Effects of Vitamin D Supplementation on Cognitive Outcomes: A Systematic Review and Meta-Analysis

Clinical studies examining the effects of vitamin D on cognition have reported inconsistent results. To date, no comprehensive study has examined this effect on the basis of sample characteristics or intervention model-related factors. This systematic review and meta-analysis of randomized controlled trials investigated the effects of vitamin D supplementation on global cognitive function and specific cognitive domains. This review was preregistered in the PROSPERO database (CRD42021249908) and comprised 24 trials enrolling 7557 participants (mean age: 65.21 years; 78.54% women). The meta-analysis revealed that vitamin D significantly influenced global cognition (Hedges' g = 0.128, p = .008) but not specific cognitive domains. A subgroup analysis indicated that the effect size of vitamin D was stronger for vulnerable populations (Hedges' g = 0.414) and those with baseline vitamin D deficiency (Hedges' g = 0.480). On the basis of subgroup analyses in studies without biological flaws (Hedges' g = 0.549), we suggest that an intervention model should correct baseline vitamin D deficiency. Our results indicate that vitamin D supplementation has a small but significant positive effect on cognition in adults.

Unraveling the Catalytic Mechanism of β-Cyclodextrin in the Vitamin D Formation

Previous experimental studies have shown that the isomerization reaction of previtamin D3 (PreD3) to vitamin D3 (VitD3) is accelerated 40-fold when it takes place within a β-cyclodextrin dimer, in comparison to the reaction occurring in conventional isotropic solutions. In this study, we employ quantum mechanics-based molecular dynamics (MD) simulations and statistical multistructural variational transition state theory to unveil the origin of this acceleration. We find that the conformational landscape in the PreD3 isomerization is highly dependent on whether the system is encapsulated. In isotropic media, the triene moiety of the PreD3 exhibits a rich torsional flexibility. However, when encapsulated, such a flexibility is limited to a more confined conformational space. In both scenarios, our calculated rate constants are in close agreement with experimental results and allow us to identify the PreD3 flexibility restriction as the primary catalytic factor. These findings enhance our understanding of VitD3 isomerization and underscore the significance of MD and environmental factors in biochemical modeling.

Unveiling the molecular Culprit of arterial stiffness in vitamin D deficiency and obesity: Potential for novel therapeutic targets

Cardiovascular diseases (CVDs) are highly associated with both vitamin D deficiency and obesity, two prevalent health conditions worldwide. Arterial stiffness, an independent predictor of CVDs, is particularly elevated in both conditions, yet the molecular mechanisms underlying this phenomenon remain elusive, hindering effective management of CVDs in this population. We recruited 20 middle-aged Emiratis, including 9 individuals with vitamin D deficiency (Vit D level ≤20 ng) and obesity (BMI ≥30) and 11 individuals as control with Vit D level >20 ng and BMI <30. We measured arterial stiffness using pulse wave velocity (PWV) and performed whole transcriptome sequencing to identify differentially expressed genes (DEGs) and enriched pathways. We validated these findings using qRT-PCR, Western blot, and multiplex analysis. PWV was significantly higher in the vitamin D deficient and obese group relative to controls (p ≤ 0.05). The DEG analysis revealed that pathways related to interleukin 1 (IL-1), nitrogen metabolism, HIF-1 signaling, and MAPK signaling were over-activated in the vitamin D deficient and obese group. We found that HIF-1alpha, NOX-I, NOX-II, IL-1b, IL-8, IL-10, and VEGF were significantly upregulated in the vitamin D deficient and obese group (p < 0.05). Our study provides new insights into the molecular mechanisms of arterial stiffness in vitamin D deficiency and obesity, demonstrating the role of oxidative stress and inflammation in this process. Our findings suggest that these biomarkers may serve as potential therapeutic targets for early prevention of CVDs. Further studies are needed to investigate these pathways and biomarkers with larger cohort.

Interaction of Telomere Length and Inflammatory Biomarkers Following Zirconia Implant Placement: A Case Series

Zirconia implants have gained popularity for their aesthetic appeal and biocompatibility, making them a preferred choice for anterior teeth replacement. This study explores the interaction between telomere length and inflammatory biomarkers in seven cases of zirconia implant placement to gain insights into postoperative cellular aging, inflammatory responses, and long-term outcomes. Zirconia implants offer advantages over titanium implants, as they do not corrode or release metal ions, leading to potential inflammation and implant failure. Monitoring immune and inflammatory biomarkers is essential to assess inflammation initiation, severity, and progression. C-reactive protein (CRP) and pro-inflammatory cytokines, like interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), play crucial roles in host immune responses, while anti-inflammatory cytokines, including interleukin-10 (IL-10), regulate and dampen immune responses. Achieving a delicate balance between pro- and anti-inflammatory cytokines is vital for maintaining a healthy immune response and preventing chronic inflammatory conditions. Telomeres, protective structures present at chromosome ends, influence cellular aging and mitochondrial function. Shorter telomeres are associated with impaired mitochondrial function, increased oxidative stress, and cellular senescence, while longer telomeres are linked to reduced inflammation and improved immune function. Understanding these mechanisms is essential for addressing age-related conditions and promoting overall well-being. In this case series, we investigated the interaction between telomere length and inflammatory biomarkers in patients who received zirconia dental implants. The study aims to improve our understanding of postoperative cellular aging, inflammatory responses, and the biocompatibility of zirconia implants, potentially leading to improved treatment protocols and patient outcomes. This innovative assessment of telomere length and inflammatory biomarkers in the context of zirconia implants provides novel insights into the field of dental implantology. By exploring the effects of zirconia implants on cellular health and inflammation, this study contributes to advancements in implant technology and patient care.

