Bioavailability refers to the amount of a substance that can be absorbed and utilized by the body. In the context of nutrition research, this term is generally interchangeable with “oral bioavailability”, which is the amount of a substance that is absorbed and utilized by the body when consumed orally. A substance’s bioavailability can be determined by a number of factors, such as the following:^[1][2]

• Route of administration: When substances are consumed orally, they can be digested, modified, and metabolized before they actually reach their target tissues. As such, a substance that is consumed orally can sometimes be less bioavailable than the same substance if inhaled intravenously or inhaled.
• Ease of absorption: The chemical qualities of a substance can make it easier or harder to absorb. Many of the nutrients that we consume require enzymes and transport proteins to effectively move them out of our intestines and into our bloodstream.
• Food matrix: Nutrients can be made less available by binding to other compounds like fiber, phytates, or oxalates.
• Food processing: Cooking, grinding, or fermenting foods can make nutrients more bioavailable (e.g., cooked meats tend to have more nutritional value than raw meats).
• Nutrient-nutrient interactions: When consumed together, certain nutrients can enhance or reduce each other’s bioavailability (e.g., black pepper improves the absorption of curcumin).

Factors that affect bioavailability