Recommend daily amount is tricky because it may not reflect our most current understanding, but it is a good starting point. For example the RDA of vitamin D is

Recommend daily amount is tricky because it may not reflect our most current understanding, but it is a good starting point. For example the RDA of vitamin D is 600IU/day, but there has been evidence that up to 10x this dose continues to provide benefit. While once you have your RDA of other vitamins, any more will just be flushed out of you so it's irrelevant.