In Vitro Assessment of Gold Nanoparticles on Telomerase Activity and Telomere Length in Human Fibroblasts

Telomerase activity coincides with lengthening of the ends of chromosomes known as telomeres. Telomere length is used as a marker for cellular aging. Telomeres shorten over time as cells divide, and certain bioactive compounds such as gold nanoparticles (AuNPs) may slow the shortening of telomeres by increasing telomerase activity. The objective of the present study is to assess the effect of AuNPs on telomerase activity and telomere length in human fibroblasts. Telomerase activity was measured using enzyme-linked immunosorbent assay (ELISA) in primary human lung fibroblasts (IMR90) and using quantitative PCR-based telomeric repeat amplification protocol (Q-TRAP) in primary human dermal fibroblasts, neonatal (HDFn). Telomere length was determined by Telomere Analysis Technology (TAT®)assay in HDFn. In IMR90, all AuNP treatments showed significant increases in telomerase activity when compared to earlier passages. HDFn treated with AuNPs at 0 ppm, 0.05 ppm, 0.5 ppm, or 5 ppm did not show significant differences in telomerase activity compared to the control group. Significant differences in telomere length in HDFn were observed at 2 weeks of 0.05 and 0.5 ppm AuNPs under oxidative culture conditions as compared to the control group. The study showed preliminary evidence that AuNPs may increase telomerase activity and decelerate the shortening of telomeres in human fibroblasts, suggesting its potential anti-aging effects, which warrants further investigation.

Hormones and Aging: An Endocrine Society Scientific Statement

Multiple changes occur across various endocrine systems as an individual ages. The understanding of the factors that cause age-related changes and how they should be managed clinically is evolving. This statement reviews the current state of research in the growth hormone, adrenal, ovarian, testicular, and thyroid axes, as well as in osteoporosis, vitamin D deficiency, type 2 diabetes, and water metabolism, with a specific focus on older individuals. Each section describes the natural history and observational data in older individuals, available therapies, clinical trial data on efficacy and safety in older individuals, key points, and scientific gaps. The goal of this statement is to inform future research that refines prevention and treatment strategies in age-associated endocrine conditions, with the goal of improving the health of older individuals.

Very Low and High Levels of Vitamin D Are Associated with Shorter Leukocyte Telomere Length in 148,321 UK Biobank Participants

Background: Shorter leukocyte telomere length (LTL) is observed in multiple age-related diseases, which are also associated with vitamin D deficiency (i.e., osteosarcopenia, neurocognitive disorders, cancer, osteoarthritis, etc.), suggesting a close association between vitamin D and LTL. In this study, we examined the relationship between vitamin D levels and LTL in older participants of the UK Biobank. Methods: Data were collected from the UK Biobank. Participants aged 60 and older (n = 148,321) were included. Baseline LTL was measured using a multiplex qPCR technique and expressed as the ratio of the telomere amplification product (T) to that of a single-copy gene (S) (T/S ratio). Serum 25-hydroxyvitamin D (25OHD) was stratified by z score and linked to LTL in a linear regression model adjusting for covariates. Results: Compared to the medium level, a low (in the range of 16.6 nmol/L, 29.7 nmol/L) or extremely low (≤16.6 nmol/L) level of serum 25OHD was associated with shorter LTL: 0.018 SD (standardized β = −0.018, 95% CI −0.033 to −0.003, p = 0.022) and 0.048 SD (standardized β = −0.048, 95% CI −0.083 to −0.014, p = 0.006), respectively. Additionally, the high serum 25OHD groups (>95.9 nmol/L) had 0.038 SD (standardized β = −0.038, 95% CI −0.072 to −0.004, p = 0.030) shorter mean LTL than the group with medium 25OHD levels. The associations above were adjusted for multiple variables. Conclusions: In this population-based study, we identified an inverted U-shape relationship between LTL and vitamin D status. Our findings could be affected by unmeasured confounders. Whether high or low vitamin D-associated shorter LTL is mechanistically related to age-related conditions remains to be elucidated.

Genetic Variants of the TERT Gene and Telomere Length in Obstructive Sleep Apnea

Introduction: Obstructive sleep apnea (OSA) is a worldwide breathing disorder that has been diagnosed globally in almost 1 billion individuals aged 30−69 years. It is characterized by repeated upper airway collapses during sleep. Telomerase reverse transcriptase (TERT) is involved in the prevention of telomere shortening. This prospective, observational study aimed to investigate the relationship between single nucleotide polymorphisms (SNPs) of TERT and the severity of OSA, taking into account hypertension and diabetes prevalence. Methods: A total of 149 patients with OSA were diagnosed using one-night video-polysomnography based on the American Academy of Sleep Medicine guidelines. The TERT SNPs and telomere length (TL) were detected using real-time quantitative polymerase chain reaction. Results: Statistical analysis showed that there is no relationship between the rs2853669 and rs2736100 polymorphisms of TERT, and the severity of OSA (p > 0.05). Moreover, no relationship between TL and the severity of OSA was observed. The G allele in the locus of rs2736100 TERT was associated with hypertension prevalence and was more prevalent in hypertensives patients (46.00% vs. 24.49%, p = 0.011). The prevalence of hypertension was higher in patients with the C allele in the locus of rs2853669 than in patients without this allele (50.79% vs. 30.23%, p = 0.010). Moreover, a lower prevalence of diabetes was observed in homozygotes of rs2736100 TERT than in heterozygotes (5.63% vs. 15.38%, p = 0.039). Conclusion: This study showed no relationship between OSA and TERT SNPs. However, SNPs of the TERT gene (rs2736100 and rs2853669) were found to affect arterial hypertension and diabetes prevalence.

Oxidative stress in Hashimoto's thyroiditis: possible adjuvant therapies to attenuate deleterious effects

A number of studies have shown that oxidative stress is related to the pathogenesis of several immunological diseases, such as Hashimoto's thyroiditis (HT), although there is no plausible mechanism to explain it. Thus, we aimed at hypothesizing and providing some possible mechanisms linking oxidative stress to autoimmunity aspects and its implications for HT, as well as adjuvant therapeutic proposals to mitigate the deleterious effects. Our hypothesis is that deficient eating habits, autoimmune regulator gene predisposing gene, dysbiosis and molecular mimicry, unfolded proteins and stress in the endoplasmic reticulum, and thymus involution appear to be the main potential factors leading to HT oxidative stress. Likewise, we show that the use of minerals selenium and zinc, vitamins D and C, as well as probiotics, can be interesting adjuvant therapies for the control of oxidative damage and poor prognosis of HT. Further clinical trials are needed to understand the real beneficial and side effects of these supplements.

