Vitamin D3 supplementation does not modify cardiovascular risk profile of adults with inadequate vitamin D status.

PURPOSE: The Nutrition Societies in Germany, Austria, and Switzerland recommend a daily intake of 20 µg vitamin D3 for adults when endogenous synthesis is absent. The current study aimed to elucidate whether this vitamin D3 dose impacts cardiovascular risk markers of adults during the winter months. METHODS: The study was conducted in Halle (Saale), Germany (51o northern latitude) as a placebo-controlled, double-blinded, randomised trial (from January to April). A total of 105 apparently healthy subjects (male and female, 20-71 years old) were included. Subjects were randomly allocated to two groups. One group received a daily 20-µg vitamin D3 dose (n = 54), and the other group received a placebo (n = 51) for 12 weeks. Outcome measures included blood pressure, heart rate, concentrations of renin, aldosterone, serum lipids and vascular calcification markers, and haematologic variables such as pro-inflammatory monocytes. RESULTS: Blood pressure and systemic cardiovascular risk markers remained unchanged by vitamin D3 supplementation, although serum 25-hydroxyvitamin D3 increased from 38 ± 14 to 73 ± 16 nmol/L at week 12. The placebo and vitamin D groups did not differ in their final cardiovascular risk profile. CONCLUSION: Daily supplementation of 20 µg vitamin D3 during winter is unlikely to change cardiovascular risk profile.

Vitamin D3 supplementation: Response and predictors of vitamin D3 metabolites - A randomized controlled trial.

BACKGROUND & AIMS: Large parts of the population are insufficiently supplied with vitamin D, in particular when endogenous synthesis is absent. Therefore many health care providers recommend the use of vitamin D supplements. The current study aimed to investigate the efficacy of an once-daily oral dose of 20 µg vitamin D3 to improve the vitamin D status and to evaluate predictors of response. METHODS: The study was conducted as a double-blind, randomized, placebo-controlled parallel trial from January till April 2013. In total, 105 subjects (20-71 years) were allocated to receive either a vitamin D3 supplement (20 µg/d) or a placebo for 12 weeks. Circulating levels of vitamin D3 metabolites such as the 25(OH)D3 and the 24,25(OH)2D3, and biomarkers of calcium and phosphate metabolism were quantified. RESULTS: The 25(OH)D3 serum concentrations in the placebo group decreased from 38 ± 15 nmol/L at baseline to 32 ± 14 nmol/L and 32 ± 13 nmol/L at weeks 8 and 12 of the study, respectively (p < 0.01). In the vitamin D3 group, the serum 25(OH)D3 concentration increased from 38 ± 14 nmol/L at baseline to 70 ± 15 nmol/L and 73 ± 16 nmol/L at weeks 8 and 12 of vitamin D3 supplementation (p < 0.001), respectively. As a result, 94% of the vitamin D3-supplemented participants reached 25(OH)D3 concentrations of ≥50 nmol/L and thereof 46% attained 25(OH)D3 levels of ≥75 nmol/L until the end of the study. The extent of the 25(OH)D3 increase upon vitamin D3 supplementation depended on 25(OH)D3 baseline levels, age, body weight and circulating levels of triglycerides. In contrast to 25(OH)D3, the response of 24,25(OH)2D3 to the vitamin D3 treatment was affected only by baseline levels of 24,25(OH)2D3 and age. CONCLUSIONS: The average improvement of 25(OH)D3 levels in individuals who received 20 µg vitamin D3 per day during the winter months was 41 nmol/L compared to individuals without supplementation. As a result almost all participants with the vitamin D3 supplementation attained 25(OH)D3 concentrations of 50 nmol/L and higher. The suitability of 24,25(OH)2D3 as a marker of vitamin D status needs further investigation. Clinical trial registration number at clinicaltrials.gov: NCT01711905.

Bioavailability of vitamin D(2) and D(3) in healthy volunteers, a randomized placebo-controlled trial.

BACKGROUND: The bioequivalence of the different forms of vitamin D, ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3), has been questioned. Earlier studies have suggested that vitamin D2 is less biologically active than vitamin D3. OBJECTIVE AND DESIGN: In a parallel study, we tested the effects of supplementation with 50-µg/d doses of vitamin D2 or D3 or a placebo over a period of 8 weeks on 25(OH)D2, 25(OH)D3, their sum 25(OH)D (primary outcome variables), and PTH in healthy volunteers applying a double-blind, randomized study design. The study was conducted during the winter of 2012 in Halle (Saale), Germany, at latitude 51°47N, when UVB irradiation is virtually absent. Blood samples for the determinations of vitamin D status and PTH were collected at baseline and after 4 and 8 weeks of supplementation. RESULTS: In the placebo group (n = 19), 25(OH)D3 decreased from 39.4 ± 14.2 to 31.1 ± 12.4 nmol/L after 8 weeks (P < .01). In the vitamin D3 group (n = 42), the concentrations of 25(OH)D3 increased from 41.5 ± 22.8 nmol/L at baseline to 88.0 ± 22.1 nmol/L after 8 weeks (P < .01). In the group receiving vitamin D2 (n = 46), the 25(OH)D2 concentrations increased significantly, whereas the 25(OH)D3 concentration fell from 36.4 ± 13.3 nmol/L at baseline to 16.6 ± 6.3 nmol/L after 8 weeks (P < .01). The total 25(OH)D was not different between the groups at baseline but differed significantly between the groups after 4 and 8 weeks (P < .001). CONCLUSIONS: Vitamin D3 increases the total 25(OH)D concentration more than vitamin D2. Vitamin D2 supplementation was associated with a decrease in 25(OH)D3, which can explain the different effect on total 25(OH)D.