LDL cholesterol is divided into several types. Researchers found adding up to three eggs per day does raise some types of LDL cholesterol, but it didn’t significantly raise levels of the types of LDL known to clog arteries.
“We found that the dietary cholesterol in eggs does raise the LDL-1 and LDL-2 [types] but it does not impact the small, dense LDL-3 through LDL-7 particles that are the greatest threat for cardiovascular disease risk,” says researcher Maria Luz Fernandez, PhD, of the University of Connecticut, in a news release.
Fernandez says the findings may help explain why previous studies haven’t shown a consistent relationship between increases in LDL cholesterol levels, such as those associated with eating eggs, and an increasing risk of heart disease.
In the past decade, research has shown that LDL cholesterol particles vary with respect to their potential to clog arteries and cause heart disease. The particles have been classified according to their size and density, from LDL-1 to LDL-7, with LDL-1 being the largest and LDL-7 being the smallest in diameter.
Researchers say that having predominantly smaller, dense LDL particles (greater than LDL-3) is considered to be more dangerous to heart disease-related health than having mostly larger, more buoyant particles.
In this study, researchers examined the effects of adding the liquid equivalent of three whole eggs per day or a cholesterol-free, fat-free substitute to the diets of about 50 men and premenopausal women for 30 days. A large egg contains about 213 mg of cholesterol.
The study showed that eating the additional cholesterol contained in the eggs increased the proportion of large, LDL particles but did not significantly increase the proportion of the more dangerous, smaller particles.
“We also found that egg cholesterol did not impact the small, dense LDL particles among a sub-set of participants who were generally predisposed to being most sensitive to dietary cholesterol,” says Fernandez.
But the study also showed that men had a higher concentration of the more harmful, small LDL particles than women regardless of the diet they followed.
The study appears in the June issue of the journal Metabolism and was supported by the American Egg Board and the University of Connecticut Research Foundation.