Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance

Do Liposomal Vitamin C Formulations Have Improved Bioavailability? A Scoping Review Identifying Future Research Directions

Due to the essential requirement of vitamin C (ascorbate) by humans, formulation of the vitamin to increase its bioavailability is of relevance, particularly for those with higher requirements for the vitamin. In this scoping review, studies assessing the bioavailability of liposomal versus non-liposomal ascorbate were identified through database and manual searching and relevant pharmacokinetic data were extracted. Of the 321 studies identified, 10 were included in the final review. Seven of the trials used randomised crossover designs, one used parallel groups and two were non-randomised. Vastly different liposomal formulations, ascorbate doses (0.15-10 g) and sample collection durations (4-24 h) were used, thereby making it difficult to directly compare the studies. Nevertheless, nine of the studies showed higher bioavailability of liposomal versus non-liposomal ascorbate: 1.2-5.4-fold higher Cmax and 1.3-7.2-fold higher AUC. However, none of the studies assessed ascorbate elimination; therefore, it is uncertain whether the ratios of liposomal to non-liposomal ascorbate in urine are equivalent to those observed in plasma. Furthermore, only two of the studies assessed in vivo cellular uptake and only two assessed potential biological effects. Thus, future studies should include urinary elimination and cellular uptake kinetics, assess participants with low baseline status and investigate potential biological effects. SUMMARY: Due to the essential requirement of vitamin C by humans, formulations to increase its uptake into the body are of relevance, particularly in those with higher requirements for the vitamin. In this review, studies assessing the uptake of liposomal versus non-liposomal vitamin C were investigated; liposomal vitamin C comprising the vitamin encapsulated within lipids. Ten studies were identified, which administered different liposomal formulations, vitamin C doses (0.15-10 g) and sample collection durations (4-24 h). Nine of the studies showed higher uptake of liposomal vitamin C. Future studies should assess urinary excretion, cellular uptake and biological effects of liposomal vitamin C.

Effects of Vitamin C Supplementation on Total Antioxidant Status, Inflammation, and Histopathological Changes in Aged Rats

This study aims to determine the effect of orally administered vitamin C (Vit C) supplementation on physiological and histopathological changes in aged rats of different genders. A total of 28 Sprague-Dawley aged male and female rats were randomly divided into four groups of seven animals per group. The study groups included the aged male control (MC), aged male with Vit C (MVC) (500 mg/kg vitamin C, orally) supplementation, female aged control (FC), and female aged with vitamin C (FVC) (500 mg/kg vitamin C, orally) supplementation groups. At the end of the study, which lasted 31 days, blood, brain, heart, liver, and kidney tissues were collected from rats under ketamine (87 mg/kg) and xylazine (13 mg/kg) anesthesia. The results indicated that although Vit C supplementation had no effect on serum Vit C levels, gender had an effect on serum Vit C levels (p < 0.05). However, Vit C supplementation and gender did not affect serum IL-6, IL-1β, TOS, and OSI levels (p > 0.05). Vit C supplementation, without the effect of gender, significantly increased TNF-α levels in MVC groups compared to MC groups (p < 0.05), while it significantly decreased them in FVC groups compared to FC groups (p < 0.05). In addition, Vit C significantly reduced histopathological alterations in brain, heart, and liver tissues associated with aging, including oxidative stress and inflammation. In conclusion, it was observed that orally administered 500 mg/kg Vit C supplementation to old rats is not an effective way to increase the Vit C pool in the body, but gender has an impact on the blood Vit C concentrations.

The roles of vitamin C in infectious diseases: A comprehensive review

Vitamin C is a versatile nutrient with essential antioxidant properties and roles in amino acid metabolism, collagen promotion, and hormone synthesis. It has long been regarded as benefitting infectious disease management, although its specific roles remain uncertain. The dominant view is that this efficacy not only stems from its redox regulation in the body but also from its profound impact on the immune system. This review provides a comprehensive overview of Vitamin C's effects on redox regulation and shows how the vitamin influences various immune cells and cell-intrinsic innate immunity signaling pathways, thereby updating and expanding our previous perspectives. Clinically, though some studies and case series have suggested potential benefits of Vitamin C in preventing and (or) treating respiratory tract infections and sepsis and septic shock, the evidence remains controversial. The current data is insufficient to support the routine clinical use of Vitamin C in managing these diseases and requires further rigorous evaluation to establish definitive efficacy and safety profiles. This review thoroughly examines current clinical research progress on Vitamin C, summarizes the primary controversies and their underlying causes, and proposes directions for future clinical research. Furthermore, preclinical evidence shows potential roles for Vitamin C in the supplementary treatment of the "Big Three" infectious diseases: acquired immunodeficiency syndrome (AIDS), tuberculosis, and malaria; however, systematic clinical studies in these areas are lacking. We examine related in vitro and animal studies, as well as clinical trials, and discuss potential roles for Vitamin C as a treatment and (or) adjuvant therapy.

High-dose vitamin C promotes mitochondrial biogenesis in HCT116 colorectal cancer cells by regulating the AMPK/PGC-1α signaling pathway

BACKGROUND

Mitochondrial dysfunction is closely associated with cancer development. Colorectal cancer (CRC) cells often exhibit altered energy metabolism, characterized by increased glycolysis and reduced oxidative phosphorylation. Enhancing mitochondrial biogenesis and function may represent a promising therapeutic approach. High-dose vitamin C has demonstrated anti-tumor properties and the ability to reverse the Warburg effect, but its role in regulating mitochondrial biogenesis and function remains unclear.

METHODS

We evaluated the altered mitochondrial functional status of HCT116 colorectal cancer cells compared to FHC colorectal epithelial cells, assessed the effects of high-dose vitamin C on mitochondrial biogenesis and function in HCT116 cells, and explored the underlying regulatory mechanisms.

RESULTS

HCT116 cells exhibited mitochondrial dysfunction compared to FHC cells, including decreased expression of electron transport chain complexes III and IV, reduced TFAM levels, and lower mtDNA content. Vitamin C treatment significantly enhanced mitochondrial biogenesis and function, as reflected by increased AMPK phosphorylation, upregulation of PGC-1α, SOD2, NRF2, TFAM, MT-CYB, and MTCO1, elevated mtDNA content, restored membrane potential, enhanced oxidative phosphorylation, and reduced glycolytic activity. Furthermore, vitamin C markedly suppressed HCT116 cell viability and clonogenic capacity, while these effects were substantially diminished by cotreatment with Compound C.

CONCLUSION

This study demonstrates that high-dose vitamin C ameliorates mitochondrial dysfunction and promotes mitochondrial biogenesis and function in colorectal cancer cells through activation of the AMPK-PGC-1α signaling pathway, thereby suppressing tumor cell proliferation. These findings suggest that vitamin C may serve as a promising therapeutic agent for targeting mitochondrial metabolism in colorectal cancer.

Vitamin C improves gut Bifidobacteria in humans

Aims: Numerous beneficial effects of vitamin C (ascorbic acid) supplementation have been reported in the literature. However, data on its effects toward the gut microbiome are limited. We assessed the effect of vitamin C supplementation on the abundance of beneficial bacterial species in the gut microbiome. Materials and methods: Stool samples were analyzed for relative abundance of gut microbiome bacteria using next-generation sequencing-based profiling and metagenomic shotgun analysis. Results: Supplementation with vitamin C increased the abundance of bacteria of the genus Bifidobacterium (p = 0.0001) and affected various species. Conclusion: The beneficial effects of vitamin C supplementation may be attributed to modulation of the gut microbiome and the consequent health benefits thereof.

