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Sustaining an ageing population: the role of micronutrients in frailty and cognitive impairment.
O'Connor, D, Molloy, AM, Laird, E, Kenny, RA, O'Halloran, AM
The Proceedings of the Nutrition Society. 2023;(3):315-328
Abstract
Age-related frailty and cognitive decline are complex multidimensional conditions that significantly impact the ability of older adults to sustain functional capacity and independence. While underlying causes remain poorly understood, nutrition continually emerges as one associated risk element. Many studies have addressed the importance of adequate nutrition in delaying the onset of these conditions, but the specific role of micronutrients is not well established. The consideration of pre-frailty as an outcome variable is also limited in the current literature. In this review, we focus on the potential value of maintaining micronutrient sufficiency to sustaining the health of the ageing population. Using data from the Irish longitudinal study on ageing, we consider several vitamins known to have a high prevalence of low status in older adults and their impact on pre-frailty, frailty and cognitive impairment. They include vitamin B12 and folate, both of which are associated with multiple biological mechanisms involved in long-term health, in particular in cognitive function; vitamin D, which has been associated with increased risk of musculoskeletal disorders, depression and other chronic diseases; and the carotenoids, lutein and zeaxanthin, that may help mitigate the risk of frailty and cognitive decline via their antioxidant and anti-inflammatory properties. We show that low concentrations of folate and carotenoids are implicated in poorer cognitive health and that the co-occurrence of multiple nutrient deficiencies confers greatest risk for frailty and pre-frailty in the Irish longitudinal study on ageing cohort. These health associations contribute to evidence needed to optimise micronutrient status for health in the older adult population.
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Towards a consensus definition of allostatic load: a multi-cohort, multi-system, multi-biomarker individual participant data (IPD) meta-analysis.
McCrory, C, McLoughlin, S, Layte, R, NiCheallaigh, C, O'Halloran, AM, Barros, H, Berkman, LF, Bochud, M, M Crimmins, E, T Farrell, M, et al
Psychoneuroendocrinology. 2023;:106117
Abstract
BACKGROUND Allostatic load (AL) is a multi-system composite index for quantifying physiological dysregulation caused by life course stressors. For over 30 years, an extensive body of research has drawn on the AL framework but has been hampered by the lack of a consistent definition. METHODS This study analyses data for 67,126 individuals aged 40-111 years participating in 13 different cohort studies and 40 biomarkers across 12 physiological systems: hypothalamic-pituitary-adrenal (HPA) axis, sympathetic-adrenal-medullary (SAM) axis, parasympathetic nervous system functioning, oxidative stress, immunological/inflammatory, cardiovascular, respiratory, lipidemia, anthropometric, glucose metabolism, kidney, and liver. We use individual-participant-data meta-analysis and exploit natural heterogeneity in the number and type of biomarkers that have been used across studies, but a common set of health outcomes (grip strength, walking speed, and self-rated health), to determine the optimal configuration of parameters to define the concept. RESULTS There was at least one biomarker within 9/12 physiological systems that was reliably and consistently associated in the hypothesised direction with the three health outcomes in the meta-analysis of these cohorts: dehydroepiandrosterone sulfate (DHEAS), low frequency-heart rate variability (LF-HRV), C-reactive protein (CRP), resting heart rate (RHR), peak expiratory flow (PEF), high density lipoprotein cholesterol (HDL-C), waist-to-height ratio (WtHR), HbA1c, and cystatin C. An index based on five biomarkers (CRP, RHR, HDL-C, WtHR and HbA1c) available in every study was found to predict an independent outcome - mortality - as well or better than more elaborate sets of biomarkers. DISCUSSION This study has identified a brief 5-item measure of AL that arguably represents a universal and efficient set of biomarkers for capturing physiological 'wear and tear' and a further biomarker (PEF) that could usefully be included in future data collection.
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Plasma lutein and zeaxanthin concentrations associated with musculoskeletal health and incident frailty in The Irish Longitudinal Study on Ageing (TILDA).
