Impact of thermal processing on polyphenols, carotenoids, glucosinolates, and ascorbic acid in fruit and vegetables and their cardiovascular benefits

Bioactive compounds in fruit and vegetables have a positive impact on human health by reducing oxidative stress, inflammation, and the risk of chronic diseases such as cancer, cardiovascular (CV) diseases, and metabolic disorders. However, some fruit and vegetables must be heated before consumption and thermal processes can modify the amount of nutraceuticals, that is, polyphenols, carotenoids, glucosinolates, and ascorbic acid, that can increase or decrease in relation to different factors such as type of processing, temperature, and time but also the plant part (e.g., flower, leaf, tuber, and root) utilized as food. Another important aspect is related to the bioaccessibility and bioavailability of nutraceuticals. Indeed, the key stage of nutraceutical bioefficiency is oral bioavailability, which involves the release of nutraceuticals from fruit and vegetables in gastrointestinal fluids, the solubilization of nutraceuticals and their interaction with other components of gastrointestinal fluids, the absorption of nutraceuticals by the epithelial layer, and the chemical and biochemical transformations into epithelial cells. Several studies have shown that thermal processing can enhance the absorption of nutraceuticals from fruit and vegetable. Once absorbed, they reach the blood vessels and promote multiple biological effects (e.g., antioxidant, anti-inflammatory, antihypertensive, vasoprotective, and cardioprotective). In this review, we described the impact of different thermal processes (such as boiling, steaming and superheated steaming, blanching, and microwaving) on the retention/degradation of bioactive compounds and their health-promoting effects after the intake. We then summarized the impact of heating on the absorption of nutraceuticals and the biological effects promoted by natural compounds in the CV system to provide a comprehensive overview of the potential impact of thermal processing on the CV benefits of fruit and vegetables.

Improved Antioxidant Status after Diet Supplementation with Novel Natural-Based Supplement in Combat Athletes

BACKGROUND

Intense physical activity is known to generate high levels of oxidative stress, and supplementation with bioactive products with powerful antioxidant effects is often recommended. In this context, the present study aims to evaluate the potential benefits of supplementing the diet of professional combat fighters with a new bioactive formulation based on Aronia melanocarpa (black chokeberry) and bee pollen, a natural combination with a balanced ratio of macro- and micronutrients, rich in proteins and polyphenols.

METHODS

A total of 31 professional combat fighters were selected to participate in this study. Due to allergic medical history, two were excluded, and the remaining 29 were divided into two groups: 14 in the control and 15 in the supplementation group. The supplemented group consumed daily 40 g of novel supplement based on a combination of dried black chokeberry and bee pollen (1:2 ratio) for 4 weeks.

RESULTS

A statistically significant increase in plasma antioxidant capacity was observed in the supplemented group compared to control related to the time and group factors at the end of this study. During this study, a significant increase in neutrophils was recorded in both groups. Supplementation with black chokeberry and bee pollen generated no significant modifications in inflammatory markers, body composition, glycemia, maximum aerobic capacity, blood glycemia, hemoglobin or red cell line.

CONCLUSION

This clinical study pointed out a positive result in terms of plasma antioxidant capacity upon administration of the novel nutraceutical formulation.

Preoperative and postoperative administration of vitamin C in cardiac surgery patients - settings, dosages, duration, and clinical outcomes: a narrative review

