Diet (zinc)–gene interaction related to inflammatory/immune response in ageing: possible link with frailty syndrome?

Dietary profiling of physical frailty in older age phenotypes using a machine learning approach: the Salus in Apulia Study

PURPOSE

Growing awareness of the biological and clinical value of nutrition in frailty settings calls for further efforts to investigate dietary gaps to act sooner to achieve focused management of aging populations. We cross-sectionally examined the eating habits of an older Mediterranean population to profile dietary features most associated with physical frailty.

METHODS

Clinical and physical examination, routine biomarkers, medical history, and anthropometry were analyzed in 1502 older adults (65 +). CHS criteria were applied to classify physical frailty, and a validated Food Frequency Questionnaire to assess diet. The population was subdivided by physical frailty status (frail or non-frail). Raw and adjusted logistic regression models were applied to three clusters of dietary variables (food groups, macronutrients, and micronutrients), previously selected by a LASSO approach to better predict diet-related frailty determinants.

RESULTS

A lower consumption of wine (OR 0.998, 95% CI 0.997-0.999) and coffee (OR 0.994, 95% CI 0.989-0.999), as well as a cluster of macro and micronutrients led by PUFAs (OR 0.939, 95% CI 0.896-0.991), zinc (OR 0.977, 95% CI 0.952-0.998), and coumarins (OR 0.631, 95% CI 0.431-0.971), was predictive of non-frailty, but higher legumes intake (OR 1.005, 95%CI 1.000-1.009) of physical frailty, regardless of age, gender, and education level.

CONCLUSIONS

Higher consumption of coffee and wine, as well as PUFAs, zinc, and coumarins, as opposed to legumes, may work well in protecting against a physical frailty profile of aging in a Mediterranean setting. Longitudinal investigations are needed to better understand the causal potential of diet as a modifiable contributor to frailty during aging.

Insights Into Pulp Biomineralization in Human Teeth

Introduction

Mineralized pulp (MP) compromises tooth function and its causation is unknown. The hypothesis of this study is that pulp mineralization is associated with pulpal tissue adaptation, increased mineral densities, and decreased permeabilities of tubular dentin and cementum. Methods will include correlative spatial mapping of physicochemical and biochemical characteristics of pulp, and contextualize these properties within the dentin-pulp complex (DPC) to reveal the inherent vunerabilities of pulp.

Methods

Specimens (N = 25) were scanned using micro X-ray computed tomography (micro-XCT) to visualize MP and measure mineral density (MD). Elemental spatial maps of MP were acquired using synchrotron X-ray fluorescence microprobe (μXRF) and energy dispersive X-ray spectroscopy (EDX). Extracted pulp tissues were sectioned for immunolabelling and the sections were imaged using a light microscope. Microscale morphologies and nanoscale ultrastructures of MP were imaged using scanning electron (SEM) and scanning transmission electron microscopy (STEM) techniques.

Results

Heterogeneous distribution of MD from 200 to 2,200 mg/cc, and an average MD of 892 (±407) mg/cc were observed. Highly mineralized pulp with increased number of occluded tubules, reduced pore diameter in cementum, and decreased connectivity in lateral channels were observed. H&E, trichrome, and von Kossa staining showed lower cell and collagen densities, and mineralized regions in pulp. The biomolecules osteopontin (OPN), osteocalcin (OCN), osterix (OSX), and bone sialoprotein (BSP) were immunolocalized around PGP 9.5 positive neurovascular bundles in MP. SEM and STEM revealed a wide range of nano/micro particulates in dentin tubules and spherulitic mineral aggregates in the collagen with intrafibrillar mineral surrounding neurovascular bundles. EDX and μXRF showed elevated counts of Ca, P, Mg, and Zn inside pulp and at the dentin-pulp interface (DPI) in the DPC.

Conclusion

Colocalization of physical and chemical, and biomolecular compositions in MP suggest primary and secondary biomineralization pathways in pulp and dentin at a tissue level, and altered fluid dynamics at an organ level. Elevated counts of Zn at the mineralizing front in MP indicated its role in pulp biomineralization. These observations underpin the inherent mechano- and chemo-responsiveness of the neurovascular DPC and help elucidate the clinical subtleties related to pulpitis, dentin-bridge, and pulp stone formation.

