Antioxidant vitamins and mortality in older persons: findings from the nutrition add-on study to the Medical Research Council Trial of Assessment and Management of Older People in the Community

Exploring the impact of age, and body condition score on erythrocytic B1-Dependent transketolase activity in cats: A comprehensive analysis of thiamine status

One of the key factors influencing aging and morbidity is the overall antioxidant status and regenerative capacity. In examining contributors to the antioxidant status, we analyzed the thiamine status in felines and the influence of age, gender, and body condition score. We measured erythrocytic B1-dependent specific transketolase (STKT) activity, an enzyme in the pentose phosphate pathway, in a group of 60 sexually intact, healthy, and specific pathogen-free felines (44 females, 16 males, aged 1-17 years) with thiamine diphosphate (TDP; 0.3 and 3 mM) and without it. Only two parameters (STKT activity with and without 0.3 mM TDP) decreased with age. After adjusting for age, statistical thresholds were established using these and other age-independent parameters, identifying 15 felines with subclinical thiamine deficiency. The red blood cell proteomics analysis revealed that the pentose phosphate shunt, glycolysis, and oxidative stress response were the most affected pathways in deficient felines, confirming the above diagnosis. Age emerged as the primary factor associated with thiamine deficiency, supported by the enrichment of neurodegenerative diseases with a proteotoxicity component; five young-adult felines showed marginal or acute B1 deficiency, and six were adult-mature with a more chronic deficiency, possibly linked to cognitive decline, all with an underweight to ideal body condition scores. Only three senior-adult felines were deficient and overweight-obese. Detecting thiamine deficiency emphasizes the need for more accurate reference values, the establishment of advanced preventive or therapeutic measures to enhance the well-being of aging companion animals, and potential extensions to human health, particularly concerning cognitive function.

Associations between serum retinol and all-cause mortality among adults with prediabetes and diabetes: A cohort study

We aimed to explore the associations between serum retinol and all-cause mortality among people with prediabetes and diabetes. The study included 2582 participants with prediabetes and 1654 with diabetes aged ≥40 years from the National Health and Nutrition Examination Survey 2001-2006. Serum retinol was collected from laboratory tests and categorized into five groups, including <50, 50-60, 60-70, 70-80, and ≥80 μg/dL. Deaths were obtained by linkage to National Death Index up to December 31, 2019. Cox proportional hazards models were used to estimate the associations between serum retinol and all-cause mortality. During the follow-up, 993 participants with prediabetes died and 874 participants with diabetes died. There were U-shaped associations between serum retinol and mortality among participants with prediabetes and diabetes, separately. Among participants with prediabetes, compared to serum retinol levels of 50-60 μg/dL, the hazard ratio (HR) (95% confidence interval [CI]) of mortality was 1.40 (95% CI 1.11 to 1.76) and 1.26 (95% CI 1.00 to 1.57) for serum retinol <50 or ≥80 μg/dL, respectively. Among participants with diabetes, compared to serum retinol levels of 50-60 μg/dL, the hazard ratio (HR) (95% confidence interval [CI]) of mortality was 1.25 (95% CI 0.96 to 1.62) and 1.21 (95% CI 0.91 to 1.62) for serum retinol <50 or ≥80 μg/dL, respectively. The U-shaped associations between serum retinol and mortality still existed among participants aged ≥60 years with prediabetes or diabetes but were not statistically significant among those aged 40-59 years with prediabetes or diabetes. In conclusion, both low and excessive serum retinol tended to be with higher mortality risk among people with abnormal blood glucose.

Associations of serum vitamin C concentrations with risk of all-cause and cause-specific mortality among individuals with and without type 2 diabetes

PURPOSE

Compared with people without diabetes, people with type 2 diabetes (T2D) are at higher risk of both subnormal vitamin C status and increased oxidative stress. We aimed to investigate the associations of serum vitamin C concentrations with all-cause and cause-specific mortality among adults with and without T2D.

METHODS

The current analysis included 20,045 adults (2691 people with T2D and 17,354 without T2D) from the Third National Health and Nutrition Examination Survey (NHANES III) and NHANES 2003-2006. Cox proportional hazards regression models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Restricted cubic spline analyses were used to examine the dose-response relationship.

RESULTS

After a median follow-up of 17.3 years, 5211 deaths were documented. Individuals with T2D had a lower level of serum vitamin C concentrations compared with those without T2D (the median value: 40.1 vs. 44.9 μmol/L). Furthermore, the dose-response relationship between serum vitamin C and mortality showed different patterns between participants with and without T2D. In individuals without T2D, there was a nonlinear association of serum vitamin C concentrations with all-cause, cancer, and CVD mortality, with the lowest risk around a serum vitamin C concentration of 48.0 μmol/L (all Poverall < 0.05, Pnonlinearity < 0.05). In contrast, among those with T2D in the similar concentration range, higher serum vitamin C levels (ranged from 0.46 to 116.26 μmol/L) were linearly associated with lower all-cause and cancer mortality (both Poverall < 0.05, Pnonlinearity > 0.05). Significant additive interaction was observed between diabetes status and serum vitamin C levels with regard to all-cause and cancer mortality (P < 0.001). In addition, C-reactive protein, gamma-glutamyl transpeptidase, and HbA1c explained 14.08, 8.96, and 5.60% of the association between serum vitamin C and all-cause mortality among individuals with T2D, respectively.

CONCLUSIONS

Higher serum vitamin C concentrations were significantly associated with lower risk of mortality in participants with T2D in a linear dose-response manner, while a nonlinear association was observed in participants without T2D, with an apparent threshold around 48.0 μmol/L. These findings suggest that the optimal vitamin C requirement may differ in individuals with and without T2D.

The Role of Vitamin C in Human Immunity and Its Treatment Potential Against COVID-19: A Review Article

The outbreak of the COVID-19 pandemic has left clinicians around the world searching for viable prevention and treatment options to use against the virus. The important physiologic properties of vitamin C have been well documented regarding its use by immune cells and its role as an antioxidant. It has previously shown potential as a prophylactic and treatment option for other respiratory viruses, and because of this, there has been intrigue into whether these positive outcomes translate into a cost-effective prevention and treatment option for COVID-19. To this point, there have only been a few clinical trials performed to assess the validity of this notion, with very few showing definitive positive outcomes when vitamin C has been incorporated into prophylactic or treatment protocols to use against coronavirus. When being used to specifically treat the severe complications that arise from COVID-19, vitamin C is a reliable option to treat COVID-19-induced sepsis but not pneumonia or acute respiratory distress syndrome (ARDS). As a treatment option, high-dose therapy has shown flashes of promise in a few studies although investigators in these studies often subject the testing group to multimodal therapies that include vitamin C as opposed to just vitamin C alone. Given the role that vitamin C has shown to uphold regarding the human immune response, it is currently advised for all individuals to maintain a normal physiologic range of plasma vitamin C through diet or supplements for adequate prophylactic protection against the virus. More research with definitive outcomes will be needed before it is recommended to provide high-dose vitamin C therapy to prevent or treat COVID-19.

Moodithaya S, K. A, Kumar Chatterjee P. Micronutrients- The crucial dietary elements in Covid-19 pandemic: A review

The mutation of the SARS-CoV-2 virus, which cause person-to-person transmission, is the pivotal reason for the pandemic outbreak in the year 2020. Infection symptoms include fever, dry cough, lethargy, severe pneumonia, respiratory distress syndrome, and death. COVID-19 induces a systemic inflammatory reaction that impairs the immune system, commonly known as cytokine release syndrome. Pro-inflammatory cytokines and chemokines are abundant in COVID-19 sufferers' bodies. COVID-19 has a disproportionate impact on the elderly, both directly and through several comorbidities associated with age. Nutrition is without hesitation, a crucial factor in maintaining good health. Some nutrients are essential for the immune system's health and function, exhibiting synergistic actions in critical immune response steps. Vitamin D, C, and Zinc stand out among these nutrients because they have immunomodulatory properties and help to maintain physical tissue barriers. Considering the viability of the virus, nutrients that boost the immunity henceforth the severity of viral infections declines with improved prognosis become important. As a result, the purpose of this review is to provide a complete outline of vitamins D, C, and zinc's involvement during the immune response towards infection, and to enlighten their commensal action of maintaining physical barriers including integument and mucous membrane. Appropriate vitamin D, C, and zinc consumption may represent a feasible pharmacological intervention during the COVID-19 pandemic due to the high surge in population interaction and the commencement of inflammation.  

