New study reports that eggs are artery cloggers
For decades, the regular consumption of eggs has been linked to the development of atherosclerosis. In recent years, however, the potential harm from high cholesterol intake, and specifically from egg yolks, has been deemed by a number of researchers to be an insignificant factor. A new study adds fuel to the fire of that academic debate. Canadian researchers published their findings online on August 1 in the journal Atherosclerosis.
The study group was comprised of 1,262 consecutive patients attending vascular prevention clinics in Canada. The researchers assessed total plaque area (TPA) in the patients to determine if the atherosclerosis burden, as a marker of arterial damage, was related to egg intake. To provide perspective on the magnitude of the effect, they also analyzed the effect of smoking (pack-years).
The patients had baseline measurement of TPA by duplex ultrasound, and filled out questionnaires regarding their lifestyle and medications, including pack-years of smoking, and the number of egg yolks consumed per week times the number of years consumed (egg-yolk years). The average patient age was 61.5 years and 47% were women.
The researchers found that carotid plaque area increased linearly with age after age 40; however, it increased exponentially with pack-years of smoking and with egg-yolk years. Plaque area in patients consuming less than two eggs per week (388 patients) was 125 ± 129 mm2, versus 132 ± 142 mm2 in those consuming three or more eggs per week (603 patients). With multiple regression analysis, egg-yolk years remained significant after adjusting for coronary risk factors. (Regression analysis includes techniques for modeling and analyzing several variables, when the focus is on the relationship between a dependent variable and one or more independent variables. More specifically, regression analysis helps one understand how the typical value of the dependent variable changes when any one of the independent variables is varied, while the other independent variables are held fixed.)
The researchers concluded that their findings suggested that regular consumption of egg yolk should be avoided by persons at risk of cardiovascular disease. They proposed that their findings should be tested in a prospective study with more detailed information about diet, and other possible confounders such as exercise and waist circumference.
Highlights of the study:
- Carotid total plaque area (TPA) increases linearly with age.
- TPA increases exponentially with smoking pack-years.
- TPA increases exponentially with egg-yolk years.
- The effect size of egg yolks appears to be approximately 2/3 that of smoking.
- Probably egg yolks should be avoided by persons at risk of vascular disease.