Estimated Average Requirement (EAR) is the average daily nutrient intake level that is estimated to meet the requirements of half - 50% - of the healthy individuals in a particular life stage and gender group.
Because the needs of the other half of the population will not be met by this amount, the EAR is increased by about 20% to arrive at the RDA.
Before setting the EAR, a specific criterion of adequacy is selected, based on a careful review of the literature. When selecting the criterion, reduction of disease risk is considered along with many other health parameters.
Genetics is the study of genes, genetic variation, and heredity in living organisms. A gene is the basic physical and functional unit of heredity. Genes, which are made up of DNA, act as instructions to make molecules called proteins.
The Human Genome Project has estimated that humans have 20,000 - 25,000 genes. Every person has two copies of each gene, one inherited from each parent. Most genes are the same in all people, but less than 1% of genes are slightly different between people. Poplar tree genome suggests more than 45,000 genes.