Food composition vs nutrient bioavailability
Food composition tables:
Nutrient content(determined by chemical analyses) of different foods.
Nutrient bioavailability:
Concerned with the fraction of ingested nutrient available for utilization or storage in normal physiological function after absorption from the gut. Bioavailability is influenced by: Chemical form of nutrient, state of food matrix, presence of suppressors or cofactors.
Synergistic effects among nutrients and other components in digesta Formation of stable structures that are slowly metabolized, and so on.