Murphy, CH, Duggan, E, Davis, J, O'Halloran, AM, Knight, SP, Kenny, RA, McCarthy, SN, Romero-Ortuno, R
Experimental gerontology. 2023;:112013
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Abstract
INTRODUCTION Lutein and zeaxanthin are diet-derived carotenoids that are proposed to help mitigate frailty risk and age-related declines in musculoskeletal health via their anti-oxidant and anti-inflammatory properties. Therefore, this study aimed to investigate the association between lutein and zeaxanthin status and indices of musculoskeletal health and incident frailty among community-dwelling adults aged ≥50 years in the Irish Longitudinal Study on Ageing (TILDA). METHODS Cross-sectional analyses (n = 4513) of plasma lutein and zeaxanthin concentrations and grip strength, usual gait speed, timed up-and-go (TUG), probable sarcopenia (defined as grip strength <27 kg in men, <16 kg in women), and bone mass (assessed using calcaneal broadband ultrasound stiffness index) were performed at Wave 1 (2009-2011; baseline). In the longitudinal analyses (n = 1425-3100), changes in usual gait speed (at Wave 3, 2014-2015), grip strength (Wave 4, 2016) and TUG (at Wave 5, 2018), incident probable sarcopenia (at Wave 4) and incident frailty (Fried's phenotype, Frailty Index, FRAIL Scale, Clinical Frailty Scale-classification tree, at Wave 5) were determined. Data were analysed using linear and ordinal logistic regression, adjusted for confounders. RESULTS Cross-sectionally, plasma lutein and zeaxanthin concentrations were positively associated with usual gait speed (B [95 % CI] per 100-nmol/L higher concentration: Lutein 0.59 [0.18, 1.00], Zeaxanthin 1.46 [0.37, 2.55] cm/s) and inversely associated with TUG time (Lutein -0.07 [-0.11, -0.03], Zeaxanthin -0.14 [-0.25, -0.04] s; all p < 0.01), but not with grip strength or probable sarcopenia (p > 0.05). Plasma lutein concentration was positively associated with bone stiffness index (0.54 [0.15, 0.93], p < 0.01). Longitudinally, among participants who were non-frail at Wave 1, higher plasma lutein and zeaxanthin concentrations were associated lower odds of progressing to a higher frailty category (e.g. prefrailty or frailty) by Wave 5 (ORs 0.57-0.89, p < 0.05) based on the Fried's phenotype, FRAIL Scale and the Clinical Frailty Scale, and in the case of zeaxanthin, Frailty Index. Neither plasma lutein nor zeaxanthin concentrations were associated with changes in musculoskeletal indices or incident probable sarcopenia (p > 0.05). CONCLUSION Higher plasma lutein and zeaxanthin concentrations at baseline were associated with a reduced likelihood of incident frailty after ~8 years of follow up. Baseline plasma lutein and zeaxanthin concentrations were also positively associated with several indices of musculoskeletal health cross-sectionally but were not predictive of longitudinal changes in these outcomes over 4-8 years.
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Vitamin D and COVID-19-Revisited.
Subramanian, S, Griffin, G, Hewison, M, Hopkin, J, Kenny, RA, Laird, E, Quinton, R, Thickett, D, Rhodes, JM
Journal of internal medicine. 2022;(4):604-626
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Abstract
Vitamin D, when activated to 1,25-dihydroxyvitamin D, is a steroid hormone that induces responses in several hundred genes, including many involved in immune responses to infection. Without supplementation, people living in temperate zones commonly become deficient in the precursor form of vitamin D, 25-hydroxyvitamin D, during winter, as do people who receive less sunlight exposure or those with darker skin pigmentation. Studies performed pre-COVID-19 have shown significant but modest reduction in upper respiratory infections in people receiving regular daily vitamin D supplementation. Vitamin D deficiency, like the risk of severe COVID-19, is linked with darker skin colour and also with obesity. Greater risk from COVID-19 has been associated with reduced ultraviolet exposure. Various studies have examined serum 25-hydroxyvitamin D levels, either historical or current, in patients with COVID-19. The results of these studies have varied but the majority have shown an association between vitamin D deficiency and increased risk of COVID-19 illness or severity. Interventional studies of vitamin D supplementation have so far been inconclusive. Trial protocols commonly allow control groups to receive low-dose supplementation that may be adequate for many. The effects of vitamin D supplementation on disease severity in patients with existing COVID-19 are further complicated by the frequent use of large bolus dose vitamin D to achieve rapid effects, even though this approach has been shown to be ineffective in other settings. As the pandemic passes into its third year, a substantial role of vitamin D deficiency in determining the risk from COVID-19 remains possible but unproven.
