Cholesterol is a vital lipid that plays important roles in maintaining cell membrane structure, hormone synthesis, and aiding in the synthesis of bile acids for digestion. Excess cholesterol can lead however to conditions such as atherosclerosis, where cholesterol accumulates in arterial walls, increasing the risk of heart disease. Understanding cholesterol metabolism in humans is therefore important for promoting cardiovascular health. Cholesterol enters the body primarily from animal-based foods. In the small intestine, cholesterol is absorbed by specific transporters known as Niemann-Pick C1-Like 1 (NPC1L1) proteins. Once absorbed, cholesterol is incorporated into chylomicrons, lipoprotein particles that transport lipids, including cholesterol, through the lymphatic system and eventually into the bloodstream. In addition to dietary cholesterol, humans also synthesize cholesterol in the liver via HMG-CoA reductase. When cellular cholesterol levels are low, the liver increases the synthesis of HMG-CoA reductase, increasing cholesterol production. Conversely, when cellular cholesterol levels are high, the liver downregulates HMG-CoA reductase activity, reducing cholesterol production. Cholesterol and other lipids are not water-soluble and must be transported in the blood in association with lipoproteins. Lipoproteins are structures composed of proteins, lipids, and cholesterol. The major lipoproteins involved in cholesterol transport are low-density lipoprotein (LDL) and high-density lipoprotein (HDL). LDL transports cholesterol from the liver to peripheral tissues, whilst HDL collects excess cholesterol from peripheral tissues and transports it back to the liver for excretion or for recycling. To deliver cholesterol to cells, LDL binds to LDL receptors, initiating receptor-mediated endocytosis. Once inside the cell, cholesterol is released from the LDL particles and utilized for various cellular functions. HDL plays a critical role in the reverse cholesterol transport pathway, involving removal of excess cholesterol from peripheral tissues and returning it to the liver for excretion. HDL transports cholesterol from cells and tissues transferring it to other lipoproteins or directly to the liver. This process helps maintain cholesterol homeostasis and protects against atherosclerosis. Inside cells, cholesterol can be converted into cholesterol esters by acyl-CoA cholesterol acyltransferase (ACAT). Cholesterol esters are stored as lipid droplets within cells thereby regulating cholesterol levels, preventing the accumulation of free cholesterol. Cholesterol is eliminated from the body through two primary routes: biliary excretion and faecal elimination. In the liver, cholesterol is converted into bile acids, which are secreted into the bile and stored in the gallbladder. During digestion, bile acids are released into the small intestine, where they aid in the absorption of dietary fats. After fulfilling their role in digestion, bile acids are reabsorbed in the terminal ileum and transported back to the liver through the enterohepatic circulation. In the liver, some bile acids are re-secreted into the bile, whilst others are converted back into cholesterol. The remaining cholesterol is eventually excreted from the body. Thus, cholesterol metabolism is tightly regulated in man, involving the absorption, synthesis, transport, utilization, and elimination of cholesterol. Balanced cholesterol metabolism is essential for maintaining cellular functions, hormone synthesis, and overall cardiovascular health. We provide a large product catalogue of research reagents for investigating cholesterol metabolism, including Apolipoprotein A I antibodies, Caveolin-1 antibodies, Hormone sensitive lipase antibodies, Apolipoprotein A I ELISA Kits, and Apolipoprotein E ELISA Kits. Explore our full cholesterol metabolism product range below and discover more, for less.