Watching TV for an average of six hours a day could shorten the viewer’s life expectancy by almost five years, indicates research published online in the British Journal of Sports Medicine.
The impact rivals that of other well known behavioural risk factors, such as smoking and lack of exercise, the study suggests.
Sedentary behaviour — as distinct from too little exercise — is associated with a higher risk of death, particularly from heart attack or stroke. Watching TV accounts for a substantial amount of sedentary activity, but its impact on life expectancy has not been assessed, say the authors….
- 15-minute exercise plan ‘healthy’ (bbc.co.uk)
- Daily exercise can extend your life by three years (mirror.co.uk)
- 5 Countries with the Highest Life Expectancy (5facts.org)
Watching television for more than two hours a day is associated with significantly higher risks of type 2 diabetes, cardiovascular disease and death from all causes, finds a comprehensive analysis of prior research recently published in Journal of the American Medical Association.
Eight international studies suggest two hours of daily television viewing is associated with a 20 percent higher risk of type 2 diabetes, a 15 percent higher chance of cardiovascular disease, and a 13 percent increased risk of all-cause mortality for men and women.
The findings suggest each two hour increment of daily TV watching results in an absolute risk of 176 new cases of type 2 diabetes, 38 new cases of fatal cardiovascular disease, and 104 new cases of all-cause mortality among 100,000 persons each year.
The researchers’ findings are based on a meta-analysis of eight studies about the broader health impacts of television watching.
Meta-analyses assess a cluster of previous research studies within a highly similar area. The findings sometimes suggest commonalities or aggregate patterns, which are more evidence-based than the findings from individual studies. Meta-analyses also suggest areas where more comprehensive research is desirable – and sometimes identify new research agendas.
The studies were done in four nations and published between 1970-2010. The authors note the current study is the first quantitative and systematic assessment of television viewing and health research.
In the meta-analysis of television viewing’s health impacts, its two authors only assessed research undergirded by large sample sizes. All eight studies featured long durations of participant follow-up, and well-established prospective study methods. Prospective studies follow the health of a cohort, or group of similar persons, over time and often assess the consequences of a common exposure (such as television viewing) on health outcomes.
The authors, from the University of Southern Denmark and the Harvard School of Public Health, explain the first generation of research tied prolonged television viewing with unhealthy eating habits and less exercise. The authors add a second generation of research suggested an association between TV viewing and biological risk factors, such as obesity and adverse lipid levels.
The current findings represent a third generation of research that suggests an association between prolonged television viewing and disease risks, including type 2 diabetes and cardiovascular disease. Moreover, the current findings suggest prolonged television viewing is linked to an elevated risk of death from all causes.
Within the article, the authors discuss how TV viewing displaces time on other activities, such as sleeping, exercise, and reading. The authors explain future researchers need to better contextualize the impact of TV viewing and health outcomes. For example, they suggest future research might assess the health impacts of TV watching in comparison with a range of the activities it displaces.
The authors also suggest reversing current emphases to note the impact of reducing TV watching on health outcomes. They write (and we quote): ‘Further study is needed to determine whether reducing prolonged TV viewing can prevent chronic disease morbidity and mortality’ (end of quote).
While MedlinePlus.gov does not have a health topic page devoted to the health impacts of TV viewing, a medical encyclopedia article about television watching is available. The article explains the American Academy of Pediatrics recommends no television viewing for children under age two, and fewer than two hours per day for older children.
Of course, the current research suggests the impact of prolonged television viewing may be deleterious to adult health. It will be interesting to see the extent that future research is consistent with the eight studies identified in the current meta-analysis and how these yield suggestions for a more therapeutic use of our time.
To find the encyclopedia article, type ‘television watching’ in the search box on MedlinePlus.gov’s home page. Then, click on ‘television watching.’
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Despite the fact that nearly one-third of American households have a firearm, studies show that having a gun in the home poses a household a greater health risk than a potential benefit. A new study released in the American Journal of Lifestyle Medicine (published by SAGE) examined scientific research on both sides of the debate to put hard numbers to this on-going discussion.
