Kidney stones form when excessive concentrations of substances, usually minerals, precipitate within the kidney and form solid masses. Most kidney stones are smooth and asymptomatic, although an accumulation can clog the kidney and cause inefficient filtering. Some stones break or have more crystal content and cause severe pain with their sharp edges. The most common types of kidney stones occur as a result of imbalances, which affect urine acidity, mineral ratios and water balance. Some supplements may be able to dissolve and prevent kidney stones.
Vitamin C
Although the medical consensus for many years was that high levels of vitamin C caused kidney stones, the evidence is now mixed and depends on the type of kidney stone. According to the Linus Pauling Institute, higher daily intake of vitamin C was associated with lower serum levels of uric acid, which can precipitate out within joints to cause gout or within the kidneys to form stones. Further, daily vitamin C intake was found to be inversely associated with risk of gout and uric acid-derived kidney stones, with higher intakes being associated with greater risk reductions. Therefore, it seems that vitamin C can prevent and possibly dissolve kidney stones made from uric acid crystals.
Calcium oxalate-derived kidney stones occur when urine is highly acidic and oxalate is overabundant within the kidneys. Because oxalate is a metabolite of vitamin C, there is some concern that high vitamin C intake could increase the risk of calcium oxalate kidney stones. According to the Linus Pauling Institute, some studies have found that supplemental vitamin C increases urinary oxalate levels, while others have not. Further, some studies have shown higher risks of calcium oxalate kidney stone formation when supplementing with vitamin C, while others have not. If your diet is high in oxalic acid-producing items, such as alcohol, asparagus, beets, caffeine, chocolate, coffee, nuts, spinach and tea, then megadosing vitamin C might not be prudent.
Struvite kidney stones are caused by kidney or urinary tract infections and derived from magnesium and ammonia. Vitamin C's antioxidant and immune boosting properties can help prevent or fight infections, while the ascorbic acid in vitamin C can actually dissolve the kidney stones and prevent them from forming, according to "Vitamins: Fundamental Aspects in Nutrition and Health."
Black Cherry Concentrate
Uric acid-derived kidney stones are often caused by diets rich in animal protein and purines. Foods such as organ meats, red meat, turkey, mushrooms, some beans, beer and wine increase serum levels of uric acid, which precipitate out as crystals, causing gout within joints and stones in the kidneys. Black cherries and concentrated black cherry juice can lower serum levels of uric acid and contribute to dissolving the precipitated crystals within the joints and kidneys, as cited in The New Encyclopedia of Vitamins, Minerals, Supplements, and Herbs.
Black cherries can also dissolve calcium phosphate stones, which are very common. Calcium phosphate stones are easily dissolved by acidic urine, which occurs with consumption of many sour fruits, such as cherries, lemons, grapefruits and cranberries.
Magnesium
Magnesium's benefit for kidney stones is associated with its ability to increase calcium solubility in the urine and decrease its absorption in the kidneys. Consequently, magnesium supplementation may prevent kidney stone formation, especially those composed of calcium oxalate. Magnesium may also help reduce the size of existing stones by binding to the calcium, which slowly dissolves the stones.
References
- Oregon State University: Linus Pauling Institute: Vitamin C
- "Vitamins: Fundamental Aspects in Nutrition and Health"; G. Combs; 2008
- The New Encyclopedia of Vitamins, Minerals, Supplements and Herbs; Nicola Reavley; 1999
