These 2 Supplements Could Increase Your Risk of Kidney Stones, Study Says

Research shows that long-term use of these supplements may have consequences.

We all know medications can come with risks—if you've heard the end of a commercial for certain medicine, you certainly know this to be true. While we're all used to talking to our doctor about the prescription and over-the-counter (OTC) medications we take, we tend to not apply that same caution to the supplements we swallow. Many people take supplements without considering how they'll interact with other pills they take or the affect they could have on their health. Unfortunately, while some supplements can do your body good, others may have damaging results and adverse effects, especially if taken in excess. Research has found that two supplements in particular can increase your risk of kidney stones. Read on to find out which ones to be wary of.

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Long-term calcium and vitamin D supplement usage is associated with excessive calcium levels.

Shot of a young woman taking supplements at home

Researchers from the Creighton University's Bone Metabolism Unit sought to discover whether long-term use of calcium and vitamin D supplements is safe, publishing their findings in a 2014 study in the journal Menopause. The researchers observed 163 healthy, post-menopausal women between the ages of 57 and 85 after randomly assigning them to receive a vitamin D supplement of 400, 800, 1600, 2400, 3200, 4000, or 4800 international units a day. Their calcium intake was also increased from 691 to 1,200 to 1,400 milligrams per day.

After measuring their blood and urinary calcium levels every three months for a year, the researchers found that 33 percent of the participants developed high urinary levels of calcium, or hypercalciuria, at some point during the study's timeframe. They also found that about 10 percent of the participants developed high blood levels of calcium, also known as hypercalcemia.

"Because of the unpredictable response, it is not clear whether it is the extra calcium, the vitamin D, or both together that cause these problems," J. Christopher Gallagher, MD, the principal investigator for the study and director of the Bone Metabolism Unit at Creighton University Medical Center, said in a statement.

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And high levels of calcium can result in kidney stones.

Shot of a young man suffering from stomach pain while lying sitting a sofa at home

According to Gallagher, hypercalciuria "can contribute to kidney stones," he explained in a statement. That excess calcium in the urine can form salts that crystallize, resulting in kidney stones, the experts at Cincinnati Children's Hospital Medical Center explain. "The use of calcium and vitamin D supplementation may not be as benign as previously thought," Gallagher said.

Symptoms of kidney stones include severe pain on either side of your lower back, a stomach ache that doesn't go away, blood in the urine, nausea, vomiting, fever, chills, or urine that smells bad or looks cloudy, per the National Kidney Foundation (NKF).

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Calcium and vitamin D are some of the most common supplements taken in the U.S.

Close up view of young woman holding ginseng vitamins and minerals pills in hand with capsule bottle on table. High angle view

Around 77 percent of adult Americans take dietary supplements, per a 2019 survey from the Council for Responsible Nutrition (CRN), and vitamin D and calcium are some of the most popular ones out there. According to the survey, following multivitamins, vitamin D is the most popular supplement with 31 percent of adults taking it. And around 20 percent say they take calcium supplements.

The 2014 study also notes that both calcium and vitamin D supplements are "widely recommended" for post-menopausal women in order to prevent osteoporosis, a bone disease likely to occur in people with low calcium levels.

You should avoid exceeding the daily suggested guidelines for these two supplements.

Bottle of omega 3 fish oil capsules pouring into hand

Due to the results of their study, the researchers caution that people should not exceed supplement guidelines suggested by the Institute of Medicine; maximum daily levels are 600 to 800 international units of vitamin D and 800 to 1,200 milligrams of calcium.

"It is important to monitor blood and urine calcium levels in people who take these supplements on a long-term basis," Gallagher said, noting that's "rarely done in clinical practice."

Certainly, you'll want to do what you can to avoid kidney stones—in addition to being painful, they can increase the risk of kidney damage and of developing chronic kidney disease, according to the NKF.

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