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|Objectives||To investigate whether carotid plaque burden is influenced by egg yolk consumption|
|Study design||Prospective study|
|Study population||1,262 consecutive patients (mean age 61.5 years, 47% women, 13% with diabetes) referred to vascular prevention clinics at an University Hospital London, Ontario, Canada|
|Primary variable||Carotid total plaque area (TPA)|
Figure 1. Carotid plaque area increases exponentially with increasing quintiles of egg yolk consumption.
Regular consumption of egg yolk should be avoided by people at risk of cardiovascular disease.
This study shows a strong association between egg yolk consumption and carotid plaque burden. Indeed, the magnitude of the effect is generally similar to that seen with smoking (not shown here); the effect on plaque burden associated with the upper quintile of egg yolk consumption was about 70% of that seen in the upper smoking quintile, i.e. corresponding to at least 40 pack-years exposure. The effect on the arteries of egg yolks and smoking appears to be additive (in press, Atherosclerosis).
Dietary cholesterol, as found in egg yolks, not only raises LDL cholesterol levels, but also increases the susceptibility of LDL to oxidation; concomitant effects of vascular inflammation and oxidative stress contribute to endothelial dysfunction.(2) Furthermore, the effects of egg yolk consumption on postprandial lipaemia are relevant in the context of residual cardiovascular risk, in reducing postprandial clearance of atherogenic chylomicron remnants by about 50%.(3)
Emerging evidence also suggests that interaction between dietary phosphatidylcholine (otherwise referred to as lecithin), which is found in eggs, and the gut flora may be relevant. The gut flora or microbiota play an intermediate metabolic role in converting choline, released by hydrolysis of phosphatidylcholine, to trimethylamine, which then undergoes oxidation in the liver. Studies in animal models have shown an association between dietary choline, plasma levels of oxidative metabolites of trimethylamine, and plaque development.(4) Thus, these mechanistic data provide further support for a deleterious association between egg yolk consumption and atherosclerotic plaque development.
In conclusion, the findings from this study suggest that reducing or avoiding egg yolk consumption may be another, emerging and relevant therapeutic lifestyle change to reducing residual cardiovascular risk in the high-risk patient. These data warrant testing in a prospective randomized outcomes trial.
1. Spence JD, Eliasziw W, DiCiccoM et al. Carotid plaque area: a tool for targeting and evaluating vascular preventive therapy. Stroke 2002;33:2916-22.