Kidney stones--renal calculi--are small stones that form in the kidneys. These stones cause excruciating pain, and if they don't pass on their own they often require medical treatment for removal. Kidney stones are caused by a number of things, one being a vitamin D supplement overdose. However, other vitamins contained in multivitamins may work to reduce the risk of developing them.
Vitamin D
Vitamin D works along with calcium in the body to keep the bones strong and to create new bones. Vitamin D is obtained through food and sunlight and is considered a fat-soluble vitamin, since the body stores it. An overdose in vitamin D can cause kidney stones. Vitamin D overdose--hypervitaminosis D--occurs when too much vitamin D is taken in supplement form. Although MayoClinic.com states that vitamin D toxicity is rare, the risk is increased in individuals who have kidney disease or other kidney disorders.The exact dose of vitamin D that causes kidney stones is not known; however, the risk increases when the upper limit is exceeded, which according to Harvard Health Publications is 50mcg. Most complete multivitamins contain 5mcg--200 IU--or less of vitamin D per serving.
Vitamin C
Water-soluble antioxidant vitamin C may actually reduce the risk of developing kidney stones. As reported in the book "The Complete Idiot's Guide to Vitamins and Minerals," a previous study found that people with high levels of vitamin C had the lowest risk for developing kidney stones. Most multivitamins contain 100 percent of the recommended daily allowance of vitamin C, which is 90mg for men and 75mg for women. The tolerable upper limit of vitamin C is 2,000mg.
Calcium
The mineral calcium is included in many multivitamin supplements, since it is important for bone health and growth through every stage of life. Although past presumptions were that calcium increases the risk of developing kidney stones, recent studies have shown that calcium may in fact decrease the risk of developing kidney stones, according to "The Complete Idiot's Guide to Vitamins and Minerals." If you are deficient in calcium your physician might recommend taking a multivitamin supplement, which contains calcium and vitamin D. Vitamin D works to increase the uptake of calcium into the body.
Considerations
If you are susceptible to developing kidney stones or you develop symptoms of kidney stones, contact your physician before taking any multivitamin supplement. Get as many vitamins and minerals as you can through proper eating to eliminate the need to take multivitamin supplements.
References
- PubMed Health: Kidney stones
- MayoClinic.com; Vitamin D toxicity: What if you get too much?; Katherine Zeratsky; Dec 2010
- Harvard Health Publications: Listing of Vitamins
- "The Complete Idiot's Guide to Vitamins and Minerals"; Alan Pressman et al.; 2007
