The kidneys are designed to filter the body's blood and get rid of waste material. However, for unknown reasons sometimes this efficient process fails and kidney stones form. For many years taking vitamin C has been linked to developing kidney stones. According to the Linus Pauling Institute vitamin C's reputation for causing kidney stones not supported by research.
Vitamin C Chemistry
Vitamin C is also called ascorbic acid. This water soluble chemical must be obtained from the diet and has numerous important functions in the body. One of its main purposes is to help make collagen, the basic building block for connective tissues. Vitamin C is also needed to make enzymes and the nerve chemical messenger norepinephrine. Vitamin C is also one of the more powerful antioxidants in our diet, meaning it protects molecules inside cells from free radical degradation. When vitamin C is metabolized, a byproduct called oxalate is produced and enters the bloodstream. Oxalate is a waste that normally is excreted by the kidneys.
Kidney Function
The kidneys act as blood filters and chemical regulators. They remove waste material as well as excess water from the body. Kidneys also retain or excrete certain other chemicals such as electrolytes in order to keep their proportions or balance constant in the blood. Thus, the kidneys can be thought of as very sensitive detectors of the blood's chemistry to determine what must be retained or excreted. Normally, oxalate is excreted along with other wastes such as uric acid.
How Kidney Stones Form
Kidney stones are also known as ureterolithiasis, meaning they are hard, stony mineralizations that look much like ordinary pebbles. It is not known why some people get kidney stones but the process may begin with increased oxalate concentrations in the urinary system. The increased concentration allows calcium-oxalate crystals to start forming, which then build up in the kidneys. Over time, the stones increase in size. In most people, the stones pass in the urine before they become too large but in others the stones remain and are not passed.
Effect of Vitamin C
Taking too much vitamin C has long been thought to contribute to kidney stones. This is because taking too much vitamin C can increase serum oxalate concentrations, and most kidney stones are oxalate-based. Therefore, the cause and effect seemed appropriate. Yet the Linus Pauling Institute maintains this association is unfounded since little scientific evidence supports that association. In contrast, the Institute cites research demonstrating the beneficial effects of vitamin C, even at high doses. They conclude that people should not worry about kidney stones and vitamin C, especially when taking less than 2 g per day.
