Most kidney stones are made of calcium. About 85% of kidney stones contain the mineral, and many people who are prone to stones have high levels of calcium in their urine.\n<\/p>\n
That may not be a reason to toss out your calcium supplements just yet. Several dietary factors can play into kidney stone risk, and getting the right amount of calcium can do more good than harm for your kidneys.\n<\/p>\n
How Calcium and Oxalate Form Stones <\/p>\n
After the body processes food, waste products are left behind and flushed out by the kidneys through urine. When not enough water moves through the kidneys, the waste particles can stick together and crystallize into stones.\n<\/p>\n
The most common type of stone forms when calcium binds with oxalate<\/a>, an antinutrient that is found in plant foods. This can happen when the levels of oxalate or calcium in the urine are too high.\n<\/p>\n It’s especially common in people with idiopathic hypercalciuria, a condition marked by excessive calcium in the urine despite a normal calcium intake. People with hyperparathyroidism also have elevated blood calcium levels<\/a>, which puts them at greater risk of developing kidney stones.\n<\/p>\n For people without hypercalciuria, consuming too much calcium could raise the risk of forming stones. However, other factors, like not drinking enough water or eating too much salt are far more likely to increase that risk, explained Amy Yau, MD<\/a>, a nephrologist and clinical assistant professor of internal medicine at The Ohio State University Wexner Medical Center.\n<\/p>\n Excess Calcium Isn’t the Main Cause of Kidney Stones <\/p>\n Some patients may be advised to take calcium supplements for bone health or other reasons. If they get enough calcium from food sources, supplements could put them over the recommended daily intake of 1,000-1,300 milligrams, and the excess may wash out in the urine.\n<\/p>\n Still, taking too much calcium is not a primary reason people develop kidney stones, said Melanie Betz, RD<\/a>, a dietitian and author of The Kidney Dietitian blog.\n<\/p>\n \u201cIf you have calcium oxalate kidney stones, you actually want to make sure that you are getting enough calcium,\u201d Betz said.\n<\/p>\n Getting Enough Calcium Reduces Kidney Stone Risk <\/p>\n Studies have shown that a low calcium diet is associated with a higher risk of forming kidney stones.<\/p>\n When you eat lots of vegetables and fruits that are high in oxalates<\/a>, like beets and almonds, you need enough calcium to bind with the oxalates and excrete them through your stool. Otherwise, oxalates are absorbed and excreted in urine, where they can form stones.\n<\/p>\n \u201cMaking sure you’re eating enough calcium is the most effective way to get urine levels of oxalate down if they’re even high in the first place,\u201d Betz said. \u00a0\n<\/p>\n A High Sodium Diet Is More Likely to Cause Stones <\/p>\n Yau said that when she sees patients with calcium-oxalate stones, she first recommends cutting back on salt rather than calcium intake.\n<\/p>\n \u201cThe biggest reason for having high calcium in the urine is actually not from eating too much calcium or calcium supplements\u2014it’s actually from eating too much salt,\u201d she said.\n<\/p>\n When you eat moderate amounts of salt, your body retains that sodium and reabsorbs calcium along with it. But too much salt will force your kidneys to wash both out in the urine, where calcium can crystallize into stones, Yau explained.\n<\/p>\n Staying well hydrated can also help flush out calcium and oxalates before they can bind in the kidneys.\n<\/p>\n Food-Based Calcium Is Better Than Supplements <\/p>\n The body can more easily retain and use calcium when it’s consumed through food rather than supplements.<\/p>\n \u201cAs a society, we are so quick to jump to supplements. It’s almost like we forget that you can get nutrition from food, and many times, this being one of them, it\u2019s actually better,\u201d Betz said.\n<\/p>\n Dairy is perhaps the best dietary source of calcium because the body absorbs it well. Calcium-rich plant-based foods, like fortified almond milk and leafy greens, often contain oxalates, which limit calcium absorption.\n<\/p>\n Still, Betz says not to avoid oxalates. Following a strict low-oxalate diet means you may miss out on potassium, magnesium, phytate, and fiber\u2014all of which lower the risk of kidney stones.\n<\/p>\n There are some instances in which taking a supplement makes sense. People who have undergone gastric bypass surgeries or have Crohn\u2019s disease<\/a> and other digestive diseases tend to easily absorb oxalate, raising their risk of developing stones. These patients may benefit from taking a calcium supplement to help bind with those oxalates and reduce their stone risk.<\/p>\n Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process<\/a> to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.<\/p>\n American Medical Association. What doctors wish patients knew about kidney stones<\/a>.<\/p>\n<\/li>\n National Kidney Foundation. Calcium oxalate<\/a>.<\/p>\n<\/li>\n Meher D, Agarwal V, Das S, et al. Idiopathic hypercalciuria: a comprehensive review of clinical insights and management strategies<\/a>.\u00a0Cureus. 2025;17(4):e81778. doi:10.7759\/cureus.81778<\/p>\n<\/li>\n National Institutes of Health, Office of Dietary Supplements. Calcium fact sheet for professionals<\/a>.<\/p>\n<\/li>\n Ferraro PM, Bargagli M, Trinchieri A, Gambaro G. Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian-Vegan Diets<\/a>.\u00a0Nutrients. 2020;12(3):779. Published 2020 Mar 15. doi:10.3390\/nu12030779<\/p>\n<\/li>\n Ticinesi A, Nouvenne A, Meschi T, et al. The optimal dietary calcium intake for preventing incident and recurrent symptomatic kidney stone disease<\/a>. Mayo Clin Proc. 2022;97(8):1416\u20131418. doi:10.1016\/j.mayocp.2022.06.024<\/p>\n<\/li>\n Mitchell T, Kumar P, Reddy T, et al. Dietary oxalate and kidney stone formation<\/a>.\u00a0Am J Physiol Renal Physiol. 2019;316(3):F409-F413. doi:10.1152\/ajprenal.00373.2018<\/p>\n<\/li>\n MedlinePlus. Calcium in diet<\/a>.<\/p>\n<\/li>\n Siener R, Ernsten C, Speller J, Scheurlen C, Sauerbruch T, Hesse A. Intestinal oxalate absorption, enteric hyperoxaluria, and risk of urinary stone formation in patients with Crohn’s disease<\/a>.\u00a0Nutrients. 2024;16(2):264. doi:10.3390\/nu16020264<\/p>\n<\/li>\n<\/ol>\n\n
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