Vitamin C Improves Dasatinib Concentrations Under Hypochlorhydric Conditions of the Simulated Stomach Duodenum Model

PURPOSE

pH-dependent drug-drug interactions (DDIs) with poorly soluble, weakly basic drugs may lead to clinical implications. Dasatinib is a tyrosine kinase inhibitor with reduced absorption in patients on acid-reducing agents (ARAs). The objective of this study is to investigate the influence of gastric pH on dasatinib supersaturation and determine if vitamin C (L-ascorbic acid) can improve dasatinib concentrations under simulated hypochlorhydric gastric conditions.

METHODS

A dynamic, in vitro, multi-compartment, simulated stomach duodenum (SSD) model mimicking fluid volumes and transfer rates was used to investigate the concentration of BCS class IIb drugs versus time curves. Dasatinib and lamotrigine were explored under normal, fasted, simulated gastric fluids (pH 2) (FaSGF), hypochlorhydric simulated gastric fluids (pH 4.5) (FaSGF_hypo) and FaSGF_hypo with 1000 mg of vitamin C.

RESULTS

Significant supersaturation of dasatinib was observed in the duodenum compartment of the SSD model in FaSGF. A 90% reduction in dasatinib AUC_∞ was observed in FaSGF_hypo. Upon addition of vitamin C to FaSGF_hypo, drug concentrations were restored to those observed in FaSGF. Lamotrigine AUC_∞ in the duodenal compartment were similar in both FaSGF and FaSGF_hypo. The in vitro trends observed for dasatinib and lamotrigine are reflective of the trends observed in vivo in subjects receiving treatment with ARAs.

CONCLUSIONS

The SSD model serves as a good in vitro tool for assessing the effect of pH-dependent DDIs on bioavailability of weakly basic drugs with solubility/ dissolution limited absorption. Vitamin C provides a promising approach for improving bioavailability of poorly soluble, weakly basic drugs in hypochlorhydric patients.

Perspective: Role of Micronutrients and Omega-3 Long-Chain Polyunsaturated Fatty Acids for Immune Outcomes of Relevance to Infections in Older Adults-A Narrative Review and Call for Action

The immune system is weakened by advancing age, often referred to as immunosenescence, increasing the vulnerability to, and frequently the severity of, infectious diseases in older people. This has become very apparent in the current coronavirus disease 2019 (COVID-19) pandemic for which older people are at higher risk of severe outcomes, even those who are fully vaccinated. Aging affects both the innate and adaptive immune systems and is characterized by an imbalanced inflammatory response. Increasing evidence shows that optimal status of nutrients such as vitamins C, D, and E and selenium and zinc as well as the omega-3 (n-3) fatty acids DHA and EPA can help compensate for these age-related changes. While inadequate intakes of these nutrients are widespread in the general population, this is often more pronounced in older people. Maintaining adequate intakes is a challenge for them due to a range of factors such as physical, physiological, and cognitive changes; altered absorption; and the presence of noncommunicable diseases. While nutritional requirements are ideally covered by a balanced diet, this can be difficult to achieve, particularly for older people. Fortified foods and nutritional complements are effective in achieving adequate micronutrient intakes and should be considered as a safe and cost-effective means for older people to improve their nutritional status and hence support their defense against infections. Complementing the diet with a combination of micronutrients, particularly those playing a key role in the immune system such as vitamins C, D, and E and selenium and zinc as well as DHA and EPA, is recommended for older people. Optimal nutrition to support the immune system in older people will remain essential, particularly in the face of the current COVID-19 pandemic and, thus, developing strategies to ensure adequate nutrition for the growing number of older adults will be an important and cost-effective investment in the future.

Associations of Serum Biomarkers of Fruit and Vegetable Intake With the Risk of Cause–Specific Mortality and All–Cause Mortality: A National Prospective Cohort Study

Objective

The purpose of this study was to evaluate the associations of serum biomarkers of fruit and vegetable intake (vitamin C and carotenoids) with cause–specific mortality and all–cause mortality in a nationally representative sample of US adults.

Methods

We analyzed data from 12,530 participants from the National Health and Nutrition Examination Survey III (1988–1994). The Cox proportional hazards models with restricted cubic spline were used for the analysis.

Results

During 246,027 person–years of follow–up, 4,511 deaths occurred, including 1,395 deaths from cardiovascular disease, 1,072 deaths from heart disease, 323 deaths from cerebral disease, and 954 deaths from cancer. The serum vitamin C was significantly associated with the cancer and all–cause mortality, with hazard ratios (HRs) (95% CIs) for each one SD of 0.80 (0.71–0.91) and 0.91 (0.86–0.96). The serum alpha–carotene was significantly associated with the cancer mortality, with HRs (95% CIs) of 0.70 (0.54–0.90), 0.68 (0.48–0.95), 0.64 (0.43–0.95), and 0.44 (0.33–0.60) for comparisons of groups 2–5 with group 1 in model 2, respectively. The change for each one SD in the composite biomarker score, equivalent to a 0.483 times/month difference in total fruits and vegetables intake, gave an HR of 0.79 (0.69–0.90) for cancer mortality.

Conclusion

Inverse associations were found between serum vitamin C, carotenoids, and composite biomarker score and outcomes expect for cerebral disease, heart disease, and cardiovascular disease mortality. This finding supports an increase in dietary fruit and vegetable intake as a primary prevention strategy for cancer and all–cause mortality.

Association between serum retinol and overall and cause-specific mortality in a 30-year prospective cohort study

How retinol as a clinical indicator of vitamin A status is related to long-term mortality is unknown. Here we report the results of a prospective analysis examining associations between serum retinol and risk of overall and cause-specific mortality. During a 30-year cohort follow-up, 23,797 deaths were identified among 29,104 men. Participants with higher serum retinol experienced significantly lower overall, CVD, heart disease, and respiratory disease mortality compared to men with the lowest retinol concentrations, reflecting 17–32% lower mortality risk (P_trend < 0.0001). The retinol-overall mortality association is similar across subgroups of smoking intensity, alcohol consumption, body mass index, trial supplementation, serum alpha-tocopherol and beta-carotene concentrations, and follow-up time. Mediation analysis indicated that <3% of the effects of smoking duration and diabetes mellitus on mortality were mediated through retinol concentration. These findings indicate higher serum retinol is associated with lower overall mortality, including death from cardiovascular, heart, and respiratory diseases.

Vitamin A, of which retinol is the major form in the circulation, is a determinant of human health but whether vitamin A status is associated with mortality is not well understood. Here the authors report that in a prospective observational analysis of 29 104 men, higher serum retinol associates with lower risk of overall and cause-specific mortality.

The apparent inverse association between dietary carotene intake and risk of cardiovascular mortality disappeared after adjustment for other cardioprotective dietary intakes: The Japan collaborative cohort study

BACKGROUND AND PURPOSE

An effect of dietary carotenes on risk of cardiovascular disease (CVD) is uncertain. We aimed to investigate whether the association between dietary carotenes intake and risk of CVD mortality will persist after controlling for the intakes of potential cardioprotective dietary factors that correlate with dietary alpha- and/or beta-carotenes.

METHODS AND RESULTS

We followed up a total of 58,646 Japanese between 1988 and 1990 and 2009. We used a food frequency questionnaire (FFQ) to determine the dietary intakes of carotenes, and estimated the hazard ratios (HRs) and 95% confidence intervals (CIs) of CVD mortality in relation to carotene intake by the proportional hazard regression developed by David Cox. During 965,970 person-years of follow-up (median 19.3 years), we identified 3388 total CVD deaths. After adjusting for demographic and lifestyle factors, dietary intakes of alpha-carotene were significantly associated with the reduced risk of mortality from coronary heart disease (CHD); adjusted HR (95% CI) in the highest versus lowest quintiles of intake was 0.75 (0.58-0.96; P-trend = 0.02) and dietary intakes of beta-carotene were significantly associated with the reduced risk of mortality from CVD, CHD, and other CVD; adjusted HRs (95% CIs) were 0.88 (0.79-0.98; P-trend = 0.04), 0.78 (0.61-0.99; P-trend = 0.01), and 0.81 (0.67-0.98; P-trend = 0.04), respectively. However, after further adjusting for the dietary intakes of potassium, calcium, vitamins C, E, or K, these associations disappeared.

CONCLUSIONS

-Dietary alpha- and beta-carotene intakes were not associated with risk of CVD mortality after controlling for intakes of other potential cardioprotective nutrients.

