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.
The researchers used data from the China Kadoorie Biobank (CKB) study, an ongoing prospective study of around half a million adults aged 30 to 79. 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.
The egg consumption study, published this week in the BMJ’s Heart journal, focused on the 416,213 participants who were free of prior cancer, 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 cohort study period, 13.1% of participants reported daily consumption and 9.1% reported never or very rare consumption 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, the researchers concluded.
In particular, daily egg consumers (up to one egg a day) had a 26% lower risk of haemorrhagic stroke, a 28% lower risk of haemorrhagic stroke death and an 18% lower risk of CVD death, the researchers found.
In addition, there was a 12% reduction in risk of ischaemic heart disease observed for people consuming eggs daily, when compared with those who ate eggs 'never or rarely'.
Cracking the consensus
The nutritional implications of egg consumption remain controversial. Eggs are a prominent source of dietary cholesterol but also contain high-quality protein, vitamins and bioactive components such as phospholipids and carotenoids.
Previous investigations into the relationship between egg consumption and CVD have been inconsistent, with the majority finding insignificant associations between egg consumption and coronary heart disease or stroke.
Indeed, the most recent meta-analysis on the topic, led by Dr Dominik Alexander and published in the Journal of American College Nutrition in 2016, found that consumption up to one egg a day had “no significant association” with CVD compared with consuming two eggs per week.
As the CKB cohort study was an observational study no “firm conclusions” can be drawn about cause and effect. Nevertheless, the authors stressed that their study benefitted from a “large sample size” and took established and potential risk factors for CVD into account.
Looking at possible implications on clinical practice, the authors surmised: “The present study finds that there is an association between moderate level of egg consumption and a lower cardiac event rate.”
Source: BMJ, Heart
Published online ahead of print: DOI: 10.1136/heartjnl-2017-312651
‘Associations of egg consumption with cardiovascular disease in a cohort study of 0.5 million Chinese adults’
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