BACKGROUND: Consumption of dietary cholesterol from eggs has shown to increase the ratio of total to HDL cholesterol in humans, which has been suggested to increase the risk of CHD. However, until now no systematic review has been published about the direct effects between egg consumption and CHD/CVD.
OBJECTIVES:
-To review all prospective studies which published information about eggs in relationship with total cardiovascular disease, heart disease, or stroke.
-To define the amount of consumption found to be related with possible effects on these diseases.
-To define possible effect modification by confounders.
DATA SOURCE: The Pubmed database was searched (No start date - May 25th, 2010) for relevant articles using the keywords "dietary cholesterol, dietary fat, egg, or eggs" combined with "prospective, cohort, follow-up, or longitudinal". The exact search term is described Here.
Prospective studies published in the English language were included. Reference lists were searched for additional articles.
RESULTS: 23 articles were found which provided information about 19 different cohorts. Of these, 0 articles were excluded.
Disease risk.
-2 cohorts provided information about total CVD risk. Suggestive evidence was found for an increased CVD risk of egg consumption among subjects with pre-existing type 2 diabetes.
-10 cohorts provided information about CHD risk, including 5,678+ cases. No evidence was found for an association with any level of egg consumption. However, suggestive evidence was found for an increased CHD risk of high egg consumption among subjects with pre-existing type 2 diabetes.
-2 cohorts provided information about heart failure, including 2,224 cases. Suggestive evidence was found for an increased heart failure risk of high egg consumption.
-4 cohorts provided information about stroke risk, including 2,818 cases. No evidence was found for an association with any level of egg consumption.
Mortality risk.
-No data was found about the relation with total CVD mortality.
-8 cohorts provided information about CHD mortality, including 3,757+ cases. No evidence was found for an association with any level of egg consumption.
-4 cohorts provided information about stroke mortality, including 3,978 cases. Inconclusive evidence was found for an association.
CONCLUSION: No evidence was found for an overall association between any level of egg consumption and total CVD risk, CHD risk, stroke risk, CHD mortality, and stroke mortality. However, suggestive evidence was found for an increased heart failure risk of high egg consumption, and suggestive evidence was found for an increased total CVD- and CHD risk of high egg consumption (≥ 6-7 eggs/week) among subjects with type 2 diabetes.
Any increased risks were practically restricted to findings from Western cohorts, and any protective effects were practically restricted to findings from Asian cohorts. No other effect modification was found by any variables, including baseline cholesterol levels and hypertension.
LIMITATIONS: No evidence was found for an overall association between any level of egg consumption and any CVD end point, except for a possible association with the condition called heart failure. But since the amount of evidence is limited, and no results from cohorts of very large size were included, the possibility of an effect on CVD among specific subgroups of the population can not be excluded. Though no evidence was found for an association with CVD, current evidence shows high egg consumption might increase risk of all-cause mortality.
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