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Title: Understanding a Low Vitamin D State in the Context of COVID-19.
Walsh, JB, McCartney, DM, Laird, É, McCarroll, K, Byrne, DG, Healy, M, O'Shea, PM, Kenny, RA, Faul, JL
Frontiers in pharmacology. 2022;:835480
Abstract
While a low vitamin D state has been associated with an increased risk of infection by SARS-CoV-2 in addition to an increased severity of COVID-19 disease, a causal role is not yet established. Here, we review the evidence relating to i) vitamin D and its role in SARS-CoV-2 infection and COVID-19 disease ii) the vitamin D status in the Irish adult population iii) the use of supplemental vitamin D to treat a deficient status and iv) the application of the Bradford-Hill causation criteria. We conclude that reverse causality probably makes a minimal contribution to the presence of low vitamin D states in the setting of COVID-19. Applying the Bradford-Hill criteria, however, the collective literature supports a causal association between low vitamin D status, SARS-CoV-2 infection, and severe COVID-19 (respiratory failure, requirement for ventilation and mortality). A biologically plausible rationale exists for these findings, given vitamin D's role in immune regulation. The thresholds which define low, deficient, and replete vitamin D states vary according to the disease studied, underscoring the complexities for determining the goals for supplementation. All are currently unknown in the setting of COVID-19. The design of vitamin D randomised controlled trials is notoriously problematic and these trials commonly fail for a number of behavioural and methodological reasons. In Ireland, as in most other countries, low vitamin D status is common in older adults, adults in institutions, and with obesity, dark skin, low UVB exposure, diabetes and low socio-economic status. Physiological vitamin D levels for optimal immune function are considerably higher than those that can be achieved from food and sunlight exposure alone in Ireland. A window exists in which a significant number of adults could benefit from vitamin D supplementation, not least because of recent data demonstrating an association between vitamin D status and COVID-19. During the COVID pandemic, we believe that supplementation with 20-25ug (800-1000 IU)/day or more may be required for adults with apparently normal immune systems to improve immunity against SARS-CoV-2. We expect that higher monitored doses of 37.5-50 ug (1,500-2,000)/day may be needed for vulnerable groups (e.g., those with obesity, darker skin, diabetes mellitus and older adults). Such doses are within the safe daily intakes cited by international advisory agencies.
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Perspective: Vitamin D deficiency and COVID-19 severity - plausibly linked by latitude, ethnicity, impacts on cytokines, ACE2 and thrombosis.
Rhodes, JM, Subramanian, S, Laird, E, Griffin, G, Kenny, RA
Journal of internal medicine. 2021;(1):97-115
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BACKGROUND SARS-CoV-2 coronavirus infection ranges from asymptomatic through to fatal COVID-19 characterized by a 'cytokine storm' and lung failure. Vitamin D deficiency has been postulated as a determinant of severity. OBJECTIVES To review the evidence relevant to vitamin D and COVID-19. METHODS Narrative review. RESULTS Regression modelling shows that more northerly countries in the Northern Hemisphere are currently (May 2020) showing relatively high COVID-19 mortality, with an estimated 4.4% increase in mortality for each 1 degree latitude north of 28 degrees North (P = 0.031) after adjustment for age of population. This supports a role for ultraviolet B acting via vitamin D synthesis. Factors associated with worse COVID-19 prognosis include old age, ethnicity, male sex, obesity, diabetes and hypertension and these also associate with deficiency of vitamin D or its response. Vitamin D deficiency is also linked to severity of childhood respiratory illness. Experimentally, vitamin D increases the ratio of angiotensin-converting enzyme 2 (ACE2) to ACE, thus increasing angiotensin II hydrolysis and reducing subsequent inflammatory cytokine response to pathogens and lung injury. CONCLUSIONS Substantial evidence supports a link between vitamin D deficiency and COVID-19 severity but it is all indirect. Community-based placebo-controlled trials of vitamin D supplementation may be difficult. Further evidence could come from study of COVID-19 outcomes in large cohorts with information on prescribing data for vitamin D supplementation or assay of serum unbound 25(OH) vitamin D levels. Meanwhile, vitamin D supplementation should be strongly advised for people likely to be deficient.
