The Role of Vitamin D in the Aging Adult

The Role of Toll-Like Receptors and Vitamin D in Cardiovascular Diseases-A Review

Cardiovascular diseases are the leading cause of mortality worldwide. Therefore, a better understanding of their pathomechanisms and the subsequent implementation of optimal prophylactic and therapeutic strategies are of utmost importance. A growing body of evidence states that low-grade inflammation is a common feature for most of the cardiovascular diseases in which the contributing factors are the activation of toll-like receptors (TLRs) and vitamin D deficiency. In this article, available data concerning the association of cardiovascular diseases with TLRs and vitamin D status are reviewed, followed by a discussion of new possible approaches to cardiovascular disease management.

Vitamin D deficiency was common among nursing home residents and associated with dementia: a cross sectional study of 545 Swedish nursing home residents

Background

Residents of nursing homes may have low 25-hydroxyvitamin D (25OHD) concentrations. Associations between vitamin D and cognitive performance, dementia and susceptibility to infections are not clearly established. The aim of this study was to investigate the prevalence of vitamin D deficiency and to identify associated factors among residents of nursing homes for elderly.

Methods

In this cross-sectional study blood samples for analysis of 25OHD were collected from all participating residents of Swedish nursing homes for the elderly from January to March 2012.

Exclusion criteria: dementia too severe to collect a blood test, terminally ill or refusing participation. Outcome Measures: Serum 25OHD concentrations. Logistic regression to evaluate factors associated with vitamin D deficiency (25OHD < 25 nmol/L).

Results

Blood samples were obtained from 545 of 901 residents of 22 nursing homes. Mean age 86 years (SD 6.9), 68% were women. Prevalence of vitamin D supplementation 17%, dementia 55%, lack of appetite ≥3 months 45% and any antibiotic treatment during the last 6 months 30%. Serum 25OHD concentrations: mean 34 nmol/L (SD 21, median 27, range 4–125), 82% (448/545) had 25OHD < 50 nmol/L and 41% (224/545) had 25OHD < 25 nmol/L. Adjusted OR (95% CI; p-value) for possible predictors of vitamin D deficiency (25OHD < 25 nmol/L): vitamin D supplementation 0.075 (0.031–0.18; p < 0.001), lack of appetite ≥3 months 0.75 (0.50–1.1; p = 0.15), hours outdoors/week 0.99 (0.96–1.0; p = 0.62), Fitzpatrick skin phototype (4–6) 0.69 (0.44–1.1; p = 0.12); dementia 2.3 (1.5–3.4; p < 0.001) and antibiotics last 6 months 1.6 (1.1–2.6; p < 0.029), adjusted for age and gender.

Conclusions

Vitamin D deficiency was common among nursing home residents and strongly associated with dementia. Regardless of causality or not, it is important to be alert for vitamin D deficiency in nursing homes residents with dementia. As expected vitamin D supplementation was associated with less vitamin D deficiency, however lack of appetite, staying outdoors and skin phototype were not significant predictors. Antibiotic treatments during the last 6 months were associated with vitamin D deficiency, potentially supporting the hypothesis that vitamin D deficiency is associated with infections.

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.

Role of circulating factors in cardiac aging

Worldwide increase in life expectancy is a major contributor to the epidemic of chronic degenerative diseases. Aging, indeed, simultaneously affects multiple organ systems, and it has been hypothesized that systemic alterations in regulators of tissue physiology may regulate this process. Cardiac aging itself is a major risk factor for cardiovascular diseases and, because of the intimate relationship with the brain, may contribute to increase the risk of neurodegenerative disorders. Blood-borne factors may play a major role in this complex and still elusive process. A number of studies, mainly based on the revival of parabiosis, a surgical technique very popular during the 70s of the 20th century to study the effect of a shared circulation in two animals, have indeed shown the potential that humoral factors can control the aging process in different tissues. In this article we review the role of circulating factors in cardiovascular aging. A better understanding of these mechanisms may provide new insights in the aging process and provide novel therapeutic opportunities for chronic age-related disorders.

Effects of bioactive compounds on senescence and components of senescence associated secretory phenotypes in vitro

Senescence is a permanent cell cycle arrest that is accompanied by changes in cell morphology and physiology occurringin vitroandin vivo.

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.

Interaction of Vitamin D and Smoking on Inflammatory Markers in the Urban Elderly

Objectives:

Epidemiological studies have reported that vitamin D deficiency is associated with inflammatory disease. Smoking is a well-known risk factor for inflammation. However, few studies have investigated the interactive effect of vitamin D deficiency and smoking on inflammation. This study aims to investigate the interaction of vitamin D and smoking with inflammatory markers in the urban elderly.

Methods:

We used data from the Korean Elderly Environmental Panel Study, which began in August 2008 and ended in August 2010, and included 560 Koreans ≥60 years old living in Seoul. Data was collected via questionnaires that included items about smoking status at the first visit. Vitamin D levels, high-sensitivity C-reactive protein (hs-CRP), and white blood cell (WBC) counts were repeatedly measured up to three times.

Results:

The association of vitamin D and hs-CRP was significant after adjusting for known confounders (β=-0.080, p=0.041). After separate analysis by smoking status, the association of vitamin D deficiency and hs-CRP in smokers was stronger than that in nonsmokers (smokers: β=-0.375, p=0.013; non-smokers: β=-0.060, p=0.150). Smoking status was an effect modifier that changed the association between vitamin D deficiency and hs-CRP (interaction estimate: β=-0.254, p=0.032). Vitamin D was not significantly associated with WBC count (β=0.003, p=0.805).

Conclusions:

Vitamin D deficiency was associated with hs-CRP in the urban elderly. Smoking status was an effect modifier of this association. Vitamin D deficiency was not significantly associated with WBC count.

Discrepancy between Vitamin D Total Immunoassays due to Various Cross-reactivities

BACKGROUND

The purpose of this study was to find out the cause of discrepancy between various automated immunoassays for 25-hydroxy-vitamin D (25-[OH]D).

METHODS

National Institute of Standards & Technology Standard Reference Material (SRM) 972a is SRM for 25-(OH)D and consists of 4 vials of frozen serum with different concentrations of 25-(OH)D. Each concentration was measured 6 times in 3 different immunoassays: ADVIA Vitamin D Total assay (Siemens Healthcare, Erlangen, Germany), ARCHITECT 25-(OH)D (Abbott Laboratories, Abbott Park, IL, USA), and COBAS Vitamin D Total assay (Roche Diagnostics, Basel, Switzerland).

RESULTS

When using the certified reference values of SRM 972a as it is, discarding the cross-reactivity of each immunoassay, for ADVIA, the coefficient of determination (R(2)) as a score of regression analysis was 0.8995 and maximal difference between measured value and certified reference value was 3.6 ng/mL in level 3. The R(2) and maximal differences of ARCHITECT were 0.5377 and 6.9 ng/mL, respectively, in level 4. Those of COBAS were 0.3674 and 22.3 ng/mL, respectively, in level 4. When considering cross-reactivities of each immunoassays to various 25-(OH)D metabolites, the ADVIA had R(2) and maximal difference of 0.9254 and 3.3 ng/mL, respectively, in level 3. For ARCHITECT, the R(2) and maximal differences were 0.7602 and 5.1 ng/mL, respectively, in level 1. Those of COBAS were 0.9284 and 4.9 ng/mL, respectively, in level 1.

CONCLUSIONS

The cause of discrepancies between vitamin D immunoassays was mainly on the difference in cross-reactivities to various vitamin D metabolites. The discrepancies can be considerably decreased by considering cross-reactivities of each immunoassay.