Vitamin D Binding Protein and Vitamin D Levels in Multi-Ethnic Population

Introduction

Low levels of 25-hydroxyvitamin D (25(OH)D) has been associated with many negative health outcomes including falls and fractures. 25(OH)D is largely bound to vitamin D binding protein (VDBP). There is increasing evidence that free or bioavailable 25(OH)D may be a better measure of vitamin D deficiency.

Objective

To determine the prevalence of 25(OH)D deficiency and VDBP levels in multi-ethnic population, and its impact on muscle strength.

Design and methods

Cross-sectional study of older adults in Western region of Singapore. 295 participants from three ethnic groups were selected from the Healthy Older People Everyday (HOPE) cohort for measurements of total 25(OH)D and VDBP levels. Total 25(OH)D, VDBP, frailty status, Timed-Up-and-Go (TUG) and grip strength (GS) were assessed. Albumin, free and bioavailable 25(OH)D were only available for 256 participants.

Results

53% of Malay and 55% of Indians were deficient in 25(OH)D compared with 18.2% of ethnic Chinese participants. Chinese also had higher total 25(OH)D concentrations with a mean of 29.1 ug/l, (p = <0.001). Chinese had the lowest level of VDBP (169.6ug/ml) followed by Malay (188.8 ug/ml) and Indian having the highest (220.1 ug/ml). Calculated bioavailable and free 25(OH)D levels were significantly higher in Chinese, followed by Malays and Indians, which also correlated with better grip strength measures amongst the Chinese.

Conclusion

The Malays and Indians had overall lower free, bioavailable and total 25(OH)D compared with ethnic Chinese. Chinese ethnic group also had the lowest VDBP and better overall grip strength.

     

Vitamin D and Obesity

Obesity is a significant health problem world-wide, particularly in developed nations. Vitamin D deficiency is pandemic, and has been implicated in a wide variety of disease states. This paper seeks to examine the consistently reported relationship between obesity and low vitamin D concentrations, with reference to the possible underlying mechanisms. The possibility that vitamin D may assist in preventing or treating obesity is also examined, and recommendations for future research are made. There is a clear need for adequately-powered, prospective interventions which include baseline measurement of 25D concentrations and involve adequate doses of supplemental vitamin D. Until such studies have been reported, the role of vitamin D supplementation in obesity prevention remains uncertain.     

维生素D与妊娠

维生素D不仅参与了钙磷代谢,与细胞分化、生长发育和免疫调节也有明显的关系.维生素D缺乏在妊娠期妇女非常普遍,并会导致先兆子痫、妊娠期糖尿病、牙周病及细菌性阴道病的发生增加,并影响胎儿宫内生长发育,增加子代患自身免疫性疾病、过敏性疾病的风险,使呼吸道抗感染能力下降.妊娠期妇女发生维生素D缺乏的风险较高,监测和补充维生素D很有必要,合适的剂量还需进一步研究.     

Vitamin D and Psoriasis

Skin can serve as the source of vitamin D when exposed to sunlight so that cutaneous 7-dehydrocholesterol can be converted to the vitamin. Skin is also a target organ for the hormone form of vitamin D: 1,25-(OH)2D3. Both skin keratinocytes grown in tissue culture and samples of human skin have the nuclear receptor for 1,25(OH)2D3. New results suggest that this hormone or its analogs may be effective in treating some forms of psoriasis.     

Vitamin D and tuberculosis

Tuberculosis is highly prevalent worldwide, accounting for nearly two million deaths annually. Vitamin D influences the immune response to tuberculosis, and vitamin D deficiency has been associated with increased tuberculosis risk in different populations. Genetic variability may influence host susceptibility to developing active tuberculosis and treatment response. Studies examining the association between genetic polymorphisms, particularly the gene coding for the vitamin D receptor (VDR), and TB susceptibility and treatment response are inconclusive. However, sufficient evidence is available to warrant larger epidemiologic studies that should aim to identify possible interactions between VDR polymorphisms and vitamin D status.     

