BMJ: People
who consume an egg a day could significantly reduce their risk of
cardiovascular diseases compared with eating no eggs, suggests a study
carried out in China, published in the journal Heart. Cardiovascular
disease (CVD) is the leading cause of death and disability worldwide,
including China, mostly due to ischaemic heart disease and stroke
(including both haemorrhagic and ischaemic stroke).
Unlike
ischaemic heart disease, which is the leading cause of premature death
in most Western countries, stroke is the most responsible cause in
China, followed by heart disease.
Although
ischaemic stroke accounted for the majority of strokes, the proportion
of haemorrhagic stroke in China is still higher than that in high income
countries.
Eggs
are a prominent source of dietary cholesterol, but they also contain
high-quality protein, many vitamins and bioactive components such as
phospholipids and carotenoids.
Previous
studies looking at associations between eating eggs and impact on
health have been inconsistent, and most of them found insignificant
associations between egg consumption and coronary heart disease or
stroke.
Therefore,
a team of researchers from China and the UK led by Professor Liming Li
and Dr Canqing Yu from the School of Public Health, Peking University
Health Science Center, set out to examine the associations between egg
consumption and cardiovascular disease, ischaemic heart disease, major
coronary events, haemorrhagic stroke and ischaemic stroke.
They
used data from the China Kadoorie Biobank (CKB) study, an ongoing
prospective study of around half a million (512,891) adults aged 30 to
79 from 10 different geographical areas in China.
The
participants were recruited between 2004–2008 and were asked about the
frequency of their egg consumption. They were followed up to determine
their morbidity and mortality.
For
the new study, the researchers focused on 416,213 participants who were
free of prior cancer, cardiovascular disease (CVD) and diabetes.
From
that group at a median follow-up of 8.9 years, a total of 83,977 cases
of CVD and 9,985 CVD deaths were documented, as well as 5,103 major
coronary events.
At
the start of the study period, 13.1% of participants reported daily
consumption (usual amount 0.76 egg/day) and 9.1% reported never or very
rare consumption (usual amount 0.29 egg/day) of eggs.
Analysis
of the results showed that compared with people not consuming eggs,
daily egg consumption was associated with a lower risk of CVD overall.
In
particular, daily egg consumers (up to one egg/day) had a 26% lower
risk of haemorrhagic stroke – the type of stroke with a higher
prevalence rate in China than in high-income countries – a 28% lower
risk of haemorrhagic stroke death and an 18% lower risk of CVD death.
In
addition, there was a 12% reduction in risk of ischaemic heart disease
observed for people consuming eggs daily (estimated amount 5.32
eggs/week), when compared with the ‘never/rarely’ consumption category
(2.03 eggs/week).
This
was an observational study, so no firm conclusions can be drawn about
cause and effect, but the authors said their study had a large sample
size and took into account established and potential risk factors for
CVD.
The
authors concluded: “The present study finds that there is an
association between moderate level of egg consumption (up to 1 egg/day)
and a lower cardiac event rate.
“Our
findings contribute scientific evidence to the dietary guidelines with
regard to egg consumption for the healthy Chinese adult.”
[Ends]
Journal: Heart