Dysphagia, texture modification, the elderly and micronutrient deficiency: a review

Dysphagia is an underlying symptom of many health issues affecting a person's ability to swallow. Being unable to swallow correctly may limit food intake and subsequently micronutrient status. The elderly may be the most at risk group of suffering dysphagia as well as most likely to be deficient in micronutrients. The use of texture-modified meals is a common approach to increasing dysphagia sufferer's food intake. The modification of food may affect the micronutrient content and currently there is a limited number of studies focusing on micronutrient content of texture-modified meals. This review considers the prevalence of dysphagia within the elderly UK community whilst assessing selected micronutrients. Vitamin B₁₂, C, D, folate, zinc and iron, which are suggested to be most likely deficient in the general elderly UK population, were reviewed. Each micronutrient is considered in terms of prevalence of deficiency, metabolic function, food source and processing stability to provide an overview with respect to elderly dysphagia sufferers.

Low level of Vitamin C and dysregulation of Vitamin C transporter might be involved in the severity of COVID-19 Infection

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been spreading around the world at an exponential pace, leading to millions of individuals developing the associated disease called COVID-19. Due to the novel nature and the lack of immunity within humans, there has been a collective global effort to find effective treatments against the virus. This has led the scientific community to repurpose Food and Drug Administration (FDA) approved drugs with known safety profiles. Of the many possible drugs, vitamin C has been on the shortlist of possible interventions due to its beneficial role as an immune booster and inherent antioxidant properties. Within this manuscript, a detailed discussion regarding the intracellular function and inherent properties of vitamin C is conducted. It also provides a comprehensive review of published research pertaining to the differences in expression of the vitamin C transporter under several pathophysiologic conditions. Finally, we review recently published research investigating the efficacy of vitamin C administration in treating viral infection and life-threatening conditions. Overall, this manuscript aims to present existing information regarding the extent to which vitamin C can be an effective treatment for COVID-19 and possible explanations as to why it may work in some individuals but not in others.

Zinc, Vitamin D and Vitamin C: Perspectives for COVID-19 With a Focus on Physical Tissue Barrier Integrity

Some nutrients play key roles in maintaining the integrity and function of the immune system, presenting synergistic actions in steps determinant for the immune response. Among these elements, zinc and vitamins C and D stand out for having immunomodulatory functions and for playing roles in preserving physical tissue barriers. Considering the COVID-19 pandemic, nutrients that can optimize the immune system to prevent or lower the risk of severe progression and prognosis of this viral infection become relevant. Thus, the present review aims to provide a comprehensive overview of the roles of zinc and vitamins C and D in the immune response to viral infections, focusing on the synergistic action of these nutrients in the maintenance of physical tissue barriers, such as the skin and mucous membranes. The evidence found in the literature shows that deficiency of one or more of these three elements compromises the immune response, making an individual more vulnerable to viral infections and to a worse disease prognosis. Thus, during the COVID-19 pandemic, the adequate intake of zinc and vitamins C and D may represent a promising pharmacological tool due to the high demand for these nutrients in the case of contact with the virus and onset of the inflammatory process. Ongoing clinical trials will help to clarify the role of these nutrients for COVID-19 management.

The Long History of Vitamin C: From Prevention of the Common Cold to Potential Aid in the Treatment of COVID-19

From Pauling's theories to the present, considerable understanding has been acquired of both the physiological role of vitamin C and of the impact of vitamin C supplementation on the health. Although it is well known that a balanced diet which satisfies the daily intake of vitamin C positively affects the immune system and reduces susceptibility to infections, available data do not support the theory that oral vitamin C supplements boost immunity. No current clinical recommendations support the possibility of significantly decreasing the risk of respiratory infections by using high-dose supplements of vitamin C in a well-nourished general population. Only in restricted subgroups (e.g., athletes or the military) and in subjects with a low plasma vitamin C concentration a supplementation may be justified. Furthermore, in categories at high risk of infection (i.e., the obese, diabetics, the elderly, etc.), a vitamin C supplementation can modulate inflammation, with potential positive effects on immune response to infections. The impact of an extra oral intake of vitamin C on the duration of a cold and the prevention or treatment of pneumonia is still questioned, while, based on critical illness studies, vitamin C infusion has recently been hypothesized as a treatment for COVID-19 hospitalized patients. In this review, we focused on the effects of vitamin C on immune function, summarizing the most relevant studies from the prevention and treatment of common respiratory diseases to the use of vitamin C in critical illness conditions, with the aim of clarifying its potential application during an acute SARS-CoV2 infection.

Inadequacy of Immune Health Nutrients: Intakes in US Adults, the 2005-2016 NHANES

A well-functioning immune system is essential for human health and well-being. Micronutrients such as vitamins A, C, D, E, and zinc have several functions throughout the immune system, yet inadequate nutrient intakes are pervasive in the US population. A large body of research shows that nutrient inadequacies can impair immune function and weaken the immune response. Here, we present a new analysis of micronutrient usual intake estimates based on nationally representative data in 26,282 adults (>19 years) from the 2005-2016 National Health and Nutrition Examination Surveys (NHANES). Overall, the prevalence of inadequacy (% of population below estimated average requirement [EAR]) in four out of five key immune nutrients is substantial. Specifically, 45% of the U.S. population had a prevalence of inadequacy for vitamin A, 46% for vitamin C, 95% for vitamin D, 84% for vitamin E, and 15% for zinc. Dietary supplements can help address nutrient inadequacy for these immune-support nutrients, demonstrated by a lower prevalence of individuals below the EAR. Given the long-term presence and widening of nutrient gaps in the U.S.-specifically in critical nutrients that support immune health-public health measures should adopt guidelines to ensure an adequate intake of these micronutrients. Future research is needed to better understand the interactions and complexities of multiple nutrient shortfalls on immune health and assess and identify optimal levels of intake in at-risk populations.

Association between plasma retinol levels and the risk of all-cause mortality in general hypertensive patients: A nested case-control study

To evaluate the association between plasma retinol levels with all-cause mortality and investigate the possible effect modifiers in general hypertensive patients with no previous cardiovascular disease (CVD). This case-control study was nested in the China Stroke Primary Prevention Trial (CSPPT), a randomized, double-blind, controlled trial conducted in 32 communities in Anhui and Jiangsu provinces in China. The current study included 617 cases of all-cause mortality and 617 controls matched on age (≤1 year), sex, treatment group, and study site. All-cause mortality was the main outcome in this analysis, which included death due to any reason. The median follow-up duration was 4.5 years. Overall, there was a U-shaped relation of plasma retinol with all-cause mortality. In the threshold effect analysis, the risk of all-cause mortality significantly decreased with the increase in plasma retinol (per 10 μg/dL increments: OR, 0.73; 95% CI: 0.61-0.87) in participants with plasma retinol <58.3 μg/dL and increased with the increase in plasma retinol (per 10 μg/dL increments: OR, 1.08; 95% CI: 1.01-1.16) in those with plasma retinol ≥58.3 μg/L. In participants with plasma retinol <58.3 μg/dL, a stronger inverse association was observed in those with higher time-averaged SBP (≥140 vs <140 mm Hg; P-interaction = .034), or higher vitamin E levels (≥11.5 [quartile 4]; vs <11.5 μg/mL; P-interaction = .013). The present study demonstrated that there was a U-shaped relationship of plasma retinol levels with the risk of all-cause mortality in general hypertensive patients, with a turning point around 58.3 μg/dL.

Dietary Vitamin C Deficiency Is Associated With Health-Related Quality of Life and Cardiac Event-free Survival in Adults With Heart Failure

BACKGROUND

Vitamin C deficiency is prevalent in adults with heart failure (HF). Little is known about the relationship of dietary vitamin C deficiency with health outcomes in adults with HF.

OBJECTIVE

The study's aim was to determine the relationships of vitamin C deficiency measured at baseline with health-related quality of life (HRQOL) and cardiac event-free survival in patients with HF measured 1 year later.

METHOD

A total of 251 patients with HF completed a 4-day food diary. Dietary vitamin C deficiency was defined as daily intake less than the estimated average requirement from the Institute of Medicine of 75 mg/d for men and 60 mg/d for women. Health-related quality of life was assessed using the Minnesota Living with Heart Failure Questionnaire at 12 months. Patients were followed for a median of 1 year to determine time to the first event of cardiac-related hospitalization or death. Data were analyzed by hierarchical linear and Cox proportional hazards regressions.

RESULTS

One hundred patients (40%) had vitamin C deficiency. Dietary vitamin C deficiency was associated with poorer HRQOL at 12 months (β = 0.16, P = .02) after controlling for demographic and clinical variables. During the follow-up period, 59 patients (24%) had cardiac events. In Cox regression, vitamin C deficiency predicted shorter cardiac event-free survival after adjusting for the same covariates (hazards ratio, 1.95; 95% confidence interval, 1.08-3.51).

