According to a study published in Obstetrics & Gynecology, women who took calcium + vitamin D with hormone therapy experienced greater reductions in LDL-C than those who took calcium or vitamin D alone or placebo.
To evaluate the treatment effect of calcium + vitamin D supplementation, hormone therapy, a combination of both, and neither on cardiovascular disease risk factors, a team of researchers led by P.F. Schnatz, Thomas Jefferson University, conducted a prospective, randomized, double-blind, placebo-controlled trial.
A total of 68,132 women from the Women’s Health Initiative (WHI) aged 50-79 years were randomized to the WHI-Dietary Modification (n=48,835) and WHI-Hormone Therapy trials (n=27,347). Of these, 36,282 women were randomized in the WHI-Calcium + Vitamin D trial to 1,000mg elemental calcium carbonate + 400 IU vitamin D3 daily or placebo. For this study, a total of 1,521 women who were part of both the hormone therapy and calcium + vitamin D trials were included; they represented the 6% sub-group of participants with blood sample collections at baseline, Year 1, 3, and 6.
Study authors reported a treatment effect for LDL-C vs. placebo to be –1.6mg/dL (95% CI: –5.5 to 2.2) for calcium + vitamin D alone; –9.0mg/dL (95% CI: –13.0 to 5.1) for hormone therapy alone; and –13.8mg/dL (95% CI: –17.8 to –9.8) for the combination intervention.
No evidence of a synergistic effect for calcium + vitamin D + hormone therapy on LDL-C (P=0.26) was seen except in those patients with low vitamin D intake, who saw a significant synergistic effect on LDL (P=0.03).
“The treatment effect observed in the calcium + vitamin D + hormone therapy combination group may be additive rather than synergistic,” authors concluded. They added that the patient’s current use of hormone therapy should not impact the decision to start calcium + vitamin D supplementation.
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