Triglycerides are mostly carried by chylomicrons and very low density lipoproteins (VLDL). Chylomicrons transport dietary fatty acids and cholesterol from the intestine, while VLDL transport triglycerides from the liver. Plasma triglyceride levels reflect the total mass of triglycerides, but not the number or type of particles carrying those triglycerides.
Elevation of chylomicron triglycerides does not increase atherosclerotic risk because chylomicron particles are too large to enter the arterial wall. Plasma triglycerides can also be elevated due to an increase in the triglyceride content of VLDL particles or an increase in the total number of VLDL particles. Recent studies have demonstrated that elevation of triglyceride levels due to an increase in VLDL particle number are associated with greater coronary heart disease risk. Apolipoprotein B is a measure of the number of VLDL and LDL particles and can be used to identify cases of hypertriglyceridemia that are due to increases in VLDL particle number. Wider use of apolipoprotein B measurements might be helpful in identifying those cases of hypertriglyceridemia associated with a higher risk of coronary heart disease.
References
Navar AM, The evolving story of triglycerides and coronary heart disease. JAMA 2019;321:347-348.
Ference BA,Kastelein JJP,Ray KK,etal. Association of triglyceride-lowering LPL variants and LDL-C–lowering LDLR variants with risk of coronary heart disease. JAMA 2019; doi:10.1001/jama.2018.20045