Lipidstoffwechselstörungen

Lipid metabolism, sometimes referred to by the German term Lipidstoffwechsel, covers the digestion, absorption, transport, and utilization of lipids in the body. Dietary triglycerides are emulsified by bile acids, hydrolyzed by pancreatic lipase, and absorbed by enterocytes of the small intestine. Cholesterol and fat-soluble vitamins are taken up as well. In the lymphatic system, absorbed lipids form chylomicrons that deliver triglycerides to peripheral tissues. The liver synthesizes and remodels lipids and participates in the production and clearance of circulating lipoproteins such as VLDL and HDL, which distribute cholesterol and triglycerides throughout the body.

Energy production and storage are central roles of lipid metabolism. Fatty acids are oxidized in mitochondria via beta-oxidation to generate acetyl-CoA, which fuels the TCA cycle and ATP production or, during fasting, is converted into ketone bodies. In contrast, lipogenesis creates fatty acids from acetyl-CoA, primarily in the liver and adipose tissue, especially after caloric surplus. Triglycerides are stored in adipocytes and mobilized later by lipolysis, mediated by hormone-sensitive lipase, releasing free fatty acids bound to albumin for use by tissues that require energy.

Cholesterol metabolism involves synthesis by HMG-CoA reductase, uptake via LDL receptors, and reverse transport via HDL. The production of signaling lipids, such as eicosanoids, and the maintenance of cellular membranes depend on diverse fatty acids. Regulation occurs through hormones (insulin promotes storage; glucagon and adrenaline promote mobilization) and transcription factors such as SREBP and PPARs. Disturbances of lipid metabolism contribute to disorders including dyslipidemias, obesity, and non-alcoholic fatty liver disease, making lipid homeostasis a central concern in nutrition and medicine.