RDA (Recommended Daily Allowance) officially determines the levels of intake of essential nutrients. Based on scientific knowledge, the Food and Nutrition Board decides what is to be adequate in order to meet the known nutritional needs of practically all healthy individuals. The Food and Nutrition Board is a subcommittee of the National Research Committee and has been responsible for the RDA’s since 1941. The Board, as of 1996, has offered ten revisions since their first publication in 1943. The RDA serves as the basis for the USRDA established by the Food and Drug Administration (FDA) for labelling purposes.
RDA (Recommended Dietary Allowance) and RDI (Reference Daily Intake) were designed to avoid deficiency-induced diseases. Their guidance was not meant to treat chronic conditions or subclinical deficiencies. It was assumed that the populace was in good health and consumed healthy diets. Many scoff at their recommendations today because it is apparent that their minimal standards are not being met in the typical diet.
Expanding knowledge in the second half of this century has made it clear that criteria based solely on RDA’s is insufficient for evaluating the potential impact diet may have on health. As a result, emphasis in dietary advice has shifted from proteins, vitamins, and minerals to food components that are associated with chronic diseases.
For the healthy person, it is generally advised not to exceed five times the RDA without medical supervision. For example, fat soluble vitamins can build within the body over a period of time, creating other unwanted conditions, plus certain supplements can interfere with diagnostic tests. In addition, certain supplements can aggravate any pre-existing condition.
RNA (ribonucleic acid) is a single strand of nucleotides with uracil replacing thiamine found in DNA. RNA is synthesized from DNA in the nucleus of a cell, but carries out its function in the cytoplasm, where it copies the genetic code of DNA and directs the protein synthesis within the cytoplasm. There are three distinct types of RNA that are involved in protein synthesis with varying size, shape, origin, and function.
1) Messenger RNA (mRNA) is also known as “template RNA” or “informational RNA.” It functions at the site of protein synthesis and carries the genetic message from DNA to the robosome, the site of protein synthesis.
2) Ribosomal RNA (rRNA) is ribonucleic acid in the ribosome, which is believed to direct the arrangement of the amino acids of proteins into their proper sequence within the polypeptide chain.
3) Transfer RNA (tRNA) is also known as “soluble RNA” or “acceptor RNA.” It occurs free in the cytoplasmic fluid and transfers the activated amino acids to a specific site on the ribosomal RNA template. This results in an alignment of amino acids in a particular sequence to form the primary structure of a protein.
