A randomized controlled trial found that vitamin D3 supplementation combined with calcium may be associated with significant reductions in both systolic and diastolic blood pressures among overweight elderly patients over a 12-month period.
In the multicenter, double-blind study, published in the Journal of the Endocrine Society, researchers enrolled 257 participants aged ≥ 65 years with a body mass index (BMI) of > 25 and serum 25-hydroxyvitamin D levels of 10 to 30 ng/mL. After excluding dropouts and one participant without baseline vitamin D data, 221 ambulatory adults completed the trial (111 on low-dose and 110 on high-dose vitamin D3 supplementation).
The study population had notable comorbidities: 69% had prediabetes, 65% were hypertensive, and 64% had dyslipidemia. At baseline, 48% of the participants were receiving antihypertensive medications and 34% had blood pressure ≥ 130/80 mmHg without treatment.
The trial included regular compliance checks, with participants attending visits every 3 months and receiving biweekly phone calls. Blood pressure measurements were taken after 5 minutes of rest, with repeated readings for elevated measurements. All participants also received 1,000 mg of calcium citrate daily.
The participants in the high-dose vitamin D3 group (3,750 IU/day) experienced mean systolic reductions of 4.2 mmHg (P = .023) and diastolic reductions of 3.02 mmHg (P = .01) after 1 year. Those receiving low-dose vitamin D3 supplementation (600 IU/day) showed nonsignificant reductions in systolic (2.8 mmHg, P = .089) and diastolic (2.6 mmHg, P = .089) pressures.
In the patients with a BMI > 30 (n = 99), significant systolic blood pressure decreases were observed in both dosage groups (high-dose: from 132.9 ± 17.6 to 125.8 ± 11.5 mmHg, P = .006; low-dose: from 132.0 ± 17.2 to 124.5 ± 16.9 mmHg, P = .024). Diastolic pressure significantly decreased only in the high-dose group (from 77.3 ± 10.6 to 73.3 ± 7.9 mmHg, P = .020).
Among hypertensive participants (n = 143), defined as having systolic pressure ≥ 130 mmHg or diastolic pressure ≥ 80 mmHg at study entry, significant reductions were observed regardless of vitamin D dosage or BMI category. In this group, systolic pressure decreased from 136.5 ± 14.0 to 126.5 ± 11.8 mmHg (P < .001) and diastolic from 79.8 ± 8.2 to 72.8 ± 8.7 mmHg (P < .001).
Multivariate linear mixed model analysis revealed that systolic pressure changes were significantly associated with BMI (β = .29, P = .05) and baseline systolic blood pressure (β = .16, P < .001), but not with vitamin D treatment dose. For diastolic blood pressure, significant associations were found with BMI (β = .280, P = .007), sex (lower in women, β = –2.640, P = .008), and baseline diastolic blood pressure (β = .238, P < .001).
The study excluded patients with diabetes, severe chronic diseases, major organ failure, or conditions affecting bone metabolism. Only nine of the participants reported regular physical activity, limiting analysis of lifestyle effects on blood pressure outcomes.
The researchers acknowledged several limitations of the study, including the exploratory nature of their analyses and the absence of a placebo-only control group. The study population was primarily sedentary, overweight, and included many with prediabetes, which may limit generalizability to other populations.
The trial was conducted at the American University of Beirut Medical Center, St. Joseph University Hospital, and Rafic Hariri Governmental University Hospital, with support from several institutional and NIH grants.
All authors stated that they have no conflict of interest.
