One of them can cause renal damage, says medical expert. High doses of vitamin A can cause hypercalcemia and make someone appear to have hyperparathyroidism, said John Morley, MD, in a talk at the March 2011 annual American Medical Directors Association meeting. "Watch for this -- it's very common," he said. "Some patients are taking four different vitamin A combinations a day. We see this all the time in my endocrine practice." Also: "Ginseng causes hypertension. Get rid of ginseng and the blood pressure goes down," Morley reported. And "colloidal silver causes kidney damage."