Egg Consumption and Risk of Coronary Heart Disease and Stroke
Egg Consumption and Risk of Coronary Heart Disease and Stroke
Objective. To investigate and quantify the potential dose-response association between egg consumption and risk of coronary heart disease and stroke.
Design. Dose-response meta-analysis of prospective cohort studies.
Data sources. PubMed and Embase prior to June 2012 and references of relevant original papers and review articles.
Eligibility criteria for selecting studies. Prospective cohort studies with relative risks and 95% confidence intervals of coronary heart disease or stroke for three or more categories of egg consumption.
Results. Eight articles with 17 reports (nine for coronary heart disease, eight for stroke) were eligible for inclusion in the meta-analysis (3 081 269 person years and 5847 incident cases for coronary heart disease, and 4 148 095 person years and 7579 incident cases for stroke). No evidence of a curve linear association was seen between egg consumption and risk of coronary heart disease or stroke (P=0.67 and P=0.27 for non-linearity, respectively). The summary relative risk of coronary heart disease for an increase of one egg consumed per day was 0.99 (95% confidence interval 0.85 to 1.15; P=0.88 for linear trend) without heterogeneity among studies (P=0.97, I=0%). For stroke, the combined relative risk for an increase of one egg consumed per day was 0.91 (0.81 to 1.02; P=0.10 for linear trend) without heterogeneity among studies (P=0.46, I=0%). In a subgroup analysis of diabetic populations, the relative risk of coronary heart disease comparing the highest with the lowest egg consumption was 1.54 (1.14 to 2.09; P=0.01). In addition, people with higher egg consumption had a 25% (0.57 to 0.99; P=0.04) lower risk of developing hemorrhagic stroke.
Conclusions. Higher consumption of eggs (up to one egg per day) is not associated with increased risk of coronary heart disease or stroke. The increased risk of coronary heart disease among diabetic patients and reduced risk of hemorrhagic stroke associated with higher egg consumption in subgroup analyses warrant further studies.
Cardiovascular disease is now a public health crisis, affecting millions of people in both developed and developing countries. Although the rate of death attributable to the disease has declined in developed countries in the past several decades, it is still the leading cause of death and extorts a heavy social and economic toll globally. In low and middle income countries, the prevalence of cardiovascular disease has increased dramatically. By 2020, the disease is forecasted to be the major cause of morbidity and mortality in most developing nations.
In recent decades, concern has mounted regarding the high prevalence and costs associated with cardiovascular disease, with growing interest in altering risk factors and reversing this global epidemic. Among the known risk factors for cardiovascular disease, levels of low density lipoprotein (LDL) cholesterol have aroused particular attention. In the Women’s Health Study, after a mean follow-up of eight years, participants with the highest levels of LDL cholesterol showed a notably higher risk of cardiovascular events than those with the lowest levels. In addition, several meta-analyses of observational studies and randomized controlled trials have found that a reduction in concentrations of LDL cholesterol could significantly reduce the risk of coronary heart disease and stroke incidence and mortality. Diet is an important determinant of serum cholesterol, but dietary cholesterol has only a modest contribution to plasma concentrations of LDL cholesterol. On the other hand, dietary cholesterol may prompt the oxidation of LDL and increase postprandial lipemia, which could raise the risk of vascular disease. To minimize the elevation of blood cholesterol and reduce the risk of cardiovascular disease, the American Heart Association (AHA) has recommended the public to consume less than 300 mg/day of cholesterol.
Since eggs are a major source of dietary cholesterol, with one large egg containing almost 210 mg of cholesterol, the public has been recommended to limit egg consumption unless the intake of other foods high in cholesterol is restricted. However, eggs are also an inexpensive and low calorie source of many other nutrients, including minerals, proteins, and unsaturated fatty acids, which could lower the risk of cardiovascular disease. Additionally, in populations following a carbohydrate restricted diet, dietary cholesterol from eggs could increase plasma concentrations of high density lipoprotein (HDL) cholesterol, which has been suggested to protect against vascular disease. Therefore, some organizations have recommended that reducing egg intake might not be important for healthy people with normal levels of cholesterol in the blood. Food based dietary guidelines from countries including Nepal, Thailand, and South Africa recommend consuming eggs every day or regularly as part of a healthy diet.
Several prospective cohort studies have examined the association between egg consumption and risk of coronary heart disease and stroke. However, the relation between egg consumption and risk of cardiovascular disease remains controversial. Therefore, we conducted a dose-response meta-analysis of prospective cohort studies to quantify the association between egg consumption and risk of coronary heart disease and stroke.
