Synthetic or food-derived vitamin C--are they equally bioavailable?

Gender difference in the association between composite dietary antioxidant index and all-cause mortality

Background

Existing studies on the association between the composite dietary antioxidant index (CDAI) and all-cause mortality are controversial. We aimed to analyze the association of CDAI with all-cause mortality, and determine the influence of gender on this association.

Methods

The data of adult participants (age ≥ 18) from the National Health and Nutrition Examination Survey (NHANES) cycles spanning 2001 to 2018 were analyzed. The NHANES-issued identifiers for participants enabled the linkage of data from the NHANES Public Use Linked Mortality File.

Results

The study encompassed a sample of 15,651 individuals. The mean CDAI was 0.52 ± 6.06. The restricted cubic spline revealed that the hazard ratio (HR) of all-cause mortality decreased significantly with increasing CDAI. However, this negative association existed only when the CDAI was less than 5. Multivariate Cox regression analysis showed that compared to the first CDAI quartile, the HR of all-cause mortality was significantly decreased in the third and fourth quartiles (both p < 0.001), and the p-value of the trend test was <0.001. In the subgroup analysis, a notably strong negative association between CDAI and the risk of all-cause mortality was only observed in men (p for interaction <0.001).

Conclusion

Higher CDAI is associated with a reduced risk of all-cause mortality exclusively in adult males, underscoring the substantial influence of gender on this relationship.

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.

Antioxidant and Anti-Inflammatory Effects of Bioactive Compounds in Atherosclerosis

Atherosclerosis, a chronic inflammatory disease characterized by the accumulation of lipids and immune cells within arterial walls, remains a leading cause of cardiovascular morbidity and mortality worldwide. Oxidative stress and inflammation are central to its pathogenesis, driving endothelial dysfunction, foam cell formation, and plaque instability. Emerging evidence highlights the potential of bioactive compounds with antioxidant and anti-inflammatory properties to mitigate these processes and promote vascular health. This review explores the mechanisms through which bioactive compounds-such as polyphenols, carotenoids, flavonoids, omega-3 fatty acids, coenzyme Q10, and other natural compounds-modulate oxidative stress and inflammation in atherosclerosis. It examines their effects on key molecular pathways, including the inhibition of reactive oxygen species (ROS) production, suppression of nuclear factor-κB (NF-κB), and modulation of inflammatory cytokines. By integrating current knowledge, this review underscores the therapeutic potential of dietary and supplemental bioactive compounds as complementary strategies for managing atherosclerosis, paving the way for future research and clinical applications.

Vitamin C: From Self-Sufficiency to Dietary Dependence in the Framework of Its Biological Functions and Medical Implications

Vitamin C is an organic compound biosynthesized in plants and most vertebrates. Since its discovery, the benefits of vitamin C use in the cure and prevention of various pathologies have been frequently reported, including its anti-oxidant, anti-inflammatory, anticoagulant, and immune modulatory properties. Vitamin C plays an important role in collagen synthesis and subsequent scurvy prevention. It is also required in vivo as a cofactor for enzymes involved in carnitine and catecholamine norepinephrine biosynthesis, peptide amidation, and tyrosine catabolism. Moreover, as an enzymatic cofactor, vitamin C is involved in processes of gene transcription and epigenetic regulation. The absence of the synthesis of L-gulono-1,4-lactone oxidase, a key enzyme in the pathway of vitamin C synthesis, is an inborn metabolism error in some fishes and several bird and mammalian species, including humans and non-human primates; it is caused by various changes in the structure of the original GULO gene, making these affected species dependent on external sources of vitamin C. The evolutionary cause of GULO gene pseudogenization remains controversial, as either dietary supplementation or neutral selection is evoked. An evolutionary improvement in the control of redox homeostasis was also considered, as potentially toxic H2O2 is generated as a byproduct in the vitamin C biosynthesis pathway. The inactivation of the GULO gene and the subsequent reliance on dietary vitamin C may have broader implications for aging and age-related diseases, as one of the most important actions of vitamin C is as an anti-oxidant. Therefore, an important aim for medical professionals regarding human and animal health should be establishing vitamin C homeostasis in species that are unable to synthesize it themselves, preventing pathologies such as cardiovascular diseases, cognitive decline, and even cancer.

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.

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.