CONCLUSION

Vitamin C deficiency was associated with poorer HRQOL and shorter cardiac event-free survival in patients with HF. The findings suggest that encouraging patients with HF to consume a diet rich in fruits/vegetables to prevent vitamin C deficiency may lead to better health outcomes.

Influence of Dietary Ingredients on Lean Body Percent, Uremic Toxin Concentrations, and Kidney Function in Senior-Adult Cats

The goal of this study was to determine if modification of currently available maintenance foods with alternative ingredients, botanicals (fruit and vegetables), and increased amounts of functional lipids (fish oil) would delay the age-associated decline in glomerular filtration rate (GFR) and lean body mass (LBM) in senior-adult cats. Forty-four healthy cats (mean age, 12.2 years; range 10.7 to 14.0 years) were fed one of three foods (n = 14 or 15 per group) for six months: control food with 32.6% protein (as fed), or control food supplemented with increasing amounts of functional food bioactives: fish oil, fruit and vegetables, different protein sources, and <32.0% protein [functional foods one (FF1) and two (FF2)]. Senior-adult cats were compared before and after the feeding trial with 20 young-adult cats (mean age, 3.5 years; range 2.1 to 4.9 years). Compared with younger cats, older cats had decreased lean-body percent and serum albumin concentrations. Feeding FF1 and FF2 for six months increased lean-body percent, maintained serum albumin concentrations, increased GFR, decreased serum symmetric dimethylarginine (SDMA) concentrations, and decreased concentrations of the uremic toxin 3-indoxyl sulfate. These dietary changes may assist in offsetting sarcopenia and the chronic inflammation associated with aging in senior-adult cats.

Serum Beta Carotene and Overall and Cause-Specific Mortality

RATIONALE

Although the health effects of beta carotene have been studied extensively, a systematic examination of serum concentrations and long-term mortality, including cardiovascular disease mortality, has not been reported.

OBJECTIVE

Explore whether serum beta carotene is associated with overall and cause-specific mortality and to elucidate the strength and dose-response of the association.

METHODS AND RESULTS

We conducted a prospective serological analysis of 29 103 men in the ATBC study (Alpha-Tocopherol, Beta-Carotene Cancer Prevention). During 31 years of follow-up, 23 796 deaths occurred, including deaths because of cardiovascular disease (9869), cancer (7692), respiratory disease (2161), diabetes mellitus (119), injuries and accidents (1255), and other causes (2700). Serum beta carotene was assayed using high-performance liquid chromatography. Adjusting for major risk factors measured, men with higher serum beta carotene had significantly lower all-cause mortality (hazard ratios=0.81, 0.71, 0.69, and 0.64 for quintile 2 (Q2)-Q5 versus Q1, respectively; P_trend<0.0001). Serum beta carotene was significantly associated with risk of death from cardiovascular disease, heart disease, stroke, cancer, respiratory disease, diabetes mellitus, injuries and accidents, and other causes (Q5 versus Q1, hazard ratio=0.21-0.73, all P_trend<0.0001). The all-cause mortality association was not materially impacted by adjustment for fruit and vegetable consumption (albeit, estimated with some measurement error) and was generally similar across subgroups of smoking intensity, alcohol consumption, trial supplementation, and duration of follow-up, but was significantly modified by age, years of smoking, and body mass index, with stronger inverse associations among men who were younger, smoked fewer years, and had a lower body mass index (all P_interaction≤0.0025).

CONCLUSIONS

This study provides evidence that higher beta carotene biochemical status is associated with lower overall, cardiovascular disease, heart disease, stroke, cancer, and other causes of mortality. The dose-response associations over a 30-year period were not attenuated by adjustment for other important risk factors and support greater fruit and vegetable consumption as a means to increase beta carotene status and promote longevity.

Relationship Between Serum Alpha-Tocopherol and Overall and Cause-Specific Mortality

RATIONALE

Although there has been a long-standing interest in the human health effects of vitamin E, a comprehensive analysis of the association between circulating vitamin E and long-term mortality has not been conducted.

OBJECTIVE

Determine whether serum α-tocopherol (the predominant form of vitamin E) is related to long-term overall and cause-specific mortality and elucidate the dose-response relationships with better quantification of the associations.

METHODS AND RESULTS

We conducted a biochemical analysis of 29 092 participants in the ATBC Study (Alpha-Tocopherol, Beta-Carotene Cancer Prevention) that originally tested vitamin E and β-carotene supplementation. Serum α-tocopherol was measured at baseline using high-performance liquid chromatography, and during a 30-year follow-up we identified 23 787 deaths, including deaths from cardiovascular disease (9867), cancer (7687), respiratory disease (2161), diabetes mellitus (119), injuries and accidents (1255), and other causes (2698). After adjusting for major risk factors, we found that men with higher serum α-tocopherol had significantly lower all-cause mortality (hazard ratios=0.83, 0.79, 0.75, and 0.78 for quintile 2 (Q2)-Q5 versus Q1, respectively; P_trend<0.0001), and significantly decreased mortality from cardiovascular disease, heart disease, stroke, cancer, respiratory disease, and other causes, with risk reductions from 17% to 47% for the highest versus lowest quintile. The α-tocopherol association with overall mortality was similar across subgroups of smoking intensity, years of smoking, alcohol consumption, trial supplementation, and duration of follow-up. The association was, however, significantly modified by baseline age and body mass index, with stronger inverse associations for younger men and men with a lower body mass index ( P_interaction≤0.006).

CONCLUSIONS

In this long-term prospective cohort study, higher baseline serum α-tocopherol biochemical status was associated with lower risk of overall mortality and mortality from all major causes. Our data support the long-term health benefits of higher serum α-tocopherol for overall and chronic disease mortality and should be replicated in other more diverse populations.

Dietary and circulating vitamin C, vitamin E, β-carotene and risk of total cardiovascular mortality: a systematic review and dose-response meta-analysis of prospective observational studies

OBJECTIVE

The present review aimed to quantify the association of dietary intake and circulating concentration of major dietary antioxidants with risk of total CVD mortality.

DESIGN

Systematic review and meta-analysis.

SETTING

Systematic search in PubMed and Scopus, up to October 2017.ParticipantsProspective observational studies reporting risk estimates of CVD mortality across three or more categories of dietary intakes and/or circulating concentrations of vitamin C, vitamin E and β-carotene were included. A random-effects meta-analysis was conducted.

RESULTS

A total of fifteen prospective cohort studies and three prospective evaluations within interventional studies (320 548 participants and 16 974 cases) were analysed. The relative risks of CVD mortality for the highest v. the lowest category of antioxidant intakes were as follows: vitamin C, 0·79 (95 % CI 0·68, 0·89; I 2=46 %, n 10); vitamin E, 0·91 (95 % CI 0·79, 1·03; I 2=51 %, n 8); β-carotene, 0·89 (95 % CI 0·73, 1·05; I 2=34 %, n 4). The relative risks for circulating concentrations were: vitamin C, 0·60 (95 % CI 0·42, 0·78; I 2=65 %, n 6); α-tocopherol, 0·82 (95 % CI 0·76, 0·88; I 2=0 %, n 5); β-carotene, 0·68 (95 % CI 0·52, 0·83; I 2=50 %, n 6). Dose-response meta-analyses demonstrated that the circulating biomarkers of antioxidants were more strongly associated with risk of CVD mortality than dietary intakes.

CONCLUSIONS

The present meta-analysis demonstrates that higher vitamin C intake and higher circulating concentrations of vitamin C, vitamin E and β-carotene are associated with a lower risk of CVD mortality.

Dietary intake and blood concentrations of antioxidants and the risk of cardiovascular disease, total cancer, and all-cause mortality: a systematic review and dose-response meta-analysis of prospective studies

Background

High dietary intake or blood concentrations (as biomarkers of dietary intake) of vitamin C, carotenoids, and vitamin E have been associated with reduced risk of cardiovascular disease, cancer, and mortality, but these associations have not been systematically assessed.

Objective

We conducted a systematic review and meta-analysis of prospective studies of dietary intake and blood concentrations of vitamin C, carotenoids, and vitamin E in relation to these outcomes.

Design

We searched PubMed and Embase up to 14 February 2018. Summary RRs and 95% CIs were calculated with the use of random-effects models.

