Citric Acid and Kidney Stones

What is it? How can it help?

Citric acid is an organic acid and a natural component of many fruits and fruit juices. It is not a vitamin or mineral and is not required in the diet. However, citric acid, not to be confused with ascorbic acid (vitamin C), is beneficial for people with kidney stones. It inhibits stone formation and breaks up small stones that are beginning to form. Citric acid is protective; the more citric acid in your urine, the more protected you are against forming new kidney stones. Citrate, used in calcium citrate supplements and in some medications (such as potassium citrate), is closely related to citric acid and also has stone prevention benefits. These medications may be prescribed to alkalinize your urine.

How does citric acid protect against kidney stones?

Citric acid makes urine less favorable for the formation of stones. In its natural form, such as from citrus fruits, citric acid does not alkalinize the urine as citrate (from medication) does. Rather, it prevents small stones from becoming “problem stones” by coating them and preventing other material from attaching and building onto the stones.

What are the best food sources of citric acid?

Citric acid is most prevalent in citrus fruits and juices. Of these fruits, lemons and limes have the most citric acid. While oranges, grapefruits, and berries also contain appreciable amounts, lemons and limes will most significantly contribute to the citric acid content of your urine.

Pharmacological doses of citric acid, prescribed as potassium citrate, are effective in the treatment of stones. However, treatment may be costly and require as many as 12 tablets daily.

A half-cup (4 ounces) of pure lemon juice per day or 32 ounces of prepared lemonade provide about the same amount of citric acid as does pharmacological therapy.

In addition to increasing your citric acid consumption, drinking adequate fluids (at least ten 8-ounce glasses per day) – more in hot weather or when physical activity promotes heavy perspiration – may be the most powerful way to decrease your risk of developing stones.