Association between dietary vitamin C intake and gout among American adults

Introduction

Gout is a common type of inflammatory arthritis. Vitamin C is a potent antioxidant that neutralizes reactive oxygen species. However, the association between dietary vitamin C levels and gout remains unclear. This study evaluated the relationship between dietary vitamin C intake and gout.

Methods

Cross-sectional data from individuals aged > 20 years who participated in the National Health and Nutrition Examination Survey between 2013 and 2018 were collected. Details on gout, dietary vitamin C intake, and several other essential variables were recorded.

Results

There were 12589 participants, 5% (652/12589) of whom experienced gout. Compared with individuals with lower vitamin C consumption in the Q1 group (≤19.9 mg/day), the adjusted odds ratio(OR)values for dietary vitamin C intake and gout in the Q2 group (19.9-49.7 mg/day), Q3 group (49.7-110.375 mg/day), and Q4 group (≥110.375 mg/day) were 0.87 (95% confidence interval (CI): 0.69-1.1, P = 0.237), 0.81 (95% CI: 0.64-1.02, P = 0.076), and 0.77 (95% CI: 0.6-0.99, P= 0.042), respectively. Accordingly, the association between dietary vitamin C intake and gout exhibited an L-shaped curve (nonlinear, P = 0.245) in a restricted cubic spline. Subgroup analysis revealed significant interactions between vitamin C levels and gout according to sex (P < 0.05). When we used data on dietary vitamin C from the second survey, we observed a similar inverse association between vitamin C intake and gout. The vitamin C was also negatively associated with hyperuricemia (OR, 0.94; 95% CI, 0.9-0.98, P=0.005). Compared with Q1, the adjusted OR values for dietary vitamin C and hyperuricemia in Q2, Q3, and Q4 were 0.77 (95% CI: 0.69-0.86, P = 0.65), 0.81 (95% CI: 0.72-0.91, P = 0.014), and 0.72 (95% CI: 0.64-0.81, P < 0.001), respectively. No association was observed between vitamin C supplementation and gout.

Conclusion

The population-based data indicate that dietary vitamin C intake is inversely associated with gout. These findings support the potential role of vitamin C in preventing gout.

Lifestyle Changes in Aging and their Potential Impact on POAG

Primary open angle glaucoma is a primary mitochondrial disease with oxidative stress triggering neuroinflammation, eventually resulting in neurodegeneration. This affects many other areas of the brain in addition to the visual system. Aging also leads to inflammaging - a low-grade chronic inflammatory reaction in mitochondrial dysfunction, so these inflammatory processes overlap in the aging process and intensify pathophysiological processes associated with glaucoma. Actively counteracting these inflammatory events involves optimising treatment for any manifest systemic diseases while maintaining chronobiology and improving the microbiome. Physical and mental activity also provides support. This requires a holistic approach towards optimising neurodegeneration treatment in primary open angle glaucoma in addition to reducing intraocular pressure according personalised patient targets.

Rheology and Extrusion Printing of κ-Carrageenan/Olive Oil Emulsion Gel Tablets with Varying Surface Area to Volume Ratios for Release of Vitamin C and Curcumin

In this work, κ-carrageenan and olive oil at different oil to κ-carrageenan ratios (OCR) are homogenized to create emulsion gels. Interestingly, confocal imaging shows that the oil droplets are stabilized in the κ-carrageenan-structured gel matrix without using any surfactants. Rheological studies show that the oil droplets enhanced the oscillatory yield stress and the maximum printable height of the emulsion gels. The creation of the emulsion gels with an OCR of 1:9-3:7 led to an improvement in the structural integrity of extrusion printed structures. The emulsion gel with an OCR of 3:7 efficiently encapsulates vitamin C in the aqueous phase and curcumin in the hydrophobic oil phase, enabling the extrusion 3D printing of tablets with varying surface area to volume (SA/V) ratios. The release of vitamin C and curcumin is influenced by the preparation method of printing versus casting and the SA/V ratio of the tablets. The hollow cylinder with the highest SA/V ratio was observed to have the highest vitamin C release, whereas for curcumin, the printed tablets had a higher release compared to the cast tablet. Additionally, through rheo-dissolution experiments, we observe a lower modulus and higher vitamin C release from the 3D-printed disc versus the higher modulus and lower vitamin C release from the cast disc tablet.