Vitamin C or ascorbic acid is a water-soluble vitamin capable of directly donating electrons to reactive oxygen species, attenuating electrical remodeling, and cardiac dysfunction in patients undergoing cardiac surgery (CS), considered one of the most effective defenses against free radicals in the blood, thus being one of the first antioxidants consumed during oxidative stress. The aim of this review is to assess the effects of perioperative administration of vitamin C in CS patients. A comprehensive literature search was conducted in order to identify prospective cohort studies and/or randomized controlled trials reporting on the perioperative effects of vitamin C among adult patients undergoing CS. Studies published between January 1980 to December 2022 were included in our search, resulting in a total of 31 articles that met all our inclusion criteria. There seems to be a beneficial effect of vitamin C supplementation in arrhythmias such as in postoperative atrial fibrillation, reduction of ICU length of stay, and hospital length of stay, reduction in postoperative ventilation time, in inotropic demand, and in postoperative fatigue. Vitamin C can act as a scavenger of free radicals to decrease the peroxidation of the lipids present in the cell membrane, and to protect the myocardium postoperatively from ischemia/reperfusion injury, thus attenuating oxidative stress and inflammation. It represents a readily available and cost-effective strategy that could improve the outcome of patients undergoing CS, by reducing the risk of serious cardiovascular adverse events, both perioperatively and postoperatively.

Antioxidative and Anti-Inflammatory Activity of Ascorbic Acid

Ascorbic acid, as a one of the basic exogenous vitamins, occurs in the body in the form of ascorbate, known for its strong antioxidant and anti-inflammatory properties. The presented review shows not only the importance of ascorbate as a free radical scavenger but also summarizes its antioxidant action based on other mechanisms, including the activation of intracellular antioxidant systems and its effect on the NFκB/TNFα pathway and apoptosis. Ascorbate interacts with small-molecule antioxidants, including tocopherol, glutathione, and thioredoxin; it can also stimulate biosynthesis and the activation of antioxidant enzymes, such as superoxide dismutase, catalase, or glutathione peroxidase. Moreover, ascorbate promotes the activity of transcription factors (Nrf2, Ref-1, AP-1), which enables the expression of genes encoding antioxidant proteins. Additionally, it supports the action of other exogenous antioxidants, mainly polyphenols. In this regard, both DNA, proteins, and lipids are protected against oxidation, leading to an inflammatory reaction and even cell death. Although ascorbate has strong antioxidant properties, it can also have pro-oxidant effects in the presence of free transition metals. However, its role in the prevention of DNA mutation, inflammation, and cell apoptosis, especially in relation to cancer cells, is controversial.

Combating Ischemia-Reperfusion Injury with Micronutrients and Natural Compounds during Solid Organ Transplantation: Data of Clinical Trials and Lessons of Preclinical Findings

Although extended donor criteria grafts bear a higher risk of complications such as graft dysfunction, the exceeding demand requires to extent the pool of potential donors. The risk of complications is highly associated with ischemia-reperfusion injury, a condition characterized by high loads of oxidative stress exceeding antioxidative defense mechanisms. The antioxidative properties, along with other beneficial effects like anti-inflammatory, antiapoptotic or antiarrhythmic effects of several micronutrients and natural compounds, have recently emerged increasing research interest resulting in various preclinical and clinical studies. Preclinical studies reported about ameliorated oxidative stress and inflammatory status, resulting in improved graft survival. Although the majority of clinical studies confirmed these results, reporting about improved recovery and superior organ function, others failed to do so. Yet, only a limited number of micronutrients and natural compounds have been investigated in a (large) clinical trial. Despite some ambiguous clinical results and modest clinical data availability, the vast majority of convincing animal and in vitro data, along with low cost and easy availability, encourage the conductance of future clinical trials. These should implement insights gained from animal data.

Novel Combined Antioxidant Strategy against Hypertension, Acute Myocardial Infarction and Postoperative Atrial Fibrillation

Reactive oxygen species (ROS) play a physiological role in the modulation of several functions of the vascular wall; however, increased ROS have detrimental effects. Hence, oxidative stress has pathophysiological impacts on the control of the vascular tone and cardiac functions. Recent experimental studies reported the involvement of increased ROS in the mechanism of hypertension, as this disorder associates with increased production of pro-oxidants and decreased bioavailability of antioxidants. In addition, increased ROS exposure is found in ischemia-reperfusion, occurring in acute myocardial infarction and cardiac surgery with extracorporeal circulation, among other settings. Although these effects cause major heart damage, at present, there is no available treatment. Therefore, it should be expected that antioxidants counteract the oxidative processes, thereby being suitable against cardiovascular disease. Nevertheless, although numerous experimental studies agree with this notion, interventional trials have provided mixed results. A better knowledge of ROS modulation and their specific interaction with the molecular targets should contribute to the development of novel multitarget antioxidant effective therapeutic strategies. The complex multifactorial nature of hypertension, acute myocardial infarction, and postoperative atrial fibrillation needs a multitarget antioxidant strategy, which may give rise to additive or synergic protective effects to achieve optimal cardioprotection.

