(More TV Viewing = Increased Risk of Death + Heart Disease) - study

...Television viewing (TV), a highly prevalent behaviour, is associated with higher cardiovascular risk independently of physical activity. The relationship with mortality, however, is relatively unknown.

...We examined the prospective relationship between TV time and all-cause, cardiovascular and cancer mortality in a population-based cohort [The European Prospective Investigation into Cancer and Nutrition (EPIC), Norfolk] of 13 197 men and women [age [SD (standard deviation)]: 61.5 ± 9.0 years]. Participants were free from stroke, myocardial infarction and cancer at baseline in 1998–2000 and were followed up for death ascertainment until 2009 (9.5 ± 1.6 years). TV time, total physical activity energy expenditure (PAEE), education level, smoking status, alcohol consumption, anti-hypertensive and lipid-lowering medication use, participant and family history of disease and total energy intake were self-reported; height and weight were measured by standardized procedures. Hazard ratios (HRs) [95% confidence interval (CI)] for mortality were estimated per 1-h/day increase in TV.
...

...Each 1-h/day increase in TV time was associated with increased hazard of all-cause (HR = 1.04, 95% CI = 1.01–1.09; 1270 deaths) and cardiovascular (HR = 1.07, 95% CI = 1.01–1.15; 373 deaths), but not cancer mortality (HR = 1.04, 95% CI = 0.98–1.10; 570 deaths). This was independent of gender, age, education, smoking, alcohol, medication, diabetes history, family history of cardiovascular disease and cancer, body mass index (BMI) and PAEE. They were similar when stratified by gender, age, education, BMI and PAEE. The population-attributable fraction for all-cause mortality comparing the highest TV tertile (>3.6 h/day) with the lowest ( extra DIV

Potential pathways linking TV time to all-cause and cardiovascular mortalities are likely to be diverse and need further exploration. Some possible mechanisms were examined within the current study. First of all, extensive adjustment for PAEE diminishes the likelihood that our results can be explained by displacement of (even low intensity) physical activity. Secondly, as previously suggested, high exposure to high-caloric food advertisements increases (unconscious) snacking and the overall amount of food consumed. However, the effect of TV time on mortality in our study was independent of total energy intake. Given the amount of measurement error usually associated with self-reported dietary intake, we cannot exclude residual confounding by dietary intake. Our results were, however, independent of overall adiposity (BMI). In contrast, central obesity (i.e. waist circumference) might have a mediating role between TV time and mortality, although the associations were only marginally non-significant after adjustment for this variable. Causal inference cannot be made, however, about the association between TV time and all other variables measured at baseline. Higher levels of adiposity may also lead to increased TV time, as recently shown for objectively measured total sedentary time. Other pathways include intermediate cardiovascular and metabolic risk factors previously suggested to be independently associated with TV time. Current and future studies examining pathophysiological processes that are specific for sedentary behaviours and not just the effect of absence of physical activity are an important and emerging area of research, which may support the current epidemiological evidence. One of these biological processes, shown in animal models, is the acute drop in skeletal muscle lipoprotein lipase activity caused by muscle inactivity (absence of muscle contractions) and resulting in disruption of triglyceride and high-density lipoprotein cholesterol metabolism. Consistently, observations in free-living humans by objective monitoring of body movement suggested that regular interruptions in sedentary time are beneficially associated with level of triglycerides, and urge the need for future epidemiological and experimental studies further exploring these findings.

The present study has several strengths. The large population-based sample enabled us to control for potential reverse causality by excluding participants with relevant health conditions at baseline and by additionally excluding those who died within the first 2 years of follow-up. Furthermore, we were able to adjust for non-categorized overall PAEE and not just (categorized) time spent in leisure, or moderate to vigorous physical activity, minimizing residual confounding. In addition to previously demonstrated criterion validity, our PAEE measure has previously also been shown to predict cardiovascular and all-cause mortality in this cohort. We also adjusted our analyses for several relevant covariates, including energy intake. However, the following study limitations should also be highlighted. First, TV time was self-reported. Measurement error may have biased the associations observed towards the null, leading to an underestimation of the true associations. Furthermore, as TV time was only measured at baseline, changes in this behaviour might additionally have caused misclassification and, therefore, attenuation of the associations found. The self-report and categorical nature of some covariates may have resulted in residual confounding. Some confounding might still exist for other non-measured psychosocial determinants of health, such as social network interaction/loneliness, which might be correlated with TV time, especially in older individuals. Finally, as we excluded participants with baseline chronic disease to minimize the possibility of reverse causality and increase internal validity, the associations found are relative to this cohort of healthy middle-aged Caucasians, and may not generalize to other populations. Large prospective studies, using repeated measurements with longer duration of follow-up and preferably using objective measures of physical activity and sedentary time, are warranted to extend the present results and confirm dose–response effects and indicators of population health risk on different types of mortality in different populations.

In conclusion, in this population-based cohort of middle-aged Caucasians, higher levels of TV time increased the risk for mortality from all causes and CVD, independently of physical activity levels. Given the high prevalence of excessive TV watching, resulting in a substantial PAF, these results indicate the importance of public health recommendations aimed at decreasing TV time and possibly overall sedentary behaviour. These recommendations should be in addition to the established public health recommendations for physical activity.
...


Please visit the link provided for the complete story.