While this is true, excess folic acid (in the milligram levels) has been seen to mask symptoms of
vitamin B12 deficiency. Also, excessive amounts have been found to prevent action of
some medications such as anti-epilepsy. These are some of the reasons why the upper limit of 1000 micrograms (1 milligram) has been set. However, if you accidentally take too many supplements in a day, you will not likely absorb higher than 1000 milligrams.