The relationship between blood
cholesterol and
heart disease is well-established, with the lowering of serum
low-density lipoprotein (
LDL)-cholesterol being the primary target of preventive
therapy. Furthermore, epidemiological studies report lower risk for
heart disease with higher concentrations of
high-density lipoprotein (
HDL)-cholesterol. There has also been considerable interest in studying the relationship between
dietary cholesterol intake and
heart disease risk. Eggs are one of the richest sources of
cholesterol in the diet. However, large-scale epidemiological studies have found only tenuous associations between the intake of eggs and
cardiovascular disease risk. Well-controlled, clinical studies show the impact of
dietary cholesterol challenges via egg intake on serum
lipids is highly variable, with the majority of individuals (~2/3 of the population) having only minimal responses, while those with a significant response increase both
LDL and
HDL-cholesterol, typically with a maintenance of the
LDL/
HDL cholesterol ratio. Recent drug trials targeting
HDL-cholesterol have been unsuccessful in reducing cardiovascular events, and thus it is unclear if raising
HDL-cholesterol with chronic egg intake is beneficial. Other important changes with egg intake include potentially favorable effects on
lipoprotein particle profiles and enhancing HDL function. Overall, the increased
HDL-cholesterol commonly observed with
dietary cholesterol feeding in humans appears to also coincide with improvements in other markers of HDL function. However, more investigation into the effects of
dietary cholesterol on HDL functionality in humans is warranted. There are other factors found in eggs that may influence risk for
heart disease by reducing serum
lipids, such as
phospholipids, and these may also modify the response to
dietary cholesterol found in eggs. In this review, we discuss how eggs and
dietary cholesterol affect serum
cholesterol concentrations, as well as more advanced
lipoprotein measures, such as
lipoprotein particle profiles and HDL metabolism.