Vitamin C measurement in critical illness: challenges, methodologies and quality improvements

Background There is renewed interest in high-dose vitamin C interventions in clinical medicine due to its antioxidant properties, safe use and cost-effectiveness. Yet, randomised control trials (RCTs) employing these interventions are failing to include robust analytical methodology and proper sample handling and processing techniques. Consequently, comparisons between studies becomes impossible as there is no metrological traceability and results may be prone to pre-analytical errors. Content Through published vitamin C stability studies, method comparison papers and data from vitamin C external quality assurance programs, an assessment was made on the functionality of current methods for critically ill patient samples. Summary Data was obtained from two external quality assurance programs, two papers assessing sample stability and interlaboratory agreement and a publication on vitamin C method comparisons. A shift from spectrophotometric and enzymatic methodologies to high performance liquid chromatography (HPLC) greatly improved the variability and interlaboratory agreement. Therefore, the current analytical performance of vitamin C HPLC methodologies are acceptable for the requirements of a high-dose vitamin C RCTs. Outlook Recommendations across the total testing process of vitamin C have been provided to improve the quality of the results. The harmonisation of sample handling and processing procedures will further improve the reliability of current analytical methodologies.

Does Evidence Exist to Blunt Inflammatory Response by Nutraceutical Supplementation during COVID-19 Pandemic? An Overview of Systematic Reviews of Vitamin D, Vitamin C, Melatonin, and Zinc

More than one year has passed since the first cases of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome (SARS)-CoV-2 coronavirus were reported in Wuhan (China), rapidly evolving into a global pandemic. This infectious disease has become a major public health challenge in the world. Unfortunately, to date, no specific antivirals have been proven to be effective against COVID-19, and although a few vaccines are available, the mortality rate is not decreasing but is still increasing. One therapeutic strategy has been focused on infection prevention and control measures. In this regard, the use of nutraceutical supports may play a role against some aspect of the infection, particularly the inflammatory state and the immune system function of patients, thus representing a strategy to control the worst outcomes of this pandemic. For this reason, we performed an overview including meta-analyses and systematic reviews to assess the association among melatonin, vitamin C, vitamin D, zinc supplementation and inflammatory markers using three databases, namely, MEDLINE, PubMed Central and the Cochrane Library of Systematic Reviews. According to the evidence available, an intake of 50,000 IU/month of vitamin D showed efficacy in CRP. An amount of 1 to 2 g per day of vitamin C demonstrated efficacy both in CRP and endothelial function, and a dosage of melatonin ranging from 5 to 25 mg /day showed good evidence of efficacy in CRP, TNF and IL6. A dose of 50 mg/day of elemental zinc supplementation showed positive results in CRP. Based on the data reported in this review, the public health system could consider whether it is possible to supplement the current limited preventive measures through targeted nutraceutical large-scale administration.

Correction: Hill, A.; et al. Effects of Vitamin C on Organ Function in Cardiac Surgery Patients: A Systematic Review and Meta-Analysis. Nutrients 2019, 11, 2103

The authors thank the readers for pointing out the issues [...].