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Perspective: Vitamin D supplementation prevents rickets and acute respiratory infections when given as daily maintenance but not as intermittent bolus: implications for COVID-19.
Griffin, G, Hewison, M, Hopkin, J, Kenny, RA, Quinton, R, Rhodes, J, Subramanian, S, Thickett, D
Clinical medicine (London, England). 2021;(2):e144-e149
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The value of vitamin D supplementation in the treatment or prevention of various conditions is often viewed with scepticism as a result of contradictory results of randomised trials. It is now becoming apparent that there is a pattern to these inconsistencies. A recent large trial has shown that high-dose intermittent bolus vitamin D therapy is ineffective at preventing rickets - the condition that is most unequivocally caused by vitamin D deficiency. There is a plausible biological explanation since high-dose bolus replacement induces long-term expression of the catabolic enzyme 24-hydroxylase and fibroblast growth factor 23, both of which have vitamin D inactivating effects. Meta-analyses of vitamin D supplementation in prevention of acute respiratory infection and trials in tuberculosis and other conditions also support efficacy of low dose daily maintenance rather than intermittent bolus dosing. This is particularly relevant during the current COVID-19 pandemic given the well-documented associations between COVID-19 risk and vitamin D deficiency. We would urge that clinicians take note of these findings and give strong support to widespread use of daily vitamin D supplementation.
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Investigating the Relationship between Vitamin D and Persistent Symptoms Following SARS-CoV-2 Infection.
Townsend, L, Dyer, AH, McCluskey, P, O'Brien, K, Dowds, J, Laird, E, Bannan, C, Bourke, NM, Ní Cheallaigh, C, Byrne, DG, et al
Nutrients. 2021;13(7)
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Plain language summary
Persistence of symptoms following COVID-19 infection is known as long COVID and occurs in up to a third of sufferers and can last for as long as 6 months post infection. Tiredness and reduced capacity to exercise are characteristic of long COVID, however why these symptoms persist in a handful of patients is unknown. Vitamin D deficiency is gaining attention for its potential to improve symptoms of tiredness, however there are few studies examining its relationship with long COVID. This observational study of 149 patients who had been diagnosed with COVID-19 aimed to determine the relationship between symptoms of long COVID, inflammation in the body and vitamin D levels. The results showed that fatigue was common, but there was no association between vitamin D levels and fatigue, inflammation, or capacity to exercise. Interestingly women were more likely to experience fatigue in this study. It was concluded that fatigue and reduced exercise capacity are independent of vitamin D in those who have had COVID-19. This study could be used by healthcare professionals to understand symptoms of long COVID, and that vitamin D may not be effective for those symptoms.
Abstract
The emergence of persistent symptoms following SARS-CoV-2 infection, known as long COVID, is providing a new challenge to healthcare systems. The cardinal features are fatigue and reduced exercise tolerance. Vitamin D is known to have pleotropic effects far beyond bone health and is associated with immune modulation and autoimmunity. We hypothesize that vitamin D levels are associated with persistent symptoms following COVID-19. Herein, we investigate the relationship between vitamin D and fatigue and reduced exercise tolerance, assessed by the Chalder Fatigue Score, six-minute walk test and modified Borg scale. Multivariable linear and logistic regression models were used to evaluate the relationships. A total of 149 patients were recruited at a median of 79 days after COVID-19 illness. The median vitamin D level was 62 nmol/L, with n = 36 (24%) having levels 30-49 nmol/L and n = 14 (9%) with levels <30 nmol/L. Fatigue was common, with n = 86 (58%) meeting the case definition. The median Borg score was 3, while the median distance covered for the walk test was 450 m. No relationship between vitamin D and the measures of ongoing ill-health assessed in the study was found following multivariable regression analysis. These results suggest that persistent fatigue and reduced exercise tolerance following COVID-19 are independent of vitamin D.
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Preventing vitamin D deficiency during the COVID-19 pandemic: UK definitions of vitamin D sufficiency and recommended supplement dose are set too low.
