Fettwege

Fettwege is a term used in physiology and nutrition to describe the pathways by which fats (primarily triglycerides) are processed in living organisms. The Fettwege encompass digestion, absorption, transport through the circulatory and lymphatic systems, storage, and eventual utilization for energy or structural needs. The concept highlights the integration of multiple organ systems in lipid metabolism, including the digestive tract, liver, adipose tissue, and muscle.

In digestion and absorption, bile salts emulsify dietary fats, allowing pancreatic lipase to hydrolyze triglycerides into free fatty acids and monoglycerides. These products form micelles that are absorbed by enterocytes. Within intestinal cells, fatty acids are re-esterified into triglycerides and packaged with cholesterol and apolipoproteins into chylomicrons, which enter the lymphatic system and then reach the bloodstream.

Circulating triglycerides are acted on by lipoprotein lipase on capillary walls, releasing fatty acids for uptake by muscle and adipose tissue. In tissues, fatty acids undergo beta-oxidation in mitochondria to generate acetyl-CoA and energy, or are re-esterified for storage as triglycerides. In the liver, fatty acids can be oxidized, used for ketogenesis in fasting conditions, or assembled into very-low-density lipoproteins (VLDL) for export to other tissues.

Two major branches are distinguished: exogenous fats from the diet and endogenous fats produced by the liver. Disruptions of Fettwege can contribute to medical conditions such as fat malabsorption, dyslipidemias, obesity, and metabolic diseases. See also lipid metabolism, digestion, and lipoproteins.