Vitamin C supplementation and C-reactive protein levels: Findings from a systematic review and meta-analysis of clinical trials

Background and purpose C-reactive protein (CRP) is an inflammatory biomarker which prognosticates cardiovascular disease. Previous studies have reached mixed conclusions regarding the effect of vitamin C on reducing CRP or hs-CRP level. The present systematic review and meta-analysis was conducted to resolve these inconsistencies. Materials and methods: Related articles published up to August 2018 were searched through PubMed, Scopus, Ovid, ISI web of science, Embase, and Cochrane databases by relevant keywords. Clinical trials which examined the effect of either vitamin C supplementation or vitamin C-enriched foods on CRP and hs-CRP levels were included. A total of 11 studies with 14 data sets involving 818 subjects were included. Results Overall, the pooled analysis revealed that vitamin C could decrease CRP level relative to placebo group (Weighted mean difference [WMD]=-0.73 mg/L: 95% CI: -1.30 to -0.15, p=0.013) with a considerable heterogeneity (I2=98%, p<0.001). Moreover, subgroup analyses revealed that the beneficial effect of vitamin C on CRP level alternation only was found in male (p=0.003), non-smoker (p=0.041), healthy (p=0.029) and younger participants (p=0.010). Vitamin C could improve CRP level only at doses of less than 500 mg/day (p=0.009). Regarding hs-CRP changes, the pooled analysis did not show any significant effect of vitamin C (WMD=-0.65 mg/L: 95% CI: -2.03 to 0.72, p=0.35). This finding was confirmed by all subgroup analyses expect for high quality articles in which hs-CRP level was elevated after vitamin C supplementation (p=0.026). Conclusion In conclusion, supplementation with vitamin C might have a significant effect only on CRP reduction. Further studies are needed to confirm this effect.

Effects of Vitamin C on Organ Function in Cardiac Surgery Patients: A Systematic Review and Meta-Analysis

Background: Cardiac surgery is associated with oxidative stress and systemic inflammation, which both contribute to postoperative organ dysfunction. Vitamin C is a pleiotropic, antioxidant, and potentially organ-protective micronutrient. Past clinical trials and meta-analyses have focused predominantly on occurrence of postoperative atrial fibrillation. Therefore, we investigated the influence of perioperative vitamin C administration on clinically relevant parameters closer related to the patient’s recovery, especially organ function, and overall outcomes after cardiac surgery. Methods: Randomized controlled trials (RCTs) comparing perioperative vitamin C administration versus placebo or standard of care in adult patients undergoing cardiac surgery were identified through systematic searches in Pubmed, EMBASE, and CENTRAL on 23 November 2018. Published and unpublished data were included. Assessed outcomes include organ function after cardiac surgery, adverse events, in-hospital mortality, intensive care unit, and hospital length-of-stay. Data was pooled only when appropriate. Results: A total of 19 RCTs with 2008 patients were included in this meta-analysis. Vitamin C significantly decreased the incidence of atrial fibrillation (p = 0.008), ventilation time (p < 0.00001), ICU length-of-stay (p = 0.004), and hospital length-of-stay (p < 0.0001). However, on average, vitamin C had no significant effects on in-hospital mortality (p = 0.76), or on the incidence of stroke (p = 0.82). High statistical heterogeneity was observed in most analyses. Conclusions: Vitamin C impacts clinically and economically important outcomes, such as ICU and hospital length-of-stay, duration of mechanical ventilation and lowers the incidence of atrial fibrillation. Due to missing reports on organ dysfunction, this meta-analysis cannot answer the question, if vitamin C can improve single- or multiorgan function after cardiac surgery.

Vitamin C Can Shorten the Length of Stay in the ICU: A Meta-Analysis

A number of controlled trials have previously found that in some contexts, vitamin C can have beneficial effects on blood pressure, infections, bronchoconstriction, atrial fibrillation, and acute kidney injury. However, the practical significance of these effects is not clear. The purpose of this meta-analysis was to evaluate whether vitamin C has an effect on the practical outcomes: length of stay in the intensive care unit (ICU) and duration of mechanical ventilation. We identified 18 relevant controlled trials with a total of 2004 patients, 13 of which investigated patients undergoing elective cardiac surgery. We carried out the meta-analysis using the inverse variance, fixed effect options, using the ratio of means scale. In 12 trials with 1766 patients, vitamin C reduced the length of ICU stay on average by 7.8% (95% CI: 4.2% to 11.2%; p = 0.00003). In six trials, orally administered vitamin C in doses of 1⁻3 g/day (weighted mean 2.0 g/day) reduced the length of ICU stay by 8.6% (p = 0.003). In three trials in which patients needed mechanical ventilation for over 24 hours, vitamin C shortened the duration of mechanical ventilation by 18.2% (95% CI 7.7% to 27%; p = 0.001). Given the insignificant cost of vitamin C, even an 8% reduction in ICU stay is worth exploring. The effects of vitamin C on ICU patients should be investigated in more detail.

