The role of serum 25 (OH) vitamin D level in the correlation between lipid profile, body mass index (BMI), and blood pressure

Fat Distribution as a Determinant of Vitamin D Status: A Cross-Sectional Study of Adults in the United States

BACKGROUND

This study aimed to elucidate correlations between obesity-related indicators and vitamin D (VD) status in a nationally representative sample of U.S. adults.

METHODS

We analysed data from 9168 adults aged 20-59 years obtained from the 2011-2018 National Health and Nutrition Examination Survey. Serum 25 hydroxyvitamin D [25(OH)D] levels were measured and categorised into quartiles. Anthropometric measurements, including weight, waist circumference, and fat mass in various body regions quantified through dual-energy X-ray absorptiometry, were collected. Multiple imputation was employed to replace missing data. The importance of obesity-related indicators and serum 25(OH)D concentration was explored using multiple linear regression adjusted for demographics, lifestyle factors, dietary intake, and clinical biomarkers, and stepwise regression.

RESULTS

Weight, waist circumference, and fat mass across all body regions were inversely associated with serum 25(OH)D levels (all p < 0.001). Notable differences were observed between men and women. Stepwise regression revealed a strong inverse correlation between visceral adipose tissue and serum 25(OH)D concentration in men [β 95% CI: -13.04 (-18.10, -7.99), p < 0.001], whereas in women, only weight was significantly correlated with serum 25(OH)D concentration [β 95% CI: -0.20 (-0.28, -0.12), p < 0.001]. Demographic attributes, seasonal sunlight exposure, dietary VD, calcium, phosphorus, and magnesium intake, and biomarkers including alkaline phosphatase and creatinine also emerged as significant predictors.

CONCLUSIONS

Besides conventional obesity measures, abdominal fat metrics exhibit robust associations with VD deficiency, especially in men. Public health initiatives and clinical management strategies for hypovitaminosis D in obese populations should consider nuanced aspects of adiposity distribution alongside other demographic, lifestyle, and dietary factors influencing VD.

Healthy eating index and bone health markers in adults with metabolically healthy and unhealthy obese phenotypes

Background

The Healthy Eating Index (HEI) estimates the diet quality, and low HEI scores are associated with adverse bone outcomes. However, the relationship between HEI scores and bone health in individuals who are obese but otherwise healthy or obese with comorbidities remains unclear.

Objective

We aimed to evaluate the association of HEI scores with bone mineral density (BMD), bone regulating hormones and bone turnover markers in individuals with metabolically healthy obese (MHO) and metabolically unhealthy obese (MUO) phenotypes.

Methods

This was a cross-sectional analysis of 122 adults who were overweight or obese. A questionnaire was completed to obtain demographic data. Body composition and BMD were assessed by a Dual Energy X-Ray Absorptiometry (DXA) exam. The HEI scores and dietary components were calculated using a 24-h dietary recall. Blood samples were collected for the analysis of serum 25-hydroxyvitamin D (s25OHD), total osteocalcin (OC), parathyroid hormone (PTH), and C-terminal telopeptide (CTx) concentrations. The MHO and MUO phenotypes were classified according to the absence or presence of metabolic abnormalities.

Results

The sample mean age was 37.91 ± 12.66 years, 50.8% were men, mean body mass index (BMI) was 30.01 ± 4.63 kg/m2, and 45.9% were classified as the MUO phenotype. The mean HEI scores were 54.42 ± 16.25 and 61.48% had low-diet quality. HEI scores were positively associated with s25OHD in the MUO phenotype group (β = 0.194, 95%CI = 0.038-0.350, p = 0.016). Certain dietary score components, such as fruits, seafood and plant protein, added sugars, whole grains, and fatty acids were also associated with bone health markers. However, HEI scores were not associated with BMD measures, neither with other bone regulating hormones and turnover markers.

Conclusion

There was a positive association between HEI scores and s25OHD in adults who were overweight or obese with MUO phenotype. Additionally, the adequate consumption of specific food groups may benefit bone mass and metabolism. These results emphasize the importance of lifestyle interventions encouraging healthy eating habits to prevent s25OHD deficiency, poor bone health, and cardiometabolic complications.

Vitamin D status, including serum levels and sun exposure are associated or correlated with bone mass measurements diagnosis, and bone density of the spine

BACKGROUND

Osteoporosis is a health complication worldwide, especially in developing countries. The prevalence was reported to be 18.3% globally. While the effect of biochemical factors on fracture risk/odds has been documented, the association/correlation between serum 25(OH)D levels, vitamin D dietary intake, and sun exposure with bone mineral density (BMD) remains controversial. This study aimed to evaluate the association and correlation between vitamin D status, including serum levels, dietary intakes, and sun exposure with BMD. We hypothesized that vitamin D-related factors would have different correlations/associations with BMD, which would help better evaluate future studies' results.

METHODS

A total of 186 individuals were included in this study (winter 2020). BMD was measured by Dual-energy X-ray absorptiometry. Blood serum levels of 25(OH)D, phosphorus, calcium, parathyroid hormone (PTH), and calcitonin were tested using standard lab tests. Valid and reliable questionnaires were used for sun exposure assessment and dietary intakes.

RESULTS

There was a significant protective association between spine BMD (classifications, two groups) (OR = 0.69, 95%CI: 0.50-0.94; p-value = 0.023), BMD diagnosis (classifications, two groups) (OR = 0. 69, 95%CI: 0.49-0.87; p-value = 0.036) and sun exposure. There was a significant and moderate correlation between Spine measurements (Spine BMD: Pearson correlation coefficient = 0.302, p-value = 0.046; Spine T-score: Pearson correlation coefficient = 0.322, p-value = 0.033, Spine Z-score: Pearson correlation coefficient = 0.328, p-value = 0.030) and serum 25(OH)D. In addition, participants with osteopenia and osteoporosis significantly consume a higher amount of soluble fiber than the normal BMD group. There was no significant correlation between vitamin D intake and BMD.

CONCLUSION

In conclusion, serum 25(OH)D levels and sun exposure are correlated and associated with BMD. However, prospective studies are needed to investigate the association between dietary vitamin D intake and BMD.

Shift Work and Serum Vitamin D Levels: A Systematic Review and Meta-Analysis

Vitamin D deficiency and insufficiency are highly prevalent conditions worldwide due to several factors, including poor sun exposure. Shift workers may be exposed to the risk of hypovitaminosis D due to fewer opportunities for sunlight exposure compared to day workers. A systematic review of the PubMed, SCOPUS, and EMBASE databases was conducted according to the Preferred Reporting Items for Systemic Reviews and Meta-Analyses (PRISMA) statement to investigate the effect of shift work on vitamin D levels. Mean differences (MD) and 95% confidence intervals (CI) of serum 25-OH-D levels in shift workers and non-shift workers were calculated. A total of 13 cross-sectional studies were included in the meta-analysis. We found significantly lower levels of serum 25-OH-D in shift workers compared with non-shift workers (MD: −1.85, 95% CI [−2.49 to −1.21]). Heterogeneity among included studies was high (I2 = 89%, p < 0.0001), and neither subgroup analysis nor meta-regression were able to identify specific sources of the heterogeneity that may be related to the different characteristics of shift work among studies. The monitoring of serum vitamin D levels and prompt correction of any deficiencies should be considered in shift workers. Notably, since a large part of the observations are derived from Koreans, larger epidemiological studies are needed in other populations.