role of “good” and “bad” genes is overemphasized in disease, when a perfectly viable option in disease prevention already exists – healthy eating, physical activity and mitigating the effect of environmental factors.
Prevention of chronic disease through expanded education of individuals should be at the top of the agenda for government leaders, educators and health professionals.
Focused efforts to encourage healthy eating habits and more physical activity, combined with strategies to decrease exposure to harmful chemicals, will likely have a greater impact on health than genetic research. This approach has significant potential to decrease the ever-increasing health care expense burden currently strangling the U.S. The U.S. spent $2.5 trillion on health care in 2009 alone.
The U.S. Centers for Disease Control (CDC) estimates that if 10 percent of adults began a regular walking program, $5.6 billion in heart disease costs could be saved.15 The CDC also states that if an overweight person decreases their weight by 10 percent they would realize savings of up to $5,300 in medical costs associated with type 2 diabetes, heart disease, stroke, high cholesterol and hypertension.
Governments should consider diverting some of the millions of dollars earmarked for genetic research to support effective and informative educational programs to encourage healthy eating habits and greater physical activity.
While genetic research has led to extraordinary discoveries and knowledge associated with human variation in health and disease, we simply can’t afford to sit back and wait for genetics to discover treatments that will rescue us from poor nutritional and lifestyle choices.
If we continue to emphasize genetic research in lieu of encouraging the necessary diet and lifestyle changes, the epidemics of obesity, type 2 diabetes, heart disease and cancer will continue to diminish the quality and length of life of individuals worldwide.
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