Antioxidants: a comprehensive review

Antioxidants had a growing interest owing to their protective roles in food and pharmaceutical products against oxidative deterioration and in the body and against oxidative stress-mediated pathological processes. Screening of antioxidant properties of plants and plant derived compounds requires appropriate methods, which address the mechanism of antioxidant activity and focus on the kinetics of the reactions including the antioxidants. Many studies have been conducted with evaluating antioxidant activity of various samples of research interest using by different methods in food and human health. These methods were classified methods described and discussed in this review. Methods based on inhibited autoxidation are the most suited for termination-enhancing antioxidants and, for chain-breaking antioxidants while different specific studies are needed for preventive antioxidants. For this purpose, the most commonly methods used in vitro determination of antioxidant capacity of food and pharmaceutical constituents are examined and also a selection of chemical testing methods is critically reviewed and highlighting. In addition, their advantages, disadvantages, limitations and usefulness were discussed and investigated for pure molecules and raw plant extracts. The effect and influence of the reaction medium on performance of antioxidants is also addressed. Hence, this overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceuticals, and dietary supplement industries. Also, the most important advantages and shortcomings of each method were detected and highlighted. The underlying chemical principles of these methods have been explained and thoroughly analyzed. The chemical principles of methods of 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical scavenging, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical (ABTS·+) scavenging, ferric ions (Fe3+) reducing assay, ferric reducing antioxidant power (FRAP) assay, cupric ions (Cu2+) reducing power assay (Cuprac), Folin-Ciocalteu reducing capacity (FCR assay), superoxide radical anion (O2·-), hydroxyl radical (OH·) scavenging, peroxyl radical (ROO·) removing, hydrogen peroxide (H2O2) decomposing, singlet oxygen (1O2) quenching assay, nitric oxide radical (NO·) scavenging assay and chemiluminescence assay are overviewed and critically discussed. Also, the general antioxidant aspects of the main food and pharmaceutical components were discussed through several methods currently used for detecting antioxidant properties of these components. This review consists of two main sections. The first section is devoted to the main components in food and their pharmaceutical applications. The second general section includes definitions of the main antioxidant methods commonly used for determining the antioxidant activity of components. In addition, some chemical, mechanistic, and kinetic properties, as well as technical details of the above mentioned methods, are provided. The general antioxidant aspects of main food components have been discussed through various methods currently used to detect the antioxidant properties of these components.

Harnessing nutrients and natural products for sustainable drug development against aging

Developing treatments for age-related diseases requires cost-effective and efficient approaches. Nutrients and natural metabolites offer safer alternatives to synthetic drugs. Aging increases the need for solutions that protect health and repair cells. Recent studies show that nutrients and natural products reduce oxidative stress, regulate metabolism, and influence longevity-related genes. This review focuses on vitamins, minerals, antioxidants, and natural products that improve healthspan and combat aging. It also discusses challenges such as standardization, clinical validation, and regulatory approval. Finally, emerging trends, such as personalized nutrition and advanced delivery systems, highlight the potential of these metabolites for addressing aging.

Nutritional Support of Chronic Obstructive Pulmonary Disease

Background: COPD is a heterogenous disease of the respiratory tract caused by diverse genetic factors along with environmental and lifestyle-related effects such as industrial dust inhalation and, most frequently, cigarette smoking. These factors lead to airflow obstruction and chronic respiratory symptoms. Additionally, the increased risk of infections exacerbates airway inflammation in COPD patients. As a consequence of the complex pathomechanisms and difficulty in treatment, COPD is among the leading causes of mortality both in the western countries and in the developing world. Results: The management of COPD is still a challenge for the clinicians; however, alternative interventions such as smoking cessation and lifestyle changes from a sedentary life to moderate physical activity with special attention to the diet may ameliorate patients' health. Here, we reviewed the effects of different dietary components and supplements on the conditions of COPD. Conclusions: COPD patients are continuously exposed to heavy metals, which are commonly present in cigarette smoke and polluted air. Meanwhile, they often experience significant nutrient deficiencies, which affect the detoxification of these toxic metals. This in turn can further disrupt nutritional balance by interfering with the absorption, metabolism, and utilization of essential micronutrients. Therefore, awareness and deliberate efforts should be made to check levels of micronutrients, with special attention to ensuring adequate levels of antioxidants, vitamin D, vitamin K2, magnesium, and iron, as these may be particularly important in reducing the risk of COPD development and limiting disease severity.

Modulating oxidative stress: a reliable strategy for coping with community-acquired pneumonia in older adults

Community-acquired pneumonia (CAP) remains one of the leading respiratory diseases worldwide. With the aging of the global population, the morbidity, criticality and mortality rates of CAP in older adults remain high every year. Modulating the signaling pathways that cause the inflammatory response and improve the immune function of patients has become the focus of reducing inflammatory damage in the lungs, especially CAP in older adults. As an important factor that causes the inflammatory response of CAP and affects the immune status of the body, oxidative stress plays an important role in the occurrence, development and treatment of CAP. Furthermore, in older adults with CAP, oxidative stress is closely associated with immune senescence, sarcopenia, frailty, aging, multimorbidity, and polypharmacy. Therefore, multiple perspectives combined with the disease characteristics of older adults with CAP were reviewed to clarify the research progress and application value of modulating oxidative stress in older adults with CAP. Clearly, there is no doubt that targeted modulation of oxidative stress benefits CAP in older adults. However, many challenges and unknowns concerning how to modulate oxidative stress for further practical clinical applications exist, and more targeted research is needed. Moreover, the limitations and challenges of modulating oxidative stress are analyzed with the aim of providing references and ideas for future clinical treatment or further research in older adults with CAP.

The Prevalence, Risk Factors, and Clinical Outcomes of Vitamin C Deficiency in Adult Hospitalised Patients: A Retrospective Observational Study

Background/Objectives: Assessment of vitamin C status rarely occurs in hospital patients within high-income countries on the assumption that vitamin C deficiency (VCD) is rare, and evidence on prevalence, risk factors, and clinical outcomes of VCD is limited. This study aimed to describe the prevalence of VCD, characteristics of patients with VCD, and identify risk factors and clinical outcomes associated with VCD status in adult hospitalised patients. Methods: This retrospective observational study included adult inpatients from five metropolitan hospitals within a single public health service in Australia which provides tertiary, acute, and sub-acute care, over a 3.5-year period. Non-fasting vitamin C levels were examined for the prevalence of VCD, defined as <11.4 µmol/L. Multivariate regression models were used to identify risk factors and clinical outcomes associated with VCD. Results: The prevalence of VCD was 22.9% (n = 1791), comprising 23.2% (n = 1717) and 16.2% (n = 74) within acute and sub-acute settings, respectively. VCD prevalence was high in acute setting subgroups including patients with malnutrition (30%, n = 611) and patients admitted to ICU during hospitalisation (37.3%, n = 327). Malnutrition (OR 1.50, 95% CI 1.19-1.91, p < 0.001) and male gender (OR 1.47, 95% CI 1.17-1.86, p = 0.001) were associated with VCD. VCD was not associated with clinical outcomes including in-hospital death, hospital or intensive care unit LOS, or hospital-acquired complications. Conclusions: VCD exists within adult hospital patients in high-income countries, and early, targeted detection of VCD in this setting is warranted. Further research is needed to explore the impact of VCD on hospital clinical outcomes.

A case report of renal oxalosis and secondary hyperoxaluria due to chronic high vitamin C consumption

Renal oxalosis occurs from supersaturation of the urine with oxalate in the presence of calcium, resulting in deposition of calcium oxalate crystals within renal tissue and, consequently, progressive renal disease. One of the causes of secondary hyperoxaluria is a high intake of vitamin C, which exceeds the renal excretion capacity, and can induce renal oxalosis. We present a case involving a 67-year-old patient with chronic kidney disease and proteinuria, associated with secondary hyperoxaluria and renal oxalosis, who reported prolonged, excessive intake of vitamin C supplements. The patient presented with a gradual worsening of his renal function and proteinuria during the last 6-month period, after an episode of SARS-CoV-2 infection. The kidney biopsy revealed calcium oxalate crystals within the renal tissue. Thorough investigation and history-taking revealed a substantial increase in vitamin C supplementation during the SARS-CoV-2 infection (up to 3 g daily), indicating secondary hyperoxaluria as the causative factor. Overall during the pandemic, supplement consumption dramatically increased and patients were not adequately informed about the risks of various over-the-counter products. Excessive intake of vitamin C, popularized for its supposed health benefits, can lead, among others, to secondary hyperoxaluria and renal oxalosis. Prompt recognition is pivotal to initiate management and to prevent irreversible kidney damage.

Tandem metabolic reaction-based sensors unlock in vivo metabolomics

Mimicking metabolic pathways on electrodes enables in vivo metabolite monitoring for decoding metabolism. Conventional in vivo sensors cannot accommodate underlying complex reactions involving multiple enzymes and cofactors, addressing only a fraction of enzymatic reactions for few metabolites. We devised a single-wall-carbon-nanotube-electrode architecture supporting tandem metabolic pathway-like reactions linkable to oxidoreductase-based electrochemical analysis, making a vast majority of metabolites detectable in vivo. This architecture robustly integrates cofactors, self-mediates reactions at maximum enzyme capacity, and facilitates metabolite intermediation/detection and interference inactivation through multifunctional enzymatic use. Accordingly, we developed sensors targeting 12 metabolites, with 100-fold-enhanced signal-to-noise ratio and days-long stability. Leveraging these sensors, we monitored trace endogenous metabolites in sweat/saliva for noninvasive health monitoring, and a bacterial metabolite in the brain, marking a key milestone for unraveling gut microbiota-brain axis dynamics.