Results

Sixty-nine prospective studies (99 publications) were included. The summary RR per 100-mg/d increment of dietary vitamin C intake was 0.88 (95% CI: 0.79, 0.98, I2 = 65%, n = 11) for coronary heart disease, 0.92 (95% CI: 0.87, 0.98, I2 = 68%, n = 12) for stroke, 0.89 (95% CI: 0.85, 0.94, I2 = 27%, n = 10) for cardiovascular disease, 0.93 (95% CI: 0.87, 0.99, I2 = 46%, n = 8) for total cancer, and 0.89 (95% CI: 0.85, 0.94, I2 = 80%, n = 14) for all-cause mortality. Corresponding RRs per 50-μmol/L increase in blood concentrations of vitamin C were 0.74 (95% CI: 0.65, 0.83, I2 = 0%, n = 4), 0.70 (95% CI: 0.61, 0.81, I2 = 0%, n = 4), 0.76 (95% CI: 0.65, 0.87, I2 = 56%, n = 6), 0.74 (95% CI: 0.66, 0.82, I2 = 0%, n = 5), and 0.72 (95% CI: 0.66, 0.79, I2 = 0%, n = 8). Dietary intake and/or blood concentrations of carotenoids (total, β-carotene, α-carotene, β-cryptoxanthin, lycopene) and α-tocopherol, but not dietary vitamin E, were similarly inversely associated with coronary heart disease, stroke, cardiovascular disease, cancer, and/or all-cause mortality.

Conclusions

Higher dietary intake and/or blood concentrations of vitamin C, carotenoids, and α-tocopherol (as markers of fruit and vegetable intake) were associated with reduced risk of cardiovascular disease, total cancer, and all-cause mortality. These results support recommendations to increase fruit and vegetable intake, but not antioxidant supplement use, for chronic disease prevention.

Dietary Antioxidants, Circulating Antioxidant Concentrations, Total Antioxidant Capacity, and Risk of All-Cause Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Observational Studies

The associations of various dietary or circulating antioxidants with the risk of all-cause mortality in the general population have not been established yet. A systematic search was performed in PubMed and Scopus, from their inception up to October 2017. Prospective observational studies reporting risk estimates of all-cause mortality in relation to dietary intake and/or circulating concentrations of antioxidants were included. Random-effects meta-analyses were conducted. Forty-one prospective observational studies (total n = 507,251) involving 73,965 cases of all-cause mortality were included. The RRs of all-cause mortality for the highest compared with the lowest category of circulating antioxidant concentrations were as follows: total carotenes, 0.60 (95% CI: 0.46, 0.74); vitamin C, 0.61 (95% CI: 0.53, 0.69); selenium, 0.62 (95% CI: 0.45, 0.79); β-carotene, 0.63 (95% CI: 0.57, 0.70); α-carotene, 0.68 (95% CI: 0.58, 0.78); total carotenoids, 0.68 (95% CI: 0.56, 0.80); lycopene, 0.75 (95% CI: 0.54, 0.97); and α-tocopherol, 0.84 (95% CI: 0.77, 0.91). The RRs for dietary intakes were: total carotenoids, 0.76 (95% CI: 0.66, 0.85); total antioxidant capacity, 0.77 (95% CI: 0.73, 0.81); selenium, 0.79 (95% CI: 0.73, 0.85); α-carotene, 0.79 (95% CI: 0.63, 0.94); β-carotene, 0.82 (95% CI: 0.77, 0.86); vitamin C, 0.88 (95% CI: 0.83, 0.94); and total carotenes, 0.89 (95% CI: 0.81, 0.97). A nonsignificant inverse association was found for dietary zinc, zeaxanthin, lutein, and vitamin E. The nonlinear dose-response meta-analyses demonstrated a linear inverse association in the analyses of dietary β-carotene and total antioxidant capacity, as well as in the analyses of circulating α-carotene, β-carotene, selenium, vitamin C, and total carotenoids. The association appeared to be U-shaped in the analyses of serum lycopene and dietary vitamin C. The present study indicates that adherence to a diet with high antioxidant properties may reduce the risk of all-cause mortality. Our results confirm current recommendations that promote higher intake of antioxidant-rich foods such as fruit and vegetables.

Atherothrombosis and Oxidative Stress: Mechanisms and Management in Elderly

SIGNIFICANCE

The incidence of cardiovascular events (CVEs) increases with age, representing the main cause of death in an elderly population. Aging is associated with overproduction of reactive oxygen species (ROS), which may affect clotting and platelet activation, and impair endothelial function, thus predisposing elderly patients to thrombotic complications. Recent Advances: There is increasing evidence to suggest that aging is associated with an imbalance between oxidative stress and antioxidant status. Thus, upregulation of ROS-producing enzymes such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and myeloperoxidase, along with downregulation of antioxidant enzymes, such as superoxide dismutase and glutathione peroxidase, occurs during aging. This imbalance may predispose to thrombosis by enhancing platelet and clotting activation and eliciting endothelial dysfunction. Recently, gut-derived products, such as trimethylamine N-oxide (TMAO) and lipopolysaccharide, are emerging as novel atherosclerotic risk factors, and gut microbiota composition has been shown to change by aging, and may concur with the increased cardiovascular risk in the elderly.

CRITICAL ISSUES

Antioxidant treatment is ineffective in patients at risk or with cardiovascular disease. Further, anti-thrombotic treatment seems to work less in the elderly population.

FUTURE DIRECTIONS

Interventional trials with antioxidants targeting enzymes implicated in aging-related atherothrombosis are warranted to explore whether modulation of redox status is effective in lowering CVEs in the elderly. Antioxid. Redox Signal. 27, 1083-1124.

Vitamin C and Immune Function

Vitamin C is an essential micronutrient for humans, with pleiotropic functions related to its ability to donate electrons. It is a potent antioxidant and a cofactor for a family of biosynthetic and gene regulatory enzymes. Vitamin C contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system. Vitamin C supports epithelial barrier function against pathogens and promotes the oxidant scavenging activity of the skin, thereby potentially protecting against environmental oxidative stress. Vitamin C accumulates in phagocytic cells, such as neutrophils, and can enhance chemotaxis, phagocytosis, generation of reactive oxygen species, and ultimately microbial killing. It is also needed for apoptosis and clearance of the spent neutrophils from sites of infection by macrophages, thereby decreasing necrosis/NETosis and potential tissue damage. The role of vitamin C in lymphocytes is less clear, but it has been shown to enhance differentiation and proliferation of B- and T-cells, likely due to its gene regulating effects. Vitamin C deficiency results in impaired immunity and higher susceptibility to infections. In turn, infections significantly impact on vitamin C levels due to enhanced inflammation and metabolic requirements. Furthermore, supplementation with vitamin C appears to be able to both prevent and treat respiratory and systemic infections. Prophylactic prevention of infection requires dietary vitamin C intakes that provide at least adequate, if not saturating plasma levels (i.e., 100–200 mg/day), which optimize cell and tissue levels. In contrast, treatment of established infections requires significantly higher (gram) doses of the vitamin to compensate for the increased inflammatory response and metabolic demand.

Dietary, circulating beta-carotene and risk of all-cause mortality: a meta-analysis from prospective studies

Observational studies evaluating the relation between dietary or circulating level of beta-carotene and risk of total mortality yielded inconsistent results. We conducted a comprehensive search on publications of PubMed and EMBASE up to 31 March 2016. Random effect models were used to combine the results. Potential publication bias was assessed using Egger’s and Begg’s test. Seven studies that evaluated dietary beta-carotene intake in relation to overall mortality, indicated that a higher intake of beta-carotene was related to a significant lower risk of all-cause mortality (RR for highest vs. lowest group = 0.83, 95%CI: 0.78–0.88) with no evidence of heterogeneity between studies (I² = 1.0%, P = 0.416). A random-effect analysis comprising seven studies showed high beta-carotene level in serum or plasma was associated with a significant lower risk of all-cause mortality (RR for highest vs. lowest group = 0.69, 95%CI: 0.59–0.80) with low heterogeneity (I² = 37.1%, P = 0.145). No evidence of publication bias was detected by Begg’s and Egger’s regression tests. In conclusion, dietary or circulating beta-carotene was inversely associated with risk of all-cause mortality. More studies should be conducted to clarify the dose-response relationship between beta-carotene and all-cause mortality.

