It is already known that cardiovascular disease
affects millions of people and as a major source of
dietary cholesterol, eggs have been investigated by
several epidemiologic studies in relation to risk of
coronary heart disease and stroke, however, whether
egg consumption increases the future risk of
coronary heart disease and stroke remains unclear.
The objective of this meta-analysis was to
investigate and quantify the potential dose-response
association between egg consumption and risk of
coronary heart disease and stroke.
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).
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.
This study shows that consumption of up to one egg
per day was not associated with increased risk of
coronary heart disease or stroke. Similar results
were obtained in subgroup analyses. However, among
diabetic participants, higher egg consumption was
associated with a significantly elevated risk of
coronary heart disease. On the other hand, higher
egg intake was associated with a lower risk of
hemorrhagic stroke. These subgroup results should be
interpreted with caution, because only a few studies
focused on diabetic participants and particular
stroke subtypes.
Some studies have found an inverse association
between egg consumption and stroke risk. For example,
an analysis of the Third National Health and
Nutrition Examination Survey 1988-1994 (NHANES III)
dataset found a significant inverse association
between higher egg consumption and stroke mortality
among men. A cohort study from Japan found that
increased consumption of animal products (including
eggs) was associated with reduced risk of total and
hemorrhagic stroke death.
For more information
Egg consumption and risk of coronary heart disease
and stroke: dose-response meta-analysis of
prospective cohort studies. BMJ 2013;346:e8539.
http://dx.doi.org/10.1136/bmj.e8539
Ying Rong, doctoral student, Li Chen, research
fellow, Tingting Zhu, research fellow, Yadong Song,
research fellow, Miao Yu, research fellow, Zhilei
Shan, research fellow, Amanda Sands, doctoral
student, Frank B Hu, professor, Liegang Liu,
professor.
(MDN)
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