The majority of kidney stones form due to an overabundance of calcium in the urinary system. As calcium accumulates in the kidneys over time, solid calcium deposits can build up in the kidneys, break off as stones and travel through the urinary tract, causing distress and tremendous pain. While the exact causes of kidney stones are largely unknown, a number of factors are known to contribute to kidney stone formation.
Genetics and Family History
Family history and genetics play a large role in determining one's calcium metabolism and other factors that lead to kidney stone formation. According to the National Institute of Diabetes and Dietary and Kidney Diseases (NIDDK), individuals with a family history of kidney stones are more likely to inherit the genetic factors that promote calcium accumulation and kidney stone formation. Certain extremely rare kidney stones such as cystine stones form as a result of an inherited genetic condition in how the kidneys process the amino acid cystine.
Age
The majority of kidney stones cases result from the build-up of calcium in the urinary tract over time. While calcium kidney stones can in theory occur at any age, the NIDDK explains that individuals over the age of 50 are twice as likely to have kidney stones than adults in their 30s.
Dietary Oxalate
The most common type of kidney stones form as a result of calcium combining with oxalate in the GI and urinary tracts. High dietary levels of oxalate can promote kidney stone formation. The NIDDK and the the Oxalosis and Hyperoxaluria Foundation recommend that individuals at risk for calcium kidney stones avoid oxalate-rich foods. These include vegetables such as chard, spinach, beets and squash, soybean crackers, coffee and some black teas.
Calcium Intake
Interestingly, calcium-rich foods are not known to promote kidney stone formation. The NIDDK and the American Urological Association (AUA) explain, in fact, that a diet low in calcium-containing foods can actually increase risk for kidney stones. Calcium supplements however may help to promote kidney stone formation. It is recommended by the AUA that individuals at risk for calcium kidney stones avoid calcium supplements as well as vitamin D supplements that help the body to absorb calcium. Calcium-containing antacids should also be avoided.
Acidic Urine
Low pH or acidic conditions can help to precipitate calcium and form stones in the kidneys and urinary tract. The NIDDK describes a number of factors that can contribute to urinary acidity. A diet rich in meat and protein can cause acidic urine. Insulin resistance also causes urine to become acidic, placing diabetics and obese individuals at risk for kidney stones. Acidic urine may also simply be a problem of insufficient fluid intake. It is recommended that those at risk for kidney stones drink at least 12 glasses of water per day to normalize urinary pH as well as to help flush out extra calcium from the urinary tract.
