Vitamin D3 Repletion Improves Vascular Function and Reduces Full Length Osteopontin in Vitamin D Deficient African American Subjects

by | Sep 27, 2022 | 2022, Blood Pressure, Cardiovascular Health, Kidney Health, Vitamin D - Recommended Levels

Written by Taylor Woosley, Staff Writer. Monthly supplementation of 100,000 IU of cholecalciferol was associated with a 2-fold increase in vitamin D levels, from 17 ± 5 ng/mL to 35 ± 7 ng/mL (p < 0.0001) after 12 weeks. Serum levels of log transformed flOPN were significantly reduced (p=0.03) and log FGF-23 was increased in the treated group (p = 0.04).

vitamin D A low vitamin D status is emerging as a very common condition worldwide, and several studies have highlighted a strong association with chronic diseases1. Vitamin D is a group of secosteroids, with the most important compounds in this group being vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol)2. Vitamin D requirements for optimal human health defines vitamin D deficiency or insufficiency as having serum 25(OH)D concentrations lower than 50 nmol/l (20 ng/ml)3. Low levels of vitamin D may be a risk factor for adverse outcomes, including chronic kidney disease and cardiovascular disease4.

African Americans are prone to suboptimal vitamin D status5. Melanin in the skin absorbs UV rays from the sun, and higher melanin concentrations can contribute to impaired vitamin D production in adults with darker pigmentation6. While low vitamin D status is highly prevalent with an estimated 55% of the US adult population having levels at or below 30 ng/ml, of significant over 80% of African Americans have deficient levels7.

Sinha et al. conducted a randomized, placebo-controlled study to assess whether a vitamin D supplementation in a deficient African American cohort with controlled hypertension and preserved kidney function experienced improved clinical and biochemical indicators of cardiovascular and kidney pathology. Subjects (n=65, aged 18-70 years old) were randomized to receive a monthly dose of 100,000 IU of cholecalciferol or placebo for three months. Participants underwent a physical examination and brief medical history. Blood and urine samples, including blood pressure, vascular function, endothelial function, and pulse wave velocity (PWV) were assessed at baseline and 12 weeks. Furthermore, plasma levels of full length osteopontin (flOPN), C-terminal FGF-23, and PAI-1 were measured using ELISA kits.

Chi-Square tests were used to compare baseline characteristics between groups for categorical variables. Multivariable regression was utilized to evaluate the relationship between vitamin D and participant variables. The maximum-likelihood mixed-effects repeated-measures model was assessed to analyze the efficacy of the intervention. Significant findings of the 12-week randomized, placebo-controlled trial are as follows:

  • A monthly dose of 100,000 IU of cholecalciferol was associated with a 2-fold increase in vitamin D levels, from 17 ± 5 ng/mL to 35 ± 7 ng/mL (p < 0.0001) after 12 weeks. This increase was associated with an ~12% decrease in serum iPTH (p < 0.01).
  • Serum levels of log transformed flOPN were significantly reduced (p=0.03) and log FGF-23 was increased in the treated group (p = 0.04). Furthermore, the increase in log FGF-23 was positively associated with a trend in eGFR (p = 0.06) and diastolic BP (p = 0.05).
  • The decrease in log flOPN was negatively correlated with PWV (p = 0.04) and positively associated with diastolic BP (p = 0.02).

Results of this study show that vitamin D repletion improved circulating levels of cardiorenal biomarkers in high-risk African American subjects. Monthly supplementation of 100,000 IU cholecalciferol correlated with lower PWV and lower flOPN, along with significantly reducing iPTH levels. Further research should include using a larger and more diverse subject group to valid findings and increase generalizability. Study limitations include the degree of statistical significance and sensitivity to smaller effect sizes due to the small subject group.

Source: Sinha, Satyesh K., Ling Sun, Michelle Didero, David Martins, Keith C. Norris, Jae Eun Lee, Yuan-Xiang Meng et al. “Vitamin D3 Repletion Improves Vascular Function, as Measured by Cardiorenal Biomarkers in a High-Risk African American Cohort.” Nutrients 14, no. 16 (2022): 3331.

© 2022 by the authors. Li‐ censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con‐ ditions of the Creative Commons At‐ tribution (CC BY) license (https://cre‐ ativecommons.org/licenses/by/4.0/).

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Posted September 27, 2022.

Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.

References:

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