Cholesterol carried by remnant lipoproteins, which are formed by the metabolism of very-low-density lipoproteins (VLDL) and chylomicrons (lipoproteins that are rich in triglycerides). High concentrations of remnant-like particle (RLP) cholesterol have been linked to coronary heart disease.
For many decades, medical researchers have recognized that people with high cholesterol levels are at increased risk for cardiovascular disease. Yet some people develop cardiovascular disease despite having normal levels of total cholesterol and “bad” low-density lipoprotein (LDL) cholesterol. Some researchers believe that high levels of RLP cholesterol, which doesn’t show up on conventional lipid screening tests, may account for the higher risk of cardiovascular disease.
In a study reported in The American Journal of Medicine in 1998, researchers at the University of Texas Southwestern Medical Center in Dallas, Texas, studied 63 men who had coronary artery disease despite having normal total cholesterol and LDL cholesterol levels. They found that the men had elevated levels of RLP cholesterol.
High RLP cholesterol levels may also play a role in the high rate of cardiovascular disease among people with metabolic syndrome, a constellation of conditions that tend to run together—notably high blood pressure, insulin resistance, and blood lipid abnormalities—and may predispose people to developing Type 2 diabetes. Even people with mild forms of these abnormalities are known to be at increased risk for cardiovascular disease. In a study reported in Diabetes Care in 2005, Japanese researchers found that RLP cholesterol levels were elevated in individuals with mild abnormalities and suggested that this elevation may explain the high incidence of cardiovascular disease among people with metabolic syndrome.