Leukocyte Telomere Length as a Molecular Biomarker of Coronary Heart Disease

Background. This work is a review of preclinical and clinical studies of the role of telomeres and telomerase in the development and progression of coronary heart disease (CHD). Materials and methods. A search for full-text publications (articles, reviews, meta-analyses, Cochrane reviews, and clinical cases) in English and Russian was carried out in the databases PubMed, Oxford University Press, Scopus, Web of Science, Springer, and E-library electronic library using keywords and their combinations. The search depth is 11 years (2010–2021). Results. The review suggests that the relative leukocyte telomere length (LTL) is associated with the development of socially significant and widespread cardiovascular diseases such as CHD and essential hypertension. At the same time, the interests of researchers are mainly focused on the study of the relative LTL in CHD. Conclusions. Despite the scientific and clinical significance of the analyzed studies of the relative length of human LTL as a biological marker of cardiovascular diseases, their implementation in real clinical practice is difficult due to differences in the design and methodology of the analyzed studies, as well as differences in the samples by gender, age, race, and ethnicity. The authors believe that clinical studies of the role of the relative length of leukocyte telomeres in adult patients with coronary heart disease are the most promising and require large multicenter studies with a unified design and methodology.

Bioinformatics network analyses of growth differentiation factor 11

Growth differentiation factor 11 (GDF11) has been implicated in rejuvenating functions in age-related diseases. The molecular mechanisms connecting GDF11 with these anti-aging phenomena, including reverse age-related cardiac hypertrophy and vascular and neurogenic rejuvenation, remain unclear. In this study, we sought to uncover the molecular functions of GDF11 using bioinformatics and network-driven analyses at the human gene and transcription levels using the gene co-expression network analysis, the protein–protein interaction network analysis, and the transcription factor network analysis. Our findings suggested that GDF11 is involved in a variety of functions, such as apoptosis, DNA repair, telomere maintenance, and interaction with key transcription factors, such as MYC proto-oncogene, specificity protein 1, and ETS proto-oncogene 2. The human skin fibroblast premature senescence model was established by UVB. The treatment with 10 ng/mL GDF11 in this cell model could reduce cell damage, reduce the apoptosis rate and the expression of caspase-3, and increase the length of telomeres. Therefore, our findings shed light on the functions of GDF11 and provide insights into the roles of GDF11 in aging.

Change of vitamin D status and all-cause mortality among Chinese older adults: a population-based cohort study

BACKGROUND

The association of vitamin D with all-cause mortality remains controversial and longitudinal evidence exploring the potential effects of change in vitamin D status is limited in the oldest old (aged ≥ 80 years old). We aimed to study the relationship between vitamin D change and all-cause mortality among older Chinese adults including the oldest old.

METHODS

The data of Chinese Longitudinal and Health Longevity Study in 2012 and 2014 wave was used for baseline data. Mortality was assessed in the subsequent 2018 survey waves. Cox proportional hazard regression models were used to calculate hazard ratios (HRs) and 95% confidence interval (CI) of all-cause mortality related to vitamin D change, including maintaining deficiency or no deficiency, deficiency to no deficiency, and no deficiency to deficiency, using below 50 nmol/L as definition of deficiency.

RESULTS

The mean age of the total 1362 participants was 84.4 ± 12.1(60-113) years. The prevalence of vitamin D deficiency was 67.5% and 68.4% in 2012 and 2014 wave respectively, and significantly differed by sex and age at baseline. Cox regression showed that participants with deficiency to no deficiency and maintaining no deficiency of vitamin D status had decreased HR for all-cause mortality, compared to the maintaining deficiency group. The HRs for mortality were 0.70(95%CI: 0.50-0.96, p = 0.028) and 0.47(95%CI: 0.33-0.68, p < 0.001) respectively in the adjusted model. Also, females and the oldest old had a greatest reduction in mortality risk. And no significant difference in mortality in the no deficiency to deficiency group.

CONCLUSIONS

Not only maintaining no deficiency, but also the change from deficiency to no deficiency of vitamin D status were associated with lower risk of all-cause mortality, especially in the female and oldest-old participants initially with low vitamin D level.

Telomere length in leucocytes and solid tissues of young and aged rats

Background: Telomeres are protective nucleoprotein structures at the end of chromosomes that shorten with age. Telomere length (TL) in peripheral blood mononuclear cells (PBMCs) has been proposed as surrogate marker for TL in the entire organism. Solid evidence that supports this concept is lacking.

Methods: Relative TL (RTL) was measured in PBMCS and multiple solid tissues from 24 young (4 months) and 24 aged (14 months) Sprague-Dawley (SD) rats. The mRNA expression of telomerase (TERT) and shelterin proteins TERF-1 and TERF-2 was also measured.

Results: Mean RTL in PBMCs and solid tissues of young rats ranged from 0.64 ± 0.26 in large intestine to 1.07 ± 0.22 in skeletal muscle. RTL in PBMCs correlated with that in kidney (r = 0.315, p = 0.008), skeletal muscle (r = 0.276, p = 0.022), liver (r = 0.269, p = 0.033), large intestine (r = −0.463, p = 7.035E-5) and aorta (r = −0.273, p = 0.028). A significant difference of RTL between young and aged animals was only observed in aorta (0.98 ± 0.15 vs. 0.76 ± 0.11, p = 1.987E-6), lung (0.76 ± 0.14 vs. 0.85 ± 0.14, p = 0.024) and visceral fat (0.83 ± 0.14 vs. 0.92 ± 0.15, p = 0.44). The expression of TERT significantly differed between the tested organs with highest levels in liver and kidney. Age-related differences in TERT expression were found in PBMCs, skeletal muscle, and visceral fat. mRNA expression of TERF-1 and TERF-2 was tissue-specific with the highest levels in liver. Age-related differences in TERF-1 and TERF-2 expression were inconsistent.

Conclusions: The present study questions the utility of RTL in PBMCs as a biomarker for the individual assessment of aging.