Association between serum zinc levels and basic physical functioning: secondary data analysis of NHANES 2011-14

Background

Serum zinc (Zn) levels have been shown to be associated with functional status; however, it is not clear whether this association differs by other sociodemographic characteristics. We examined the association between serum Zn levels and physical functioning difficulty in a representative sample of older adults in the US.

Design and methods

A cross-sectional study was conducted on participants 50 years and older from the 2011–12 and 2013–14 National Health and Nutrition Examination Surveys (n = 1136). Serum Zn levels were analyzed as tertiles. The main outcome of interest was physical functioning difficulty, defined as self-reported difficulty of basic physical functioning that included walking, transferring, dressing, and feeding.

Results

Mean Zn levels (SE) were 0.67(0.1), 0.81(0.1), and 0.98(0.1) μg/mL in the low, middle, and high Zn groups, respectively. Approximately 24.9% participants reported physical functioning difficulty. In the multivariable model, we found a significant multiplicative interaction between sex and serum Zn (P for interaction =0.028) and between education and serum Zn (P for interaction = 0.001) on basic physical functioning difficulty. The stratified analysis revealed that among men, compared to those with low serum Zn, the odds of having physical functioning difficulty were lower in men who had high serum Zn [aOR 0.43 (95% CI: 0.25–0.76)]. For women, compared to those with low serum Zn the odds of having physical functioning difficulty were higher in women who had middle serum Zn [aOR 2.67 (1.58–4.50)]. Among individuals with less than high school education, the odds of having physical functioning difficulty were lower in those who had middle serum Zn compared to those who had low serum Zn [aOR 0.48 (0.26–0.89)]. However, the odds of having physical functioning difficulty were higher in those who had middle serum Zn compared to those who had low serum Zn for individuals with high school [aOR 5.72 (1.92–17.00)] and beyond high school education [aOR 1.77 (1.05–2.97)], respectively.

Conclusion

Sex and educational attainment interact with serum Zn levels to influence basic physical functioning difficulty in older adults.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40795-021-00461-z.

Malnutrition in Older Adults-Recent Advances and Remaining Challenges

Malnutrition in older adults has been recognised as a challenging health concern associated with not only increased mortality and morbidity, but also with physical decline, which has wide ranging acute implications for activities of daily living and quality of life in general. Malnutrition is common and may also contribute to the development of the geriatric syndromes in older adults. Malnutrition in the old is reflected by either involuntary weight loss or low body mass index, but hidden deficiencies such as micronutrient deficiencies are more difficult to assess and therefore frequently overlooked in the community-dwelling old. In developed countries, the most cited cause of malnutrition is disease, as both acute and chronic disorders have the potential to result in or aggravate malnutrition. Therefore, as higher age is one risk factor for developing disease, older adults have the highest risk of being at nutritional risk or becoming malnourished. However, the aetiology of malnutrition is complex and multifactorial, and the development of malnutrition in the old is most likely also facilitated by ageing processes. This comprehensive narrative review summarizes current evidence on the prevalence and determinants of malnutrition in old adults spanning from age-related changes to disease-associated risk factors, and outlines remaining challenges in the understanding, identification as well as treatment of malnutrition, which in some cases may include targeted supplementation of macro- and/or micronutrients, when diet alone is not sufficient to meet age-specific requirements.

Frailty syndrome: A target for functional nutrients?

Frailty is a late life phenotype characterized by a decline in physiological reserve across several organ systems, resulting in the increased susceptibility to endogenous and/or exogenous stressors. Although the etiology of frailty remains poorly understood, an interconnected network of putative mechanisms linked to the ageing process has been proposed. However, frailty is a dynamic process that may be prevented, delayed, or even reversed. The syndromic nature of frailty requires a multidomain approach, such as proper nutrition, as part of modifiable environmental factors, and represents one of the most promising and least costly ways to prevent and reduce frailty among older adults. Nutrient deficiencies have been consistently associated with frailty; however, mounting evidence also supports the hypothesis that beyond the traditional nutritional value, specific dietary components may exert function-enhancing effects and mitigate the extent of frailty. Thus, further mechanistic studies, along with large clinical trials, are imperative to establish the exact role of functional nutrients in the clinical management of frailty. Here, we provide a contemporary discussion of how emerging functional nutrients may contribute to modify the trajectory of the frailty syndrome.