Abstract and Introduction
Abstract
Objective. To investigate and quantify the potential dose-response association between egg consumption and risk of coronary heart disease and stroke.
Design. Dose-response meta-analysis of prospective cohort studies.
Data sources. PubMed and Embase prior to June 2012 and references of relevant original papers and review articles.
Eligibility criteria for selecting studies. Prospective cohort studies with relative risks and 95% confidence intervals of coronary heart disease or stroke for three or more categories of egg consumption.
Results. Eight articles with 17 reports (nine for coronary heart disease, eight for stroke) were eligible for inclusion in the meta-analysis (3 081 269 person years and 5847 incident cases for coronary heart disease, and 4 148 095 person years and 7579 incident cases for stroke). No evidence of a curve linear association was seen between egg consumption and risk of coronary heart disease or stroke (P=0.67 and P=0.27 for non-linearity, respectively). The summary relative risk of coronary heart disease for an increase of one egg consumed per day was 0.99 (95% confidence interval 0.85 to 1.15; P=0.88 for linear trend) without heterogeneity among studies (P=0.97, I=0%). For stroke, the combined relative risk for an increase of one egg consumed per day was 0.91 (0.81 to 1.02; P=0.10 for linear trend) without heterogeneity among studies (P=0.46, I=0%). In a subgroup analysis of diabetic populations, the relative risk of coronary heart disease comparing the highest with the lowest egg consumption was 1.54 (1.14 to 2.09; P=0.01). In addition, people with higher egg consumption had a 25% (0.57 to 0.99; P=0.04) lower risk of developing hemorrhagic stroke.
Conclusions. Higher consumption of eggs (up to one egg per day) is not associated with increased risk of coronary heart disease or stroke. The increased risk of coronary heart disease among diabetic patients and reduced risk of hemorrhagic stroke associated with higher egg consumption in subgroup analyses warrant further studies.
Introduction
Cardiovascular disease is now a public health crisis, affecting millions of people in both developed and developing countries. Although the rate of death attributable to the disease has declined in developed countries in the past several decades, it is still the leading cause of death and extorts a heavy social and economic toll globally. In low and middle income countries, the prevalence of cardiovascular disease has increased dramatically. By 2020, the disease is forecasted to be the major cause of morbidity and mortality in most developing nations.
In recent decades, concern has mounted regarding the high prevalence and costs associated with cardiovascular disease, with growing interest in altering risk factors and reversing this global epidemic. Among the known risk factors for cardiovascular disease, levels of low density lipoprotein (LDL) cholesterol have aroused particular attention. In the Women’s Health Study, after a mean follow-up of eight years, participants with the highest levels of LDL cholesterol showed a notably higher risk of cardiovascular events than those with the lowest levels. In addition, several meta-analyses of observational studies and randomized controlled trials have found that a reduction in concentrations of LDL cholesterol could significantly reduce the risk of coronary heart disease and stroke incidence and mortality. Diet is an important determinant of serum cholesterol, but dietary cholesterol has only a modest contribution to plasma concentrations of LDL cholesterol. On the other hand, dietary cholesterol may prompt the oxidation of LDL and increase postprandial lipemia, which could raise the risk of vascular disease. To minimize the elevation of blood cholesterol and reduce the risk of cardiovascular disease, the American Heart Association (AHA) has recommended the public to consume less than 300 mg/day of cholesterol.
Since eggs are a major source of dietary cholesterol, with one large egg containing almost 210 mg of cholesterol, the public has been recommended to limit egg consumption unless the intake of other foods high in cholesterol is restricted. However, eggs are also an inexpensive and low calorie source of many other nutrients, including minerals, proteins, and unsaturated fatty acids, which could lower the risk of cardiovascular disease. Additionally, in populations following a carbohydrate restricted diet, dietary cholesterol from eggs could increase plasma concentrations of high density lipoprotein (HDL) cholesterol, which has been suggested to protect against vascular disease. Therefore, some organizations have recommended that reducing egg intake might not be important for healthy people with normal levels of cholesterol in the blood. Food based dietary guidelines from countries including Nepal, Thailand, and South Africa recommend consuming eggs every day or regularly as part of a healthy diet.
Several prospective cohort studies have examined the association between egg consumption and risk of coronary heart disease and stroke. However, the relation between egg consumption and risk of cardiovascular disease remains controversial. Therefore, we conducted a dose-response meta-analysis of prospective cohort studies to quantify the association between egg consumption and risk of coronary heart disease and stroke.
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