Leukocyte telomere length as a compensatory mechanism in vitamin D metabolism

Vitamin D deficiency is common among postmenopausal women. Telomere length can be a potential protective mechanism for age-related diseases. The objective of our study is to examine the association of vitamin D supplementation on leukocyte telomere length (LTL) in healthy postmenopausal women with vitamin D deficiency. The study was designed as a placebo-controlled study to investigate the short-term effects of vitamin D supplementation and seasonal changes on vitamin D related parameters, including 25(OH)D, 1,25(OH)2D parathormone (PTH), Vitamin D binding protein (VDBP), vitamin D receptor (VDR), and telomere length in a cohort of postmenopausal women (n = 102). The group was divided as supplementation (n = 52) and placebo groups (n = 50). All parameters were measured before and after treatment. Serum VDBP levels were measured by ELISA method and VDR, GC (VDBP) gene expressions and relative telomere lengths were measured in peripheral blood mononuclear cells (PBMC) using a quantitative real-time PCR method. The results demonstrate that baseline levels were similar between the groups. After vitamin D supplementation 25(OH)D, 1,25(OH)2D, PTH and VDBP levels were changed significantly compared to the placebo group. At the end of the study period, LTL levels were significantly increased in both groups and this change was more prominent in placebo group. The change in GC expression was significant between treatment and placebo groups but VDR expression remained unchanged. Even though the study was designed to solely assess the effects of vitamin D supplementation, LTL was significantly increased in the whole study group in summer months suggesting that LTL levels are affected by sun exposure and seasonal changes rather than supplementation. The study displayed the short-term effect of Vitamin D supplementation on vitamin D, PTH levels, LTL and vitamin D associated gene expressions. The relation between Vitamin D and LTL is not linear and could be confounded by several factors such as the population differences, regional and seasonal changes in sun exposure.

Associations between Vitamin D, Omega 6:Omega 3 Ratio, and Biomarkers of Aging in Individuals Living with and without Chronic Pain

Elevated inflammatory cytokines and chronic pain are associated with shorter leukocyte telomere length (LTL), a measure of cellular aging. Micronutrients, such as 25-hydroxyvitamin D (vitamin D) and omega 3, have anti-inflammatory properties. Little is known regarding the relationships between vitamin D, omega 6:3 ratio, LTL, inflammation, and chronic pain. We investigate associations between vitamin D, omega 6:3 ratio, LTL, and C-reactive protein (CRP) in people living with/without chronic pain overall and stratified by chronic pain status. A cross-sectional analysis of 402 individuals (63% women, 79.5% with chronic pain) was completed. Demographic and health information was collected. Chronic pain was assessed as pain experienced for at least three months. LTL was measured in genomic DNA isolated from blood leukocytes, and micronutrients and CRP were measured in serum samples. Data were analyzed with general linear regression. Although an association between the continuous micronutrients and LTL was not observed, a positive association between omega 6:3 ratio and CRP was detected. In individuals with chronic pain, based on clinical categories, significant associations between vitamin D, omega 6:3 ratio, and CRP were observed. Findings highlight the complex relationships between anti-inflammatory micronutrients, inflammation, cellular aging, and chronic pain.

Association of Telomere Length and Serum Vitamin D Levels with Type 2 Diabetes Mellitus and its Related Complications: A Possible Future Perspective

Evidence show that shortened telomere length (TL) and low Vitamin D levels can increase the risk of type 2 diabetes mellitus (T2DM) and its associated complications. T2DM has been considered as an age-related disease, it may be associated with TL. The study aimed to evaluate the association of TL and Vitamin D levels with complications of T2DM and the impact of Vitamin D on TL in patients with T2DM. This 1-year cross-sectional study was conducted at a tertiary care hospital on 90 patients. Height, weight, body mass index, waist-hip ratio was calculated. Fasting blood sugars, postprandial blood sugar, and glycated hemoglobin (HbA1c) were analyzed. Absolute TL was obtained from quantitative real-time polymerase chain reaction (qPCR). Vitamin D estimation was done by chemiluminescent immunoassay. Descriptive analysis of the data was done using R i386 3.6.3. The study found a positive correlation between TL and Vitamin D levels (r = 0.64; P < 0.0001). The interaction with high HbA1c levels and lower levels of Vitamin D led to the shortening of TL (P = 0.0001). The median of TL and mean of Vitamin D levels were significantly less in the diabetic group (P < 0.0001). Vitamin D levels positively affected the TL and its levels had an inverse relation with the HbA1c levels. This association had a significant effect on the shortening of TL. Vitamin D also had a significant association with other diabetic complications that instigated the shortening of TL. Therefore, assessing the role of Vitamin D levels on the shortening of TL can prove to be crucial biomarkers in managing optimal glycemic levels in T2DM patients.

Telomere length as a biomarker of aging and diseases

As research related to healthspan and lifespan has become a hot topic, the necessity for a reliable and practical biomarker of aging (BoA), which can provide information about mortality and morbidity risk, along with remaining life expectancy, has increased. The chromosome terminus non-coding protective structure that prevents genomic instability is called a telomere. The continual shortening of telomeres, which affects their structure as well as function, is a hallmark of agedness. The aforementioned process is a potential cause of age-related diseases (ARDs), leading to a bad prognosis and a low survival rate, which compromise health and longevity. Hence, studies scrutinizing the BoAs often include telomere length (TL) as a prospective candidate. The results of these studies suggest that TL measurement can only provide an approximate appraisal of the aging rate, and its implementation into clinical practice and routine use as a BoA has many limitations and challenges. Nevertheless, measuring TL while determining other biomarkers can be used to assess biological age. This review focuses on the importance of telomeres in health, senescence, and diseases, as well as on summarizing the results and conclusions of previous studies evaluating TL as a potential BoA.

The Association between 25-Hydroxyvitamin D Concentration and Telomere Length in the Very-Old: The Newcastle 85+ Study

(1) Introduction: vitamin D may maintain the telomere length, either directly or via the inflammation effect and/or modulating the rate of cell proliferation. Whilst results from cross-sectional studies investigating the association between 25(OH)D concentration and telomere length have been mixed, there is a dearth of data from prospective studies which have assessed these associations. This study aimed to examine the association between 25(OH)D concentration in plasma and telomere length in blood cells in very-old adults (≥85 years old) at baseline, 18 months and 36 months by controlling for related lifestyle factors. (2) Methodology: our prospective cohort study comprised 775 participants from the Newcastle 85+ Study who had 25(OH)D measurements at baseline. Plasma 25(OH)D was stratified as <25 nmol/L (low), 25-50 nmol/L (moderate) and >50 nmol/L (high). Peripheral blood mononuclear cell telomere length was measured by quantitative real-time polymerase chain reaction at baseline, 18 and 36 months from baseline. (3) Results: a positive significant association was found between 25(OH)D concentration and telomere length amongst very-old participants at baseline (95% CI = 12.0-110.3, B = 61.2 ± 5.0, p = 0.015). This association was negative at 18 months (95% CI = -59.9--7.5, B = -33.7 ± 13.3, p = 0.012) but was non-significant at 36 months. (4) Conclusion: Circulating 25(OH)D concentration shows inconsistent relationships with telomere length over time in very-old (85+ year old) adults.