The pharmacology of vitamin C

Ascorbic acid, the reduced form of vitamin C, is a ubiquitous small carbohydrate. Despite decades of focused research, new metabolic functions of this universal electron donor are still being discovered and add to the complexity of our view of vitamin C in human health. Although praised as an unsurpassed water-soluble antioxidant in plasma and cells, the most interesting functions of vitamin C seem to be its roles as specific electron donor in numerous biological reactions ranging from the well-known hydroxylation of proline to cofactor for the epigenetic master regulators ten-eleven translocation enzymes and Jumonji domain-containing histone-lysine demethylases. Some of these functions may have important implications for disease prevention and treatment and have spiked renewed interest in, eg, vitamin C's potential in cancer therapy. Moreover, some fundamental pharmacokinetic properties of vitamin C remain to be established including if other mechanisms than passive diffusion governs the efflux of ascorbate anions from the cell. Taken together, there still seems to be much to learn about the pharmacology of vitamin C and its role in health and disease. This review explores new avenues of vitamin C and integrates our present knowledge of its pharmacology. SIGNIFICANCE STATEMENT: Vitamin C is involved in multiple biological reactions of which most are essential to human health. Hundreds of millions of people are considered deficient in vitamin C according to accepted guidelines, but little is known about the long-term consequences. Although the complexity of vitamin C's physiology and pharmacology has been widely disregarded in clinical studies for decades, it seems clear that a deeper understanding of particularly its pharmacology holds the key to unravel and possibly exploit the potential of vitamin C in disease prevention and therapy.

Exploring the Ascorbate Requirement of the 2-Oxoglutarate-Dependent Dioxygenases

In humans, the 2-oxoglutarate-dependent dioxygenases (2-OGDDs) catalyze hydroxylation reactions involved in cell metabolism, the biosynthesis of small molecules, DNA and RNA demethylation, the hypoxic response and the formation of collagen. The reaction is catalyzed by a highly oxidizing ferryl-oxo species produced when the active site non-heme iron engages molecular oxygen. Enzyme activity is specifically stimulated by l-ascorbic acid (ascorbate, vitamin C), an effect not well mimicked by other reducing agents. In this perspective article we discuss the reliance of the 2-OGDDs on ascorbate availability. We draw upon findings from studies with different 2-OGDDs to piece together a comprehensive theory for the specific role of ascorbate in supporting enzyme activity. Our discussion centers on the capacity for ascorbate to act as an efficient radical scavenger and its propensity to reduce and chelate transition metals. In addition, we consider the evidence supporting stereospecific binding of ascorbate in the enzyme active site.

The association between vitamin C and breast cancer, prostate cancer and colorectal cancer: A systematic review and meta-analysis

BACKGROUND

For a comprehensive evaluation and due to the inconsistent results of previous studies, we performed this meta-analysis with the aim of vitamin C effect on breast cancer and prostate cancer and colorectal cancer.

METHODS

PubMed, Scopus and Web of Science were searched to identify studies on the association between vitamin C and breast cancer, prostate cancer and colorectal cancer through September 11, 2023. The pooled RR and the 95 % confidence intervals were used to measure the association between vitamin C and breast cancer, prostate cancer and colorectal cancer by assuming a random effects meta-analytic model. Newcastle-Ottawa scale was used for quality appraisal.

RESULTS

A total of 69 studies were included. The pooled RR for the association between vitamin C (dietary) and breast cancer in the cohort study was 0.99 [95 % CI: 0.95, 1.03], but the pooled RR in the case-control study was 0.72 [95 % CI: 0.60, 0.85]. No association was found between vitamin E (supplemental, total intake) and breast cancer in studies. The pooled RR for the association between vitamin C (dietary) and prostate cancer was 0.88 [95 % CI: 0.77, 1.00], which represents a decrease in prostate cancer. No association was found between vitamin C (supplemental) and prostate cancer in studies. The pooled RR for the association between vitamin C (dietary) and colorectal cancer was 0.55 [95 % CI: 0.42, 0.73], which represents a decrease in colorectal cancer.

CONCLUSION

Our analysis shows an inverse significant relationship between vitamin C (dietary) and breast cancer in the case-control study. Also between vitamin C (dietary) and prostate cancer and colorectal cancer in studies, which represents a decrease in cancers.

A Guinea Pig Model of Pediatric Metabolic Dysfunction-Associated Steatohepatitis: Poor Vitamin C Status May Advance Disease

Background/Objectives: Children and teenagers display a distinct metabolic dysfunction-associated steatohepatitis (MASH) phenotype, yet studies of childhood MASH are scarce and validated animal models lacking, limiting the development of treatments. Poor vitamin C (VitC) status may affect MASH progression and often co-occurs with high-fat diets and related metabolic imbalances. As a regulator of DNA methylation, poor VitC status may further contribute to MASH by regulating gene expression This study investigated guinea pigs-a species that, like humans, depends on vitC in the diet-as a model of pediatric MASH, examining the effects of poor VitC status on MASH hallmarks and global DNA methylation levels. Methods: Sixty-two juvenile guinea pigs were exposed to a high-fat diet for 16 weeks. Results: Juvenile guinea pigs exhibited hepatic histopathology representative of pediatric MASH, confirmed by portal inflammation and fibrosis. Consistent with pediatric MASH, juvenile guinea pigs displayed increased lobular and portal inflammation (p < 0.05 and p < 0.0001, respectively) but less steatosis (p < 0.001) compared to adults. Compared to the controls, the guinea pigs deprived in VitC showed lower body weight (p < 0.01), higher expression of hepatic inflammatory genes (p < 0.05), and a lower global hydroxymethylcytosine to methylcytosine ratio in the high-fat groups (p < 0.05). Conclusions: Our study validates guinea pigs as a model of pediatric MASH and suggests that VitC contributes to an altered gene expression signature through the regulation of DNA hydroxymethylation. We postulate that nutritional co-deficiencies in MASH, such as low VitC, may accelerate disease progression and deserve further attention.

Prevalence, risk factors, and clinical outcomes of vitamin C deficiency in adult hospitalized patients in high-income countries: a scoping review

BACKGROUND

Assessment for vitamin C deficiency (VCD) is rarely undertaken in an acute hospital setting in high-income countries. However, with growing interest in VCD in community settings, there is emerging evidence investigating the prevalence and impact of VCD during hospitalization.

OBJECTIVES

In this scoping review, the prevalence of VCD in adult hospitalized patients is explored, patient characteristics are described, and risk factors and clinical outcomes associated with VCD are identified.

METHODS

A systematic scoping review was conducted in accordance with the PRISMA-ScR framework. The Ovid MEDLINE, Ovid Embase, Scopus, CINAHL Plus, Allied and Complementary Medicine Database, and the Cochrane Library databases were searched for interventional, comparative, and case-series studies that met eligibility criteria, including adult hospital inpatients in high-income countries, as defined by the Organization for Economic Co-operation and Development, that reported VCD prevalence using World Health Organization reference standards. These standards define VCD deficiency as plasma or serum vitamin C level <11.4 µmol/L, wholeblood level <17 µmol/L, or leukocytes <57 nmol/108 cells.

RESULTS

Twenty-three articles were included, representing 22 studies. The cumulative prevalence of VCD was 27.7% (n = 2494; 95% confidence interval [CI], 21.3-34.0). High prevalence of VCD was observed in patients with severe acute illness and poor nutritional status. Scurvy was present in 48% to 62% of patients with VCD assessed in 2 studies (n = 71). Being retired (P = 0.015) and using excessive amounts of alcohol and tobacco (P = 0.0003) were independent risk factors for VCD (n = 184). Age was not conclusively associated with VCD (n = 631). Two studies examined nutrition associations (n = 309); results were inconsistent. Clinical outcomes for VCD included increased risk of frailty (adjusted odds ratio, 4.3; 95%CI, 1.33-13.86; P = 0.015) and cognitive impairment (adjusted odds ratio, 2.93; 95%CI, 1.05-8.19, P = 0.031) (n = 160).

CONCLUSIONS

VCD is a nutritional challenge facing the healthcare systems of high-income countries. Research focused on early identification and treatment of patients with VCD is warranted.

SYSTEMATIC REVIEW REGISTRATION

Open Science Framework ( https://doi.org/10.17605/OSF.IO/AJGHX ).

