If you’ve ever had a kidney stone, you surely remember it. The pain can be unbearable, coming in waves until the tiny stone passes through your urinary plumbing and out of the body. For many, kidney stones aren’t a one-time thing: in about half of people who have had one, another appears within seven years without preventive measures. Preventing kidney stones isn’t complicated but it does take some determination. Prevention efforts include drinking plenty of water, getting enough calcium from food, cutting back on salt (sodium), limiting animal protein, and avoiding stone-forming foods like beets, chocolate, spinach, rhubarb, tea, and others.
File this under “if a little bit is good, a lot isn’t necessarily better:” taking high-dose vitamin C appears to double a man’s risk of developing painful kidney stones. In an article published yesterday in JAMA Internal Medicine, Swedish researchers detail a connection between kidney stone formation and vitamin C supplements among more than 23,000 Swedish men. Over an 11-year period, about 2% of the men developed kidney stones. Men who reported taking vitamin C supplements were twice as likely to have experienced the misery of kidney stones. Use of a standard multivitamin didn’t seem to up the risk. Many people believe that extra vitamin C can prevent colds, supercharge the immune system, detoxify the body, protect the heart, fight cancer, and more. To date, though, the evidence doesn’t support claims that extra vitamin C is helpful. If high-dose vitamin C doesn’t improve health, then any hazard from it, even a small one, is too much.