Vitamin D status and risk of type 2 diabetes in the Norwegian HUNT cohort study: does family history or genetic predisposition modify the association?

Serum vitamin D, blood pressure and hypertension risk in the HUNT study using observational and Mendelian randomization approaches

Limited studies have triangulated the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels and systolic blood pressure (SBP), diastolic blood pressure (DBP) or hypertension risk utilizing both observational and Mendelian randomization (MR) approaches. We employed data from the Norwegian Trøndelag Health Study (HUNT) to conduct cross-sectional (n = 5854) and prospective (n = 3592) analyses, as well as one-sample MR (n = 86,324). We also used largest publicly available data for two-sample MR. Our cross-sectional analyses showed a 25 nmol/L increase in 25(OH)D was associated with a 1.73 mmHg decrease in SBP (95% CI - 2.46 to - 1.01), a 0.91 mmHg decrease in DBP (95% CI - 1.35 to - 0.47) and 19% lower prevalence of hypertension (OR 0.81, 95% CI 0.74 to 0.90) after adjusting for important confounders. However, these associations disappeared in prospective analyses. One-sample and two-sample MR results further suggested no causal relationship between serum vitamin D levels and blood pressure or hypertension risk in the general population.

Associations of Serum Vitamin D With Dental Caries and Periodontitis: The HUNT Study

OBJECTIVE

To study the relationships of serum 25-hydroxyvitamin D [25(OH)D] with dental caries and periodontitis in a general Norwegian adult population.

METHODS

We analysed a subsample of 1605 participants from the Trøndelag Health Study (HUNT) in Norway that had serum 25(OH)D levels measured in HUNT3 (2006-08) and oral health assessed in the HUNT4 Oral Health Study (2017-19). Negative binomial and Poisson regression models were used to estimate the ratios of means (RMs; for count oral outcomes) and prevalence ratios (PRs; for dichotomous oral outcomes).

RESULTS

Serum 25(OH)D was inversely associated with the number of decayed teeth in a dose-response gradient (<30.0 nmol/L: RM 1.41, 95% CI 1.07-1.85; 30.0-49.9 nmol/L: 1.14, 0.98-1.32 and ≥75.0 nmol/L: 0.84, 0.67-1.04, as compared to the 50.0-74.9 nmol/L group, P for trend <.001). Each 25 nmol/L decrease in 25(OH)D level was associated with a 15% (RM 1.15, 95% CI 1.05-1.26) increase in the mean number of decayed teeth. Serum 25(OH)D <30.0 nmol/L was associated with a 35% higher prevalence of severe periodontitis (PR 1.35, 95% CI 1.00-1.83). No association was observed between 25(OH)D and the number of natural teeth.

CONCLUSION

The present study suggested that serum 25(OH)D level had an inverse and dose-response association with the number of decayed teeth, and serum 25(OH)D <30 nmol/L was associated with a higher prevalence of severe periodontitis in this Norwegian adult population.

Serum 25-hydroxyvitamin D, genetic susceptibility, and the risk of incident type 2 diabetes: A prospective cohort in East China

BACKGROUND

The serum vitamin D level varies widely by population, and studies have linked vitamin D levels with the risk of type 2 diabetes mellitus (T2DM). However, the relationship is inconsistent and the impact of vitamin D on T2DM among East Chinese adults is unclear. The study aimed to investigate the association between serum 25-hydroxyvitamin D (25[OH]D) levels and the risk of T2DM and evaluated whether the association is modified by genetic predisposition.

METHODS

In the Survey on Prevalence in East China for Metabolic Diseases and Risk Factors (SPECT-China) cohort, 1862 participants free of T2DM at baseline were included. A weighted genetic risk score was calculated with 28 variants associated with T2DM. Hierarchical logistic models were used to examine the association of serum 25(OH)D and genetic risk with T2DM.

