Re: Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies
In the meta-analysis, Rong et al. concluded that egg intake was generally not related to the risk of coronary heart disease (CHD) or stroke. I have several concerns.
First, the authors stated that the study with the longest follow-up time would be selected if there were multiple publications for one study. For the Nurses’ Health Study, Bernstein et al. has updated data on egg and CHD in 2010, which should been included in the meta-analysis.
Second, in the NHANES III study, Scrafford et al reported a significant inverse association between high egg intake and stroke mortality among men (relative risk: 0.33, 95% confidence interval: 0.14 to 0.82), but a null association among women. It seems that Rong et al missed male data (refer to Fig 5 in the published meta-analysis). Would egg intake be protective against stroke after including the male result?
Further, eggs are a rich source of high quality protein and vitamins, making it biologically plausible to prevent cardiovascular disease. As addressed by Rong et al in the discussion, regular egg consumers are more likely to eat red and processed meat and other "unhealthy" food. So is it possible that the beneficial effect of egg intake, if any, was diminished by red and processed meat intake, with the fact that intake of meat, in particular processed meat has been indicated to increase the risk of CHD and stroke, and that none of the included studies in the meta-analysis controlled for meat intake?
Competing interests:
No competing interests
07 March 2013
Guo-Chong Chen
Student
Town, Suzhou 215123, China
School of Public Health, Soochow University
Department of Epidemiology, School of Public Health, Soochow University, 199 Renai Road, Dushu Lake Higher Education
Rapid Response:
Re: Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies
In the meta-analysis, Rong et al. concluded that egg intake was generally not related to the risk of coronary heart disease (CHD) or stroke. I have several concerns.
First, the authors stated that the study with the longest follow-up time would be selected if there were multiple publications for one study. For the Nurses’ Health Study, Bernstein et al. has updated data on egg and CHD in 2010, which should been included in the meta-analysis.
Second, in the NHANES III study, Scrafford et al reported a significant inverse association between high egg intake and stroke mortality among men (relative risk: 0.33, 95% confidence interval: 0.14 to 0.82), but a null association among women. It seems that Rong et al missed male data (refer to Fig 5 in the published meta-analysis). Would egg intake be protective against stroke after including the male result?
Further, eggs are a rich source of high quality protein and vitamins, making it biologically plausible to prevent cardiovascular disease. As addressed by Rong et al in the discussion, regular egg consumers are more likely to eat red and processed meat and other "unhealthy" food. So is it possible that the beneficial effect of egg intake, if any, was diminished by red and processed meat intake, with the fact that intake of meat, in particular processed meat has been indicated to increase the risk of CHD and stroke, and that none of the included studies in the meta-analysis controlled for meat intake?
Competing interests: No competing interests