High-Dose Vitamin D Reduces Bone Density Loss From Aromatase Inhibitor Drugs

Research suggests high dose vitamin D supplements may reduce bone density loss from AI drugs used to treat breast cancer

by Dr. C.H. Weaver M.D. 8/2019

The results of a clinical trial presented at the 2019 annual meeting of the American Society of Clinical Oncology suggest that high-dose vitamin D can prevent bone mineral density (BMD) loss in patients with breast cancer receiving aromatase inhibitors (AIs) and not lead to calcium toxicity regardless of the amount of exercise in which patients engaged.

AIs which are used to treat both early and advanced ER + breast cancer can cause bone loss and osteoporotic fractures

While the recommended daily allowance of 600 IU of vitamin D is known to protect postmenopausal women from bone loss, its impact on AI-induced bone loss has not previously been studied

Doctors assigned 116 patients who had non-metastatic breast cancer and were starting AI treatment to receive 24 weeks of either a placebo, high-dose vitamin D (50,000 IU/week), or high-dose vitamin D plus moderate exercise consisting of walking and resistance band training.

The researchers reported that those receiving high-dose vitamin D alone had the highest serum vitamin D levels at 24 weeks (average, 63.6 ng/mL), followed by those in the vitamin D and exercise group (60.3 ng/mL). Those in the placebo group had an average serum vitamin D level of only 32.0 ng/mL.

Both vitamin D groups maintained their hip BMD, whereas there was a significant reduction in hip BMD in the placebo group, relative to baseline.

High-dose vitamin D significantly reduced hip BMD loss in breast cancer patients on AIs suggesting that vitamin D supplementation may be beneficial for early stage breast cancer patients at risk of losing BMD. A larger comparative clinical trial is planned.

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