THURSDAY, April 9 (HealthDay News) -- In premenopausal breast cancer patients who are undergoing adjuvant chemotherapy, vitamin D supplementation at even double the current recommended dietary allowance is too low to increase serum 25-hydroxyvitamin D (25-OHD) to sufficient levels, according to a report published online ahead of print April 6 in the Journal of Clinical Oncology.
Katherine D. Crew, M.D., of Columbia University in New York City, and colleagues studied 103 premenopausal breast cancer patients who were prescribed daily supplements containing 400 IU of vitamin D3, which is twice the recommended dietary allowance, and 1,000 milligrams of calcium carbonate.
At baseline, the researchers found that 74 percent of the patients were vitamin D deficient (defined as a serum 25-OHD of less than 20 ng/mL), and that deficiency rates were higher in black and Hispanic women (80 percent and 84 percent, respectively) than in white women (66 percent). After one year of vitamin D supplementation, the investigators found that sufficient levels (defined as 30 ng/mL or greater) were achieved by less than 15 percent of white and Hispanic women and by none of the black women.
"Although the recommended dietary allowance of vitamin D in premenopausal women is only 200 IU daily, our study suggests that a dose of 400 IU daily is inadequate in breast cancer patients, even to maintain skeletal health, and is probably too low for meaningful anticancer effects," the authors write. "Although the efficacy of vitamin D supplementation for reducing breast cancer mortality is still uncertain, it may be prudent to follow serum levels of 25-OHD and replete to sufficient levels in premenopausal women with breast cancer to improve bone health for this large and growing population of breast cancer survivors."
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