Ultraviolet index and location are important determinants of vitamin D status in people with human immunodeficiency virus

Association between serum 25-hidroxyvitamin D concentrations and ultraviolet index in Portuguese older adults: a cross-sectional study

Background

The older population is a risk group for hypovitaminosis D. The Ultraviolet Index (UVI) can be an indicator of potential for cutaneous synthesis of vitamin D but physiological and other environmental factors also influence vitamin D synthesis and status. Knowledge about vitamin D status in Portuguese older adults is limited. This study aims to explore the association between Ultraviolet Index and serum 25-hidroxyvitamin D3 [25(OH)D] levels accounting for other potential influential factors.

Methods

A cross-sectional study was conducted between December 2015 and June 2016, in 1497 Portuguese older adults (≥ 65 years) within Nutrition UP 65 project. For each participant, serum 25(OH)D was determined and the mean UVI (mUVI) in the respective residence district was calculated for the previous 30 days. Stepwise linear regression analyses were conducted for the following periods of blood collection: between December and June, December and March and April and June. Standardized regression coefficients (Sβ) and 95% confidence intervals were calculated.

Results

The median 25(OH)D concentration was 35.9 nmol/L. The UVI was independently and positively associated with 25(OH)D in the models for December–June (Sβ = 0.244, 95% CI: 0.198; 0.291, P < 0.001) and April–June (Sβ = 0.295, 95% CI: 0.299; 0.362, P < 0.001) and independently and negatively associated in December–March period (Sβ = −0.149, 95% CI: -0.211; −0.087, P < 0.001).

Conclusions

In this sample with high vitamin D deficiency frequency, the UVI was a predictor of 25(OH)D levels but the direction of the association varied according to the blood collection period. Our results suggest that accounting for the time of year in future research regarding vitamin status and related public health recommendations may be relevant.

Electronic supplementary material

The online version of this article (10.1186/s12877-017-0644-8) contains supplementary material, which is available to authorized users.

Vitamin D and bone loss in HIV

PURPOSE OF REVIEW

Bone health has become an increasingly important aspect of the care of HIV-infected patients as bone loss with antiretroviral therapy (ART) initiation is significant and osteopenia and osteoporosis are highly prevalent. Vitamin D is tightly linked to calcium balance and bone health, and vitamin D deficiency is common in HIV. This review outlines the epidemiology of vitamin D deficiency in HIV, summarizes our current understanding of the relationship between vitamin D and bone loss in HIV and the impact of vitamin D supplementation in this patient group.

RECENT FINDINGS

Although data are conflicting as to whether vitamin D deficiency is more prevalent among HIV-infected individuals than in the general population, there are several reasons for why this patient group may be at heightened risk. Studies linking vitamin D deficiency to bone loss in HIV are limited; however, data from randomized clinical trials suggest a benefit of vitamin D supplementation for the prevention of bone loss with ART initiation and for the treatment of bone loss with bisphosphonate therapy.

SUMMARY

There are too limited data to recommend universal screening of vitamin D status or supplementation to all HIV-infected individuals. However, testing 25-hydroxyvitamin D levels in those at risk for deficiency and treating patients found to be deficient or initiating ART or bisphosphonate therapy should be considered. Further study on vitamin D supplementation is needed regarding the potential benefit on immune activation and restoration in this patient group.

Associations between vitamin D metabolites, antiretroviral therapy and bone mineral density in people with HIV

RATIONALE

To see if vitamin D and antiretroviral therapy are associated with bone mineral density (BMD) in people with HIV.

RESULT

Lower hip BMD was associated with tenofovir (an antiretroviral medicine) in those with 25(OH)D ≥50 nmol/L.

SIGNIFICANCE

The relationship between antiretroviral therapy and hip BMD differs depending on vitamin D status.

INTRODUCTION

People with HIV have an increased risk of low BMD and fractures. Antiretroviral therapy contributes to this increased risk. The aim of this study was to evaluate associations between vitamin D metabolites and antiretroviral therapy on BMD.

METHODS

The simplification of antiretroviral therapy with tenofovir-emtricitabine or abacavir-lamivudine trial (STEAL) was an open-label, prospective randomised non-inferiority study that compared simplification of current nucleoside reverse transcriptase inhibitors (NRTIs) to fixed-dose combination tenofovir-emtricitabine (TDF-FTC) or abacavir-lamivudine. Serum 25(OH)D and 1,25(OH)2D were measured in 160 individuals (90 receiving TDF-FTC, 70 receiving other NRTIs) at baseline from this study. Multivariable linear regression models were constructed to evaluate the covariates of 1,25(OH)2D and BMD.