Author David Hemenway studied the various risks of having a gun in the home, including accidents, suicide, homicide, and intimidation. Additionally, the benefits of having a firearm in a household were also examined and those benefits included deterrence, and thwarting crimes (self-defense). From this in-depth look, it was concluded that homes with guns were not safer or deter more crime than those that do not. In fact, it was found that in homes with children or women, the health risks were even greater.
“There is compelling evidence that a gun in the home is a risk factor for intimidation and for killing women in their homes, and it appears that a gun in the home may more likely be used to threaten intimates than to protect against intruders,” wrote Hemenway. “On the potential benefit side, there is no good evidence of a deterrent effect of firearms or that a gun in the home reduces the likelihood or severity of injury during an altercation or break-in.”
The article entitled “Risks and Benefits of a Gun in the Home” from the American Journal of Lifestyle Medicine is available free for a limited time here.
Choosing the appropriate way to present risk statistics is key to helping people make well-informed decisions. A new Cochrane Systematic Review[abstract]*** found that health professionals and consumers may change their perceptions when the same risks and risk reductions are presented using alternative statistical formats.
Risk statistics can be used persuasively to present health interventions in different lights. The different ways of expressing risk can prove confusing and there has been much debate about how to improve the communication of health statistics.
For example, you could read that a drug cuts the risk of hip fracture over a three year period by 50%. At first sight, this would seem like an incredible breakthrough. In fact, what it might equally mean is that without taking the drug 1% of people have fractures, and with the drug only 0.5% do. Now the benefit seems to be much less. Another way of phrasing it would be that 200 people need to take the drug for three years to prevent one incidence of hip fracture. In this case, the drug could start to look a rather expensive option.
Statisticians have terms to describe each type of presentation. The statement of a 50% reduction is typically expressed as a Relative Risk Reduction (RRR). Saying that 0.5% fewer people will have broken hips is an Absolute Risk Reduction (ARR). Saying that 200 people need to be treated to prevent one occurrence is referred to as the Number Needed to Treat (NNT). Furthermore, these effects can be shown as a frequency, where the effect is expressed as 1 out of 200 people avoiding a hip fracture.
In the new study, Cochrane researchers reviewed data from 35 studies assessing understanding of risk statistics by health professionals and consumers. They found that participants in the studies understood frequencies better than probabilities. Relative risk reductions, as in “the drug cuts the risk by 50%”, were less well understood. Participants perceived risk reductions to be inappropriately greater compared to the same benefits presented using absolute risk or NNT.
“People perceive risk reductions to be larger and are more persuaded to adopt a health intervention when its effect is presented in relative terms,” said Elie Akl of the Department of Medicine, University at Buffalo, USA and first author on the review. “What we don’t know yet is whether doctors or policymakers might actually make different decisions based on the way health benefits are presented.”
Although the researchers say further studies are required to explore how different risk formats affect behaviour, they believe there are strong logical arguments for not reporting relative values alone. “Relative risk statistics do not allow a fair comparison of benefits and harms in the same way as absolute values do,” said lead researcher Holger Schünemann of the Department of Clinical Epidemiology and Biostatistics at McMaster University in Ontario, Canada. “If relative risk is to be used, then the absolute change in risk should also be given, as relative risk alone is likely to misinform decisions.”
Cochrane Reviews are “ systematic reviews of primary research in human health care and health policy. They investigate the effects of interventions (literally meaning to intervene to modify an outcome) for prevention, treatment and rehabilitation. They also assess the accuracy of a diagnostic test for a given condition in a specific patient group and setting.”
February 17, 2011 20:30
Wider implementation of policies is needed to save lives and reduce the health impact of harmful alcohol drinking, says a new report by WHO. Harmful use of alcohol results in the death of 2.5 million people annually, causes illness and injury to many more, and increasingly affects younger generations and drinkers in developing countries.
