"Aromatase inhibitor are commonly used in the treatment of breast cancer and are associated with increases in the rate of bone loss and fracture.

Supplementation with Vitamin D has now been shown to prevent these effects. The researchers sought to assess the association between Vitamin D levels at baseline, after three months of supplementation, and bone loss after one year on aromatase inhibitor therapy.

Additionally, they investigated the relationship between increases in Vitamin D levels and the associated bone loss.

This was a prospective cohort study that included consecutive women initiating Aromatase inhibitors for early breast cancer from January/2006 to June/2009 (N=230).

Serum Vitamin D was measured at baseline and at three months, and bone loss was defined as lumbar spine absolute loss and bone loss rate.

Participants were supplemented with daily oral calcium (1g) and 800IU Vitamin D3.
In addition, patients with baseline Vitamin D levels less than 30 ng/ml, were given an additional 16,000 IU of Vitamin D every two weeks.

In the overall population (N=156), increasing levels of Vitamin D at 3 months were correlated to progressively less lumbar spine bone loss rates and to absolute bone loss. Both findings were highly statistically significant.

Of note, in the subset of patients with baseline deficiency, baseline Vitamin D levels appeared directly related to bone mass density loss.

They concluded that increases in Vitamin D levels due to to supplementation prevents the bone loss associated with aromatase inhibitors independently of baseline Vitamin D levels.

Therefore, Vitamin D supplements at doses higher doses than the standard 400 to 800 IU/day are useful to minimize bone loss in women starting on aromatase inhibitors."