RESULTS

After a 5-year follow-up, 132 cases of T2DM were documented. We observed no significant association between quartiles of serum 25(OH)D and T2DM risk after multivariable adjustment (χ 2 = 0.571, Pfor trend = 0.426). Compared to those in the lowest quartile of 25(OH)D, the odds ratios (ORs) (95% confidence interval [CI]) for participants with increased quartiles were 1.29 (0.74-2.25), 1.35 (0.77-2.36), and 1.27 (0.72-2.24), respectively. We observed a positive association of glycated hemoglobin (HbA1c) with 25(OH)D at baseline (β = 1.752, P = 0.001) and after follow-up (β = 1.385, P = 0.003), and a negative association of ln conversion homeostasis model assessment (HOMA)-β with 25(OH)D at baseline (β = -0.982, P = 0.021). There was no significant interaction between 25(OH)D and diabetes genetic predisposition on the risk of T2DM (χ 2 = 2.710, Pfor interaction = 0.100). The lowest OR (95% CI) of T2DM was among participants with low genetic risk and the highest quartile of 25(OH)D (0.17 [0.05-0.62]).

CONCLUSION

Serum 25(OH)D may be irrelevant to the risk of incident T2DM among East Chinese adults regardless of genetic predisposition.

The Power of Vitamin D: Is the Future in Precision Nutrition through Personalized Supplementation Plans?

In the last few decades, vitamin D has undeniably been one of the most studied nutrients. Despite our ability to produce vitamin D through sunlight exposure, its presence in several natural food sources and fortified foods, and its widespread availability as a dietary supplement, vitamin D deficiency is a serious public health problem, affecting nearly 50% of the global population. Low serum levels of vitamin D are being associated with increased susceptibility to numerous health conditions, including respiratory infections, mental health, autoimmune diseases, and different cancer types. Although the association between vitamin D status and health is well-established, the exact beneficial effects of vitamin D are still inconclusive and indefinite, especially when considering the prevention and treatment of different health conditions and the determination of an appropriate dosage to exert those beneficial effects in various population groups. Therefore, further research is needed. With constant improvements in our understanding of individual variations in vitamin D metabolism and requirements, in the future, precision nutrition and personalized supplementation plans could prove beneficial.

Age at Menarche, age at Natural Menopause, and Risk of Lung and Colorectal Cancers: A Mendelian Randomization Study

Background

The roles of age at menarche and age at menopause in the etiology of lung and colorectal cancers are unclear.

Objective

We aimed to investigate potential causal associations between age at menarche, age at natural menopause, and risk of lung and colorectal cancers using a Mendelian randomization (MR) approach.

Methods

From the Trøndelag Health Study in Norway, we defined two cohorts of 35 477 and 17 118 women to study the effects of age at menarche and age at natural menopause, respectively. We ran univariable MR to evaluate the potential causal associations. We performed multivariable MR adjusting for genetic variants of adult body mass index (BMI) to estimate the direct effect of age at menarche.

Results

Genetically predicted 1-year increase in age at menarche was associated with a lower risk of lung cancer overall (hazard ratio [HR, 0.64; 95% CI, 0.48-0.86), lung adenocarcinoma (HR, 0.61; 95% CI, 0.38-0.99), and lung non-adenocarcinoma (HR, 0.66; 95% CI, 0.45-0.95). After adjusting for adult BMI using a multivariable MR model, the direct effect estimates reduced to HR 0.72 (95% CI, 0.54-0.95) for lung cancer overall, HR 0.67 (95% CI, 0.43-1.03) for lung adenocarcinoma, and HR 0.77 (95% CI, 0.54-1.09) for lung non-adenocarcinoma. Age at menarche was not associated with colorectal cancer. Moreover, genetically predicted age at natural menopause was not associated with lung and colorectal cancers.

Conclusion

Our MR study suggested that later age at menarche was causally associated with a decreased risk of lung cancer overall and its subtypes, and adult BMI might be a mediator.

Longitudinal changes in vitamin D concentrations and the association with type 2 diabetes mellitus: the Tromsø Study

AIM

We aimed to investigate the relationship between pre- and post-diagnostic 25-hydroxyvitamin D (25(OH)D) concentrations and type 2 diabetes (T2DM) over a period of 30 years in individuals who developed T2DM compared to healthy controls.

METHODS

This case-control study included 254 participants with blood samples collected at five different time-points (T1-T5) between 1986 and 2016. Of the 254 participants, 116 were diagnosed with T2DM between T3 and T4, and were considered cases; the remaining 138 were controls. Linear mixed regression models were used to examine pre- and post-diagnostic changes in 25(OH)D concentrations, and logistic regression was used to examine associations between these concentrations and T2DM at each time-point.

