The Truth About Vitamin D: Can You Get Too Much Vitamin D?

WebMD feature series on vitamin D.

From the WebMD Archives

Can I get too much vitamin D?

Too much of any good thing is a bad thing. Too much vitaminD can cause an abnormally high bloodcalcium level, which could result in nausea, constipation, confusion, abnormal heart rhythm, and even kidney stones.

It's nearly impossible to get too much vitamin D from sunlight or from foods (unless you take way too much cod liver oil). Nearly all vitamin D overdoses come from supplements.

The Institute of Medicine's Food and Nutrition Board's old 1997 recommendations suggested that 2,000 IU per day of vitamin D is safe for adults and that 1,000 IU per day is safe for infants up to 12 months of age. Many observers expected a drastic increase in the IOM's 2010 update.

That didn't exactly happen. The IOM committee did increase its "upper level intake" -- that is, the boundary at which it feared vitamin D would become unsafe. That dose is 4,000 IU/day for adults, 3,000 IU/day for kids ages 4-8, 2,500 IU/day for kids ages 1-3, 1,500 IU/day for infants ages 6-12 months, and 1,000 IU/day for infants ages 0-6 months.

But some recent studies suggest that healthy adults can tolerate more than 10,000 IU of vitamin D per day. John Jacob Cannell, MD, executive director of The Vitamin D Council, notes that the skin makes 10,000 IU of vitamin D after 30 minutes of full-body sun exposure. He suggests that 10,000 IU of vitamin D is not toxic.

According to the National Institutes of Health, 25-OHD levels that are consistently over 200 ng/mL are "potentially toxic."

The IOM committee found no conclusive evidence that increased vitamin D levels confer increased health benefits, "challenging the concept that '

more is better.'"

Next: What kind of vitamin D is best? next button

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WebMD Feature Reviewed by Laura J. Martin, MD on November 30, 2010

Sources

SOURCES:

Ross, A.C. Institute of Medicine, "Dietary Reference Intakes for Calcium and Vitamin D," Nov. 30, 2010.

Cannell, J.J. and Hollis, B.W. Alternative Medicine Review, March 2008; vol 13: pp 6-20.

Holick, M.F. Journal of Clinical Endocrinology and Metabolism, March 2008; vol 93: pp 677-681.

Autier, P. and Gandini, S. Archives of Internal Medicine, Sept. 10, 2007; vol 167: pp 1730-1737.

Holick, M.F. and Chen, T.C. American Journal of Clinical Nutrition, 2008; vol 87: pp 1080S-1086S.

Bordelon, P. American Family Physician, Oct. 15, 2009; vol 80: pp 841-846.

Rovner, A.J. and O'Brien, K.O. Archives of Pediatric and Adolescent Medicine, June 2008; vol 162: pp 513-519.

Pepper, K.J. Endocrinology Practice, 2009; vol 15: pp 95-103.

WebMD Health News: " Vitamin D Deficiency Worsens Breast Cancer?"

WebMD Feature: " Are You Getting Enough Vitamin D?"

WebMD Health News: " Vitamin D Deficiency May Hurt Heart."

WebMD Health News: " Calcium/Vitamin D Slows Weight Gain."

WebMD Health News: " Vitamin D Fights Colon Cancer."

WebMD Health News: " Vitamin D Compounds May Fight Prostate Cancer."

National Institutes of Health Office of Dietary Supplements, Dietary Supplement Fact Sheet: Vitamin D, updated Nov. 13, 2009.

The Vitamin D Council web site.

 

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