Griffin, G, Hewison, M, Hopkin, J, Kenny, RA, Quinton, R, Rhodes, J, Subramanian, S, Thickett, D
Clinical medicine (London, England). 2021;(1):e48-e51
Abstract
There is growing evidence linking vitamin D deficiency with risk of COVID-19. It is therefore distressing that there is major disagreement about the optimal serum level for 25-hydroxyvitamin D (25(OH)D) and appropriate supplement dose. The UK Scientific Advisory Committee for Nutrition has set the lowest level for defining sufficiency (10 ng/ml or 25 nmol/L) of any national advisory body or scientific society and consequently recommends supplementation with 10 micrograms (400 IU) per day. We have searched for published evidence to support this but not found it. There is considerable evidence to support the higher level for sufficiency (20 ng/ml or 50 nmol/L) recommended by the European Food Safety Authority and the American Institute of Medicine and hence greater supplementation (20 micrograms or 800 IU per day). Serum 25(OH)D concentrations in the UK typically fall by around 50% through winter. We believe that governments should urgently recommend supplementation with 20-25 micrograms (800-1,000 IU) per day.
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Evaluation of Clinical Practice Guidelines on Fall Prevention and Management for Older Adults: A Systematic Review.
Montero-Odasso, MM, Kamkar, N, Pieruccini-Faria, F, Osman, A, Sarquis-Adamson, Y, Close, J, Hogan, DB, Hunter, SW, Kenny, RA, Lipsitz, LA, et al
JAMA network open. 2021;(12):e2138911
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Abstract
IMPORTANCE With the global population aging, falls and fall-related injuries are ubiquitous, and several clinical practice guidelines for falls prevention and management for individuals 60 years or older have been developed. A systematic evaluation of the recommendations and agreement level is lacking. OBJECTIVES To perform a systematic review of clinical practice guidelines for falls prevention and management for adults 60 years or older in all settings (eg, community, acute care, and nursing homes), evaluate agreement in recommendations, and identify potential gaps. EVIDENCE REVIEW A systematic review following Preferred Reporting Items for Systematic Reviews and Meta-analyses statement methods for clinical practice guidelines on fall prevention and management for older adults was conducted (updated July 1, 2021) using MEDLINE, PubMed, PsycINFO, Embase, CINAHL, the Cochrane Library, PEDro, and Epistemonikos databases. Medical Subject Headings search terms were related to falls, clinical practice guidelines, management and prevention, and older adults, with no restrictions on date, language, or setting for inclusion. Three independent reviewers selected records for full-text examination if they followed evidence- and consensus-based processes and assessed the quality of the guidelines using Appraisal of Guidelines for Research & Evaluation II (AGREE-II) criteria. The strength of the recommendations was evaluated using Grades of Recommendation, Assessment, Development, and Evaluation scores, and agreement across topic areas was assessed using the Fleiss κ statistic. FINDINGS Of 11 414 records identified, 159 were fully reviewed and assessed for eligibility, and 15 were included. All 15 selected guidelines had high-quality AGREE-II total scores (mean [SD], 80.1% [5.6%]), although individual quality domain scores for clinical applicability (mean [SD], 63.4% [11.4%]) and stakeholder (clinicians, patients, or caregivers) involvement (mean [SD], 76.3% [9.0%]) were lower. A total of 198 recommendations covering 16 topic areas in 15 guidelines were identified after screening 4767 abstracts that proceeded to 159 full texts. Most (≥11) guidelines strongly recommended performing risk stratification, assessment tests for gait and balance, fracture and osteoporosis management, multifactorial interventions, medication review, exercise promotion, environment modification, vision and footwear correction, referral to physiotherapy, and cardiovascular interventions. The strengths of the recommendations were inconsistent for vitamin D supplementation, addressing cognitive factors, and falls prevention education. Recommendations on use of hip protectors and digital technology or wearables were often missing. None of the examined guidelines included a patient or caregiver panel in their deliberations. CONCLUSIONS AND RELEVANCE This systematic review found that current clinical practice guidelines on fall prevention and management for older adults showed a high degree of agreement in several areas in which strong recommendations were made, whereas other topic areas did not achieve this level of consensus or coverage. Future guidelines should address clinical applicability of their recommendations and include perspectives of patients and other stakeholders.