High egg intake may prevent coronary artery disease

Eating more than one egg a day does not result in any cardiovascular disease (CVD) but even appears to be preventive of coronary artery disease (CAD), suggest the results of a systematic review and meta-analysis.

[O]ur analysis suggests that higher consumption of eggs was not associated with increased risk of CVD, but with a reduction in risk of CAD,” the investigators said.

Medline, Embase, Scopus, Web of Science, and the Cochrane Database of Systematic Reviews were thoroughly searched from inception in 1966 through January 2020 for observational studies reporting the association between egg consumption and CVD events. Two investigators reviewed data independently. Conflicts were resolved through consensus. Random-effects meta-analyses were carried out, and sources of heterogeneity were analysed.

Twenty-three prospective studies with a median follow-up of 12.28 years met the inclusion criteria. A total of 1,415,839 individuals were included, comprising 123,600 cases and 157,324 CVD events. [Am J Med 2021;134:76-83.E2]

Higher egg consumption did not correlate with a significantly increased risk of overall CVD events (pooled hazard ratio [HR], 0.99, 95 percent confidence interval [CI], 0.93–1.06; p<0.001; I², 72.1 percent) compared with consumption of no or 1 egg/day.

In a previous meta-analysis of eight observational studies, no significant association was noted between egg intake and CVD events, but a substantial heterogeneity was observed due to adjusted variables in the included studies. [BMJ 2013;346:e8539]

Likewise, a recent meta-analysis showed no association between moderate egg consumption (≤1 egg/day) and CVD risk overall, which was consistent with a subgroup analysis of the current study. [BMJ 2020;368:m513]

“[Based on] evidence to date, either 1 egg or >1 egg consumption is not associated with CVD,” the investigators said.

Interestingly, consuming more than 1 egg/day resulted in markedly lower risk of CAD (pooled HR, 0.89, 95 percent CI, 0.86–0.93; p<0.001; I², 0 percent) compared with consumption of no or 1 egg/day.

A previous meta-analysis of seven prospective studies also found no significant association with CAD by comparing high vs low egg intake (summary relative risk estimates, 0.97, 95 percent CI, 0.88–1.07), but the results might have been confounded by the inclusion of diabetic patients with higher CVD risks due to dietary patterns than nondiabetic patients. [J Am Coll Nutr 2016;35:704-716; Diabetes Metab Syndr Obes 2014;7:121-137]

“Egg consumption may reduce CAD via a mechanism of promoted carotenoid absorption, enhanced high-density lipoprotein cholesterol function, and increased bioactive compounds (eg, lutein and zeaxanthin), resulting in protecti[on] against atherosclerosis,” the investigators said. [Am J Clin Nutr 2015;102:75-83; J Nutr 2004;134:1887-1893; Nutrients 2015;7:2731-2747; JAMA 2007;298:786-798]

“The discrepancy of previous studies may be due to small sample sizes, a lack of adjustment for overall dietary pattern, ethnic difference, and only adjusting for blood glucose instead of excluding diabetic patients,” they added.