Vitamin Glossary "R"

• radiation necrosis- death of an area of tissue or bone surrounded by healthy parts.

   

• receptors-special biological structures found on cells where active molecules such as hormones, enzymes, and neurotransmitters are attached to the cell surface. The cell then responds to the presence of the chemical in the receptor. Loss of and/or damage to receptors is one important event in aging.

   

• reduction-a chemical reaction in which an electron is donated to the reduced entity.

   

• refereed journals-scientific journals in which a committee of scientists review papers before they are published, checking for adequate experimental design and whether the experimental results support the conclusions reached.

   

• reflex sympathetic dystrophy- a chronic condition where pain does not subside an muscle function begins to deteriorate.

   

• regeneration-regrowth of lost body cells, tissues, organs, and limbs.

   

• renal insufficiency- the reduced capacity of the kidney care to perform its functions.

   

• retinoid-a substance closely related chemically to vitamin A. (Vitamin A is retinoic acid and its esters, or retinyl alcohol.) Retinoids regulate growth of epithelial cells (skin, lung, and gut) and are often powerful antioxidants and cancer preventing agents. The early stages of some epithelial cancers can be converted back into normal tissue by some retinoids. Retinoids are also chemically closely related to and made from carotenoids.

   

• RNA-ribonucleic acid, which carries instructions from DNA (deoxyribonucleic acid) in the nucleus to cell polyribosomes, where proteins are made according to the RNA instructions copied from the DNA master version of the cell's blueprints.

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