15 Mar Calcium-Vitamin D Supplementation: Effects on Vitamin D and Cholesterol Levels
MedicalResearch.com: What are the main findings of the study?
Dr. Schnatz: In a subsample of 576 women from the parent WHI CaD (calcium plus vitamin D supplementation) trial* , there was a significant (38%) increase in mean serum 25OHD3 concentrations after two years (95% CI 1.29-1.47, p< 0.001) for women randomized to CaD (24.3ng/mL vs. 18.2 ng/mL).
Women randomized to CaD had a 4.5 mg/dL mean decrease in LDL-C which was statistically significant. After accounting for serum 25OHD3 concentration, the effect of CaD was attenuated, suggesting that higher concentrations of 25OHD3, in response to CaD supplementation, are associated with improved LDL-C.
In observational analyses, higher concentrations of 25OHD3 were associated with significantly higher HDL-C along with significantly lower LDL-C and TG concentrations.
* 1,000 mg of elemental calcium plus 400 IU of vitamin D3 daily
MedicalResearch.com: Were any of the findings unexpected?
Dr. Schnatz: The fact that in this prospective study women randomized to CaD had a statistically significant decrease in LDL-C was expected, since this had been shown previously. Also as expected, CaD did not have a significant effect on HDL-C and triglycerides.
This study is unique, however, because it suggests the mechanism behind how CaD lowers LDL-C. These results support the hypothesis that higher concentrations of 25OHD3, in response to CaD supplementation, are associated with improved LDL-C.
MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Schnatz: The jury is still out on whether Vitamin D supplementation has any extra skeletal benefits. There is a clear association between Vitamin D and many non-skeletal benefits, but this has been seen in observational and retrospective studies – with a strong possibility of bias and confounding factors leading to the association seen. More conclusive evidence, from our study and the previously published results from the parent WHI randomized trial, show that CaD led to a significant, albeit modest, reduction in LDL-C.
Maintenance of healthy cholesterol levels is an important public health goal. A healthy diet, regular physical activity, and avoiding tobacco smoke should be considered the basic tenants of preventing hyperlipidemia. And for some people, lifestyle changes alone aren’t enough to reach healthy cholesterol levels and medication may be necessary. Our findings do not alter current recommendations for the maintaining/attaining healthy cholesterol levels.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Schnatz: We need more and well-designed studies to bring the pieces of the puzzle together.
Schnatz PF1, Jiang X, Vila-Wright S, Aragaki AK, Nudy M, O’Sullivan DM, Jackson R, Leblanc E, Robinson JG, Shikany JM, Womack CR, Martin LW, Neuhouser ML, Vitolins MZ, Song Y, Kritchevsky S, Manson JE.