Impact of a single oral dose of 100,000 IU vitamin D3 on profiles of serum 25(OH)D3 and its metabolites 24,25(OH)2D3, 3-epi-25(OH)D3, and 1,25(OH)2D3 in adults with vitamin D insufficiency

Cholecalciferol Supplementation Does Not Prevent the Development of Metabolic Syndrome or Enhance the Beneficial Effects of Omega-3 Fatty Acids in Obese Mice

BACKGROUND

Cholecalciferol (D3) may improve inflammation, and thus provide protection from cardiometabolic diseases (CMD), although controversy remains. Omega-3 fatty acids (ω-3FA) may also prevent the development of CMD, but the combined effects of ω-3FA and D3 are not fully understood.

OBJECTIVES

We determined the chronic independent and combined effects of D3 and ω-3FA on body weight, glucose homeostasis, and markers of inflammation in obese mice.

METHODS

We gave 8-week-old male C57BL/6J mice, which had been fed a high-fat, high-sucrose (HF) diet (65.5% kcal fat, 19.8% kcal carbohydrate, and 14% kcal protein) for 12 weeks, either a standard D3 dose (+SD3; 1400 IU D3/kg diet) or a high D3 dose (+HD3; 15,000 IU D3/kg diet). We fed 1 +SD3 group and 1 +HD3 group with 4.36% (w/w) fish oil (+ω-3FA; 44% eicosapentaenoic acid, 25% docosahexaenoic acid), and fed the other 2 groups with corn oil [+omega-6 fatty acids (ω-6FA)]. A fifth group was fed a low-fat (LF; 15.5% kcal) diet. LF and HF+ω-6+SD3 differences were tested by a Student's t-test and HF treatment differences were tested by a 2-way ANOVA.

RESULTS

D3 supplementation in the +HD3 groups did not significantly increase plasma total 25-hydroxyvitamin D and 25-hydroxyvitamin D3 [25(OH)D3] versus the +SD3 groups, but it increased 3-epi-25-hydroxyvitamin D3 levels by 3.4 ng/mL in the HF+ω-6+HD3 group and 4.0 ng/mL in the HF+ω-3+HD3 group, representing 30% and 70%, respectively, of the total 25(OH)D3 increase. Energy expenditure increased in those mice fed diets +ω-3FA, by 3.9% in the HF+ω-3+SD3 group and 7.4% in the HF+ω-3+HD3 group, but it did not translate into lower body weight. The glucose tolerance curves of the HF+ω-3+SD3 and HF+ω-3+HD3 groups were improved by 11% and 17%, respectively, as compared to the respective +ω-6FA groups. D3 supplementation, within the ω-3FA groups, altered the gut microbiota by increasing the abundance of S24-7 and Lachnospiraceae taxa compared to the standard dose, while within the ω-6FA groups, D3 supplementation did not modulate specific taxa.

CONCLUSIONS

Overall, D3 supplementation does not prevent CMD or enhance the beneficial effects of ω-3FA in vitamin D-sufficient obese mice.

The Effect of Vitamin D Supplementation on its Metabolism and the Vitamin D Metabolite Ratio

25-hydroxyvitamin D (25(OH)D) is commonly measured to assess vitamin D status. Other vitamin D metabolites such as 24,25-dihydroxyvitamin D (24,25(OH)₂D) provide additional insights into vitamin D status or metabolism. Earlier studies suggested that the vitamin D metabolite ratio (VMR), calculated as 24,25(OH)₂D/25(OH)D, could predict the 25(OH)D increase after vitamin D supplementation. However, the evidence for this additional value is inconclusive. Therefore, our aim was to assess whether the increase in 25(OH)D after supplementation was predicted by the VMR better than baseline 25(OH)D. Plasma samples of 106 individuals (25(OH)D < 75 nmol/L) with hypertension who completed the Styrian Vitamin D Hypertension Trial (NC.T.02136771) were analyzed. Participants received vitamin D (2800 IU daily) or placebo for 8 weeks. The treatment effect (ANCOVA) for 25(OH)D₃, 24,25(OH)₂D₃ and the VMR was 32 nmol/L, 3.3 nmol/L and 0.015 (all p < 0.001), respectively. Baseline 25(OH)D₃ and 24,25(OH)₂D₃ predicted the change in 25(OH)D₃ with comparable strength and magnitude. Correlation and regression analysis showed that the VMR did not predict the change in 25(OH)D₃. Therefore, our data do not support routine measurement of 24,25(OH)₂D₃ in order to individually optimize the dosage of vitamin D supplementation. Our data also suggest that activity of 24-hydroxylase increases after vitamin D supplementation.