RESULTS

25(OH)D concentrations at different time-points and the longitudinal change in concentrations differed between cases and controls, and by sex. For women, each 5-nmol/l increase in 25(OH)D concentrations was inversely associated with T2DM at T3 (odds-ratio, OR, 0.79), whereas for men, this same increase was positively associated with T2DM at T1 (OR 1.12). Cases experienced a significant decrease in pre-diagnostic 25(OH)D concentrations (p value < 0.01 for women, p value = 0.02 for men) and a significant increase in post-diagnostic 25(OH)D concentrations (p value < 0.01 for women, p value = 0.01 for men). As such, each 1-unit increase in month-specific z-score change between T1 and T3 was significantly inversely associated with T2DM (OR 0.51 for women, OR 0.52 for men), and each such increase between T3 and T5 was significantly positively associated with T2DM in women (OR 2.48).

CONCLUSIONS

25(OH)D concentrations seem to be affected by disease progression and type 2 diabetes diagnosis.

Vitamin D Status Over Time and Cognitive Function in Norwegian Older Adults: A Prospective Cohort of the HUNT Study

BACKGROUND

There is conflicting evidence regarding the association between vitamin D status and cognitive function in population studies. The use of one-time vitamin D measurement in cognitive health studies may not reflect long-term vitamin D status in the body.

OBJECTIVE

We aimed to examine the relationship of vitamin D status measured over time with the risk of neurocognitive disorders (NCDs) in Norwegian older adults.

DESIGN

Prospective cohort study.

SETTING

Regional, Trøndelag Health Study.

PARTICIPANTS

This study followed a random cohort of 717 participants from HUNT2 (1995-97) and HUNT3 (2006-08) to HUNT4 70+ (2017-19). The mean age at HUNT4 70+ was 77.7 years.

METHODS

Seasonal-standardized serum 25-hydroxyvitamin D [25(OH)D] levels in HUNT2 and HUNT3 were averaged and used as either a categorical variable (<50 and ≥50 nmol/L) or a continuous variable (per 25 nmol/L decrease). In the cohort aged 70 years or over (HUNT4 70+), NCDs consisting of mild cognitive impairment (MCI) and dementia were diagnosed by clinical experts according to the DSM-5 criteria. Logistic and linear regression models were used to estimate odds ratios (ORs) and regression coefficients (beta) with 95% confidence intervals (CIs) to assess the relationship between 25(OH)D levels and the risk of NCDs or the Montreal Cognitive Assessment (MoCA) score.

RESULTS

In total, 347 (48.4%) had NCDs in HUNT4, with 33.3% having MCI and 15.1% having dementia. Compared with participants with serum 25(OH)D ≥50 nmol/L, those with 25(OH)D <50 nmol/L had a similar risk of NCDs (OR 1.05, 95% CI 0.76 to 1.46). No association was observed with the risk of MCI (OR 1.01, 95% CI 0.71 to 1.44) or dementia (OR 1.16, 95% CI 0.70 to 1.92), respectively. In a subsample of participants evaluated with the MoCA (n=662), a 25 nmol/L decrease in serum 25(OH)D was not associated with a change in MoCA score (beta 0.33, 95% CI -0.17 to 0.85).

CONCLUSION

Vitamin D insufficiency defined by two times measurements of serum 25(OH)D with a 10-year interval was not associated with the risk of NCDs in a cohort of older Norwegian adults. Future studies utilizing multiple vitamin D measurements with a longer follow-up duration and larger sample size are warranted.

Reproductive Factors in Relation to Incidence of Lung and Colorectal Cancers in a Cohort of Norwegian Women: The HUNT Study

Context

The roles of reproductive factors in the etiology of lung and colorectal cancers, among the most common cancers in women, are unclear.

Objective

We aimed to explore whether female reproductive factors were associated with the incidence of lung and colorectal cancers.

Methods

We followed up 33 314 cancer-free women who participated in the HUNT Study in Norway from 1995-1997 to 2018. A large panel of reproductive factors were self-reported at baseline. Incident lung and colorectal cancer cases were ascertained from the Cancer Registry of Norway. Cox regression models were used to estimate hazard ratios (HRs) with 95% CIs after adjustment for important confounders.