Positive Impact of Nutritional Interventions on Serum Symmetric Dimethylarginine and Creatinine Concentrations in Client-Owned Geriatric Dogs

A prospective study was conducted in client-owned geriatric dogs to evaluate the short-term effects of a test food on serum symmetric dimethylarginine (SDMA) and creatinine (Cr) concentrations. Test food contained functional lipids (fish oil), antioxidants (lipoic acid, vitamins C and E), L-carnitine, botanicals (fruits and vegetables), controlled sodium concentration, and high quality protein sources (high bioavailability and an ideal amino acid composition). Dogs (n = 210) were fed either test food or owner's-choice foods (non-nutritionally controlled cohort). Dogs were included based on age and body weight: small (6.8 to 11.4 kg) and medium dogs (11.5 to 22.7 kg) were ≥ 9 years, whereas dogs >22.7 kg were ≥ 7 years at baseline. At baseline, all dogs had to have serum Cr concentrations within the reference interval and be free of chronic disease. Renal function biomarkers and urinalysis results at baseline, and after consuming test food or owner's-choice foods for 3 and 6 months, were evaluated. Only dogs consuming test food showed significant decreases in serum SDMA and Cr concentrations (both P ≤ 0.05) across time. At baseline or during the 6-month feeding trial, 18 dogs (8.6%) had increased serum SDMA, but normal serum Cr, consistent with IRIS Stage 1 chronic kidney disease. This included 9 dogs fed test food and 9 dogs fed owner's-choice foods. Compared with baseline, after feeding 9 dogs test food for 6 months, serum SDMA decreased in 8 dogs and increased in 1 dog. After feeding 9 dogs owner's-choice foods for 6 months, serum SDMA decreased in 4 dogs and increased in 4 dogs (remained stable in 1 dog). The decreases in serum SDMA and Cr concentrations were significant (both P = 0.03) only for dogs fed test food. These results suggest that nonazotemic dogs with elevated serum SDMA (early renal insufficiency) when fed a test food designed to promote healthy aging are more likely to demonstrate improved renal function compared with dogs fed owner's-choice foods.

Nutritional Interventions that Slow the Age-Associated Decline in Renal Function in a Canine Geriatric Model for Elderly Humans

OBJECTIVE

To determine the effects of feeding traditional and renal protective foods (RPF) supplemented with functional food bioactives on glomerular filtration rate (GFR), lean body percent (LB%), and selected circulating biomarker and metabolite concentrations in a geriatric dog model.

DESIGN

Randomized block design and cross-sectional study.

SETTING

Hill's Pet Nutrition, Inc. dog colony.

PARTICIPANTS

Eighty-one geriatric dogs (mean age, 10.4; range, 7.9-14.2 years) and 30 mature-adult dogs (mean age, 5.0; range, 3.3-6.9 years).

INTERVENTION

Geriatric dogs were fed one of three foods (n = 27 per group) for 6 months: a traditional RPF (control) that was energy dense and mildly protein-restricted, or control food supplemented with increasing amounts of functional food bioactives: fish oil, lipoic acid, fruits and vegetables, and higher quality protein sources [functional foods one (FF1) and two (FF2)]. Geriatric dogs were compared before and after the feeding trial with mature adult dogs.

MEASUREMENTS

Renal function was assessed by GFR, LB% was determined by dual energy x-ray absorptiometry, and circulating biomarkers and metabolites were measured in blood.

RESULTS

Before the feeding trial, GFR (+28.2%), LB% (+18.6%), and serum total protein (+10.0%) were higher in mature versus healthy geriatric dogs (all P<0.001). Geriatric dogs consuming all three foods increased (P<0.001) GFR over time; group averages ranged from 13.0-16.9%. Dogs fed the highest supplemented level of bioactives (FF2) had lower (P<0.001) symmetric dimethylarginine (SDMA) concentrations (-14.3%). Feeding functional foods did not alter body weight, but increased (P<0.001) serum protein concentration (+6.7%).

CONCLUSION

Supplementation with functional food bioactives can temporarily reverse the age-associated decline in renal function and serum total protein.

Antioxidant vitamin intake and mortality in three Central and Eastern European urban populations: the HAPIEE study

PURPOSE

The aim of the study was to assess the relationships between individual-level dietary intakes of antioxidant vitamins C, E and beta-carotene with all-cause and cause-specific mortality in three Central and Eastern European (CEE) populations.

METHODS

Data from the Health, Alcohol and Psychosocial factors in Eastern Europe cohort study were used. At the baseline survey, between 2002 and 2005, 28,945 men and women aged 45-69 years were examined in Novosibirsk (Russia), Krakow (Poland) and seven Czech towns. Deaths in the cohorts were identified through mortality registers. Cox regression was used to estimate the association between vitamin consumption and all-cause, cardiovascular (CVD) disease and cancer mortality.

RESULTS

In multivariable-adjusted analyses, there were no clear inverse associations between antioxidant vitamin intakes and mortality, although in some groups, several hazard ratios (HRs) were significant. For example, in men, compared with the lowest quintile of vitamin C intake, all-cause mortality in the third and fourth quintiles was lower by 28 % (HR 0.72; 95 % CI 0.61-0.85) and by 20 % (HR 0.80; 95 % CI 0.68-0.95), respectively. CVD mortality was lower by 35 % (HR 0.65; 95 % CI 0.50-0.84) and by 23 % (HR 0.77; 95 % CI 0.59-0.99) in third and fourth quintile of vitamin C intake, respectively. In women, the third and fourth quintiles of dietary intake of vitamin E were associated with reduced risk of all-cause death by 33 % (HR 0.67; 95 % CI 0.53-0.84) and by 23 % (HR 0.77; 95 % CI 0.61-0.97), respectively. Consumption of vitamin C, vitamin E and beta-carotene was not related to CVD mortality in women and to cancer mortality in either gender.

CONCLUSION

This large prospective cohort study in CEE populations with low prevalence of vitamin supplementation did not find a strong, dose-response evidence for protective effects of antioxidant vitamin intake.

Associations between antioxidants and all-cause mortality among US adults with obstructive lung function

Chronic obstructive pulmonary disease is characterised by oxidative stress, but little is known about the associations between antioxidant status and all-cause mortality in adults with this disease. The objective of the present study was to examine the prospective associations between concentrations of α- and β-carotene, β-cryptoxanthin, lutein/zeaxanthin, lycopene, Se, vitamin C and α-tocopherol and all-cause mortality among US adults with obstructive lung function. Data collected from 1492 adults aged 20-79 years with obstructive lung function in the National Health and Nutrition Examination Survey III (1988-94) were used. Through 2006, 629 deaths were identified during a median follow-up period of 14 years. After adjustment for demographic variables, the concentrations of the following antioxidants modelled as continuous variables were found to be inversely associated with all-cause mortality among adults with obstructive lung function: α-carotene (P= 0·037); β-carotene (P= 0·022); cryptoxanthin (P= 0·022); lutein/zeaxanthin (P= 0·004); total carotenoids (P= 0·001); vitamin C (P< 0·001). In maximally adjusted models, only the concentrations of lycopene (P= 0·013) and vitamin C (P= 0·046) were found to be significantly and inversely associated with all-cause mortality. No effect modification by sex was detected, but the association between lutein/zeaxanthin concentrations and all-cause mortality varied by smoking status (P interaction= 0·048). The concentrations of lycopene and vitamin C were inversely associated with all-cause mortality in this cohort of adults with obstructive lung function.

Effects of vitamin E, vitamin C and polyphenols on the rate of blood pressure variation: results of two randomised controlled trials

High blood pressure (BP) variability, which may be an important determinant of hypertensive end-organ damage, is emerging as an important predictor of cardiovascular health. Dietary antioxidants can influence BP, but their effects on variability are yet to be investigated. The aim of the present study was to assess the effects of vitamin E, vitamin C and polyphenols on the rate of daytime and night-time ambulatory BP variation. To assess these effects, two randomised, double-blind, placebo-controlled trials were performed. In the first trial (vitamin E), fifty-eight individuals with type 2 diabetes were given 500 mg/d of RRR-α-tocopherol, 500 mg/d of mixed tocopherols or placebo for 6 weeks. In the second trial (vitamin C-polyphenols), sixty-nine treated hypertensive individuals were given 500 mg/d of vitamin C, 1000 mg/d of grape-seed polyphenols, both vitamin C and polyphenols, or neither (placebo) for 6 weeks. At baseline and at the end of the 6-week intervention, 24 h ambulatory BP and rate of measurement-to-measurement BP variation were assessed. Compared with placebo, treatment with α-tocopherol, mixed tocopherols, vitamin C and polyphenols did not significantly alter the rate of daytime or night-time systolic BP, diastolic BP or pulse pressure variation (P>0·05). Treatment with the vitamin C and polyphenol combination resulted in higher BP variation: the rate of night-time systolic BP variation (P= 0·022) and pulse pressure variation (P= 0·0036) were higher and the rate of daytime systolic BP variation was higher (P= 0·056). Vitamin E, vitamin C or grape-seed polyphenols did not significantly alter the rate of BP variation. However, the increase in the rate of BP variation suggests that the combination of high doses of vitamin C and polyphenols could be detrimental to treated hypertensive individuals.

