“Low levels of vitamin D are the norm rather than the exception in South East Asia.” Estimates of vitamin D deficiency among Pakistani people are from 70 to 97%. In the United States, 50-74% of newly diagnosed premenopausal breast cancer patients are vitamin D deficient.
When vitamin D levels are low, angiogenesis (the growth of new blood vessels) and cell proliferation increase and apoptosis (natural cell death) decreases. This increases the risk of cancer. The best way to test for vitamin D levels is a blood test for 25-dihydroxy vitamin D. Women with levels greater than 50 ng/ml have a 50% lower risk of breast cancer than those with levels below 30. Low levels of vitamin D are associated with poorer prognosis in breast cancer, and vitamin D deficiency can cause secondary hyperparathyroidism with reduced bone mineral density (BMD).
The present study was done in Pakistan. Blood levels below 20 ng/ml were considered to be vitamin D deficient. Levels from 20 to 39 were suboptimal. Levels above 40 were considered optimal. Ninety breast cancer patients were studied, each with a matched control. Nearly half were premenopausal; the rest were post-menopausal. Those with breast cancer had a higher chance of having a body mass index (BMI) above 30 than did the control group.
For the entire group, the average vitamin D level was low at 9.3 ng/ml. For the control group without cancer the average level was 14.9. Over 95% of the cancer patients had vitamin D deficiency, while only 77% of the controls were deficient. None of the cancer patients had an optimal vitamin D level.
Menopausal cancer patients had higher vitamin D levels than premenopausal cancer patients (13.5% compared to 10.5%). Post-menopausal cancer patients had low bone mineral density (BMD) on testing compared to pre-menopausal patients.
CONCLUSION: Vitamin D supplementation and sun exposure are two risk factors for breast cancer that can be changed.
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