If the RDI represents the low end of the amount you need for a particular nutrient, the UL (“Upper Limit”) describes the high end. According to the National Institutes of Health, it is only advisable to begin taking a supplement if you are confident that you are not presently meeting the RDI and unlikely to exceed the UL.
Our body consists of cells and organs which are interconnected with each other. An imbalance of one nutrient might harm different organs and even the whole body. Popular dietary supplements like vitamin D and calcium also have adverse effects if they cross the UL. The main consequence of vitamin D excess in our body is a buildup of calcium in our blood (hypercalcemia), which can cause nausea and vomiting, weakness, and frequent urination. Excess calcium intake can cause constipation and even kidney problems, formation of kidney stones, and even kidney failure.
Minerals (especially taken in large doses) can also cause side effects. Tooth staining, increased urination, stomach bleeding, and uneven heart rate are just some of them.