Effect of vitamin C on endothelial function in health and disease: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Observational studies indicate that higher vitamin C intake is associated with reduced risk for cardiovascular diseases. However, randomised controlled trials (RCT) examining the effect of vitamin C on endothelial function (EF) have reported inconsistent results. The aims of this systematic review and meta-analysis were to determine the effect of vitamin C supplementation on EF and to investigate whether the effect was influenced by health status, study duration, dose and route of vitamin C administration.

METHODS

We searched the Medline, Embase, Cochrane Library, and Scopus databases from inception to May 2013 for studies that met the following criteria: 1) RCT with adult participants, 2) vitamin C administered alone, 3) studies that quantified EF using commonly applied methods including ultrasound, plethysmography and pulse wave analysis.

RESULTS

Pooling the data from 44 clinical trials showed a significant positive effect of vitamin C on EF (SMD: 0.50, 95% CI: 0.34, 0.66, P < 0.001). Stratification of the analysis by health outcome revealed improved EF in atherosclerotic (SMD: 0.84, 95% CI: 0.41, 1.26, P < 0.001), diabetic (SMD: 0.52, 95% CI: 0.21, 0.82, P < 0.001) and heart failure patients (SMD: 0.48, 95% CI: 0.08, 0.88, P < 0.02) after vitamin C supplementation. The effect size appeared to be unaffected by study design, duration, baseline plasma vitamin C concentration or route of administration of vitamin C. The meta-regression showed a significant positive association between vitamin C dose and improvement in EF (β: 0.00011, 95% CI: 0.00001, 0.00021, P = 0.03).

CONCLUSIONS

Vitamin C supplementation improved EF. The effect of vitamin C supplementation appeared to be dependent on health status, with stronger effects in those at higher cardiovascular disease risk. PROSPERO Database registration: CRD42013004567, http://www.crd.york.ac.uk/prospero/

Does vitamin C deficiency increase lifestyle-associated vascular disease progression? Evidence based on experimental and clinical studies

SIGNIFICANCE

Despite continuous advances in the prevention of cardiovascular disease (CVD), critical issues associated with an unhealthy lifestyle remain an increasing cause of morbidity and mortality in industrialized countries.

RECENT ADVANCES

A growing body of literature supports a specific role for vitamin C in a number of reactions that are associated with vascular function and control including, for example, nitric oxide bioavailability, lipid metabolism, and vascular integrity.

CRITICAL ISSUES

A large body of epidemiological evidence supports a relationship between poor vitamin C status and increased risk of developing CVD, and the prevalence of deficiency continues to be around 10%-20% of the general Western population although this problem could easily and cheaply be solved by supplementation. However, large intervention studies using vitamin C have not found a beneficial effect of supplementation. This review outlines the proposed mechanism by which vitamin C deficiency worsens CVD progression. In addition, it discusses problems with the currently available literature, including the discrepancies between the large intervention studies and the experimental and epidemiological literature.

FUTURE DIRECTIONS

Increased insights into vitamin C deficiency-mediated CVD progression will enable the design of future randomized controlled trials that are better suited to test the efficacy of vitamin C in disease prevention as well as the identification of high-risk individuals which could possibly benefit from supplementation.

Oxidative stress and vascular inflammation in aging

Vascular aging, a determinant factor for cardiovascular disease and health status in the elderly, is now viewed as a modifiable risk factor. Impaired endothelial vasodilation is a early hallmark of arterial aging that precedes the clinical manifestations of vascular dysfunction, the first step to cardiovascular disease and influencing vascular outcomes in the elderly. Accordingly, the preservation of endothelial function is thought to be an essential determinant of healthy aging. With special attention on the effects of aging on the endothelial function, this review is focused on the two main mechanisms of aging-related endothelial dysfunction: oxidative stress and inflammation. Aging vasculature generates an excess of the reactive oxygen species (ROS), superoxide and hydrogen peroxide, that compromise the vasodilatory activity of nitric oxide (NO) and facilitate the formation of the deleterious radical, peroxynitrite. Main sources of ROS are mitochondrial respiratory chain and NADPH oxidases, although NOS uncoupling could also account for ROS generation. In addition, reduced antioxidant response mediated by erythroid-2-related factor-2 (Nrf2) and downregulation of mitochondrial manganese superoxide dismutase (SOD2) contributes to the establishment of chronic oxidative stress in aged vessels. This is accompanied by a chronic low-grade inflammatory phenotype that participates in defective endothelial vasodilation. The redox-sensitive transcription factor, nuclear factor-κB (NF-κB), is upregulated in vascular cells from old subjects and drives a proinflammatory shift that feedbacks oxidative stress. This chronic NF-κB activation is contributed by increased angiotensin-II signaling and downregulated sirtuins and precludes adequate cellular response to acute ROS generation. Interventions targeted to recover endogenous antioxidant capacity and cellular stress response rather than exogenous antioxidants could reverse oxidative stress-inflammation vicious cycle in vascular aging. Lifestyle attitudes such as caloric restriction and exercise training appear as effective ways to overcome defective antioxidant response and inflammation, favoring successful vascular aging and decreasing the risk for cardiovascular disease.

Plasma retinol: a novel marker for cardiovascular disease mortality in Australian adults

BACKGROUND AND AIMS

Vitamin A affects inflammation and immune function and is thus a factor of interest in relation to cardiovascular disease (CVD). As vitamin A circulates in the plasma in the form of retinol, this study aims to describe the relationship between plasma retinol and the 5-year incidence of CVD mortality.

METHODS AND RESULTS

Community-dwelling adults (n = 441, 45% with type 2 diabetes) were recruited in Melbourne, assessed at baseline and followed for 5 years. At baseline, CVD risk factors were assessed by clinical evaluation, by personal lifestyle questionnaire and from biochemistry (plasma fasting glucose, lipids, total homocysteine, C-reactive protein, retinol and carotenoids plus the urinary albumin excretion rate over 24 h.). Dietary intake was assessed by a validated food frequency questionnaire. CVD mortality over 5-years was determined by consulting state or national registries. The majority of participants had adequate plasma retinol concentrations (≥30 μg/dL). The final Cox regression model indicated that those in the highest tertile of plasma retinol (mean ± SD) 76 ± 14 μg/dL) had a significantly lower risk of 5-year CVD mortality (hazard ratio 0.27 [95% confidence interval 0.11, 0.68], P = 0.005), an effect that was not readily explained in terms of traditional CVD risk factors or dietary intake.

CONCLUSION

In well-nourished older Australian adults, plasma retinol was inversely associated with CVD mortality via mechanisms apparently unrelated to established CVD risk factors and dietary intake.

Nitroso-redox status and vascular function in marginal and severe ascorbate deficiency

Marginal vitamin C (ascorbic acid) deficiency is a prevalent yet underappreciated risk factor for cardiovascular disease. Along with glutathione, ascorbate plays important roles in antioxidant defense and redox signaling. Production of nitric oxide (NO) and reactive oxygen species and their interaction, giving rise to nitroso and nitrosyl product formation, are key components of the redox regulation/signaling network. Numerous in vitro studies have demonstrated that these systems are interconnected via multiple chemical transformation reactions, but little is known about their dynamics and significance in vivo.

AIMS

We sought to investigate the time-course of changes in NO/redox status and vascular function during ascorbate depletion in rats unable to synthesize vitamin C.

RESULTS

We here show that both redox and protein nitros(yl)ation status in blood and vital organs vary dynamically during development of ascorbate deficiency. Prolonged marginal ascorbate deficiency is associated with cell/tissue-specific perturbations in ascorbate and glutathione redox and NO status. Scurvy develops earlier in marginally deficient compared to adequately supplemented animals, with blunted compensatory NO production and a dissociation of biochemistry from clinical symptomology in the former. Paradoxically, aortic endothelial reactivity is enhanced rather than impaired, irrespective of ascorbate status. Innovation/Conclusion: Enhanced NO production and protein nitros(yl)ation are integral responses to the redox stress of acute ascorbate deprivation. The elevated cardiovascular risk in marginal ascorbate deficiency is likely to be associated with perturbations of NO/redox-sensitive signaling nodes unrelated to the regulation of vascular tone. This new model may have merit for the future study of redox-sensitive events in marginal ascorbate deficiency.