Vitamin C supplementation in the critically ill: A systematic review and meta-analysis

BACKGROUND

Low plasma levels of vitamin C are associated with adverse outcomes, including increased mortality, in critically ill patients. Several trials have suggested that the administration of intravenous vitamin C in this setting may have beneficial effects, such as reducing the incidence of organ failure and improving survival. However, these studies have generally involved combination therapies consisting of vitamin C along with other antioxidants, confounding the effects of vitamin C alone. The primary objective of this meta-analysis is to investigate the effects of isolated intravenous supplementation of vitamin C in adults with critical illness.

METHODS

A database search was conducted for studies on the use of intravenous vitamin C in adult patients with critical illness. The primary outcome assessed was mortality at the longest follow-up time available. Secondary outcomes were the duration of mechanical ventilation, duration of vasopressor support, fluid requirements, and urine output in the first 24 h of intensive care unit admission.

RESULTS

Five studies (four randomized controlled trials and one retrospective review) enrolling a total of 142 patients were included in this meta-analysis. Compared with controls, the administration of intravenous vitamin C was associated with a decreased need for vasopressor support (standardized mean difference -0.71; 95% confidence interval (-1.16 to -0.26); p = 0.002) and decreased duration of mechanical ventilation (standardized mean difference -0.5; 95% confidence interval (-0.93 to -0.06); p = 0.03), but no difference was found in mortality (odds ratio 0.76; 95% confidence interval (0.27 to 2.16); p = 0.6). Trends were also noted toward decreased fluid requirements and increased urine output. No adverse effects were reported.

CONCLUSION

The administration of intravenous vitamin C may lead to vasopressor sparing effects and a reduced need for mechanical ventilation in the critically ill, without affecting overall mortality. However, these results should be interpreted in light of the limitations of the primary literature and should serve as a preview of upcoming trials in this area.

Vitamin C to Improve Organ Dysfunction in Cardiac Surgery Patients-Review and Pragmatic Approach

The pleiotropic biochemical and antioxidant functions of vitamin C have sparked recent interest in its application in intensive care. Vitamin C protects important organ systems (cardiovascular, neurologic and renal systems) during inflammation and oxidative stress. It also influences coagulation and inflammation; its application might prevent organ damage. The current evidence of vitamin C's effect on pathophysiological reactions during various acute stress events (such as sepsis, shock, trauma, burn and ischemia-reperfusion injury) questions whether the application of vitamin C might be especially beneficial for cardiac surgery patients who are routinely exposed to ischemia/reperfusion and subsequent inflammation, systematically affecting different organ systems. This review covers current knowledge about the role of vitamin C in cardiac surgery patients with focus on its influence on organ dysfunctions. The relationships between vitamin C and clinical health outcomes are reviewed with special emphasis on its application in cardiac surgery. Additionally, this review pragmatically discusses evidence on the administration of vitamin C in every day clinical practice, tackling the issues of safety, monitoring, dosage, and appropriate application strategy.

