February 5th, 2013
GLOBAL – Eating one egg a day does not increase the risk of coronary heart disease or stroke and may even reduce the risk, according to new research from China and the US, except for people with diabetes.
Researchers from China and the US have found that higher consumption of eggs – defined as up to one egg per day – is not associated with increased risk of coronary heart disease or stroke. The study did reveal an increased risk of coronary heart disease among diabetic patients and a reduced risk of haemorrhagic stroke associated with higher egg consumption in some groups, aspects that they suggested warrant further studies.
Professor Liegang Liu of the Tongji Medical College at Huazhong University of Science and Technology in Wuhan, China and co-authors there and at Harvard School of Public Health in the US have reported in the British Medical Journal (BMJ) their study to investigate and quantify the potential dose-response association between egg consumption and risk of coronary heart disease and stroke.
They carried out a dose-response meta-analysis of prospective cohort studies published in PubMed and Embase prior to June 2012 and references of relevant original papers and review articles. They selected prospective cohort studies with relative risks and 95 per cent confidence intervals of coronary heart disease or stroke for three or more categories of egg consumption.
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 5,847 incident cases for coronary heart disease, and 4,148,095 person years and 7,579 incident cases for stroke).
The researchers found no evidence of a curvilinear association 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 per cent confidence interval: 0.85 to 1.15; P=0.88 for linear trend) without heterogeneity among studies (P=0.97, I2=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, I2=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, the researchers found that people with higher egg consumption had a 25 per cent (0.57 to 0.99; P=0.04) lower risk of developing haemorrhagic stroke.
Rong Y., L. Chen, T. Zhu, Y. Song, M. Yu, Z. Shan, A. Sands, F.B. Hu and L. Liu. 2013. Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies. BMJ, 346. doi: http://dx.doi.org/10.1136/bmj.e8539 (Published 7 January 2013)