维生素D与妊娠

维生素D不仅参与了钙磷代谢，与细胞分化、生长发育和免疫调节也有明显的关系。维生素D缺乏在妊娠期妇女非常普遍，并会导致先兆子痫、妊娠期糖尿病、牙周病及细菌性阴道病的发生增加，并影响胎儿宫内生长发育，增加予代患自身免疫性疾病、过敏性疾病的风险，使呼吸道抗感染能力下降。妊娠期妇女发生维生素D缺乏的风险较高，监测和补充维生素D很有必要，合适的剂量还需进一步研究。     

Vitamin D and influenza

Vitamin D has become increasingly recognized in the literature for its extra-skeletal roles, including an effect on inflammation and the immune response to infection. Our goal was to describe the role of vitamin D in the immune response and implications for the risk of influenza infection in humans. In this review, we first consider literature that provides molecular and genetic support to the idea that vitamin D is related to the adaptive and innate immune responses to influenza infection in vitro and in animal models. We then discuss observational studies and randomized controlled trials of vitamin D supplementation in humans. Finally, we consider some of the knowledge gaps surrounding vitamin D and immune response that must be filled.     

Relative Efficacy of Vitamin D2 and Vitamin D3 in Improving Vitamin D Status: Systematic Review and Meta-Analysis

Background: Widespread prevalence of vitamin D deficiency has been documented globally. Commonly used interventions to address this deficiency include supplementation and/or fortification with either ergocalciferol (vitamin D₂) or cholecalciferol (vitamin D₃), but the relative efficacy of these two vitamers is unclear. The current study aimed to evaluate the relative efficacy of ergocalciferol (vitamin D₂) and cholecalciferol (vitamin D₃) for raising the serum levels of vitamin D metabolites and functional indicators including serum parathyroid (PTH) levels, isometric muscle strength, hand grip strength and bone mineral density. Methods: Randomized and non-randomized controlled studies evaluating relative efficacy of ergocalciferol and cholecalciferol were systematically reviewed to synthesize quantitative and qualitative evidence as per the recommendations of according to “Preferred Reporting Items for Systematic reviews and Meta-analysis” guidelines. Search terms were constructed on the basis of the “participants”, “intervention”, “control”, “outcome” and “study type” (PICOS) strategy to systematically search the popular electronic databases. Relevant data from studies meeting inclusion and exclusion criteria were extracted and analyzed. Meta-regression, subgroup and sensitivity analyses were performed to investigate the influence of study-level characteristics including intervention dosage, frequency of dosing, interval between the last dose and test for outcome assessment, participant characteristics and analytical methods. Results: Apparently healthy human participants (n = 1277) from 24 studies were included for meta-analysis. The quantitative analysis suggested higher efficacy of cholecalciferol than ergocalciferol in improving total 25(OH)D (mean difference: 15.69, 95%CI: 9.46 to 21.93 nmol/L) and reducing PTH levels, consistently across variable participant demographics, dosage and vehicle of supplementation. Meta-regression suggested smaller differences in the efficacy of cholecalciferol and ergocalciferol at lower doses. Average daily dose was the single significant predictor of effect size, as revealed by multivariate meta-regression analysis. Conclusions: Compared to ergocalciferol, cholecalciferol intervention was more efficacious in improving vitamin D status (serum levels of total 25(OH)D and 25(OH)D₃) and regulating PTH levels, irrespective of the participant demographics, dosage and vehicle of supplementation.     

Vitamin D and Vitamin D3 Supplementation during Photodynamic Therapy: A Review

Photodynamic therapy is an unconventional yet increasingly common method of treating dermatological diseases and cancer that is implemented more often in adults than in children. Current clinical uses include treatment of actinic keratosis, superficial basal cell carcinomas, and acne. Despite its high efficiency, photodynamic therapy support supplements have recently been reported in the literature, including calcitriol (1,25-dihydroxycholecalciferol), the active form of vitamin D, and vitamin D3 cholecalciferol. In clinical trials, photodynamic therapy enhanced with vitamin D or D3 supplementation has been reported for treatment of squamous cell skin cancers, actinic keratosis, and psoriasis. Experimental research on the effect of photodynamic therapy with vitamin D or D3 has also been carried out in breast cancer cell lines and in animal models. The aim of this review is to evaluate the usefulness and effectiveness of vitamin D and D3 as supports for photodynamic therapy. For this purpose, the Pubmed and Scopus literature databases were searched. The search keyword was: “vitamin D in photodynamic therapy”. In the analyzed articles (1979–2022), the authors found experimental evidence of a positive effect of vitamin D and D3 when used in conjunction with photodynamic therapy. An average of 6–30% (in one case, up to 10 times) increased response to photodynamic therapy was reported in combination with vitamin D and D3 as compared to photodynamic therapy alone. Implementing vitamin D and D3 as a supplement to photodynamic therapy is promising and may lead to further clinical trials and new clinical methodologies.