Vitamin D may lower blood pressure in older people with obesity

New research finds that taking more than the IOM's recommended 600 IU of vitamin D per day does not offer additional health benefits.

In a recent study published in the Journal of the Endocrine Society, researchers explored whether two doses of vitamin D3 or cholecalciferol supplementation, administered along with calcium, had an impact on blood pressure in elderly, overweight individuals.

The findings suggested that vitamin D3 supplementation did reduce systolic and diastolic blood pressure, with greater effects observed in those with higher body mass index (BMI).

Background

Vitamin D deficiency is a widespread health issue associated with various chronic conditions, including cardiovascular diseases and hypertension. Observational studies have linked lower vitamin D levels to higher blood pressure, suggesting that low vitamin D may increase the risk of hypertension. Some genetic studies even associate vitamin D-related genes with blood pressure regulation.

Despite these associations, clinical trials testing the effect of vitamin D supplementation on blood pressure have yielded mixed results. Studies involving older, vitamin D-deficient, or hypertensive participants have often reported positive outcomes associated with vitamin D supplementation, while studies in younger or healthier groups have shown no significant effect.

The researchers believe that this inconsistency could be a result of differences in study design, dose, duration, or participant characteristics like body weight and comorbidities. However, elderly individuals are particularly prone to vitamin D deficiency, high blood pressure, and related health complications, which might make them more responsive to vitamin D’s potential benefits.

About the study

In this study, the researchers aimed to address the inconsistencies regarding the association between vitamin D levels and blood pressure by comparing standard and higher doses of vitamin D3 supplementation and assessing their respective effects on blood pressure in an elderly, overweight population at risk of both hypertension and vitamin D deficiency.

All participants received daily calcium citrate tablets, which provided 1000 mg of elemental calcium, along with 500 International Units (IU) of vitamin D3. The low-dose group also received a placebo once a week, while the high-dose group received two additional vitamin D3 tablets (10,000 IU each) weekly, resulting in an equivalent daily dose of 3750 IU.

Blood pressure was measured at baseline and then at six and 12 months. The participants also attended quarterly checkups, where medication use, pill counts, and compliance were recorded. Additionally, serum vitamin D levels and other routine clinical measures were recorded periodically.

Results

The study found that vitamin D3 supplementation, combined with calcium citrate, effectively reduced blood pressure in the elderly, overweight participants. The most notable reductions were observed in the high-dose group. Overall, both systolic and diastolic blood pressure measures showed a significant decrease from baseline to 12 months.

In the high-dose group, systolic blood pressure decreased by an average of 4.2 mm mercury (Hg), while diastolic blood pressure reduced by approximately 3.02 mm Hg. The low-dose group also showed reductions in both blood pressure measures, but these changes were not statistically significant.

Participants with a BMI above 30 exhibited significant reductions in both systolic and diastolic blood pressure across both treatment groups, with larger effects being observed in the high-dose group. In contrast, participants with a BMI of 30 or below showed minimal blood pressure changes, regardless of the dose of vitamin D3 supplementation.

Hypertensive participants, especially those on antihypertensive medication, experienced significant reductions in blood pressure over time, with notable reductions in both systolic and diastolic blood pressures. Those not on antihypertensive medication showed no significant change, suggesting an enhanced effect of vitamin D in medicated hypertensive individuals.

However, when controlling for other factors, comparisons between low and high doses did not reveal a dose-dependent relationship, indicating that blood pressure reductions were generally consistent across vitamin D levels.

Conclusions

In conclusion, vitamin D supplementation, administered along with calcium supplements, can reduce blood pressure in elderly, overweight individuals, especially those with higher BMI or existing hypertension.

The blood pressure-lowering effect was observed irrespective of the dose of vitamin D3 supplementation. The findings underscore the potential therapeutic role of combined vitamin D and calcium supplementation in managing hypertension in elderly individuals with high BMI values.

Journal references:

• Rahme, M., AlShaar, L., Tamim, H., & ElHajj Fuleihan, Ghada. (2024). Blood Pressure Decreases in Overweight Elderly Individuals on Vitamin D: A Randomized Trial. Journal of the Endocrine Society, 8(12), bvae168. doi:10.1210/jendso/bvae168, https://academic.oup.com/jes/article/8/12/bvae168/7888766