Calcium citrate, especially in large doses and when not taken with a meal, may increase the risk of kidney stones for some individuals, though studies in healthy postmenopausal women have not shown an increased risk. There is no evidence to suggest calcium citrate increases the risk of gallstones; concerns about gallstones typically relate to dietary factors or other medical conditions.

That's a good reminder that we need to discuss all supplements with our medical team, even apparently harmless ones. Those of us living with prostate cancer are typically taking some pretty strong meds for that, and we're at an age when we're often also taking meds for other conditions like high blood pressure or blood clotting.

At this level of (necessary) polypharmacy, even so-called "natural" supplements can introduce unexpected complications.