Sole and combined vitamin C supplementation can prevent postoperative atrial fibrillation after cardiac surgery: A systematic review and meta-analysis of randomized controlled trials

We undertook a systematic review and meta-analysis to evaluate the effect of vitamin C supplementation (vitamin C solely or as adjunct to other therapy) on prevention of postoperative atrial fibrillation (POAF) in patients after cardiac surgery. PubMed, Embase, Web of Science, and Cochrane Library were systematically searched to identify randomized controlled trials assessing the effect of vitamin C supplementation in adult patients undergoing cardiac surgery, and the meta-analysis was performed with a random-effects model. Thirteen trials involving 1956 patients were included. Pooling estimate showed a significantly reduced incidence of POAF (relative risk [RR]: 0.68, 95% confidence interval [CI]: 0.54 to 0.87, P = 0.002) both in vitamin C alone (RR: 0.75, 95% CI: 0.63 to 0.90, P = 0.002) and as an adjunct to other therapy (RR: 0.32, 95% CI: 0.20 to 0.53, P < 0.001). The results remain stable and robust in subgroup and sensitivity analyses, and trial sequential analysis also confirmed that the evidence was sufficient and conclusive. Additionally, vitamin C could significantly decrease intensive care unit length of stay (weighted mean difference: -0.24 days, 95% CI: -0.45 to -0.03, P = 0.023), hospital length of stay (weighted mean difference: -0.95 days, 95% CI: -1.64 to -0.26, P = 0.007), and risk of adverse events (RR: 0.45, 95% CI: 0.21 to 0.96, P = 0.039). Use of vitamin C alone and as adjunct to other therapy can prevent POAF in patients undergoing cardiac surgery and should be recommended for patients receiving cardiac surgery for prevention of POAF.

The clinical benefits of perioperative antioxidant vitamin therapy in patients undergoing cardiac surgery: a meta-analysis

The clinical benefits of perioperative antioxidant vitamin therapy in cardiac patients remain controversial. Here, we conducted a meta-analysis to determine the strength of the evidence supporting the perioperative use of antioxidant vitamins in patients undergoing cardiac surgery. We searched 4 databases (PubMed, EMBASE, Science Citation Index and Cochrane Library) for randomized controlled trials that reported the effects of antioxidant vitamin therapy on patients undergoing cardiac surgery until 6 June 2016. Risk ratio (RR) or mean difference (MD) and its 95% confidence interval (95% CI) served as the summarized results. Heterogeneity among included studies was evaluated using the I2 statistic, which help determine which effect model to apply. We constructed a funnel plot to assess the existence of publication bias. Sensitivity analyses were also conducted to evaluate the robustness of the outcomes. Twelve trials with 1584 cardiac patients were included. Compared with placebo or no antioxidant vitamin therapy, administration of antioxidant vitamin therapy resulted in a reduction in postoperative atrial fibrillation (POAF) (RR 0.55, 95% CI 0.42, 0.73, P < 0.0001), duration of hospital stay (MD -0.68, 95% CI -0.98, -0.39, P < 0.00001), intensive care unit length of stay (MD -0.21, 95% CI -0.30, -0.12, P < 0.00001) and intubation time (MD -2.41, 95% CI -3.83, -0.98, P = 0.001). Our results also showed a trend towards a decrease in postoperative complications (RR 0.72, 95% CI 0.48, 1.08, P = 0.11) and duration of POAF (MD -1.950, 95% CI -3.28, 0.29, P = 0.10). This meta-analysis demonstrated that perioperative antioxidant vitamin therapy in patients undergoing cardiac surgery can reduce the incidence of POAF, duration of hospital stay, intensive care unit length of stay and intubation time.

Vitamin C for preventing atrial fibrillation in high risk patients: a systematic review and meta-analysis

Background

Atrial fibrillation (AF), a common arrhythmia contributing substantially to cardiac morbidity, is associated with oxidative stress and, being an antioxidant, vitamin C might influence it.

Methods

We searched the Cochrane CENTRAL Register, MEDLINE, and Scopus databases for randomised trials on vitamin C that measured AF as an outcome in high risk patients. The two authors independently assessed the trials for inclusion, assessed the risk of bias, and extracted data. We pooled selected trials using the Mantel-Haenszel method for the risk ratio (RR) and the inverse variance weighting for the effects on continuous outcomes.

