Nutrition 101 – Glossary – R

RDI – Definition – The Reference Daily Intake (RDI) is the daily intake of a nutrient, vitamin or mineral that meets the nutrition needs of most healthy individuals and is used to determine the Daily Value (DV) of foods on food labels. Relevance – The RDI is used for the FDA-regulated nutrition facts labeling of foods, and RDI is based on the 1968 Recommended Dietary Allowances (RDA), despite the introduction of the newer Dietary Reference Intake (DRI) system.

Resveratrol – Definition – Resveratrol is a polyphenol present in grapes, red wine, peanuts and certain berries. Relevance – Resveratrol became popular following study of the “French Paradox” and its presence in wine; while moderate alcohol intake is linked to decreased risk of heart disease, it is unknown whether resveratrol plays a role in this relationship.

Retina – Definition – A light-sensitive tissue that lines the inside back wall of eyes, kind of like wallpaper. The retina converts light into electrical impulses, which the brain interprets as visual images. Relevance – A healthy retina is needed for good vision. It is damaged in diabetic retinopathy, which is the most common eye disease in people with diabetes and a leading cause of blindness in American adults.

Retinol – Definition – Retinol is another term for vitamin A.

Retinyl esters – Definition – Retinyl esters are the form of vitamin A present in animal food products, or pre-formed retinol. Relevance – Retinyl esters can form limited reserves, which can then provide biologically active retinol to cells as needed.

Rhabdomyolysis – Definition – Rhabdomyolysis is a harmful condition in which muscle fibers are broken down and released into the bloodstream. Relevance – Rhabdomyolysis can cause severe kidney damage and can be caused by skeletal muscle injury; dark or red urine, weakness and stiffness are some symptoms and risk factors include serious crush injuries, alcoholism, drug use, seizures and more.

Rheumatoid arthritis – Definition – Rheumatoid arthritis (RA) is characterized by loss of function and stiffness in the joints, particularly those of the wrist and fingers. Relevance – Unlike osteoarthritis, RA can affect areas of the body other than joints because it is an autoimmune disease, for which the cause is unknown; RA typically begins in middle age, but it can also affect children.

Riboflavin – Definition – Riboflavin, or vitamin B2, is a water-soluble vitamin that is necessary for red blood cell production and growth and is found in dairy, green leafy vegetables, eggs, legumes, nuts and lean meats. Relevance – Riboflavin is linked to claims that it can prevent cervical cancer, migraines, acne, muscle cramps, and several other conditions. Food manufacturers are required to add riboflavin to enriched bread, cereal and grain products to prevent deficiency diseases, which tend to occur with other vitamin B complex deficiencies.