A high single annual vitamin D dose may increase fall and fracture risk

May 10, 2010

A once-a-year high dose vitamin D supplementation may increase elderly women’s rate of falls and fractures, indicates a new study.

In the randomized controlled trial, 2,256 women over the age of 70 were randomly assigned to receive either placebo or a single annual oral dose of 500,000 IU of vitamin D (cholocalciferol) for between 3 to 5 years (1). The results showed that women in the vitamin D group experienced a higher incidence of falls (15%) and fractures (26%) than women in the placebo group. The increase in fractures was greatest within the first three months after dosing.

The researchers speculate that the reason may be the dose of vitamin D used in the study – the largest total annual dose of vitamin D used in any large study like this. There might be something about giving that much vitamin D all at once that causes the body to produce less vitamin D, which ends up weakening bones, causing more falls and fractures, the researchers speculate.