Excessive amounts of some vitamins can cause kidney damage, such as excess vitamin C which may cause kidney stones. Excess amounts of the remaining vitamins are also damaging.
For healthy adults with no underlying medical conditions, high doses of vitamin C supplementation may increase the risk of developing kidney stones. Excessive vitamin D supplementation may also trigger hypercalcemia.
Excessive amounts of the remaining vitamins are also detrimental to health, e.g., excessive vitamin A predisposes to toxicity, excessive vitamin B6 increases the risk of hip fracture, excessive vitamin E increases the incidence of hemorrhagic stroke, and excessive ß-carotene increases the risk of cancer.
For healthy adults who eat a balanced diet, there is really no need to take vitamin supplements. Special populations, such as pregnant women, the elderly, children, and people with nutritional deficiencies, should take vitamin supplements under the supervision of a physician.