Eating up to one egg a day does not raise the risk of coronary heart disease (CHD) or stroke, a meta-analysis published in the BMJ suggests.

The study aimed to investigate and quantify the potential dose-response association between egg consumption and risk of CHD and stroke. The authors included prospective cohort studies with relative risks (RR) and 95% confidence intervals (CI) of CHD or stroke for three or more categories of egg consumption. Eight studies were eligible for inclusion in the meta-analysis which covered 3,081,269 person-years and 5,847 incident cases for CHD, and 4,148,095 person-years and 7,579 incident cases for stroke.

The researchers found no evidence of an association between egg consumption and risk of CHD or stroke (P = 0.67 and P = 0.27 for a non-linear association, respectively). RR of CHD for an increase of one egg consumed per day was 0.99 (95% CI:0.85-1.15; P = 0.88 for linear trend). For stroke, the combined RR for an increase of one egg/day was 0.91 (95% CI:0.81-1.02; P = 0.10 for linear trend).

This is reassuring but there was a note of caution based on a subgroup analysis of patients with diabetes. Comparing the highest with the lowest egg consumption, RR of CHD was 1.54 (95% CI:1.14-2.09; P = 0.01). However, diabetes patients with higher egg consumption had a 25% lower risk of developing haemorrhagic stroke, RR 0.75 (95% CI: 0.57-0.99; P = 0.04).

Eggs are often painted in a negative light by those offering advice on healthy eating mainly because they are a major source of dietary cholesterol, with one large egg containing almost 210 mg of cholesterol. However, eggs are also a source of minerals, proteins, and unsaturated fatty acids, which could lower the risk of cardiovascular disease.

The authors conclude that higher consumption of eggs, up to one a day, is not associated with an increased risk of CHD or stroke. However, they point out that the subgroup data in diabetes patients warrants further investigation before such reassurances can be extended to these patients as well.

Dr Peter Savill

• Rong Y, Chen L, Zhu T et al. Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies. BMJ 2013;346:e8539