Glossary

Radiopacity
A measurement of the ability of electromagnetic radiation, such as an X-ray, to pass through a particular material.
Rate-limiting step
The slowest step in a reaction that determines the overall rate.
Reactive oxygen species
Natural byproducts of oxygen metabolism that are highly reactive and significantly damage cell structures.
Recommended Daily Allowance (RDA)
The average daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all healthy individuals in a particular life stage and gender group. Now referred to as Dietary Reference Intake.
Retinopathy
Non-inflammatory damage to the retina of the eye that is ususally a result of blood supply problems.
Ribonucleic acid (RNA)
Nucleic acid polymer important in the translation of genetic information from DNA into protein products.