Mechanisms of Action
Absorption
The process by which nutrients pass from the digestive tract into the bloodstream.
Nutrient absorption is the process by which vitamins, minerals, and other compounds cross the intestinal epithelium into the bloodstream. Absorption occurs primarily in the small intestine through passive diffusion, facilitated transport, and active transport mechanisms. Factors affecting absorption include the nutrient's chemical form, gastric pH, presence of enhancers (vitamin C enhances iron absorption) or inhibitors (calcium inhibits iron absorption), gut integrity, and competition between similar nutrients at shared transporters. Fat-soluble supplements (vitamins A, D, E, K) require dietary fat for optimal absorption.