“Provitamin” — a compound that the human body can convert into a vitamin. For example, beta-carotene is a provitamin because the body can convert it into vitamin A, as needed.

“Protein” — a polypeptide or molecule made up of polypeptides. A complex, nitrogen-containing substance that is found in food and is essential for the functioning of the human body. Protein molecules consist of long chains of building blocks called amino acids. Some of these amino acids can be manufactured in the human body. Others must […]

“Prospective cohort study” — an observational study in which a group of people—known as a cohort—are interviewed or tested for risk factors (e.g., nutrient intake), and then followed up at subsequent times to determine their status with respect to a disease or condition of interest.

“Polyphenol” —  an antioxidant phytochemical (as chlorogenic acid) that tends to prevent or neutralize the damaging effects of free radicals.

“Phtyochemical” — substance derived from a plant. The term is generally reserved for molecules with biological activity.