Vitamin D Council Glossary

# A B C D E F G H I J–K L M N O P R S T U V
Affected with, suffering from, or characteristic of rickets.
see radiology.
The use of X-rays and radioactive substances in the diagnosis and treatment of disease.
A measurement of the ability of electromagnetic radiation, such as an X-ray, to pass through a particular material.
Randomized controlled trial
Most rigorous way of determining whether a cause-effect relation exists between treatment and outcome. Also useful for assessing the cost-effectiveness of a treatment.
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.
Retinoic acid
Oxidized form of vitamin A that is a regulator substance in morphogenesis. Also functions in the growth and development of bone and the maintenance of epithelium.
Various natural or synthetic derivatives of vitamin A that have many important and diverse functions throughout the body including roles in vision, regulation of cell proliferation and differentiation, growth of bone tissue, immune function, and activation of tumor suppressor genes.
Animal form of vitamin A that belongs to the family of chemical compounds known as retinoids.
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.
see osteomalacia.

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.