Results

During a median follow-up interval of 22.2 years, 467 women developed lung cancer (including 169 lung adenocarcinoma), 660 developed colon cancer, and 211 had rectal cancer. Early menarche (≤12 years) was associated with an increased incidence of lung adenocarcinoma (HR 1.43; 95% CI, 1.02-2.03). Women with one or no child had an increased colon cancer incidence (HR 1.26; 95% CI, 1.03-1.54). Hormone therapy appeared to be associated with a decreased incidence of rectal cancer (HR 0.68; 95% CI, 0.44-1.04). Results in the subgroup of postmenopausal women were similar or strengthened. Other reproductive factors were not related to the risk of lung, colon, and rectal cancers.

Conclusion

Certain reproductive factors might play a role in the etiology of lung and colorectal cancers. Further investigations are warranted to study if they are causal associations.

Association between circulating 25-hydroxyvitamin D and cardiometabolic risk factors in adults in rural and urban settings

Background

An inverse association between vitamin D status and cardiometabolic risk has been reported but this relationship may have been affected by residual confounding from adiposity and physical activity due to imprecise measures of these variables. We aimed to investigate the relationship between serum 25-hydroxyvitamin D (25(OH)D) and cardiometabolic risk factors, with adjustment for objectively-measured physical activity and adiposity.

Methods

This was a population-based cross-sectional study in 586 adults in Cameroon (63.5% women). We assessed markers of glucose homoeostasis (fasting blood glucose (BG), 2 h post glucose load BG, HOMA-IR)) and computed a metabolic syndrome score by summing the sex‐specific z‐scores of five risk components measuring central adiposity, blood pressure, glucose, HDL cholesterol and triglycerides.

Results

Mean±SD age was 38.3 ± 8.6 years, and serum 25(OH)D was 51.7 ± 12.5 nmol/L. Mean 25(OH)D was higher in rural (53.4 ± 12.8 nmol/L) than urban residents (50.2 ± 12.1 nmol/L), p = 0.002. The prevalence of vitamin D insufficiency (<50 nmol/L) was 45.7%. There was an inverse association between 25(OH)D and the metabolic syndrome score in unadjusted analyses (β = −0.30, 95% CI −0.55 to −0.05), which became non-significant after adjusting for age, sex, smoking status, alcohol intake and education level. Serum 25(OH)D was inversely associated with fasting BG (−0.21, −0.34 to −0.08)), which remained significant after adjustment for age, sex, education, smoking, alcohol intake, the season of data collection, BMI and physical activity (−0.17, −0.29 to −0.06). There was an inverse association of 25(OH)D with 2-h BG (−0.20, −0.34 to −0.05) and HOMA-IR (−0.12, −0.19 to −0.04) in unadjusted analysis, but these associations became non-significant after adjustment for potential confounders.

Conclusion

Vitamin D insufficiency was common in this population. This study showed an inverse association between vitamin D status and fasting glucose that was independent of potential confounders, including objectively measured physical activity and adiposity, suggesting a possible mechanism through insulin secretion.

Vitamin D Levels as an Important Predictor for Type 2 Diabetes Mellitus and Weight Regain Post-Sleeve Gastrectomy

Weight Loss Surgery (WLS), including sleeve-gastrectomy (SG), results in significant weight loss and improved metabolic health in severe obesity (BMI ≥ 35 kg/m2). Previous studies suggest post-operative health benefits are impacted by nutrient deficiencies, such as Vitamin D (25(OH)D) deficiency, while it is currently unknown whether nutrient levels may actually predict post-surgery outcomes. As such, this study investigated whether 25(OH)D levels could predict metabolic improvements in patients who underwent SG. Patients with severe obesity (n = 309; 75% female) undergoing SG participated in this ethics-approved, non-randomized retrospective cohort study. Anthropometry, clinical data, 25(OH)D levels and serum markers were collected at baseline, 6-, 12- and 18-months post-surgery. SG surgery resulted in significant improvements in metabolic health at 6- and 12-months post-surgery compared with baseline, as expected. Patients with higher baseline 25(OH)D had significantly lower HbA1c levels post-surgery (p < 0.01) and better post-surgical T2DM outcomes, including reduced weight regain (p < 0.05). Further analysis revealed that baseline 25(OH)D could predict HbA1c levels, weight regain and T2DM remission one-year post-surgery, accounting for 7.5% of HbA1c divergence (p < 0.01). These data highlight that higher circulating 25(OH)D levels are associated with significant metabolic health improvements post-surgery, notably, that such baseline levels are able to predict those who attain T2DM remission. This highlights the importance of 25(OH)D as a predictive biomarker of post-surgery benefits.