RESULTS

Protease inhibitor use (p = 0.02) and higher body mass index (BMI) (p = 0.002) were associated with lower 1,25(OH)2D levels in those with 25(OH)D <50 nmol/L. However, TDF-FTC use (p = 0.01) was associated with higher 1,25(OH)2D levels, but only in those with 25(OH)D ≥50 nmol/L. White ethnicity (p = 0.02) and lower BMI (p < 0.001) in those with 25(OH)D <50 nmol/L and with TDF-FTC use (p = 0.008) in those with 25(OH)D ≥50 nmol/L were associated with lower hip BMD. TDF-FTC use, higher serum calcium and serum βCTX, winter, and lower bone-specific alkaline phosphatase (BALP) and BMI were associated with lower lumbar spine BMD.

CONCLUSION

TDF-FTC use (versus non-TDF-FTC use) was associated with lower hip BMD, and this difference was more pronounced in those with 25(OH)D ≥50 nmol/L. Serum 25(OH)D <50 nmol/L was associated with lower hip BMD in all participants. Therefore, the associations between antiretroviral therapy and hip BMD differ depending on vitamin D status.

Impact of Geographic Location on Vitamin D Status and Bone Mineral Density

A significant decline of serum 25-hydroxyvitamin D concentration [25(OH)D] with increasing latitude has been reported only for Caucasians. To determine the association between serum 25(OH)D and geographic location and its impact on bone mineral density (BMD) in an Asian population, a total of 17,508 subjects (8910 men and 8598 women) from the 2008–2010 Korea National Health and Nutrition Examination Survey (KNHANES) were stratified into four age groups and analyzed for 25(OH)D and BMD according to geographic location (South, 33° N–35° N; Middle, 36° N; North, 37° N–38° N). Mean 25(OH)D were 47.7 and 41.2 nmol/L; calcium intake, 564.9 & 442.3 mg/d; femoral neck BMD, 0.829 & 0.721 g/cm²; and lumbar spine BMD, 0.960 & 0.918 g/cm² for men and women, respectively. Both men and women living in the South had significantly higher 25(OH)D and femoral neck BMD for those ≥50 years old. Lumbar spine BMD was significantly higher in men ≥50 years old, and for women 10–29 & 50–69 years old living in the South. A 1 or 2 degree difference in latitude has a significant effect on serum 25(OH)D and BMD in this low vitamin D status population. Thus, consideration of geographic location for a recommendation of vitamin D intake may be necessary.

Vitamin D deficiency is common in HIV-infected southern Australian adults

BACKGROUND

Vitamin D deficiency can have serious health consequences and may be particularly important for those living with HIV. It is unknown whether HIV infection is a risk factor for vitamin D deficiency. The aim of the study was to determine whether vitamin D deficiency is more common in HIV-infected than in HIV-uninfected individuals.

METHODS

This was a cross-sectional study of HIV-infected and uninfected individuals. A total of 997 HIV-infected participants were from a sexual health clinic in Melbourne with 25(OH)D measurements taken between 2008 and 2012. 3,653 HIV-uninfected individuals were participants in a statewide Victorian survey with 25(OH)D measurements taken between 2009 and 2010. Logistic regression models evaluated the association of HIV status with vitamin D deficiency (25[OH]D<50 nmol/l).

RESULTS

The frequency of vitamin D deficiency was significantly more common in HIV-infected (39% [95% CI 36%, 42%]) compared with HIV-uninfected individuals 23% (95% CI 15%, 31%). In multivariable analysis, males (adjusted odds ratio [aOR] 0.8; 95% CI 0.6, 0.9; P=0.001), Caucasian country of origin (aOR 0.4; 95% CI 0.3, 0.4; P<0.001), summer/autumn (aOR for autumn 0.2; 95% CI 0.1, 0.3; P<0.001), total cholesterol to high-density lipoprotein ratio >5 (aOR 1.4; 95% CI 1.2, 1.8; P<0.001) and HIV infection (aOR 1.7; 95% CI 1.4, 2.1; P<0.001) were associated with vitamin D deficiency.

CONCLUSIONS

Adults living in southern Australia with HIV were more likely to be vitamin D deficient than the general population.