Serum 25(OH)D levels after oral vitamin D3 supplementation and UVB exposure correlate

BACKGROUND

The inter-individual variation in 25(OH)D₃ increase (Δ25(OH)D₃ ) after vitamin D₃ supplementation was determined and compared with the UVB irradiation response.

METHODS

Nineteen Danish participants received 85 μg vitamin D₃ (cholecalciferol) daily for nine weeks with regular serum 25(OH)D₃ measurements. These participants had three years earlier taken part in a 9-week controlled UVB study. The Δ25(OH)D₃ was not confounded by ambient UVB, BMI or ethnicity.

RESULTS

Δ25(OH)D₃ was 53 nmol L^-1 and almost identical to Δ25(OH)D₃ (52 nmol L^-1 ) after UVB. Δ25(OH)D₃ ranged from 17 to 91 nmol L^-1 (span 74 nmol L^-1 ) and was about half of that observed after UVB irradiation (span 136 nmol L^-1 ). The interquartile ranges for vitamin D₃ supplementation (38.8-71.4 nmol L^-1 , span: 32.6 nmol L^-1 ) and UVB irradiation (35.7-65.4 nmol L^-1 , span: 29.7 nmol L^-1 ) were similar indicating a comparable response of the two interventions. As the 25(OH)D₃ start levels (R²  = 0.398, P = 3.8 × 10^-3 ), 25(OH)D₃ end levels (R²  = 0.457, P = 1.5 × 10^-3 ) and Δ25(OH)D₃ (R²  = 0.253, P = 0.028) between both interventions were correlated, this suggested a possible common individual background for the variation. Four pigment SNPs influenced the variation in the vitamin D₃ -induced and UVB-induced Δ25(OH)D₃ . A combined model including the influence of these four SNPs and the 25(OH)D₃ start level explained 86.8% (P = 1.6 × 10^-35 ) of the individual variation after vitamin D₃ supplementation.

CONCLUSION

The inter-individual variation in the two interventions was comparable and had no common demographic but a partly common genetic background.

Comorbidities in multiple sclerosis-a plea for interdisciplinary collaboration to improve the quality of life of MS patients

The negative influence of comorbidities on the quality of life of people with multiple sclerosis is evident and the problem is increasingly acknowledged by numerous international studies in long-term care. One therapeutic option would be an add-on therapy with vitamin D (VD), with the aim of achieving a therapeutically effective dose. The individually required VD dose must be tested, since the response to a certain dose is subject to variations between individuals. A possible toxicity with increased 1.25(OH)D3 (active VD metabolite) is largely prevented by increased activity of 24-hydroxylase (CYP24A1). Monitoring of serum VD levels as well as serum calcium and phosphate levels (optional Ca excretion in 24-hour urine, Ca creatinine ratio in urine) provides safety and is necessary because possible mutations on the (catabolic) CYP24A1 gene can lead to a partial or total loss of 24-hydroxylase activity and provoke hypercalcemia/hyperphosphatemia. The main therapeutic objective is to maintain functional and social independence by using drugs with a high safety profile. The prevention and optimal management of comorbidities can influence the quality of life of patients with MS (PwMS) when included in patient care. Adequate measures can reduce the burden of MS only if the risk of comorbidity is reduced through targeted monitoring, early detection and diagnosis. Such a strategy will contribute to influencing the premature mortality of patients with MS. If VD is recognized as a "multipurpose steroid hormone", it could also be used to maintain cognitive function and prevent premature possible dementia, especially as there is evidence that VD deficiency correlates with brain atrophy (hippocampus). At present, MS therapy is still a balancing act between therapeutically efficient action and the management of unexpected side effects, with VD add-on therapy being almost unproblematic and most likely to be accepted by PwMS.

