Vitamin D for Breast Cancer

Vitamin D does not reduce breast cancer incidence in randomised trials, but it is important for bone health on aromatase inhibitors.

Overview

Vitamin D does not reduce breast cancer incidence in randomised trials, but it is important for bone health on aromatase inhibitors.

Verdict

Mixed evidence

Take it for bones, not to prevent or treat the cancer.

How It Works

Vitamin D receptors are present in breast tissue and regulate proliferation and differentiation in preclinical models; clinically, its established role is calcium homeostasis and bone mineralisation.

Dosing & Protocol

Typical dose

Recommended dose: 800-2000 IU daily, particularly on aromatase inhibitors
Expected timeframe: Bone protection is a long-term measure; no acute endpoint.

Protocol

form: D3
notes: Combine with calcium and DEXA monitoring
duration: Ongoing during endocrine therapy
starting dose: 800-2000 IU daily

Evidence

What the studies say

The VITAL trial randomised over 25,000 adults to 2000 IU of vitamin D daily and found no reduction in total cancer incidence, including breast cancer, though a signal for reduced cancer mortality emerged in secondary analyses. Observational studies linking low 25(OH)D to worse breast cancer outcomes are confounded by adiposity and illness. Where vitamin D genuinely matters is bone: aromatase inhibitors accelerate bone loss, and calcium with vitamin D is standard supportive care alongside bone density monitoring.

No studies are yet linked to both Vitamin D and Breast Cancer.

Safety

Caveats

Not a cancer treatment. High doses do not improve outcomes and risk hypercalcaemia. Discuss all supplements with your oncology team.

Less likely to help if

People taking it expecting an anticancer effect.

Medical Disclaimer

The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.

Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.