Carnitine Serum Levels in Frail Older Subjects

Frailty is an expression that reconciles and condenses loss of autonomy, both physical and cognitive decline and a wide spectrum of adverse outcomes due to aging. The decrease in physical and cognitive activity is associated with altered mitochondrial function, and energy loss and consequently morbidity and mortality. In this cross-sectional study, we evaluated the carnitine levels in frailty status. The mean serum concentrations of total carnitine (TC) were lower in frail elderly subjects than in prefrail ones (p = 0.0006), higher in frail vs. robust subjects (p < 0.0001), and higher in prefrail vs. robust subjects (p < 0.0001). The mean serum concentrations of free carnitine (FC) were lower in frail elderly subjects than in prefrail ones (p < 0.0001), lower in frail vs. robust subjects (p < 0.0001) and lower in prefrail vs. robust subjects (p = 0.0009). The mean serum concentrations of acylcarnitine (AC) were higher in frail elderly subjects than in prefrail ones (p = 0.054) and were higher in pre-frail vs. robust subjects (p = 0.0022). The mean urine concentrations of TC were lower in frail elderly subjects than in prefrail ones (p < 0.05) and lower in frail vs. robust subjects (p < 0.0001). The mean urine concentrations of free carnitine were lower in frail elderly vs. robust subjects (p < 0.05). The mean urine concentrations of acyl carnitines were lower in frail elderly subjects than those in both prefrail (p < 0.0001) and robust subjects (p < 0.0001). Conclusion: high levels of carnitine may have a favorable effect on the functional status and may treat the frailty status in older subjects.

Zinc, aging, and immunosenescence: an overview

Zinc plays an essential role in many biochemical pathways and participates in several cell functions, including the immune response. This review describes the role of zinc in human health, aging, and immunosenescence. Zinc deficiency is frequent in the elderly and leads to changes similar to those that occur in oxidative inflammatory aging (oxi-inflamm-aging) and immunosenescence. The possible benefits of zinc supplementation to enhance immune function are discussed.

Cu to Zn ratio, physical function, disability, and mortality risk in older elderly (ilSIRENTE study)

Associations between copper to zinc ratio (CZr) and mortality have suggested CZr as a biomarker of aging. Nevertheless, very limited data exist on the association between serum CZr and physical or functional status of very old people. We examined the relationship between serum CZr and physical performance, muscle strength, functional status, and survival from the ilSIRENTE Study: a longitudinal study of persons aged 80 years or older (n = 346). An adjusted linear regression model was subsequently performed to calculate the regression coefficients of the associations between baseline physical and functional measures (dependent variable) with CZr or "Cu and Zn" alone taking also into account the influence of other relevant factors, including hematological (albumin, cholesterol, and urea) and inflammatory biomarkers (IL-6 and CRP) that were significantly different across CZr tertiles. CZr showed significant and stronger relationships than Cu or Zn alone with all baseline physical and functional measures in models that did not include adjustments for inflammatory parameters. CZr was also associated with physical decline, measured as "SPPB% decline" at 2 years of follow-up and mortality at 4 years of follow-up. Subjects in the high CZr tertile had a higher risk of death with an adjusted hazard ratio of 1.92 (95% CI, 1.12-3.29; p = 0.02). In conclusion, we have confirmed the role of CZr as a predictor of mortality, whereas the role of CZr as a biomarker or predictor of physical or functional performance seems to be the consequence of its strict relationships with inflammatory parameters. In this context, further investigations need to be carried out.

The frailty syndrome: a comprehensive review

The frailty syndrome is defined as unintentional weight and muscle loss, exhaustion, and declines in grip strength, gait speed, and activity. Evidence with respect to the clinical definition, epidemiology, mechanisms, interactions, assessment, prevention, and treatment of frailty in the older adult is reviewed.