Results

We identified 15 trials about preventing AF in high-risk patients, with 2050 subjects. Fourteen trials examined post-operative AF (POAF) in cardiac surgery patients and one examined the recurrence of AF in cardioversion patients. Five trials were carried out in the USA, five in Iran, three in Greece, one in Slovenia and one in Russia.

There was significant heterogeneity in the effect of vitamin C in preventing AF. In 5 trials carried out in the USA, vitamin C did not prevent POAF with RR = 1.04 (95% CI: 0.86–1.27). In nine POAF trials conducted outside of the USA, vitamin C decreased its incidence with RR = 0.56 (95% CI: 0.47–0.67). In the single cardioversion trial carried out in Greece, vitamin C decreased the risk of AF recurrence by RR = 0.13 (95% CI: 0.02–0.92).

In the non-US cardiac surgery trials, vitamin C decreased the length of hospital stay by 12.6% (95% CI 8.4–16.8%) and intensive care unit (ICU) stay by 8.0% (95% CI 3.0–13.0%). The US trials found no effect on hospital stay and ICU stay. No adverse effects from vitamin C were reported in the 15 trials.

Conclusions

Our meta-analysis indicates that vitamin C may prevent post-operative atrial fibrillation in some countries outside of the USA, and it may also shorten the duration of hospital stay and ICU stay of cardiac surgery patients. Vitamin C is an essential nutrient that is safe and inexpensive. Further research is needed to determine the optimal dosage protocol and to identify the patient groups that benefit the most.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-017-0478-5) contains supplementary material, which is available to authorized users.

Efficacy and safety of vitamin C for atrial fibrillation after cardiac surgery: A meta-analysis with trial sequential analysis of randomized controlled trials

OBJECTIVES

Antioxidant supplement is an option in preventing postoperative atrial fibrillation (AF) after cardiac surgery. However, the benefits and adverse effects of vitamin C have not been well assessed. We aimed to systematically evaluate the efficacy and safety of vitamin C in preventing postoperative AF in adult patients after cardiac surgery.

METHODS

PubMed, EMBASE, and the Cochrane library databases from inception to September 2016 were searched. Randomized controlled trials (RCTs) that evaluated the efficacy and safety of vitamin C in preventing postoperative AF in adult patients after cardiac surgery were identified. The primary outcome was the incidence of postoperative AF. Secondary outcomes included the length of intensive care unit (ICU) stay, length of hospital stay, and stroke events.

RESULTS

Eight RCTs incorporating 1060 patients were included. Compared with placebo group, vitamin C treatment was associated with a substantial reduction in postoperative AF (OR, 0.47; 95% CI, 0.36-0.62; evidence rank: moderate), with no significant heterogeneity (I² 44%; P = 0.09). Trial sequential analysis showed that the cumulative Z-curve crossed the trial sequential monitoring boundary for benefit, establishing sufficient and conclusive evidence. In addition, vitamin C administration was not associated with any length of stay, including in the ICU (evidence rank: low) and hospital (evidence rank: low), respectively.

CONCLUSIONS

Short-term treatment with vitamin C is safe, and may reduce the incidence of postoperative AF after cardiac surgery. Future studies as well as more high quality RCTs are still warranted to confirm the effects of different durations of vitamin C on cardiac surgery.

Vitamin C for the Prevention of Postoperative Atrial Fibrillation after Cardiac Surgery: A Meta-Analysis

PURPOSE

Several studies have investigated the administration of vitamin C (vitC) for the prevention of postoperative atrial fibrillation (AF) after cardiac surgery. However, their findings were inconsistent. The purpose of this meta-analysis was to evaluate the efficacy of vitC as prophylaxis for the prevention of postoperative AF in cardiac surgery.

METHODS

A systematic search of PubMed, EMBASE, Google Scholar, the Cochrane Library, and clinical trial registries, was performed. 9 studies, published from August 2001 to May 2015, were included, with a total of 1,037 patients. Patients were randomized to receive vitC, or placebo.

