**3.1 Lipid metabolism and significant of HDL**

Lipid metabolism involves several key enzymes and subtypes of lipid fractions and lipoproteins. These include lipoprotein lipase (LPL), TGs, TC, LDL, VLDL, HDL, and chylomicrons (**Figure 3**). Lipid metabolism formed the cornerstone for understanding the mechanisms involved in the atherothrombotic formation. Lipid metabolism occurs through three essential pathways, including exogenous and endogenously produced lipids, and finally the reverse cholesterol transport pathway (**Figure 3**) [27, 28]. The exogenous (dietary) pathway begins with chylomicron synthesis and secretion by the intestine. Dietary fat and cholesterol are absorbed by the duodenum and proximal jejunum. In the intestinal duodenum, dietary lipids undergo emulsification and then
