When you get 100% of a nutrient’s RDA, it means that you are getting enough of the nutrient to meet the average daily need for a generally healthy adult. “100% RDA” means that there is enough of the nutrient to cover the general biochemical need for that nutrient in the human body for one day. It does not guarantee, however, that you have enough of the nutrient to meet your personal, individual needs. For example, there are many chronic health problems that deplete certain nutrients from you body. These problems would cause your body to need more than 100% RDA as would the use of certain prescription or over-the-counter medications. The 100% RDA guideline is simply a ballpark estimate that should get you thinking in the correct general category of nutrition.
When you go over 100% RDA, it simply means that you have likely provided your body with more than enough of the nutrient to meet your body’s general biochemical needs on that day. Your body will decide what to do the extra amount. It may decide to eliminate it altogether, and so you will find it passing out of the body when you urinate or move your bowel. Your body may also decide to store the nutrient, either temporarily or for a longer period of time.
In general, it is not recommended that you go over approximately 100% RDA for any particular nutrient unless you have been advised by a healthcare professional that more is needed.