A term that once indicated suggested intake levels for nutrients. U.S. RDAs simplified the RDAs of the National Academy of Sciences by providing a single recommended allowance for the general healthy population. With few exceptions, these allowances were based on the highest RDA for each nutrient – the amounts required for young adult males. Since these values were excessively high for children, women and the elderly, U.S. RDAs have been replaced by RDIs which represent average RDAs.
– See Daily Reference Values (DRVs), Daily Values (DVs), Recommended Dietary Allowances (RDAs), Reference Daily Intakes (RDIs)
– See Fat
Beyond the culinary assets of eggs, numerous individual egg properties benefit mankind and other animals throughout a wide range of technologies:
Egg white has long been used as a facial. Egg yolks are used in shampoos and conditioners and, sometimes, soaps. Cholesterol, lecithin and some of the egg’s fatty acids are used in skin care products, such as revitalizers, make-up foundations and even lipstick.
The excellent nutrition of eggs enhances various pet foods. Egg white is used as a protein reference in feeding laboratory animals. Eggshells from processing plants are often dried, crushed and fed to laying hens as a rich calcium source and high-quality protein source (from egg white left inside the shells).
Microorganisms bred in laboratories often grow better if a small amount of egg yolk is added to the culture medium.
Medical and Pharmaceutical
Fertile eggs are used to manufacture many vaccines (including influenza shots), as a source of purified protein and as an aid in the preservation of bull semen for artificial insemination.
In some areas of the world, such as China, India and Eastern Europe, eggs have been used for centuries as the base for health potions. Today a number of nutraceutical uses of eggs are being employed and scientists are studying potential future egg benefits.
Current applications include:
Lysozyme, an egg white protein, is used as a food preservative and as an antimicrobial agent in pharmaceutical products. (Nature also provides lysozyme in human tears and saliva for infection prevention.)
Avidin is an egg white protein and biotin is a vitamin found in egg white and, to a much greater extent, in egg yolk. Avidin-biotin technology is being used in various medical diagnostic applications such as immuno-assay, histopathology and gene probes.
Sialic acid, an amino acid, has been shown to inhibit certain stomach infections.
Liposomes, fatty droplets found in eggs, are used as a controlled delivery mechanism for various drugs.
Immunoglobulin yolk (IGY), a simple egg-yolk protein which has immunological properties, is used as an anti-human-rotavirus (HRV) antibody in food products.
Phosvitin, a phosphoprotein found in egg yolk, provides antioxidant benefits in food products.
Choline, a B vitamin combined with lecithin in egg yolk, is important in brain development and is used to treat certain liver disorders. Eggs are one of the best food sources of choline.
Ovolecithin, a phospholipid found in egg yolk, has a high proportion of phosphatidycholine and contains fatty acids – such as arachidonic acid (AA) and docosahexanoic acid (DHA) – which have been shown to improve visual activity in infants and to improve fatty-acid status. Egg lecithin has both emulsifying and antioxidant properties and, beyond its usefulness in keeping the oil and vinegar of mayonnaise in suspension, it’s used chiefly in medicine.
Shell-membrane protein is being used experimentally to grow human skin fibroblasts (connective tissue cells) for severe-burn victims and, in Japan, is being used in cosmetics.