A randomized trial of pharmacological ascorbate, gemcitabine, and nab-paclitaxel for metastatic pancreatic cancer

BACKGROUND

Patients with metastatic pancreatic ductal adenocarcinoma (PDAC) have poor 5-year survival. Pharmacological ascorbate (P-AscH-, high dose, intravenous, vitamin C) has shown promise as an adjunct to chemotherapy. We hypothesized adding P-AscH- to gemcitabine and nab-paclitaxel would increase survival in patients with metastatic PDAC.

METHODS

Patients diagnosed with stage IV pancreatic cancer randomized 1:1 to gemcitabine and nab-paclitaxel only (SOC, control) or to SOC with concomitant P-AscH-, 75 g three times weekly (ASC, investigational). The primary outcome was overall survival with secondary objectives of determining progression-free survival and adverse event incidence. Quality of life and patient reported outcomes for common oncologic symptoms were captured as an exploratory objective. Thirty-six participants were randomized; of this 34 received their assigned study treatment. All analyses were based on data frozen on December 11, 2023.

RESULTS

Intravenous P-AscH- increased serum ascorbate levels from micromolar to millimolar levels. P-AscH- added to the gemcitabine + nab-paclitaxel (ASC) increased overall survival to 16 months compared to 8.3 months with gemcitabine + nab-paclitaxel (SOC) (HR = 0.46; 90 % CI 0.23, 0.92; p = 0.030). Median progression free survival was 6.2 (ASC) vs. 3.9 months (SOC) (HR = 0.43; 90 % CI 0.20, 0.92; p = 0.029). Adding P-AscH- did not negatively impact quality of life or increase the frequency or severity of adverse events.

CONCLUSIONS

P-AscH- infusions of 75 g three times weekly in patients with metastatic pancreatic cancer prolongs overall and progression free survival without detriment to quality of life or added toxicity (ClinicalTrials.gov number NCT02905578).

Comparative bioavailability of vitamins in human foods sourced from animals and plants

Vitamins are essential components of enzyme systems involved in normal growth and function. The quantitative estimation of the proportion of dietary vitamins, that is in a form available for utilization by the human body, is limited and fragmentary. This review provides the current state of knowledge on the bioavailability of thirteen vitamins and choline, to evaluate whether there are differences in vitamin bioavailability when human foods are sourced from animals or plants. The bioavailability of naturally occurring choline, vitamin D, vitamin E, and vitamin K in food awaits further studies. Animal-sourced foods are the almost exclusive natural sources of dietary vitamin B-12 (65% bioavailable) and preformed vitamin A retinol (74% bioavailable), and contain highly bioavailable biotin (89%), folate (67%), niacin (67%), pantothenic acid (80%), riboflavin (61%), thiamin (82%), and vitamin B-6 (83%). Plant-based foods are the main natural sources of vitamin C (76% bioavailable), provitamin A carotenoid β-carotene (15.6% bioavailable), riboflavin (65% bioavailable), thiamin (81% bioavailable), and vitamin K (16.5% bioavailable). The overview of studies showed that in general, vitamins in foods originating from animals are more bioavailable than vitamins in foods sourced from plants.

Combination of High-Dose Parenteral Ascorbate (Vitamin C) and Alpha-Lipoic Acid Failed to Enhance Tumor-Inhibitory Effect But Increased Toxicity in Preclinical Cancer Models

Background

Intravenous vitamin C (IVC, ascorbate [Asc]) and alpha-lipoic acid (ALA) are frequently coadministered in integrative oncology clinics, with limited understanding of combination effects or drug-drug interactions. As high-dose IVC has anticancer activity through peroxide (H2O2), it is hypothesized that IV ALA, a thiol antioxidant, might have untoward effects when combined with IVC.

Methods

In vitro combination index (CI) was investigated in 6 types of human cancer cells, using clinically relevant concentrations of Asc (0.625-20 mM) and ALA (0.25, 0.5, and 1 mM) evaluated by nonconstant ratio metrics. Cellular H2O2 was measured using HeLa cells expressing a fluorescent probe HyPer. Mouse xenografts of the metastatic breast cancer MDA-MB-231 were treated with intraperitoneal injections of ALA (10, 20, and 50 mg/kg) and Asc (0.2, 0.5, and 4 g/kg) at various dose levels.

Results

Cancer cell lines were sensitive to Asc treatment but not to ALA. There is no evidence ALA becomes a prooxidant at higher doses. The CIs showed a mixture of synergistic and antagonistic effects with different ALA and Asc combination ratios, with a "U" shape response to Asc concentrations. The ALA concentrations did not influence the CIs or cellular H2O2 formation. Adding ALA to Asc dampened the increase of H2O2. Toxicity was observed in mice receiving prolonged treatment of ALA at all doses. The Asc at all doses was nontoxic. The combination of ALA and Asc increased toxicity. The ALA at all doses did not inhibit tumor growth. The Asc at 4 g/kg inhibited tumor growth. Adding ALA 50 mg/kg to Asc 4 g/kg did not enhance the effect, but lower doses of ALA (10 or 20 mg/kg) dampened the inhibitory effect of Asc.

Conclusions

These data do not support the concurrent or relative concurrent use of high-dose intravenous ALA with prooxidative high-dose IVC in clinical oncology care with potentially increased toxicity.

Changes in Digestive Health, Satiety and Overall Well-Being after 14 Days of a Multi-Functional GI Primer Supplement

A recent review proposed a role for multi-functional food or supplement products in priming the gut to support both digestive and systemic health. Accordingly, we designed and eva-luated the effect of a multi-functional gastrointestinal (GI) primer supplement on participant-reported measures for digestive health, quality-of-life (e.g., energy/vitality and general health), and reasons for satiation (e.g., attitudes towards food and eating). In this single-arm clinical trial, 68 participants with mild digestive symptoms consumed the GI primer supplement daily for 14 days. Digestive symptoms were evaluated daily from baseline (Day 0) through Day 14. At baseline and Day 14, participants reported their stool consistency, reasons for satiation, and quality-of-life measures using validated questionnaires. At Day 14, participants reported significant improvements in all (13/13) digestive symptom parameters (p-values < 0.05) and an increase in % of stools with normal consistencies. There were significant improvements (p-values < 0.05) in energy/vitality and general health, and in specific attitudes towards food and eating (e.g., physical satisfaction, planned amount, decreased eating priority, decreased food appeal, and self-consciousness). Results suggest the GI primer supplement promotes digestive health, improves quality of life, and impacts attitudes towards food/eating. This study provides preliminary support for the gut priming hypothesis through which multi-functional digestive products may improve GI health.

Pharmacologic ascorbate induces transient hypoxia sensitizing pancreatic ductal adenocarcinoma to a hypoxia activated prodrug

Hypoxic tumor microenvironments pose a significant challenge in cancer treatment. Hypoxia-activated prodrugs like evofosfamide aim to specifically target and eliminate these resistant cells. However, their effectiveness is often limited by reoxygenation after cell death. We hypothesized that ascorbate's pro-oxidant properties could be harnessed to induce transient hypoxia, enhancing the efficacy of evofosfamide by overcoming reoxygenation. To test this hypothesis, we investigated the sensitivity of MIA Paca-2 and A549 cancer cells to ascorbate in vitro and in vivo. Ascorbate induced a cytotoxic effect at 5 mM that could be alleviated by endogenous administration of catalase, suggesting a role for hydrogen peroxide in its cytotoxic mechanism. In vitro, Seahorse experiments indicated that the generation of hydrogen peroxide consumes oxygen, which is offset at later time points by a reduction in oxygen consumption due to hydrogen peroxide's cytotoxic effect. In vivo, photoacoustic imaging showed pharmacologic ascorbate treatment at sublethal levels triggered a complex, multi-phasic response in tumor oxygenation across both cell lines. Initially, ascorbate generated transient hypoxia within minutes through hydrogen peroxide production, via reactions that consume oxygen. This initial hypoxic phase peaked at around 150 s and then gradually subsided. However, at longer time scales (approximately 300 s) a vasodilation effect triggered by ascorbate resulted in increased blood flow and subsequent reoxygenation. Combining sublethal levels of i. p. Ascorbate with evofosfamide significantly prolonged tumor doubling time in MIA Paca-2 and A549 xenografts compared to either treatment alone. This improvement, however, was only observed in a subpopulation of tumors, highlighting the complexity of the oxygenation response.

