Can Too Much Vitamin C Cause Kidney Stones?

Before you knew much about vitamins, you can probably remember seeing Popeye eat a can of spinach and grow bulging biceps in an instant. As it turns out, veggies and fruits like spinach, oranges, broccoli, strawberries, and kiwi contain a powerful nutrient – vitamin C. Although our bodies make some of the vitamins that we need for good health, it can't make vitamin C so we must get it through our diets or supplements, according to Healthline.

Vitamin C, also known as ascorbic acid, is essential for many processes in the body. Vitamin C helps the body absorb iron, heal wounds, and it keeps our immune systems strong, helping to protect us from a number of diseases. Since vitamin C is not a fat-soluble vitamin, most people don't worry about consuming amounts that can cause harm, notes Healthline. However, there are cases in which taking too much vitamin C, particularly through supplements, has been linked to the formation of kidney stones.

Vitamin C can increase a calcium salt that forms kidney stones

According to the Mayo Clinic, kidney stones are hard deposits that form inside of the kidneys. Kidney stones are made up of minerals and salts, and may result from a medical condition, medications, and even supplements. Even if you've never had a kidney stone, you're likely familiar with how painful they are. Passing a kidney stone can cause discolored urine, pain in the back and sides, nausea, and vomiting.

The recommended daily amount (RDA) for vitamin C is 75 milligrams for women, 90 milligrams for men, and 120 milligrams for pregnant women. Exceeding 2,000 milligrams of vitamin C in a day can lead to headaches, cramping, vomiting, and diarrhea (via Mayo Clinic). According to Nebraska Medicine, too much vitamin C can cause kidney stones due to an increase in calcium salt excreted in the urine called oxalate. Oxalate is responsible for the formation of some kidney stones.

Most of us get enough vitamin C through our diets so supplementation usually isn't needed. However, certain groups of people may be vitamin C deficient. Dr. Sarah Malik, a gastroenterologist at Nebraska Medicine said, "People who might be susceptible to vitamin C deficiency, such as smokers, people with severe intestinal malabsorption or cachexia and cancer patients might be at increased risk of vitamin C inadequacy, may benefit from the use of vitamin C supplements under a doctor's supervision."