Vitamin D Supplementation Improves Cognitive Function Through Reducing Oxidative Stress Regulated by Telomere Length in Older Adults with Mild Cognitive Impairment: A 12-Month Randomized Controlled Trial

BACKGROUND

Cognitive decline in older adults is a serious public health problem today. Association between vitamin D supplementation and cognition remains controversial.

OBJECTIVE

To determine whether a 12-month vitamin D supplementation improves cognitive function in elderly subjects with mild cognitive impairment (MCI), and whether it is mediated through the mechanism in which telomere length (TL) regulate oxidative stress.

METHODS

This was a double-blind, randomized, placebo-controlled trial in Tianjin, China. Participants were all native Chinese speakers aged 65 years and older with MCI. 183 subjects were randomized to an intervention group (vitamin D 800 IU/day, n = 93) or a placebo group (the matching starch granules, n = 90), and followed up for 12 months. Tests of cognitive function and mechanism-related biomarkers were evaluated at baseline, 6 months, and 12 months.

RESULTS

Repeated-measures ANOVA showed substantial improvements in the full scale intelligence quotient (FSIQ), information, digit span, vocabulary, block design, and picture arrangement scores in the vitamin D group over the placebo group (p < 0.001). Leukocyte TL was significantly higher, while serum 8-OXO-dG, OGG1mRNA, and P16INK4amRNA revealed greater decreases in the vitamin D group over the placebo group (p < 0.001). According to mixed-model repeated-measures ANOVA analysis, vitamin D group showed a significant enhancement in the FSIQ score for 12 months compared with the control (estimate value = 5.132, p < 0.001).

CONCLUSION

Vitamin D supplementation for 12 months appears to improve cognitive function through reducing oxidative stress regulated by increased TL in order adults with MCI. Vitamin D may be a promising public health strategy to prevent cognitive decline.

Telomeres and Age-Related Diseases

Telomeres are at the non-coding ends of linear chromosomes. Through a complex 3-dimensional structure, they protect the coding DNA and ensure appropriate separation of chromosomes. Aging is characterized by a progressive shortening of telomeres, which compromises their structure and function. Because of their protective function for genomic DNA, telomeres appear to play an important role in the development and progression of many age-related diseases, such as cardiovascular disease (CVD), malignancies, dementia, and osteoporosis. Despite substantial evidence that links telomere length with these conditions, the nature of these observations remains insufficiently understood. Therefore, future studies should address the question of causality. Furthermore, analytical methods should be further improved with the aim to provide informative and comparable results. This review summarize the actual knowledge of telomere biology and the possible implications of telomere dysfunction for the development and progression of age-related diseases. Furthermore, we provide an overview of analytical techniques for the measurement of telomere length and telomerase activity.

Cellular Senescence and Vitamin D Deficiency Play a Role in the Pathogenesis of Obesity-Associated Subclinical Atherosclerosis: Study of the Potential Protective Role of Vitamin D Supplementation

The exact link between obesity, vitamin D deficiency, and their relation to cellular senescence in the pathogenesis of subclinical atherosclerosis is still under debate. Therefore, the current study aims to verify the possible role of vitamin D deficiency and cellular senescence in the pathogenesis of obesity-related subclinical atherosclerosis. Moreover, it aims to investigate the possible protective role of vitamin D supplementation. Fifty-seven male albino rats were enrolled in the study and classified into four groups: negative (10) and positive control groups (10), an obese model group (24), and a vitamin-D-supplemented obese group (13). Aortic tissue samples and fasting blood samples were collected. The following biochemical investigations were performed: serum cholesterol, triglycerides, HDL-C, LDL-C, ALT, AST, CPK, CK-MB, and hs-cTnt. HOMA-IR was calculated. Moreover, serum SMP-30, 25 (OH)Vitamin D3, and eNOS were determined by the ELISA technique. Aortic gene expression of eNOS, SMP-30, and P53 was estimated by real-time qRT-PCR. Serum 25(OH) D3 and SMP-30 were lower in the obese group. In addition, the obese group showed higher serum lipid profile, HOMA-IR, eNOS, ALT, AST, CPK, CK-MB, and hs-cTnt than the control groups, while decreased levels were found in the vitamin-D-treated obese group. Gene expression of eNOS and SMP-30 were in accordance with their serum levels. A positive correlation was found between vitamin D level and SMP-30. In conclusion, obesity is associated with vitamin D deficiency and enhanced cellular senescence. They could play a role in the pathogenesis of obesity-associated subclinical atherosclerosis and endothelial dysfunction. Vitamin D supplements could play a protective role against such obesity-related comorbidity.

Application of mesenchymal stem cell therapy for aging frailty: from mechanisms to therapeutics

Aging frailty is a complex geriatric syndrome that becomes more prevalent with advancing age. It constitutes a major health problem due to frequent adverse outcomes. Frailty is characterized by disruption of physiological homeostasis and progressive decline of health status. Multiple factors contribute to development of frailty with advancing age, including genome instability, DNA damage, epigenetic alternations, stem cell exhaustion, among others. These interrelated factors comprehensively result in loss of tissue homeostasis and diminished reserve capacity in frailty. Therefore, the aged organism gradually represents symptoms of frailty with decline in physiological functions of organs. Notably, the brain, cardiovascular system, skeletal muscle, and endocrine system are intrinsically interrelated to frailty. The patients with frailty may display the diminished reserves capacity of organ systems. Due to the complex pathophysiology, no specific treatments have been approved for prevention of this syndrome. At such, effective strategies for intervening in pathogenic process to improve health status of frail patients are highly needed. Recent progress in cell-based therapy has greatly contributed to the amelioration of degenerative diseases related to age. Mesenchymal stem cells (MSCs) can exert regenerative effects and possess anti-inflammatory properties. Transplantation of MSCs represents as a promising therapeutic strategy to address the pathophysiologic problems of frail syndrome. Currently, MSC therapy have undergone the phase I and II trials in human subjects that have endorsed the safety and efficacy of MSCs for aging frailty. However, despite these positive results, caution is still needed with regard to potential to form tumors, and further large-scale studies are warranted to confirm the therapeutic efficacy of MSC therapy.