Balanced Duality: H2O2-Based Therapy in Cancer and Its Protective Effects on Non-Malignant Tissues

Conventional cancer therapy strategies, although centered around killing tumor cells, often lead to severe side effects on surrounding normal tissues, thus compromising the chronic quality of life in cancer survivors. Hydrogen peroxide (H2O2) is a secondary signaling molecule that has an array of functions in both tumor and normal cells, including the promotion of cell survival pathways and immune cell modulation in the tumor microenvironment. H2O2 is a reactive oxygen species (ROS) crucial in cellular homeostasis and signaling (at concentrations maintained under nM levels), with increased steady-state levels in tumors relative to their normal tissue counterparts. Increased steady-state levels of H2O2 in tumor cells, make them vulnerable to oxidative stress and ultimately, cell death. Recently, H2O2-producing therapies-namely, pharmacological ascorbate and superoxide dismutase mimetics-have emerged as compelling complementary treatment strategies in cancer. Both pharmacological ascorbate and superoxide dismutase mimetics can generate excess H2O2 to overwhelm the impaired H2O2 removal capacity of cancer cells. This review presents an overview of H2O2 metabolism in the physiological and malignant states, in addition to discussing the anti-tumor and normal tissue-sparing mechanism(s) of, and clinical evidence for, two H2O2-based therapies, pharmacological ascorbate and superoxide dismutase mimetics.

High-Dose Intravenous Vitamin C Combined with Docetaxel in Men with Metastatic Castration-Resistant Prostate Cancer: A Randomized Placebo-Controlled Phase II Trial

High-dose intravenous vitamin C (HDIVC) administered to produce pharmacologic concentrations shows promise in preclinical models and small clinical trials, but larger prospective randomized trials are lacking. We evaluated the clinical benefit of combining HDIVC with docetaxel in patients with progressive metastatic castration-resistant prostate cancer (mCRPC). In this double-blind, placebo-controlled phase II trial, 47 patients were randomized 2:1 to receive docetaxel (75 mg/m2 i.v.) with either HDIVC (1 g/kg) or placebo. Coprimary endpoints were PSA50 response and adverse event rates. Secondary endpoints included overall survival, radiographic progression-free survival, and quality of life measured using the Functional Assessment of Cancer Therapy-Prostate instrument. Correlative analyses included pharmacokinetics and oxidative stress markers. Eighty-nine percent of patients previously had three or more lines of therapy. The PSA50 response rate was 41% in the HDIVC group and 33% in the placebo group (P = 0.44), with comparable adverse event rates in both groups. There were no significant differences in Functional Assessment of Cancer Therapy-Prostate scores. The median radiographic progression-free survival was not significantly different between the HDIVC and placebo groups, with durations of 10.1 and 10.0 months (HR, 1.35; 95% confidence interval, 0.66-2.75; P = 0.40), respectively. The median overall survival was 15.2 months in the HDIVC group and 29.5 months in the placebo group (HR, 1.98; 95% confidence interval, 0.85-4.58; P = 0.11). HDIVC did not decrease F2-isoprostanes, indicators of oxidative stress. The study was suspended after prespecified interim analysis indicated futility in achieving primary endpoints. In this patient population, combining HDIVC with docetaxel did not improve PSA response, toxicity, or other clinical outcomes compared with docetaxel alone. Findings do not support the routine use of HDIVC in mCRPC treatment outside of clinical trials.

SIGNIFICANCE

This is the first randomized, placebo-controlled, double-blind trial to evaluate HDIVC in cancer treatment. The addition of HDIVC to docetaxel in patients with mCRPC does not improve PSA response, toxicity, or other clinical outcomes compared with docetaxel alone. The routine use of HDIVC in mCRPC treatment is not supported outside of clinical trials.

Therapeutic effects of high-dose vitamin C supplementation in patients with COVID-19: a meta-analysis

CONTEXT

Coronavirus disease 2019 (COVID-19) could induce the "cytokine storm" due to overactivation of immune system and accompanied by acute respiratory distress syndrome as a serious complication. Vitamin C has been effective in improving lung function of patients by reducing inflammation.

OBJECTIVE

The aim was to explore the therapeutic effects of high-dose vitamin C supplementation for patients with COVID-19 using meta-analysis.

DATA SOURCES

Published studies were searched from PubMed, Cochrane Library, Web of Science, EMBASE, and China National Knowledge Infrastructure databases up to August 2022 using the terms "vitamin C" and "COVID-19". Data analyses were performed independently by 2 researchers using the PRISMA guidelines.

DATA EXTRACTION

Heterogeneity between the included studies was assessed using I2 statistics. When I2 ≥50%, the random-effects model was used; otherwise, a fixed-effects model was applied. Stata 14.0 software was used to pool data by standardized mean differences (SMDs) with 95% CIs or odds ratios (ORs) with 95% CIs.

DATA ANALYSIS

The 14 studies had a total of 751 patients and 1583 control participants in 7 randomized controlled trials and 7 retrospective studies. The vitamin C supplement significantly increased ferritin (SMD = 0.272; 95% CI: 0.059 to 0.485; P = 0.012) and lymphocyte count levels (SMD = 0.376; 95% CI: 0.153 to 0.599; P = 0.001) in patients with COVID-19. Patients administered vitamin C in the length of intensive care unit staying (SMD = 0.226; 95% CI: 0.073 to 0.379; P = 0.004). Intake of vitamin C prominently alleviate disease aggravation (OR = 0.344, 95%CI: 0.135 to 0.873, P = 0.025).

CONCLUSIONS

High-dose vitamin C supplementation can alleviate inflammatory response and hinder the aggravation of COVID-19.

Vitamin C for all?

PURPOSE OF REVIEW

Vitamin C can be a potential adjunctive treatment option for critically ill individuals due to its pleiotropic effects as electron donor in many enzymatic reactions throughout the body. Recently, several important randomized controlled trials (RCTs) investigating vitamin C in critically ill patients have been published.

RECENT FINDINGS

Two recent large RCTs administering high-dose vitamin C to patients with sepsis and COVID-19 showed signs of harm. Though performed at high standard, these trials had several limitations. Recent studies in cardiac surgery and burns showed decreased cardiac enzymes and improved clinical outcomes after cardiac surgery, and decreased fluid requirements, reduced wound healing time and in-hospital mortality after burns. Vitamin C may hold benefit in the management of other ischemia/reperfusion injury populations, including postcardiac arrest patients and after solid organ transplantation. Currently, covering basal vitamin C requirements during critical illness is recommended, though the exact dose remains to be determined.

SUMMARY

Future work should address optimal vitamin C timing, since early versus late drug administration are likely distinct, and duration of therapy, where withdrawal-induced injury is possible. Additionally accurate assessment of body stores with determination of individual vitamin requirements is crucial to ascertain patient and subgroups most likely to benefit from vitamin C.

Anti-Inflammatory and Antioxidant Properties of a New Mixture of Vitamin C, Collagen Peptides, Resveratrol, and Astaxanthin in Tenocytes: Molecular Basis for Future Applications in Tendinopathies

Tendinopathy is one of the most frequent musculoskeletal disorders characterized by sustained tissue inflammation and oxidative stress, accompanied by extracellular matrix remodeling. Patients suffering from this pathology frequently experience pain, swelling, stiffness, and muscle weakness. Current pharmacological interventions are based on nonsteroidal anti-inflammatory drugs; however, the effectiveness of these strategies remains ambiguous. Accumulating evidence supports that oral supplementation of natural compounds can provide preventive, and possibly curative, effects. Vitamin C (Vit C), collagen peptides (Coll), resveratrol (Res), and astaxanthin (Asx) were reported to be endowed with potential beneficial effects based on their anti-inflammatory and antioxidant activities. Here, we analyzed the efficacy of a novel combination of these compounds (Mix) in counteracting proinflammatory (IL-1β) and prooxidant (H2O2) stimuli in human tenocytes. We demonstrated that Mix significantly impairs IL-6-induced IL-1β secretion, NF-κB nuclear translocation, and MMP-2 production; notably, a synergistic effect of Mix over the single compounds could be observed. Moreover, Mix was able to significantly counteract H2O2-triggered ROS production. Together, these results point out that Mix, a novel combination of Vit C, Coll, Resv, and Asx, significantly impairs proinflammatory and prooxidant stimuli in tenocytes, mechanisms that contribute to the onset of tendinopathies.

