Bioavailability
Definition
The proportion of a nutrient or compound that is absorbed from the digestive tract and made available for use or storage in the body. A nutrient can be present in food but have low bioavailability, meaning most of it passes through without being absorbed.
Why It Matters
Bioavailability explains why not all nutrients are created equal. For example: iron from animal sources (heme iron) has 15-35% bioavailability vs. 2-20% for plant iron (non-heme). Synthetic folic acid in enriched flour is metabolized differently from natural folate in leafy greens. Curcumin from turmeric has notoriously poor bioavailability (~1%) unless paired with piperine from black pepper (increases absorption by 2,000%). Understanding bioavailability is crucial for evaluating food labels and supplement claims.
Commonly Found In
Related Terms
Enriched (Enriched Flour)
CautionA labeling term indicating that nutrients (typically B vitamins and iron) have been added back to a refined grain product after the milling process stripped them out. 'Enriched' flour has had its bran, germ, and fiber removed, then had a fraction of the original nutrients synthetically reintroduced.
Glycemic Index (GI)
InformationalA numerical ranking system (0-100) that measures how quickly a carbohydrate-containing food raises blood glucose levels after consumption. Pure glucose is the reference food with a GI of 100. Foods are classified as Low GI (≤55), Medium GI (56-69), or High GI (≥70).