Lipids are one of many influences that affect the risk for coronary heart disease (CHD). The 2 main forms of lipids are cholesterol and triglycerides. Both travel in the bloodstream attached to proteins called lipoproteins. Higher levels of low-density lipoprotein (called bad cholesterol) increase the risk for CHD, where higher levels of high-density lipoprotein (called good cholesterol) lower the risk. The effect of triglyceride levels on the risk for CHD is much less clear. Other well-known CHD risk factors include a sedentary lifestyle, high blood pressure, diabetes, obesity, and smoking. Some of these risk factors affect triglyceride levels, which makes it difficult to be sure whether triglyceride is a risk factor for CHD or whether it is just related to obesity, diabetes, or exercise.