It was more supplemental than citation. Maybe they won't affect your kidneys. That's just something I heard when the NIH study broke in the news. Consult your doctor, etc.
The last time I saw my doctor she mentioned Calcium supplements can cause kidney stones(1). They can also be bad for your heart(2). Also, it often is not clear how pure supplements are. She advised me to get as many nutrients as I could from my regular food.