Molecular Pharmacology of Vitamin C and Relevance to Health and Obesity-A Narrative Review

The role of food constituents as pharmacological agents is an important consideration in health and obesity. Vitamin C acts as a small molecule antioxidant but is also a co-factor for numerous transition metal-dependent enzymes involved in healthy weight and energy metabolism. Vitamin C cannot be manufactured by humans and is mainly obtained from the dietary intake of fresh fruit and vegetables. There is great variability between different nutritional guidelines in the recommended daily allowance of vitamin C. Vitamin C deficiency results from an inadequate intake of vitamin C-containing foods and also increased utilization by oxidative and carbonyl stress. Risk factors for vitamin C deficiency include cigarette smoking, malnutrition, obesity, type 2 diabetes mellitus, age, race, sex, social isolation, major surgery, and Western-type diets. Despite the common belief that vitamin C deficiency is rare in affluent countries, surveys of large populations and specific patient groups suggest otherwise. Patients with obesity typically consume highly processed, energy-dense foods which contain inadequate micronutrients. As obesity increases, larger amounts of oral vitamin C are required to achieve adequate plasma and tissue concentrations, as compared to persons with a healthy weight. This is important in the control of oxidative stress and the maintenance of homeostasis and organ function. In this narrative review, the dosage, absorption, distribution, excretion, and catabolism of vitamin C are reviewed, together with the latest findings on vitamin C pharmacology in patients with obesity.

Low dietary vitamin C intake is associated with low muscle strength among elderly Korean women

Although vitamin C is one of the most important antioxidants, its effect on muscle quality is not fully understood. Therefore, we hypothesized that low dietary vitamin C intake is associated with low muscle strength. To test the hypothesis, a single 24-h dietary recall and handgrip strength test of 10,883 younger adults 19-64 y and 3,961 older adults ≥65 y from the seventh Korea National Health and Examination Survey (KNHANES VII 2016-2018) was analyzed by multivariable linear and logistic regression models, and low muscle strength was defined as handgrip strength <28 kg for men and <18 kg for women. Approximately 15.5% of Korean adults met the recommended intake of dietary vitamin C, and those with higher dietary vitamin C intake had higher total energy and protein intake. After adjusting for confounding variables, including age, body mass index, total energy intake, household income, alcohol consumption, smoking, resistance exercise, medical condition, and dietary intake of protein, vitamin E, and β-carotene, dietary vitamin C was correlated with maximal handgrip strength in younger women 19-64 y (β = 0.002; SE = 0.001; P-value = .026) and older women ≥65 y (β = 0.005; SE = 0.002; P-value = .013). Among older women ≥65 y, those in the lowest quartile of dietary vitamin C intake had a higher risk of low muscle strength compared to those in the highest quartile after adjustment of confounding factors (odds ratio, 2.16; 95% confidence interval, 1.49-3.15). These results imply that adequate dietary vitamin C intake may reduce the risk of sarcopenia in older Korean women.

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.

The Involvement of Ascorbic Acid in Cancer Treatment

Vitamin C (VC), also known as ascorbic acid, plays a crucial role as a water-soluble nutrient within the human body, contributing to a variety of metabolic processes. Research findings suggest that increased doses of VC demonstrate potential anti-tumor capabilities. This review delves into the mechanisms of VC absorption and its implications for cancer management. Building upon these foundational insights, we explore modern delivery systems for VC, evaluating its use in diverse cancer treatment methods. These include starvation therapy, chemodynamic therapy (CDT), photothermal/photodynamic therapy (PTT/PDT), electrothermal therapy, immunotherapy, cellular reprogramming, chemotherapy, radiotherapy, and various combination therapies.

The role of different nutrients in the prevention and treatment of cardiovascular diseases

Cardiovascular health is a hot topic around the world, and as the incidence of cardiovascular disease increases each year, people are increasingly focusing on the management of their heart health. Dietary and lifestyle changes as non-pharmacological treatments have been increasingly recognized as important in the prevention of cardiovascular disease and in reducing the risk of cardiovascular accidents. Awareness of different nutrients and their effects on cardiovascular health is important for establishing a good dietary pattern. This review summarizes the effects of the five major nutrients in the daily diet, namely carbohydrates, proteins, dietary fats, vitamins, and minerals, on cardiovascular health, and aims to provide a more comprehensive understanding of the effects of a healthy dietary pattern on cardiovascular health.

A Systematized Review of the Relationship Between Obesity and Vitamin C Requirements

Obesity rates have increased globally in recent decades. Body weight is used as a modifiable factor in determining vitamin requirements. Accordingly, vitamin C requirements are volumetrically scaled from data for healthy weight males to other age- and sex-based categories. Likewise, it is possible that increases in body weight due to obesity may affect vitamin C needs. A systematized literature review was performed to summarize evidence on whether obesity affects vitamin C intake or status. The literature was also scanned for potential mechanisms for the relationship. Many observational studies showed that vitamin C status is lower in overweight and obese children and adults; this may be explained by lower vitamin C intakes. Nevertheless, a reanalysis of carefully conducted intervention studies has demonstrated a lower vitamin C status in participants who were overweight or obese when given the same dose of vitamin C as subjects of normal weight. Several mechanisms have been proposed to potentially explain why vitamin C status is lower in people with obesity: changes in vitamin C partitioning between lean and adipose tissue, volumetric dilution, metabolic alterations due to obesity, and gut microbial dysbiosis. Depletion-repletion or pharmacokinetic studies that include individuals of diverse body weights and ages would be helpful to further investigate whether obesity increases requirements for vitamin C. The current evidence base supports a lower vitamin C status in people who are overweight or obese; however, the association may be attenuated by lower vitamin C intakes.

Blood Vitamin C Levels of Patients Receiving Immunotherapy and Relationship to Monocyte Subtype and Epigenetic Modification

The treatment of metastatic melanoma has been revolutionised by immunotherapy, yet a significant number of patients do not respond, and many experience autoimmune adverse events. Associations have been reported between patient outcome and monocyte subsets, whereas vitamin C (ascorbate) has been shown to mediate changes in cancer-stimulated monocytes in vitro. We therefore investigated the relationship of ascorbate with monocyte subsets and epigenetic modifications in patients with metastatic melanoma receiving immunotherapy. Patients receiving immunotherapy were compared to other cancer cohorts and age-matched healthy controls. Ascorbate levels in plasma and peripheral blood-derived mononuclear cells (PBMCs), monocyte subtype and epigenetic markers were measured, and adverse events, tumour response and survival were recorded. A quarter of the immunotherapy cohort had hypovitaminosis C, with plasma and PBMC ascorbate levels significantly lower than those from other cancer patients or healthy controls. PBMCs from the immunotherapy cohort contained similar frequencies of non-classical and classical monocytes. DNA methylation markers and intracellular ascorbate concentration were correlated with monocyte subset frequency in healthy controls, but correlation was lost in immunotherapy patients. No associations between ascorbate status and immune-related adverse events or tumour response or overall survival were apparent.

Unveiling the mechanisms for the development of rosehip-based dermatological products: an updated review

Rosa spp., commonly known as rosehips, are wild plants that have traditionally been employed as herbal remedies for the treatment of a wide range of disorders. Rosehip is a storehouse of vitamins, including A, B complex, C, and E. Among phytonutrients, vitamin C is found in the highest amount. As rosehips contain significant levels of vitamin C, they are perfect candidates for the development of skincare formulations that can be effectively used in the treatment of different skin disorders (i.e., scarring, anti-aging, hyperpigmentation, wrinkles, melasma, and atopic dermatitis). This research focuses on the vitamin C content of several Rosa sp. by their botanical and geographic origins, which according to research studies are in the following order: R. rugosa > R. montana > R. canina > R. dumalis, with lower levels in R. villosa and R. arvensis, respectively. Among rosehip species, R. canina is the most extensively studied species which also displays significant amounts of bioactive compounds, but also antioxidant, and antimicrobial activities (e.g., against Propionibacterium acnes, Staphylococcus aureus, S, epidermis, and S. haemolyticus). The investigation also highlights the use of rosehip extracts and oils to minimise the harmful effects of acne, which primarily affects teenagers in terms of their physical appearance (e.g., scarring, hyperpigmentation, imperfections), as well as their moral character (e.g., low self-confidence, bullying). Additionally, for higher vitamin C content from various rosehip species, the traditional (i.e., infusion, maceration, Soxhlet extraction) and contemporary extraction methods (i.e., supercritical fluid extraction, microwave-assisted, ultrasonic-assisted, and enzyme-assisted extractions) are highlighted, finally choosing the best extraction method for increased bioactive compounds, with emphasis on vitamin C content. Consequently, the current research focuses on assessing the potential of rosehip extracts as medicinal agents against various skin conditions, and the use of rosehip concentrations in skincare formulations (such as toner, serum, lotion, and sunscreen). Up-to-date studies have revealed that rosehip extracts are perfect candidates as topical application products in the form of nanoemulsions. Extensive in vivo studies have revealed that rosehip extracts also exhibit specific activities against multiple skin disorders (i.e., wound healing, collagen synthesis, atopic dermatitis, melasma, and anti-aging effects). Overall, with multiple dermatological actions and efficacies, rosehip extracts and oils are promising agents that require a thorough investigation of their functioning processes to enable their safe use in the skincare industry.