Vitamin D/VDR in the pathogenesis of intervertebral disc degeneration: Does autophagy play a role?

To date, the underlying mechanisms involved intervertebral disc degeneration (IDD) remain unclear, which has hindered the development of molecular biological therapy for IDD. Autophagy is vital for intracellular quality control and metabolic balance in intervertebral disc cells. Hence, autophagy homeostasis is important. Emerging evidence has implicated vitamin D (VD) and the vitamin D receptor (VDR) in IDD progression because of their effects on different autophagy steps. However, the results of clinical trials in which VD supplementation was assessed as a treatment for IDD are controversial. Furthermore, experimental studies on the interplay between VD/VDR and autophagy are still in their infancy. In view of the significance of the crosstalk between VD/VDR and autophagy components, this review focuses on the latest research on VD/VDR modulation in autophagy and investigates the possible regulatory mechanisms. This article will deepen our understanding of the relationship between VD/VDR and autophagy and suggests novel strategies for IDD prevention and treatment.

The relationship between dynapenia and vitamin D level in geriatric women with type 2 diabetes mellitus

Objective

In this study, we examined the possible relationship between dynapenia and vitamin D (VD) levels in geriatric women with type 2 diabetes mellitus (T2DM).

Methods

One hundred and twenty-two geriatric female patients aged 65-80 years with a diagnosis of T2DM were included in this prospective study. Physical examinations of the patients were performed, and biochemical tests were analyzed. The muscle strength of the patients was measured with a hand dynamometer. Dynapenia was defined as low grip strength with normal skeletal muscle mass index. In muscle strength measurements, for female patients, over 20 kg was accepted as normal and below 20 kg as decreased muscle strength. Patients were separated into three groups as <10 ng/ml, 10-30 ng/ml, and >30 ng/ml according to VD levels; according to the status of dynapenia, they were divided into two groups as dynapenic and non-dynapenic. By comparing all these parameters between these groups, the relationship between VD level and dynapenia was evaluated. In statistical analysis, significance was accepted as p<0.05.

Results

While 54 of the patients (44.3%) met the dynapenia criterion, 68 patients (55.7%) were non-dynapenic. Patients were first compared according to their dynapenia status. VD level was significantly lower in the dynapenic group (p<0.05). In the correlation analysis, a moderate positive correlation was found between muscle strength and VD (p=0.033, r: 0.23). The patients were then compared according to the VD groups. In the VD insufficient group, muscle strength (p=0.015), body mass index (p=0.025), systolic blood pressure (p<0.01), and glucose (p<0.01) were statistically significantly higher.

Conclusion

In the present study, we found a considerable relationship between VD levels and dynapenia in geriatric women with T2DM.

Vitamin D-independent benefits of safe sunlight exposure

This review examines the beneficial effects of ultraviolet radiation on systemic autoimmune diseases, including multiple sclerosis and type I diabetes, where the epidemiological evidence for the vitamin D-independent effects of sunlight is most apparent. Ultraviolet radiation, in addition to its role in the synthesis of vitamin D, stimulates anti-inflammatory pathways, alters the composition of dendritic cells, T cells, and T regulatory cells, and induces nitric oxide synthase and heme oxygenase metabolic pathways, which may directly or indirectly mitigate disease progression and susceptibility. Recent work has also explored how the immune-modulating functions of ultraviolet radiation affect type II diabetes, cancer, and the current global pandemic caused by SARS-CoV-2. These diseases are particularly important amidst global changes in lifestyle that result in unhealthy eating, increased sedentary habits, and alcohol and tobacco consumption. Compelling epidemiological data shows increased ultraviolet radiation associated with reduced rates of certain cancers, such as colorectal cancer, breast cancer, non-Hodgkins lymphoma, and ultraviolet radiation exposure correlated with susceptibility and mortality rates of COVID-19. Therefore, understanding the effects of ultraviolet radiation on both vitamin D-dependent and -independent pathways is necessary to understand how they influence the course of many human diseases.