RESULTS

Cardiac surgery patients who received vitC as prophylaxis, had a significantly lower incidence of postoperative AF (random effects OR=0.478, 95% CI 0.340 - 0.673, P < 10(-4)). No significant heterogeneity was detected across the analyzed studies (I(2)=21.7%), and no publication bias or other small study-related bias was found.

CONCLUSION

Our findings suggest that VitC is effective as prophylaxis for the prevention of postoperative AF. The administration of vitC may be considered in all patients undergoing cardiac surgery.

Blood transfusion and the risk of atrial fibrillation after cardiac surgery

BACKGROUND

Red blood cell transfusion (Tx) induces a proinflammatory state. Inflammatory mediators are associated with an increased risk of postoperative atrial fibrillation (AF). Therefore, in this study we determined the association between AF and Tx after isolated coronary artery bypass graft surgery (CABG).

METHOD

Between January 2008 and December 2010, a total of 879 patients underwent CABG. Of these, 815 (92.7%) had complete data extracted from our institution's Society of Thoracic Surgeons (STS) database. Predictors of AF development among four levels of Tx versus nontransfused patients were examined. Multivariable logistic regression and propensity score matching models were used.

RESULTS

The mean age was 65.8 years (±10.3), 77.4% were male, and 54.4% had an STS predicted risk score (mortality/morbidity) of ≥10%. A total of 564 (69.2%) had at least one unit of Tx. Adjusting for age, sex, time on pump, congestive heart failure, stroke, creatinine level (<1.5 mg per deciliter vs. ≥1.5), STS morbidity/mortality score, perioperative myocardial infarction (MI), cross-clamp time, medications, and hemoglobin level, the odds ratio (OR) of AF increased with increasing Tx (OR, 1.36; 95% confidence interval [CI], 1.11 to 1.68; p = 0.003). The odds of AF increased 61% with each increasing level of Tx (OR, 1.61; 95% CI, 1.15 to 2.26; p = 0.006, by propensity analysis).

CONCLUSIONS

Perioperative Tx may be associated with excess AF following CABG. This risk increases with increasing number of Tx.

Antioxidant supplementations for prevention of atrial fibrillation after cardiac surgery: an updated comprehensive systematic review and meta-analysis of 23 randomized controlled trials

This systematic review with meta-analysis sought to determine the impact of antioxidants (N-acetylcysteine [NAC], polyunsaturated fatty acids [PUFAs] and vitamins) on incidence of postoperative atrial fibrillation (POAF) and duration of length of hospital stay. Medline, Embase, Elsevier, Sciences online database and Google Scholar literature search was made for studies in randomized controlled trials. The effect sizes measured were odds ratio (OR) for categorical variable and standard mean difference (SMD) with 95% confidence interval (CI) for calculating differences between mean values of duration of hospitalization in intervention and control groups. A value of P < 0.1 for Q-test or I(2) > 50% indicated significant heterogeneity between the studies. Literature search of all major databases retrieved 355 studies. After screening, a total of 23 trials were identified that reported outcomes of 4278 patients undergoing cardiac surgery. Pooled effects estimates on POAF showed a significant reduction after NAC (OR: 0.56, 95% CI: 0.40-0.77, P < 0.001), PUFA (OR: 0.84, 95% CI: 0.71-0.99, P = 0.03) and vitamin C treatment (OR: 0.50, 95% CI: 0.27-0.91, P = 0.02). Hospital length of stay was not reduced after NAC therapy (SMD: 0.082, 95% CI -0.09 to 0.25, P = 0.3), but could be decreased with PUFA (SMD: -0.185, 95% CI: -0.35 to -0.018, P = 0.03) and vitamin C (SMD: -0.325, 95% CI -0.50 to -0.14, P < 0.01). In conclusion, perioperative antioxidant supplementations with NAC, PUFA and vitamin C prevent atrial fibrillation after cardiac surgery. Moreover, PUFA and vitamin C are capable to reduce hospital stay, whereas NAC lacks this capacity.