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Rene from Racine, Wisconsin, writes, “I hope you can help me understand calcium supplements and the likelihood of kidney stones. For the first time in 61 years, I had a kidney stone. I was also diagnosed with osteopenia than normal bone mass). I’d like to take a calcium citrate supplement with MK7 (a form of vitamin K), but I’ve read that citrate can increase stone formation. Can you advise and help clear up my confusion about calcium supplements for someone prone to kidney stones and osteopenia or recommend a reliable publication that I could understand? Thank you in advance.”

Looking forward to hearing from you, René. I enjoyed your beautiful city in 2016 on a book tour. Your question is good.

For starters, the two most popular types of calcium supplements are calcium carbonate and calcium citrate. The absorption of calcium citrate in the body does not rely as much on the release of stomach acid (which occurs after a meal) as calcium carbonate. This means that we can easily take calcium citrate supplements with or without a meal.

In addition to being well absorbed, there is also good evidence that calcium citrate supplements can prevent bone loss in older women. In fact, citrate is a major component of healthy bone.

Regarding calcium citrate and kidney stones, you can check out a 2019 review article written by Professor of Endocrinology Andrea Palermo of Bio-Medico University, Italy, and colleagues in Reviews in Endocrine and Metabolic Disorders. These experts cite evidence that calcium citrate supplements have a lower risk of kidney stones than calcium carbonate supplements.

And while we don’t have all the answers yet, it’s worth noting that the use of citrate salts is a widely used treatment for kidney stones. We also need to remember other strategies to reduce our risk of contracting this painful condition: drink plenty of fluids, reduce your salt intake, and avoid portions of caveman meat.

Finally, remember that the safest and most effective way to get enough calcium is through food. Although supplements are a great way to get what our diets don’t have, they can have side effects.

You didn’t ask, but here’s some other great calcium supplement information:

Starting at your 51st birthday, women need 1,200 milligrams of calcium daily from foods and supplements combined. Start checking the Nutrition Facts label for the calcium content of your favorite foods to see if you need to add a supplement.

If you take a supplement, your body cannot absorb more than 500 milligrams at a time. This means you may need to take more than one dose per day.

(Barbara Intermill is a Registered Dietitian and Certified Diabetes Educator affiliated with Monterey Peninsula Community Hospital. She is the author of “Quinn-Essential Nutrition” (Westbow Press, 2015). Email her at barbara

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