Vitamin C: Overview and Update

Vitamin C functions in enzyme activation, oxidative stress reduction, and immune function. There is considerable evidence that vitamin C protects against respiratory tract infections and reduces risk for cardiovascular disease and some cancers. Current trials are examining the efficacy of intravenous vitamin C as cancer therapy. Many experts believe that the recommended intakes for vitamin C (45 to 90 mg daily) are several orders of magnitude too low to support optimal vitamin C functionality. Also, there is a misperception that vitamin C deficiency disease (scurvy) is largely historical and rarely observed in developed nations. Physical symptoms of scurvy include swelling of the lower extremities, bleeding gums, fatigue, and hemorrhaging, as well as psychological problems, including depression, hysteria, and social introversion. The long-term safety of vitamin C supplementation seems evident as large investigations have noted reduced risk of mortality in vitamin C supplementing populations and in those with elevated plasma vitamin C concentrations.

Redox-modulatory vitamins and minerals that prospectively predict mortality in older British people: the National Diet and Nutrition Survey of people aged 65 years and over

The predictive power, for total, vascular, cancer and respiratory mortality, of selected redox-modulatory (vitamin and mineral nutrient) indices measured at baseline, was studied in the British National Diet and Nutrition Survey (community-living subset) of people aged 65 years and over. Mortality status and its primary and underlying causes were recorded for 1054 (mean age 76·6 (sd 7·4) years and 49·0 % female) participants, from the baseline survey in 1994–5 until September 2008. During this interval, 74 % of the male and 62 % of the female participants died. Total mortality was significantly predicted by baseline plasma concentrations (per sd) of vitamin C (hazard ratio (HR) 0·81; 95 % CI 0·74, 0·88), α-carotene (HR 0·90; 95 % CI 0·81, 0·99), Se (HR 0·76; 95 % CI 0·69, 0·84), Zn (HR 0·79; 95 % CI 0·72, 0·87), Cu (HR 1·27; 95 % CI 1·14, 1·42) and Fe (HR 0·81; 95 % CI 0·74, 0·89). Total mortality was also significantly predicted by baseline dietary intakes (per sd) of food energy (HR 0·86; 95 % CI 0·79, 0·94), vitamin C (HR 0·88; 95 % CI 0·80, 0·94), carotenoids (HR 0·89; 95 % CI 0·83, 0·96), Zn (HR 0·89; 95 % CI 0·82, 0·96) and Cu (HR 0·91; 95 % CI 0·84, 1·00). Prediction patterns and significance for primary vascular, cancer and respiratory mortality differed in certain respects, but not fundamentally. Model adjustment for known disease or mortality risk predictors resulted in loss of significance for some of the indices; however, plasma Se and Zn, and food energy remained significant predictors. We conclude that total and primary vascular, cancer and respiratory mortality in older British people of both sexes is predicted by several biochemical indices of redox-modulatory nutrients, some of which may reflect the respondents' acute-phase status at baseline, whereas others may reflect the healthiness of their lifestyle.

Strategies for the discovery of anti-aging compounds

IMPORTANCE OF THE FIELD

Life expectancy has increased across the globe and the number of aged people is increasing rapidly. With the rise in the average age of people, the prevalence of age related pathologies has also increased and thus the strategies to find anti-aging molecules assume significance. Anti-aging basically concerns the prevention or delaying the alterations taking place as a function of age which are manifested as age-associated illnesses.

AREAS COVERED IN THIS REVIEW

This review covers anti-aging strategies involving supplementation of dietary antioxidants such as polyphenols, vitamins E and C, lipoic acid, acetyl carnitine, carnosine and cysteine along with the application of mammalian target of rapamycin inhibitors and plasma membrane redox system activators. It also presents the use of different hormone supplementation, for example, melatonin, dehydroepiandrosterone, growth hormone and sex hormones as a tool against aging. The use of caloric restriction and calorie restriction mimetics as an anti-aging intervention is also reviewed.

WHAT THE READER WILL GAIN

The concept, use and efficacy of different anti-aging approaches.

TAKE HOME MESSAGE

Despite a lot of research and sustained ongoing efforts, finding a viable anti-aging therapy which can extend the maximum human lifespan remains elusive. However, several interventions aimed towards a longer healthy life seem promising.

Decreased plasma level of vitamin C in chronic kidney disease: comparison between diabetic and non-diabetic patients

BACKGROUND

A decreased plasma level of vitamin C has been reported to be associated with an increased risk of cardiovascular morbidity and mortality. Here, we sought to determine the vitamin C status of patients with chronic kidney disease and the pathophysiological role of vitamin C in these patients.

METHODS

We studied 58 patients and evaluated the relationship between renal function and plasma vitamin C concentration, as well as the effect of diabetes on this relationship. Endothelium-dependent flow-mediated dilation of brachial artery was measured to assess the endothelial function. Serum malondialdehyde low-density lipoprotein was measured as a marker for oxidative stress.

RESULTS

Plasma vitamin C concentration had a positive linear relationship with eGFR in both diabetic and non-diabetic patients (P = 0.006 and P = 0.004, respectively). When vitamin C concentration and eGFR relationships were compared in the two groups, vitamin C concentration was significantly lower in diabetic patients at every eGFR (P = 0.006). Flow-mediated vasodilatation of the brachial artery was positively correlated with vitamin C concentration in non-diabetic patients (P = 0.047) but not in diabetic patients. There was a negative correlation between serum malondialdehyde low-density lipoprotein and vitamin C concentration in non-diabetic patients (P = 0.044) but not in diabetic patients.

CONCLUSIONS

Renal dysfunction was associated with a decrease in plasma vitamin C level. Moreover, decreased vitamin C may cause endothelial dysfunction via an increase in oxidative stress in non-diabetic chronic kidney disease patients.

Scurvy in hospitalized elderly patients

OBJECTIVES

The aim of this study was to systematically screen hospitalized elderly patients for clinical symptoms of scurvy and to confirm the diagnosis with biological measures.

SETTINGS

Geriatric acute care ward.

MEASUREMENTS

Scurvy symptoms (one or more among perifollicular hyperkeratosis, petechiae or bruises, haemorrhagic features caused by venous puncture, severe gingivitis). We compared associated diseases, nutritional status, need for assistance for feeding, serum albumin, transthyretin, B9 and B12 vitamins, iron status and Serum Ascorbic Acid Level (SAAL) and outcome (in-hospital mortality) between scurvy and scurvy free patients.

RESULTS

18 patients with clinical symptoms of scurvy (scurvy group) were identified out of 145 consecutive patients (12%). They were compared to 23 consecutive control patients with no clinical symptoms of scurvy (scurvy-free group). SAAL was significantly lower (1.09 +/- 1.06 vs 4.87 +/- 4.2 mg x L-1, p < .001) and vitamin C deficiency more frequent (94 vs 30 %, p < .001) in the scurvy group. Moreover, in scurvy group, coronary heart disease (39 vs 9 %, p=.028), need for assistance for feeding (56 vs 13 %, p=.006) and in-hospital deaths (44 vs 9 %, p=.012) were more frequent.

CONCLUSION

Ninety-four percent of patients with clinical symptoms of scurvy had vitamin C deficiency. Our results suggest that in hospitalized elderly patients, clinical symptoms allow scurvy diagnosis. Scurvy could be a frequent disease in elderly patients admitted to acute geriatric ward.

Influence of the placebo effect on oxidative stress in healthy older adults of Mexico City

BACKGROUND

The placebo effect has been widely recognized in the randomized clinical trials; nevertheless, this effect has not been evaluated in terms of antioxidant therapy on oxidative stress (OxS).

OBJECTIVE

The objective of this study was to determine the influence of the placebo effect on OxS in healthy older adults of Mexico City.

METHODS

We carried out a double-blind controlled clinical assay with the participation of 75 healthy older adults residents for the past 10 years of Mexico City; randomly distributed into three groups of 25 subjects each after previous informed consent; control group not received any treatment, placebo group received a placebo with a pharmaceutical presentation similar to that of the treatment, whereas treatment group were administered 1000 mg of ascorbic acid and 400 IU of alpha-tocopherol. All subjects ingested the treatment daily according to study group for 12 months. We measured before and after 12 months of treatment, lipoperoxides levels (LPO), erythrocyte superoxide dismutase, glutathione peroxidase and total plasma antioxidant status with Randox Laboratories Ltd kits. The concentration of ascorbic acid and alpha-tocopherol were measured using high-performance liquid chromatography.

RESULTS

The placebo group subjects showed a statistically significant decrease in LPO concentration, in the same way as the treatment group subjects (P < 0.01), both in comparison with a control group.

CONCLUSION

Our findings suggest that the placebo has a significant effect on OxS.