Exposure to per- and polyfluoroalkyl substances and premature skin aging

Per- and polyfluoroalkyl substances (PFASs) are a ubiquitous group of persistent chemicals distributed globally in the environment. Skin aging is a notorious process that is prematurely induced by the interaction between endogenous and exogenous factors, including exposure to environmental chemicals. The existing evidence suggests that skin absorption of PFASs through dermal contact may be an important route of exposure to these chemicals in humans. On the other hand, PFASs intake by other routes may lead to PFASs bioaccumulation in the skin via tissue bio-distribution. Additionally, the presence of PFASs in consumer and cosmetic products combined with their daily close contact with the skin could render humans readily susceptible to dermal absorption. Therefore, chronic low-dose dermal exposure to PFASs can occur in the human population, representing another important route of exposure to these chemicals. Studies indicate that PFASs can threaten skin health and contribute to premature skin aging. Initiation of inflammatory-oxidative cascades, induction of DNA damage such as telomere shortening, dysregulation of genes engaged in dermal barrier integrity and its functions, signaling of the mitogen activated protein kinase (MAPK) pathway, and last but not least the down-regulation of extracellular matrix (ECM) components are among the most likely mechanisms by which PFASs can contribute to premature skin aging.

Serum and Dietary Folate and Vitamin B12 Levels Account for Differences in Cellular Aging: Evidence Based on Telomere Findings in 5581 U.S. Adults

Folate and vitamin B₁₂ are essential for a variety of metabolic processes. Both micronutrients have been shown to reduce oxidative stress significantly. The present cross-sectional investigation evaluated the association between serum and dietary folate and vitamin B₁₂ levels and leukocyte telomere length, an index of cellular aging influenced by oxidative stress. The study included 5581 adults from the National Health and Nutrition Examination Survey (NHANES). Because participants were randomly selected, results are generalizable to all civilian, noninstitutionalized U.S. adults. A blood draw provided DNA and serum folate and B₁₂ information. The quantitative polymerase chain reaction method was used to measure telomere length. The Bio-Rad Quantaphase II folate and vitamin B₁₂ radioassay kit was used to quantify levels of folate and vitamin B₁₂. Dietary folate and vitamin B₁₂ were assessed using a multipass 24 h recall. In some models, age, race, smoking pack-years, alcohol use, body mass index, total physical activity, hours fasted before the blood draw, and diabetes status were employed as covariates to minimize their influence. Findings showed that for each additional year of chronological age, telomeres were 15.6 base pairs shorter, on average (F = 378.8, p < 0.0001). Men had shorter telomeres than women after adjusting for all the covariates (F = 6.8, p = 0.0146). Serum (F = 10.5, p = 0.0030) and dietary (F = 5.0, p = 0.0325) folate concentrations were each linearly related to telomere length in women, but not in men, after controlling for age and race. Serum vitamin B₁₂ and telomere length had a nonsignificant, inverse relationship in women, with age and race controlled (F = 2.8, p = 0.1056), but no relation in men. Dietary vitamin B₁₂ was linearly related to telomere length in women, after adjusting for age and race (F = 4.3, p = 0.0468), but not in men. Overall, evidence indicates that folate and vitamin B₁₂ levels, especially folate, account for meaningful differences in cell aging in women, but not in men.

Vitamin D in physiological and pathological aging: Lesson from centenarians

Vitamin D is a secosteroid hormone that exerts a pleiotropic action on a wide spectrum of tissues, apparatuses and systems. Thus, vitamin D has assumed an increasingly dominant role as a key determinant of biological mechanisms and specific clinical conditions. Older people frequently present vitamin D deficiency, a status potentially influencing several mechanisms responsible for different age-related diseases. Centenarians symbolize the ideal model for investigating the peculiar traits of longevity, as they have reached an age close to the estimated limit of the human lifespan. Interestingly, despite the profound heterogeneity of centenarians in terms of health status, all these people share the same condition of severe vitamin D deficiency, suggesting that they may have implemented a number of adaptive strategies to cope with the age-related physiological derangement of vitamin D metabolism. The lesson deriving from centenarians' experience suggests that: i) severe vitamin D deficiency does not preclude the possibility of reaching extreme longevity, ii) strategies to prevent hypovitaminosis D may be useful to slow down the processes of "fragilization" occurring in aged people, iii) beneficial effects of vitamin D supplementation need to be confirmed regarding longevity.

Vitamin D Deficiency: Effects on Oxidative Stress, Epigenetics, Gene Regulation, and Aging

Recent advances in vitamin D research indicate that this vitamin, a secosteroid hormone, has beneficial effects on several body systems other than the musculoskeletal system. Both 25 dihydroxy vitamin D [25(OH)₂D] and its active hormonal form, 1,25-dihydroxyvitamin D [1,25(OH)₂D] are essential for human physiological functions, including damping down inflammation and the excessive intracellular oxidative stresses. Vitamin D is one of the key controllers of systemic inflammation, oxidative stress and mitochondrial respiratory function, and thus, the aging process in humans. In turn, molecular and cellular actions form 1,25(OH)₂D slow down oxidative stress, cell and tissue damage, and the aging process. On the other hand, hypovitaminosis D impairs mitochondrial functions, and enhances oxidative stress and systemic inflammation. The interaction of 1,25(OH)₂D with its intracellular receptors modulates vitamin D–dependent gene transcription and activation of vitamin D-responsive elements, which triggers multiple second messenger systems. Thus, it is not surprising that hypovitaminosis D increases the incidence and severity of several age-related common diseases, such as metabolic disorders that are linked to oxidative stress. These include obesity, insulin resistance, type 2 diabetes, hypertension, pregnancy complications, memory disorders, osteoporosis, autoimmune diseases, certain cancers, and systemic inflammatory diseases. Vitamin D adequacy leads to less oxidative stress and improves mitochondrial and endocrine functions, reducing the risks of disorders, such as autoimmunity, infections, metabolic derangements, and impairment of DNA repair; all of this aids a healthy, graceful aging process. Vitamin D is also a potent anti-oxidant that facilitates balanced mitochondrial activities, preventing oxidative stress-related protein oxidation, lipid peroxidation, and DNA damage. New understandings of vitamin D-related advances in metabolomics, transcriptomics, epigenetics, in relation to its ability to control oxidative stress in conjunction with micronutrients, vitamins, and antioxidants, following normalization of serum 25(OH)D and tissue 1,25(OH)₂D concentrations, likely to promise cost-effective better clinical outcomes in humans.