Pharmacologic Ascorbate Radiosensitizes Pancreatic Cancer but Radioprotects Normal Tissue: The Role of Oxidative Stress-Induced Lipid Peroxidation

The toxicity of ionizing radiation limits its effectiveness in the treatment of pancreatic ductal adenocarcinoma. Pharmacologic ascorbate (P-AscH-) has been shown to radiosensitize pancreatic cancer cells while simultaneously radioprotecting normal cells. We hypothesize that P-AscH- protects the small intestine while radiosensitizing pancreatic cancer cells partially through an oxidative stress mechanism. Duodenal samples from pancreaticoduodenectomy specimens of patients who underwent radio-chemotherapy ± P-AscH- and mouse tumor and jejunal samples treated with radiation ± P-AscH- were evaluated. Pancreatic cancer and non-tumorigenic cells were treated with radiation ± P-AscH- to assess lipid peroxidation. To determine the mechanism, pancreatic cancer cells were treated with selenomethionine or RSL3, an inhibitor of glutathione peroxidase 4 (GPx4). Radiation-induced decreases in villi length and increases in 4-HNE immunofluorescence were reversed with P-AscH- in human duodenum. In vivo, radiation-induced decreases in villi length and increased collagen deposition were reversed in P-AscH--treated jejunal samples. P-AscH- and radiation increased BODIPY oxidation in pancreatic cancer cells but not in non-tumorigenic cells. Selenomethionine increased GPx4 protein and activity in pancreatic cancer and reversed P-AscH--induced toxicity and lipid peroxidation. RSL3 treatment inhibited GPx4 activity and increased lipid peroxidation. Differences in oxidative stress may play a role in radioprotecting normal cells while radiosensitizing pancreatic cancer cells when treated with P-AscH-.

ESPEN practical short micronutrient guideline

BACKGROUND

Trace elements and vitamins, named together micronutrients (MNs), are essential for human metabolism. The importance of MNs in common pathologies is recognized by recent research, with deficiencies significantly impacting the outcome.

OBJECTIVE

This short version of the guideline aims to provide practical recommendations for clinical practice.

METHODS

An extensive search of the literature was conducted in the databases Medline, PubMed, Cochrane, Google Scholar, and CINAHL for the initial guideline. The search focused on physiological data, historical evidence (for papers published before PubMed release in 1996), and observational and/or randomized trials. For each MN, the main functions, optimal analytical methods, impact of inflammation, potential toxicity, and provision during enteral or parenteral nutrition were addressed. The SOP wording was applied for strength of recommendations.

RESULTS

The limited number of interventional trials prevented meta-analysis and led to a low level of evidence for most recommendations. The recommendations underwent a consensus process, which resulted in a percentage of agreement (%): strong consensus required of >90 % of votes. Altogether the guideline proposes 3 general recommendations and specific recommendations for the 26 MNs. Monitoring and management strategies are proposed.

CONCLUSION

This short version of the MN guideline should facilitate handling of the MNs in at-risk diseases, whilst offering practical advice on MN provision and monitoring during nutritional support.

Severe vitamin C deficiency associated with continuous renal replacement therapy: A case report

Hypovitaminosis C is prevalent in critically ill patients. Continuous renal replacement therapy (CRRT) clears vitamin C, increasing the risk for vitamin C deficiency. However, recommendations for vitamin C supplementation in critically ill patients receiving CRRT vary widely, from 250 mg/day to 12 g/day. This case report describes a patient who developed a severe vitamin C deficiency after prolonged CRRT despite receiving ascorbic acid (450 mg/day) supplementation in her parenteral nutrition. This report summarizes recent research investigating vitamin C status in critically ill patients receiving CRRT, discusses the patient case, and provides recommendations for clinical practice. In critically ill patients receiving CRRT, the authors of this manuscript suggest providing at least 1000 mg/day of ascorbic acid to prevent vitamin C deficiency. Baseline vitamin C levels should be checked in patients who are malnourished and/or have other risk factors for vitamin C deficiency, and vitamin C levels should be monitored thereafter every 1-2 weeks.

Malnutrition as a Risk Factor in the Development of Oral Cancer: A Systematic Literature Review and Meta-Analyses

This systematic review and meta-analyses aimed to assess whether malnutrition may increase the incidence of oral cancer. Following the PRISMA statement, the research was conducted on PubMed, Scopus, and MEDLINE via OVID without any time restrictions. The risk of bias was assessed, and the quality of evidence for each performed meta-analysis was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. Sixty-one articles met the inclusion criteria and seven studies underwent quantitative evaluation. For our meta-analysis on hypovitaminosis B, three studies with a total of 90,011 patients were included. An odds ratio of 2.22 was found. Our meta-analysis on the correlation between vitamin C and oral cancer included one study with a total of 866 patients and the derived odds ratio was 1.06. Our meta-analysis on the relationship between vitamin D deficiency and the incidence of oral cancer included three studies with a total of 12,087 patients and the odds ratio was -2.58. The GRADE system showed a moderate strength of evidence due to the presence of studies with a high risk of bias and high indirectness of the data given. The present findings suggest that an inadequate intake of vitamins, particularly vitamin D, poses a risk for the onset of oral cancer.

Understanding mechanisms of antioxidant action in health and disease

Several different reactive oxygen species (ROS) are generated in vivo. They have roles in the development of certain human diseases whilst also performing physiological functions. ROS are counterbalanced by an antioxidant defence network, which functions to modulate ROS levels to allow their physiological roles whilst minimizing the oxidative damage they cause that can contribute to disease development. This Review describes the mechanisms of action of antioxidants synthesized in vivo, antioxidants derived from the human diet and synthetic antioxidants developed as therapeutic agents, with a focus on the gaps in our current knowledge and the approaches needed to close them. The Review also explores the reasons behind the successes and failures of antioxidants in treating or preventing human disease. Antioxidants may have special roles in the gastrointestinal tract, and many lifestyle features known to promote health (especially diet, exercise and the control of blood glucose and cholesterol levels) may be acting, at least in part, by antioxidant mechanisms. Certain reactive sulfur species may be important antioxidants but more accurate determinations of their concentrations in vivo are needed to help assess their contributions.

Vitamin C - a scoping review for Nordic Nutrition Recommendations 2023

Vitamin C has multiple metabolic functions in the body, but the available information on the exact relationship between these functions and the intake necessary to maintain them is very limited. However, most attempts to objectively measure adequacy of vitamin C status, including, for example, replacement of metabolic turnover, chronic disease prevention, urinary excretion, and saturation of immune cells and body compartment, currently point toward 50 µmol/L as a reasonable target plasma concentration. As a strong correlation between body weight and vitamin C status exists, recommended intakes (RIs) for other age groups may be extrapolated from the adult RI based on weight. However, as body weights above 70 kg are becoming increasingly common - also in the Nordic region - an RI of 140 mg/day for individuals weighing 100 kg or more should be considered to compensate for the larger volume of distribution. Finally, smoking continues to be a common contributor to poor vitamin C status; therefore, it is proposed that people who smoke increase their daily vitamin C intake by 40 mg/day to compensate for the increased metabolic turnover induced by smoking.

Investigation of the biochemical and histopathological effects of vitamin C, selenium, and therapeutic ultrasound on muscle damage in rats

Muscle injury is a common type of soft tissue injury. Increased oxidative damage has been reported after muscle injuries. Therapeutic ultrasound is commonly used for such injuries. This study compared the efficacy of therapeutic ultrasound treatment and various antioxidant agents in experimental muscle injuries. For this purpose, some serum enzymes, oxidative stress, and inflammatory markers were evaluated together with histopathological examinations. Six groups were formed with 6 male Wistar albino rats in each group. These groups were control, only injury (OI), ultrasound (U), vitamin C (Vit C), selenium (S), and mixture (M). Muscle injury was caused by a laceration of the gastrocnemius muscle in all groups except the control group. No treatment was performed in the OI group. At the end of the 6-day application, all rats were sacrificed. As for serum enzymes, CK, ALT, and AST levels returned to control values in almost all treatment groups. Total oxidative status (TOS) and oxidative stress index (OSI) increased in the OI group, while they decreased in the S and M groups. In addition, the decrease in MPO activity in the blood tissue of the Vit C group was statistically significant. There were no significant changes between groups in terms of serum inflammatory markers and histological findings. This study has shown that the ingestion of vitamin C and selenium may contribute to the treatment of muscle injury in addition to therapeutic ultrasound treatment. However, further studies are needed to support these results.

