Kidney stones are painful formations of minerals in your kidneys that can take months or years to accumulate. A majority of kidney stones are a combination of calcium and oxalate, which are naturally present in your diet. While it may seem that consuming too much calcium in your diet through supplements may lead to formation of kidney stones, this may not be true of calcium citrate.
New York University Langone Medical Center says high calcium intake from foods presents no risk for kidney stone formation. However, observational studies in leading publications such as the “Journal of Urology” do indicate that too much calcium supplementation may result in a slightly higher risk of kidney stones. The increased risk from supplements may be a result of low stomach acid when you take the supplement. Food, on the other hand, stimulates the secretion of stomach acid and improves calcium absorption.
Calcium Citrate Absorption
Calcium citrate may be easier for your body to absorb than other calcium supplements, such as calcium carbonate, because there is already acid present in the supplement -- a necessity for calcium absorption. Harvard University reports that one reason people taking calcium supplements may have increased risk of kidney stones is if they take the supplement on an empty stomach, limiting absorption due to low stomach acid. This is not a problem with calcium citrate supplements. However, you obtain only around 21 percent of calcium by volume with citrate supplements. This means a 1,000 mg calcium citrate supplement provides you with 210 mg of calcium.
Daily Calcium Needs
Though calcium is a component of most kidney stones, obtaining an adequate amount in your diet though a supplement such as calcium citrate can block absorption of oxalate, the other primary nutrient in kidney stones. Men ages 19 to 70 need 1,000 mg of calcium per day. Women need the same amount until age 70, when their needs increase to 1,200 mg per day. Calcium citrate supplements may help you quickly achieve this amount if your diet is lacking.
Role of Citrate
In addition to improved calcium absorption compared to other supplements, the citrate in a calcium citrate supplement may actively help prevent kidney stone formation. A 2011 study appearing in the journal “Cells, Tissues, Organs” used microscopic and simulation study to find the mechanism through which citrate helps prevent kidney stones. University of Western Ontario researchers discovered that the electrostatic charge of citrate acts as a buffer between calcium and oxalate to prevent their bonding in the urinary tract.
- New York University Langone Medical Center: Kidney Stones
- University of Maryland Medical Center; Kidney Stones; Steven D. Ehrlich, N.M.D.; June 2010
- University of Arizona; Calcium Supplement Guidelines; Linda Houtkooper and Vanessa A. Farrell; 2004
- "Cells, Tissues, Organs"; Citrate Modulates Calcium Oxalate Crystal Growth by Face-Specific Interactions; B. Grohe, et al.; May 2011
- Columbia University; What's Up with Calcium Supplements?; September 2003
- Harvard University; Calcium Curious; July 2009