Activated carbon N-acetylcysteine microcapsule protects against nonalcoholic fatty liver disease in young rats via activating telomerase and inhibiting apoptosis

Non-alcoholic fatty liver disease (NAFLD) is becoming one of the world's most common chronic liver diseases in childhood, yet no therapy is available that has been approved by the food and drug administration (FDA). Previous studies have reported that telomere and telomerase are involved the development and progression of NAFLD. This study was designed to investigate the potential beneficial effects of activated carbon N-acetylcysteine (ACNAC) microcapsules on the development of NAFLD in young rats as well as the underlying mechanism(s) involved. Three-week old male Sprague Dawley rats were given high-fat diet (HFD) with/without ACNAC treatment for 7 consecutive weeks. Liver pathologies were determined by hematoxylin and eosin (H&E) and Oil Red O staining, as well as by changes in biochemical parameters of plasma alanine transaminase (ALT) and aspartate transaminase (AST) levels, respectively. Glucose homeostasis was evaluated by the glucose tolerance test and the liver telomere length and activity were measured by real time PCR and telomeric repeat amplification protocol (TRAP). Western blot analysis was performed to determine the expression level of Bcl-2, Bax and Caspase-3. Our results demonstrated that ACNAC supplementation improved liver pathologies of rats that received long-term HFD feeding. ACNAC supplementation prevented HFD-induced telomere shortening and improved telomerase activity. Moreover, in comparison to HFD-fed rats, ACNAC supplementation markedly increased the expression of Bcl-2, but significantly decreased the expression of Bax and Caspase-3 in juvenile rats. Together, these results indicate that ACNAC may be a promising choice for preventing and treating NAFLD among children.

Vitamin D deficiency accelerates ageing and age-related diseases: a novel hypothesis

Ageing can occur at different rates, but what controls this variable rate is unknown. Here I have developed a hypothesis that vitamin D may act to control the rate of ageing. The basis of this hypothesis emerged from studyng the various cellular processes that control ageing. These processes such as autophagy, mitochondrial dysfunction, inflammation, oxidative stress, epigenetic changes, DNA disorders and alterations in Ca²⁺ and reactive oxygen species (ROS) signalling are all known to be regulated by vitamin D. The activity of these processes will be enhanced in individuals that are deficient in vitamin D. Not only will this increase the rate of ageing, but it will also increase the probability of developing age-related diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis and cardiovascular disease. In individual with normal vitamin D levels, these ageing-related processes will occur at lower rates resulting in a reduced rate of ageing and enhanced protection against these age-related diseases.

Changes in vitamin D endocrinology during aging in adults

Worldwide, vitamin D deficiency is a common finding. Within individuals 25-hydroxyvitamin D (25OH)D) concentrations remain fairly stable over time although large differences in individual longitudinal changes exist. During aging vitamin D metabolism and activity changes in several different ways. Intestinal resistance to 1,25(OH)2D develops which hampers intestinal calcium uptake. Vitamin D receptor number decreases with aging in several organs involved in calcium metabolism and 1alpha-hydroxylase activity decreases mainly due to a decrease in renal function reducing vitamin D activation. Effects of 1,25(OH)2D on cell proliferation and differentiation may influence potential anti-cancer effects whereas regulation of telomere length may result in longevity. In older individuals, vitamin D supplementation has positive effects on fracture risk, number of falls and physical function. Supplementation in older populations warrants specific attention. Effects on "non-classical" outcomes may be revealed by ongoing large randomized clinical trials with high doses of vitamin D.

Leukocyte telomere length is linked to vascular risk factors not to Alzheimer's disease in the VITA study

Association of telomere shortening with overall dementia or Alzheimer's disease is described controversially and the pathophysiologic relevance is unclear. Whether patients, suffering from pure probable Alzheimer's disease or pure vascular dementia, have shorter leukocyte telomeres than cognitively healthy controls was determined. Leukocyte telomere lengths (LTLs) of 597 participants of the VITA study (longitudinal community-based age-cohort [mean 75.7 (±0.45) years] study: 243 male; 578 non-demented at baseline) were compared with different aspects of cognition, risk factors of dementia and survival. LTLs of 264 persons cognitively healthy at baseline (mild cognitive impaired excluded) and all follow-ups (mean = 5643 bp, SD = 736) did not show any difference to LTLs of 43 incident pure possible (mean = 5548 bp; SD = 666) or 34 incident pure probable Alzheimer's diseases (mean = 5712 bp; SD = 695; post hoc Dunnett test: MD = -95; SE = 119; p = 0.67 and MD =+68.3; SE = 132; p = 0.84, res.). 264 stably cognitively healthy showed a trend to longer telomeres than 6 incident vascular dementias (mean = 5643 bp, SD = 736 vs mean = 5101 bp, SD = 510; t test: T = 1.8; df = 268; p = 0.07). Males (n = 243; mean = 5470 bp; SD = 684) had significantly shorter telomeres than females (n = 354; mean = 5686 bp; SD = 714; t test: T = -3.7; df = 595; p = 0.0001) and died significantly earlier (113.7 vs 130.1 months: Log Rank Chi square = 12.2; p = 0.0001). Shorter telomeres were associated with prevalence of more than one vascular risk factor (n = 587; mean = 5728; SD = 723 vs mean = 5533; SD = 691; t test: T = 3.1; df = 576; p = 0.002) and, as a trend, with poorer survival (Cox Regression: Wald = 4.9; p = 0.026; OR = 0.98; 95% CI 0.96-0.99). In 75.7 years old persons, no association of LTL with incident pure Alzheimer's disease was found. Significantly shorter telomeres were associated with sum of vascular risk factors, males and early mortality in males. Exclusion of mixed dementias may improve the search for risk factors more specific for Alzheimer's disease.