Ascorbate mediates the non-enzymatic reduction of nitrite to nitric oxide

Nitric oxide (NO•) generated by nitric oxide synthases is involved in many physiological and pathophysiological processes. However, non-enzymatic formation of NO• also occurs in vivo. Here we investigated the production of NO• from nitrite, as facilitated by ascorbate, over the pH range of 2.4-7.4. Using a nitric oxide electrode, we observed at low pH a rapid generation of NO• from nitrite and ascorbate that slows with increasing pH. The formation of NO• was confirmed by its reaction with oxyhemoglobin. In the ascorbate/nitrite system a steady-state level of NO• was achieved, suggesting that a futile redox cycle of nitrite-reduction by ascorbate and NO•-oxidation by dioxygen was established. However, at pH-values of around 7 and greater, the direct reduction of nitrite by ascorbate is very slow; thus, this route to the non-enzymatic production of NO• is not likely to be significant process in vivo in environments having a pH around 7.4. The production of nitric oxide by nitrite and ascorbate would be important only in areas of lower pH, e.g. stomach/digestive system, sites of inflammation, and areas of hypoxia such as tumor tissue. In patients receiving very large doses of ascorbate delivered by intravenous infusion, plasma levels of ascorbate on the order of 20 - 30 mM can be achieved. After infusion, levels of nitrate and nitrite in plasma were unchanged. Thus, in blood and tissue that maintain a pH of about 7.4, the reduction of nitrite to nitric oxide by ascorbate appears to be insignificant, even at very large, pharmacological levels of ascorbate.

Lessons learned from "the great mimicker disease": A retrospective study of 18 patients with scurvy

Purpose

Scurvy is an uncommon medical condition that affects children and is caused by an inadequate intake of vitamin C. This study presents the characteristics of patients with scurvy to raise awareness of the diagnostic process in developing countries where laboratory testing for vitamin C levels is often not available.

Methods

A retrospective study was performed from period of 2018 to 2023. Data extraction includes patient age, sex, body mass index, constitutional symptoms, musculoskeletal, mucosal, cutaneous symptoms, other accompanying disorders, anemia, erythrocyte sedimentation rate, C-reactive protein, radiographic examination, vitamin C dose, and duration of treatment. Descriptive statistical analysis was performed in this study.

Results

Eighteen cases (17 males, 1 female) of scurvy were referred to our institution. Thirteen of 18 patients were misdiagnosed before referral. The median age at presentation was 4.5 (range, 2-11) years. The average body mass index was 13.93 ± 0.63 kg/m2. Half of patients had healthy weight. All patients presented with lower limb pain and 17 of 18 with refusal to walk. The median onset of diagnosis was 11 (range 4-48) weeks. White line of Frankel was described in all patients. Seven had anemia and 6 of 18 had increase in erythrocyte sedimentation rate and/or C-reactive protein levels. Only one patient had ascorbic acid levels evaluation before treatment since it was not readily available in our country. Treatment length varied from 2 weeks to 6 months.

Conclusion

The diagnosis of scurvy is frequently delayed due to its extreme rarity in modern society and its ability to mimic numerous other conditions. In children presenting with limb pain and/or reluctance to walk and pathognomonic radiological findings, physicians must prioritize scurvy as a differential diagnosis. In scurvy, vitamin C supplementation is curative.

Role of ascorbic acid in cardiac allograft vasculopathy

PURPOSE OF THE REVIEW

Cardiac allograft vasculopathy (CAV) is a progressive fibroproliferative disease which occurs after heart transplantation and is associated with significant long-term morbidity and mortality. Currently available strategies including statins, mammalian target of rapamycin (mTOR) inhibitors, and revascularization, have limited overall effectiveness in treating this pathology once the disease process is established. mTOR inhibitors, while effective when used early in the disease process, are not well tolerated, and hence not routinely used in post-transplant care.

RECENT DATA

Recent work on rodent models have given us a novel mechanistic understanding of effects of ascorbic acid in preventing CAV. TET methyl cytosine dioxygenase2 (TET2) reduces vascular smooth muscle cell (VSMC) apoptosis and intimal thickening. TET2 is repressed by interferon γ (IFNγ) in the setting of CAV. Ascorbic acid has been shown to promote TET2 activity and attenuate allograft vasculopathy in animal models and CAV progression in a small clinical trial.

SUMMARY

CAV remains a challenging disease process and needs better preventative strategies. Ascorbic acid improves endothelial dysfunction, reduces reactive oxygen species, and prevents development of intimal hyperplasia by preventing smooth muscle cell apoptosis and hyperproliferation. Further large-scale randomized control studies of ascorbic acid are needed to establish the role in routine post-transplant management.

Hydrogen Peroxide Mediates Pharmacological Ascorbate Induced Radio-Sensitization of Pancreatic Cancer Cells by Enhancing G2-accumulation and Reducing Cyclin B1 Protein Levels

Pharmacological ascorbate (P-AscH-, high dose, intravenous vitamin C) preferentially sensitizes human pancreas ductal adenocarcinoma (PDAC) cells to radiation-induced toxicity compared to non-tumorigenic epithelial cells. Radiation-induced G2-checkpoint activation contributes to the resistance of cancer cells to DNA damage induced toxicity. We hypothesized that P-AscH- induced radio-sensitization of PDAC cells is mediated by perturbations in the radiation induced activation of the G2-checkpoint pathway. Both non-tumorigenic pancreatic ductal epithelial and PDAC cells display decreased clonogenic survival and increased doubling times after radiation treatment. In contrast, the addition of P-AscH- to radiation increases clonogenic survival and decreases the doubling time of non-tumorigenic epithelial cells but decreasing clonogenic survival and increasing the doubling time of PDAC cells. Results from the mitotic index and propidium iodide assays showed that while the P-AscH- treatments did not affect radiation-induced G2-checkpoint activation, it enhanced G2-accumulation. The addition of catalase reverses the increases in G2-accumulation, indicating a peroxide-mediated mechanism. In addition, P-AscH- treatment of PDAC cells suppresses radiation-induced accumulation of cyclin B1 protein levels. Both translational and post-translational pathways appear to regulate cyclin B1 protein levels after the combination treatment of PDAC cells with P-AscH- and radiation. The protein changes seen are reversed by the addition of catalase suggesting that hydrogen peroxide mediates P-AscH- induced radiation sensitization of PDAC cells by enhancing G2-accumulation and reducing cyclin B1 protein levels.

Ascorbic acid modulates immune responses through Jumonji-C domain containing histone demethylases and Ten eleven translocation (TET) methylcytosine dioxygenase

Ascorbic acid is a redox regulator in many physiological processes. Besides its antioxidant activity, many intriguing functions of ascorbic acid in the expression of immunoregulatory genes have been suggested. Ascorbic acid acts as a co-factor for the Fe+2 -containing α-ketoglutarate-dependent Jumonji-C domain-containing histone demethylases (JHDM) and Ten eleven translocation (TET) methylcytosine dioxygenasemediated epigenetic modulation. By influencing JHDM and TET, ascorbic acid facilitates the differentiation of double negative (CD4- CD8- ) T cells to double positive (CD4+ CD8+ ) T cells and of T-helper cells to different effector subsets. Ascorbic acid modulates plasma cell differentiation and promotes early differentiation of hematopoietic stem cells (HSCs) to NK cells. These findings indicate that ascorbic acid plays a significant role in regulating both innate and adaptive immune cells, opening up new research areas in Immunonutrition. Being a water-soluble vitamin and a safe micro-nutrient, ascorbic acid can be used as an adjunct therapy for many disorders of the immune system.

Dietary Sources, Bioavailability, and Functions of Ascorbic Acid (Vitamin C) and Its Role in the Common Cold, Tissue Healing, and Iron Metabolism

Ascorbic acid is also popularly known as vitamin C or ascorbate. It is a water-soluble vitamin. Ascorbic acid is necessary for bone formation, wound healing, connective tissue growth, and the maintenance of healthy gum tissue. Antioxidants like ascorbic acid shield the body from free radical damage. In many illnesses and conditions, vitamin C is employed as a medicinal agent. It improves the immunity of the body, reduces the severity of allergies, and aids in the management of infectious disorders. Additionally, ascorbic acid has health benefits for conditions including atherosclerosis, cancer, the common cold, iron deficiency anemia, etc. Therefore, continuous efforts may open new avenues to understand the importance of vitamin C in managing various diseases.