Alcohol use is the third leading risk factor for poor health globally. A wide variety of alcohol-related problems can have devastating impacts on individuals and their families and can seriously affect community life. The harmful use of alcohol is one of the four most common modifi able and preventable risk factors for major noncommunicable diseases (NCDs). There is also emerging evidence that the harmful use of alcohol contributes to the health burden caused by communicable diseases such as, for example, tuberculosis and HIV/AIDS.
Related WHO Web pages
- Management of Substance Abuse (currently featuring Global status report on alcohol and health 2o11 (3 March 2011)
- Rethinking Drinking provides research-based information about how your drinking habits can affect your health. Learn to recognize the signs of alcohol problems and ways to cut back or quit drinking. Interactive tools can also help you calculate the calories and alcohol content of drinks. (US National Institutes of Health)
You are what your father ate
UMMS research suggests paternal diet affects lipid metabolizing genes in offspring
WORCESTER, Mass. — Scientists at the University of Massachusetts Medical School and the University of Texas at Austin have uncovered evidence that environmental influences experienced by a father can be passed down to the next generation, “reprogramming” how genes function in offspring. A new study published this week in Cell shows that environmental cues—in this case, diet—influence genes in mammals from one generation to the next, evidence that until now has been sparse. These insights, coupled with previous human epidemiological studies, suggest that paternal environmental effects may play a more important role in complex diseases such as diabetes and heart disease than previously believed.
“Knowing what your parents were doing before you were conceived is turning out to be important in determining what disease risk factors you may be carrying,” said Oliver J. Rando, MD, PhD, associate professor of biochemistry & molecular pharmacology at UMMS and principal investigator for the study, which details how paternal diet can increase production of cholesterol synthesis genes in first-generation offspring….
…These observations are consistent with epidemiological data from two well-known human studies suggesting that parental diet has an effect on the health of offspring. One of these studies, called the Överkalix Cohort Study, conducted among residents of an isolated community in the far northeast of Sweden, found that poor diet during the paternal grandfather’s adolescence increased the risk of diabetes, obesity and cardiovascular disease in second-generation offspring. However, because these studies are retrospective and involve dynamic populations, they are unable to completely account for all social and economic variables. “Our study begins to rule out the possibility that social and economic factors, or differences in the DNA sequence, may be contributing to what we’re seeing,” said Rando. “It strongly implicates epigenetic inheritance as a contributing factor to changes in gene function.”
The results also have implications for our understanding of evolutionary processes, says Hans A. Hofmann, PhD, associate professor of integrative biology at the University of Texas at Austin and a co-author of the study. “It has increasingly become clear in recent years that mothers can endow their offspring with information about the environment, for instance via early experience and maternal factors, and thus make them possibly better adapted to environmental change. Our results show that offspring can inherit such acquired characters even from a parent they have never directly interacted with, which provides a novel mechanism through which natural selection could act in the course of evolution.” Such a process was first proposed by the early evolutionist Jean-Baptiste Lamarck, but then dismissed by 20th century biologists when genetic evidence seemed to provide a sufficient explanation.
Taken together, these studies suggest that a better understanding of the environment experienced by our parents, such as diet, may be a useful clinical tool for assessing disease risk for illnesses, such as diabetes or heart disease. “We often look at a patient’s behavior and their genes to assess risk,” said Rando. “If the patient smokes, they are going to be at an increased risk for cancer. If the family has a long history of heart disease, they might carry a gene that makes them more susceptible to heart disease. But we’re more than just our genes and our behavior. Knowing what environmental factors your parents experienced is also important.”
The next step for Rando and colleagues is to explore how and why this genetic reprogramming is being transmitted from generation to generation. “We don’t know why these genes are being reprogrammed or how, precisely, that information is being passed down to the next generation,” said Rando. “It’s consistent with the idea that when parents go hungry, it’s best for offspring to hoard calories, however, it’s not clear if these changes are advantageous in the context of a low-protein diet.”