Happily (n)ever after: Aging in the context of oxidative stress, proteostasis loss and cellular senescence

Aging is a complex phenomenon and its impact is becoming more relevant due to the rising life expectancy and because aging itself is the basis for the development of age-related diseases such as cancer, neurodegenerative diseases and type 2 diabetes. Recent years of scientific research have brought up different theories that attempt to explain the aging process. So far, there is no single theory that fully explains all facets of aging. The damage accumulation theory is one of the most accepted theories due to the large body of evidence found over the years. Damage accumulation is thought to be driven, among others, by oxidative stress. This condition results in an excess attack of oxidants on biomolecules, which lead to damage accumulation over time and contribute to the functional involution of cells, tissues and organisms. If oxidative stress persists, cellular senescence is a likely outcome and an important hallmark of aging. Therefore, it becomes crucial to understand how senescent cells function and how they contribute to the aging process. This review will cover cellular senescence features related to the protein pool such as morphological and molecular hallmarks, how oxidative stress promotes protein modifications, how senescent cells cope with them by proteostasis mechanisms, including antioxidant enzymes and proteolytic systems. We will also highlight the nutritional status of senescent cells and aged organisms (including human clinical studies) by exploring trace elements and micronutrients and on their importance to develop strategies that might increase both, life and health span and postpone aging onset.

Impact of vitamin D receptor polymorphisms in centenarians

Vitamin D is a seco-sterol produced endogenously in the skin or obtained from certain foods. It exerts its action through binding to intracellular vitamin D receptor (VDR). Lately, the role of vitamin D has been revised regarding its potential advantage on delaying the process of aging. The aim of this study was to assess the contribution of VDR gene polymorphisms in healthy aging and longevity. We evaluated the frequency of four polymorphisms of the VDR gene (FokI, BsmI, ApaI, and TaqI) in centenarians (102 subjects, mean age: 102.3 ± 0.3 years), compared to septuagenarians (163 subjects, mean age: 73.0 ± 0.6 years) and we analyzed a variety of pathophysiologically relevant functions in centenarians. BsmI and ApaI provided a significant association with longevity: there was a highly significant difference in the frequency of BsmI genotypes (p = 0.037), ApaI genotypes (p = 0.022), and ApaI alleles (p = 0.050) in centenarians versus septuagenarians. Furthermore, we found a significant correlation of all the VDR gene polymorphisms in centenarians with some measured variables such as hand grip strength, body mass index, blood pressure, HDL cholesterol, and mini-mental state examination. We also found a correlation with the prevalence of medical history of hypertension, acute myocardial infarction, angina, venous insufficiency, dementia, chronic obstructive pulmonary disease, and arthrosis. In conclusion, this study proposes a new scenario in which the variability of the VDR gene is relevant in the aging process and emphasizes the role of VDR genetic background in determining healthy aging.

Molecular and biological hallmarks of ageing

BACKGROUND

Ageing is the inevitable time-dependent decline in physiological organ function that eventually leads to death. Age is a major risk factor for many of the most common medical conditions, such as cardiovascular disease, cancer, diabetes and Alzheimer's disease. This study reviews currently known hallmarks of ageing and their clinical implications.

METHODS

A literature search of PubMed/MEDLINE was conducted covering the last decade.

RESULTS

Average life expectancy has increased dramatically over the past century and is estimated to increase even further. Maximum longevity, however, appears unchanged, suggesting a universal limitation to the human organism. Understanding the underlying molecular processes of ageing and health decline may suggest interventions that, if used at an early age, can prevent, delay, alleviate or even reverse age-related diseases. Hallmarks of ageing can be grouped into three main categories. The primary hallmarks cause damage to cellular functions: genomic instability, telomere attrition, epigenetic alterations and loss of proteostasis. These are followed by antagonistic responses to such damage: deregulated nutrient sensing, altered mitochondrial function and cellular senescence. Finally, integrative hallmarks are possible culprits of the clinical phenotype (stem cell exhaustion and altered intercellular communication), which ultimately contribute to the clinical effects of ageing as seen in physiological loss of reserve, organ decline and reduced function.

CONCLUSION

The sum of these molecular hallmarks produces the clinical picture of the elderly surgical patient: frailty, sarcopenia, anaemia, poor nutrition and a blunted immune response system. Improved understanding of the ageing processes may give rise to new biomarkers of risk or prognosis, novel treatment targets and translational approaches across disciplines that may improve outcomes.

Molecular mechanism of endothelial and vascular aging: implications for cardiovascular disease

Western societies are aging due to an increasing life span, decreased birth rates, and improving social and health conditions. On the other hand, the prevalence of cardiovascular (CV) and cerebrovascular (CBV) diseases rises with age. Thus, in view of the ongoing aging pandemic, it is appropriate to better understand the molecular pathways of aging as well as age-associated CV and CBV diseases. Oxidative stress contributes to aging of organs and the whole body by an accumulation of reactive oxygen species promoting oxidative damage. Indeed, increased oxidative stress produced in the mitochondria and cytosol of heart and brain is a common denominator to almost all CV and CBV diseases. The mitochondrial adaptor protein p66(Shc) and the family of deacetylase enzymes, the sirtuins, regulate the aging process, determine lifespan of many species and are involved in CV diseases. GDF11, a member of TGFβ superfamily with homology to myostatin also retards the aging process via yet unknown mechanisms. Recent evidence points towards a promising role of this novel 'rejuvenation' factor in reducing age-related heart disease. Finally, telomere length is also involved in aging and the development of age-related CV dysfunction. This review focuses on the latest scientific advances in understanding age-related changes of the CV and CBV system, as well as delineating potential novel therapeutic targets derived from aging research for CV and CBV diseases.