The dynamic relationships between the active and catabolic vitamin D metabolites, their ratios, and associations with PTH

Vitamin D status, assessed by serum concentration of 25(OH)D, is the prime candidate marker for many disease-association studies, but the interplay between the subsequent 1,25-dihydroxyvitamin D (1,25(OH)₂D) and 24,25-dihydroxyvitamin D (24,25(OH)₂D) metabolites is unclear. In this study, we conducted an analysis from a large cohort of healthy, physically fit, young army recruits (n = 940). We found a significant, inverse relationship between serum 25(OH)D and 1,25(OH)₂D:24,25(OH)₂D vitamin D metabolite ratio (VMR) (r²Exp = 0.582, p < 0.0001), and demonstrated a significant association with increasing PTH concentration (p < 0.001). Circannual rhythms were evident for all vitamin D metabolites and VMRs except for 1,25(OH)₂D when fitted to Cosinor curves. We estimated 1,25(OH)₂D:24,25(OH)₂D VMR of ≥35 to be the threshold value for vitamin D insufficiency, and ≥51 to be predictive of vitamin D deficiency. Our three-dimensional model provides mechanistic insight into the vitamin D-PTH endocrine system, and further substantiates the role of 24,25(OH)₂D in human physiology. The model sets a new paradigm for vitamin D treatment strategy, and may help the establishment of vitamin D-adjusted PTH reference intervals. The study was approved by the UK Ministry of Defence research ethics committee (MODREC 165/Gen/10 and 692/MoDREC/15). ClinicalTrials.gov Identifier NCT02416895.

Evaluation of the new restandardized Abbott Architect 25-OH Vitamin D assay in vitamin D-insufficient and vitamin D-supplemented individuals

BACKGROUND

Recently, Abbott Diagnostics has restandardized the Architect 25(OH)D assay against the NIST SRM 2972. We have evaluated the analytical and clinical performance of the restandardized Architect 25(OH)D assay and compared its performance with a NIST-traceable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method and the Roche total 25(OH)D assay in vitamin D-insufficient individuals before and after vitamin D₃ supplementation.

METHODS

Frozen serum samples were obtained from 88 healthy subjects with self-perceived fatigue and vitamin D-insufficiency <50 nmol L^-1 who were randomized to receive a single 100 000 IU dose of vitamin D₃ (n = 48) or placebo (n = 40). Total 25(OH)D concentrations were measured before and 4 weeks after supplementation by the restandardized Architect 25(OH)D assay, LC-MS/MS, and Roche assay.

RESULTS

The Architect 25(OH)D assay showed an intra- and inter-assay imprecision of <5%. Comparison of the Architect assay with the LC-MS/MS method showed a good correlation in both vitamin D-insufficient and vitamin D-supplemented subjects, however, with a negative mean bias of 17.4% and 8.9%, respectively. As compared to the Roche assay, the Abbott assay underestimated 25(OH)D results in insufficient subjects (<50 nmol L^-1 ) with a mean negative bias of 17.1%, this negative bias turned into a positive bias in supplemented subjects. Overall there was a moderate agreement in classification of vitamin D-insufficient and -supplemented individuals into different vitamin D states between the Architect 25(OH)D method and LC-MS/MS.

CONCLUSION

The routine use of the restandardized Architect 25(OH)D results in a slight underestimation of circulating total 25(OH)D levels at lower concentrations and thus potential misclassification of vitamin D status.