Effect of daily 2000 IU versus 800 IU vitamin D on blood pressure among adults age 60 years and older: a randomized clinical trial

Authors: ABDERHALDEN, LAUREN - University Of Zurich; MEYER, SANDRA - University Of Zurich; DAWSON-HUGHES, BESS - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; ORAV, E - Harvard University; MEYER, URSINA - University Of Zurich; DE GODOI REZENDA, COSTA - University Of Zurich; THEILER, ROBERT - University Of Zurich; STAHELIN, HANNES - University Of Basel; RUSCHITZKA, FRANK - University Hospital Zurich; EGLI, ANDREAS - University Of Zurich; FORMAN, JOHN - Brigham & Women'S Hospital; WILLETT, WALTER - Harvard University; BISCHOFF-FERRARI, HEIKE - University Of Zurich

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2020
Publication Date: 6/15/2020
Citation: Abderhalden, L.A., Meyer, S., Dawson-Hughes, B., Orav, E.J., Meyer, U., De Godoi Rezenda, C.C., Theiler, R., Stahelin, H.B., Ruschitzka, F., Egli, A., Forman, J.P., Willett, W.C., Bischoff-Ferrari, H.A. 2020. Effect of daily 2000 IU versus 800 IU vitamin D on blood pressure among adults age 60 years and older: a randomized clinical trial. American Journal of Clinical Nutrition. https://doi.org/10.1093/ajcn/nqaa145.
DOI: https://doi.org/10.1093/ajcn/nqaa145

Interpretive Summary: Observational studies report higher blood pressure (BP) among individuals with lower vitamin D status. Whether the dosage of vitamin D supplementation has a differential effect on BP control remains unclear. This study was done to determine whether daily vitamin D supplementation with 2000 IU is more effective than 800 IU for BP control among older adults. This analysis included 250 adults age 60 years and older who had recently had elective surgery for knee osteoarthritis. Participants were randomized to receive high-dose (2000 IU) or standard-dose (800 IU) of vitamin D3 daily for 2 years. Daytime and 24-hour blood pressure was monitored at home. Systolic blood pressure declined by 2 to 4 mm Hg in both groups and the reductions did not differ significantly. However, the variability in systolic BP during the study was lower in the 2000 IU compared to the 800 IU group. We conclude that systolic blood pressure declined modestly and similarly in the 2000 IU and 800 IU groups over 2 years. The higher dose reduced systolic BP variability significantly more than the lower dose. However, the question of whether supplemental vitamin D, when compared with placebo, reduces blood pressure or the incidence of hypertension requires further study.

Technical Abstract: BACKGROUND: Observational studies report higher blood pressures (BP) among individuals with lower 25-hydroxyvitamain D concentration. Whether dosage of vitamin D supplementation has a differential effect on BP control remains unclear. OBJECTIVE: The study aimed to determine if daily vitamin D supplementation with 2000 IU is more effective than 800 IU for BP control among older adults. DESIGN: This randomized, double-blind, ancillary trial of the Zurich Multiple Endpoint Vitamin D Trial in Knee Osteoarthritis enrolled adults age 60 years and older who underwent elective surgery due to severe knee osteoarthritis. Participants were randomized to receive high-dose (2000 IU) or standard-dose (800 IU) daily vitamin D3 for 24 months. Outcomes included daytime and 24-hour mean systolic BP. Blood pressure variability and serum 25-hydroxyvitamain D concentration were examined in a post-hoc and observational analysis. RESULTS: Of the 273 participants randomized, 250 participants completed a follow-up 24-hour ambulatory BP monitoring (mean age 70.4 +/-6.4 years, 47.2% men). The difference in daytime mean systolic BP reduction between the 2000 IU (n=123) and 800 IU (n=127) groups was not statistically significant (-2.75 mm Hg vs -3.94 mm Hg; difference 1.18 mm Hg, 95% CI [-0.68, 72 3.05], P=0.21), consistent with 24-hour mean systolic BP. However, systolic BP variability was significantly reduced with 2000 IU (average real variability: -0.37 mm Hg) compared to 800 IU (0.11 mm Hg; difference -0.48 mm Hg, 95% CI [-0.94, -0.01], P=0.045). Independent of group allocation, maximal reductions in mean BP were observed at 28.7 ng/mL of achieved 25- hydroxyvitmain D concentrations. CONCLUSIONS: While daily 2000 IU and 800 IU reduced mean systolic BP over 2 years to a small and similar extent, 2000 IU reduced mean systolic BP variability significantly more compared to 800 IU. However, without a pure control group we cannot ascertain whether vitamin D supplementation effectively reduces BP.