Urine contains chemicals that prevent the formation of mineral crystals in the urinary tract. In some people, these chemicals do not work, causing mineral crystals to separate from the urine and remain in the urinary tract. When these mineral crystals stick together, they form kidney stones. Some kidney stones consist of calcium combined with other chemicals. Learn more about the relationship between calcium and kidney stones to help prevent this painful condition.
Types
The National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) reports that the most common types of kidney stones consist of calcium combined with phosphate or oxalate. Phosphate, a salt of phosphoric acid, exists in foods that contain phosphorus. High-phosphorus foods include peanut butter, cheese, cola drinks, caramels, ice cream, beer, nuts and chicken liver. Oxalate exists naturally in nuts, cocoa, cola drinks, tea, blackberries, blueberries, sweet potatoes, waxed beans, carrots and strawberries. When phosphate or oxalate crystals remain in the urinary tract, they bind with calcium to form kidney stones.
Significance
Small kidney stones pass through the urinary tract and leave the body through the urine. While they travel through the kidneys and ureters, kidney stones cause severe pain and may also cause bleeding of the urinary tract. When a stone grows too large to pass naturally, it requires surgical intervention to prevent damage to the organs of the urinary system.
Misconceptions
Some people believe that reducing calcium intake prevents the formation of kidney stones that contain calcium. The University of Maryland Medical Center indicates that a high-calcium diet does not seem to increase the risk for developing kidney stones. This means that healthy people should not restrict their calcium intake to prevent kidney stones. Only people with medical conditions that cause excess calcium in the urine should reduce their calcium intake. These conditions include Addison's disease, renal tubular acidosis, hyperthyroidism, primary hyperparathyroidism, vitamin D toxicity, Paget's disease and sarcoidosis.
Calcium Restriction
For those with high levels of calcium in the urine, reduced calcium intake also reduces the risk of kidney stone formation. Avoid foods high in calcium, such as cheese, yogurt, milk, buttermilk, ice cream, pudding, broccoli and instant oatmeal. On a calcium-restricted diet, men should consume 800 mg calcium per day, according to Jackson Siegelbaum Gastroenterology. Premenopausal women should consume 1,000 mg per day. Postmenopausal women should consume 1,200 mg per day.
Prevention
Dietary changes reduce the risk for developing calcium oxalate and calcium phosphate kidney stones. Avoid foods with high levels of these substances to prevent mineral crystals from forming in the urinary tract. Increasing the consumption of potassium and reducing the consumption of sodium also reduces the risk of kidney stone formation.
