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Taking vitamin supplements risks the formation of kidney stones
Last reviewed: 01.07.2025
Long-term use of calcium and vitamin D supplements may increase the risk of kidney stones, a group of American researchers recently discovered. Detailed results of the study will soon be presented at the 94th annual meeting of the American Society of Endocrinology.
“The use of vitamin supplements containing certain micronutrients is not as safe as previously thought,” the official report of the study notes. “Exceeding the dose currently recommended by Health Guidelines of 800 international units of vitamin D and 800-1200 mg of calcium per day may significantly increase the risk of kidney stones.”
Also, a condition known as hypercalcemia, characterized by excess calcium levels in the urine, can lead to various problems with bones and the human bladder. Doctors note that the relevance of their study is due to the excessive popularity of this type of vitamin supplements in the United States. According to statistics, today in some states, more than 66% of women of childbearing age take supplements containing calcium and vitamin D.
The study involved 163 women. All participants were randomly assigned to receive vitamin D at doses of 400, 800, 1600, 2400, 3200, 4000, or 4800 international units per day, while a separate group was given a placebo. During the study, their calcium intake was increased from an initial dose of 691 mg per day to 1200 to 1400 mg per day. The researchers measured calcium levels in their urine and blood at the start of the study and then every three months for one year. They found that about 48 participants, or 33 percent of the total, had an increased risk of kidney stones on a regular basis.
All of them were in the group of increased consumption of vitamin D and calcium. According to scientists' calculations, the risk of kidney stones at a level of 1600 international units of vitamin D and 1400 mg of calcium increases by 35%, and then increases proportionally to the increase in dosage. At the same time, researchers cannot yet answer the question - which of the two elements is more to blame for this effect. According to the researchers, their action is interdependent, that is, they will not increase the risk of kidney stones, acting separately. However, for now this is only a hypothesis and additional research is needed to confirm it.