Nephrologist Borja Quiroga warns that the consumption of vitamin D without medical supervision can cause kidney stones and even kidney failureby raising calcium levels in the blood. The United States National Library of Medicine confirms that hypervitaminosis D generates hypercalcemia, one of whose direct complications is kidney stones and permanent damage to the organ.

Quiroga, who practices in Spain, describes it bluntly: “I have seen people who have come with the kidneys full of stones“The specialist points out that vitamin D favors the intestinal absorption of calcium, which excessively saturates the kidneys and forms deposits. He has also treated cases of poisoning and kidney failure in healthy people who took the supplement without clinical indication.

A prospective analysis published in the Journal of Urology—with 193,551 participants from three cohorts at Harvard Medical School, with follow-up of more than 3.3 million person-years—found no statistically significant association between the consumption of vitamin D in usual amounts and the formation of kidney stones. However, the authors warn that a greater risk cannot be ruled out. with doses higher than those studiedand that the combination of vitamin D with calcium has been associated with a higher risk of stones in other studies.

MedlinePlus specifies that the recommended daily amount of vitamin D ranges between 400 and 800 IU depending on age, and that most people do not require more than 2,000 IU per day. The symptoms of Toxicity, in general, appears only with doses greater than 10,000 IU daily and may include fatigue, vomiting, frequent urination, high blood pressure, and irreversible kidney damage.

The nephrologist denounces that supplements are prescribed without adequately evaluating the patient’s previous health status. He only recommends them in cases of osteoporosis or diagnosed chronic kidney disease. He maintains that in healthy people “it does not improve cardiovascular risk, nor reduce tumors, nor prevent fractures,” and describes the tendency to supplement children as unjustified.

The Nephrology Magazine of the Spanish Society of Nephrology explains the underlying mechanism: Kidney is the main site of conversion of vitamin D to its active form, calcitriol. When circulating calcitriol levels rise excessively, the calcitriol-vitamin D receptor complex activates genes that increase intestinal absorption of calcium and phosphorus, which in high concentrations favor soft tissue calcifications and stone formation.

Quiroga distinguishes the vitamin D from creatine monohydratea supplement that he describes as safe and effective. He explains that for years it was misinterpreted due to its nominal similarity to creatinine, but that studies have ruled out kidney damage. He recommends choosing only pure creatine monohydrate with a certified quality seal and warns about unreliable products that circulate in some gyms: “Not everything that is sold is controlled. You have to read the labels carefully and be wary of miracle formulas.”