Vitamin D, an essential vitamin, comes from two sources. Your body manufactures vitamin D from sunlight exposure, and it is also found in fortified diary products, liver and fish. Vitamin D deficiency has become more common in the United States as people spend less time outside and use more sunscreen. Low vitamin D levels do not cause kidney stones, but taking vitamin D supplements to treat vitamin D deficiency can.
Vitamin D and Calcium
Vitamin D and calcium have an intertwined relationship; you need both for healthy bones. You can't absorb calcium from your intestines unless you have adequate vitamin D stores. Even if you get enough calcium in your diet, you don't absorb it unless you increase your vitamin D intake. Low vitamin D leads to low calcium levels, or hypocalcemia. High calcium levels -- hypercalcemia -- not low levels, cause kidney stones.
Calcium and Kidneys
If you take very large amounts of vitamin D supplements, you may absorb too much calcium, especially if you also take calcium supplements. This occurs only if you take dietary supplements, not if you spend too much time in the sun. The recommended dietary allowance of vitamin D for adults is 600 international units daily, or IU, up to age 70, then 800 IU daily thereafter. The tolerable upper limit is 4,000 IU daily, according to the Office of Dietary Supplements. Exceeding that amount may cause excess calcium absorption and increase your risk of developing kidney stones.
Effects
If you excrete excess calcium in your urine, crystals form that can eventually develop into kidney stones. Kidney stones not only cause severe pain as they pass through the urinary tract, but they can also cause blockage in the kidney that leads to permanent kidney damage.
Studies
A study conducted by Ohio State University and published in the February 2006 issue of "The New England Journal of Medicine" found that healthy menopausal women who took 1,000 mg of calcium along with 400 mg of vitamin D had a 17 percent higher risk of developing kidney stones than those taking placebo over a seven-year period.
References
- Office of Dietary Supplements: Vitamin D
- NIH Osteoporosis and Related Bone Diseases - National Resource Center: Calcium and Vitamin D: Important at Every Age
- "The New England Journal of Medicine"; Calcium Plus Vitamin D Supplementation and the Risk of Fractures; R. Jackson, et al.; February 2006
- MayoClinic.com; Hypercalcemia; May 2011
