Too much vitamin D can affect bones



December 17, 2018 - 11:28 AM

Dear Dr. Roach: I’m 70, Caucasian and slim. I was diagnosed with osteoporosis five years ago. Before that, I took Fosamax for five years. The only things I take are 1,000 mg calcium citrate, 3 mg boron and a multivitamin containing 2,000 IU vitamin D. An X-ray showed three compression fractured vertebra. I read that taking more than 1,000 IU of vitamin D can cause bone mass loss! I started crying thinking that I caused the fractures from taking too much vitamin D. I’ve stopped the multivitamin and just take 500 IU of the vitamin D. I’m outside an hour a day. Do you know of bone mass loss from too much? — V.W.

Answer: Low levels of vitamin D are a common and treatable cause of bone loss, which can ultimately lead to fractures. It’s a good idea to check the vitamin D level in people with known osteoporosis. There remains some controversy about the optimum level of vitamin D, but a level between 30 and 50 ng/mL is generally considered safe.

Very high levels of vitamin D can cause calcium to come out of bones, and can cause risk of kidney stones as well as symptoms. However, this is almost unheard of in a dose less than 4,000 units daily. I think it is very unlikely that you were taking too much vitamin D, so there’s no need to blame yourself.