Tolerable Upper Intake Levels
editA Tolerable Upper Intake Level (commonly abbreviated UL) is a value that describes the maximum intake of a particular nutrient that is likely to pose no risk of adverse health effects in most people of a specified life stage group. If one consistently ingests a particular nutrient in greater quantities than the UL he or she may increase his or her risk of deleterious health effects. The UL generally applies to the chronic ingestion of nutrients from water, unprocessed foods, fortified foods and supplements. However there are some nutrients that are only harmful when obtained from specific sources (usually supplements and fortified food) and this is specified in the UL.
How the UL is determined
editWhen possible, a UL for a particular nutrient is based on a no-observed-adverse-effect level (NOAEL). A NOAEL is the highest experimental oral dose of a nutrient that did not produce any observable negative effects in the individuals studied. If a NOAEL is not available, a a lowest-observed-adverse effect (LOAEL) level may be used. This is the lowest oral dose of a nutrient that produced adverse events in people studied. Once a NOAEL or LOAEL is determined, several uncertainty factors are applied to provide a margin of safety in the setting of missing data and the wide range of individual responses within a particular population.