Simultaneous biofortification of vitamin C and mineral nutrients in arugula microgreens

Microgreens have shown promise in improving the overall nutritional value of diets due to their high nutrient density. Agronomic biofortification, is an efficient strategy for enhancing the nutritional value of crops, including microgreens. This study aimed to biofortify vitamin C and other essential nutrients in arugula microgreens using four treatments containing 0.25 % ascorbic acid, pH adjusted with different bases: KOH, Ca(OH)2, ZnCO3, or NaOH and a deionized water control. The results indicate that ascorbic acid-treated microgreens had more vitamin C, greater fresh weight and % dry matter than the control. The ascorbic acid + Zn treatment had an 135 % average increase in vitamin C compared to the control. Microgreens treated with ascorbic acid also showed increased levels of minerals that are present in the nutrient solution, such as potassium, sodium, calcium, and zinc. This research contributes to the growing interest in microgreens biofortification and their role in addressing multi-nutrient deficiencies.

Growth of Romaine Lettuce in Eggshell Powder Mixed Alginate Hydrogel in an Aeroponic System for Water Conservation and Vitamin C Biofortification

Vitamin C is crucial for physical well-being, and its deficiency can lead to severe health consequences. Biofortification has been used to address this deficiency by enhancing vitamin C in plants. Additionally, soilless agriculture has been used to conserve and optimize water use in comparison to conventional agriculture. While hydrogels have been shown to improve water conservation and are used for biofortification in crops, their application has only been explored in soil-based and hydroponic farming. The aeroponics system is a plant-growing method that has shown potential for increasing yields and biomass while conserving water and nutrients. In this paper, we have developed an aeroponic-compatible medium to grow romaine lettuce (Lactuca sativa L.) with eggshell powder (ESP) mixed with calcium-alginate hydrogel as a substrate and nutrient source aiming to conserve water and incorporate vitamin C through biofortification. Herein, lower water spray time and higher intervals, with varied gel types and ESP concentrations, resulted in healthy lettuce growth. Plants treated with 0.5% ascorbic acid-absorbed ESP-mixed alginate hydrogel for biofortification showed higher levels of vitamin C compared to the traditional method. This study suggests using an alginate hydrogel-ESP-based substrate in aeroponics to reduce water usage and enhance plant biofortification of vitamin C.

Smartphone survey data reveal the timecourse of changes in mood outcomes following vitamin C or kiwifruit intervention in adults with low vitamin C

Vitamin C-rich foods can improve mood; however, the timecourse of these benefits is unknown. This study utilised intensive longitudinal smartphone surveys from a three-armed placebo-controlled trial to determine mood-related changes following supplementation with vitamin C (250 mg tablet/d), kiwifruit (2 SunGold™ kiwifruit/d) or a placebo (1 tablet/d). Secondary data were analysed from the KiwiC for Vitality trial (Trial ID: ACTRN12617001031358). Adults (n 155, 63 % female, aged 18-35 years) with low plasma vitamin C (<40 μmol/l) completed a 14-d lead-in, 28-d intervention and 14-d washout. Participants self-reported vitality (SF-36), mood (POMS total mood disturbance), flourishing (flourishing scale), sleep quality, sleep quantity and physical activity every second day using smartphone surveys. Plasma vitamin C, measured fortnightly, reached saturation after 2 weeks of vitamin C or kiwifruit supplementation. Kiwifruit supplementation improved vitality and mood within 4 days, peaking around 14-16 days, and improved flourishing from day 14. Vitamin C marginally improved mood until day 12. Incremental AUC analyses revealed significant overall effects of kiwifruit consumption on vitality and mood compared with placebo, which were stronger than effects for vitamin C tablets, but attenuated when adjusting for covariates. Sensitivity analyses of participants with low baseline vitamin C status revealed improved mood (vitamin C and kiwifruit) and flourishing (kiwifruit only). This is the first study to use intensive smartphone surveys to model the day-to-day timecourse of mood-related states following vitamin C intervention and highlights the value of using smartphone surveys to reveal the temporal changes in mood-related outcomes following nutrient supplementation.

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.

Dietary and supplementary vitamin C intake and the risk of lung cancer: A meta‑analysis of cohort studies

Previous cohort studies reported inconsistent findings regarding the association between dietary or supplementary vitamin C intake and lung cancer risk. These associations were investigated by conducting a meta-analysis of cohort studies. The PubMed and EMBASE databases were utilized, using keywords related to the topic from inception to April 15, 2022. Pooled effect sizes, such as relative risk (RR) or hazard ratio (HR) with 95% confidence intervals (CIs), were calculated using a random-effects model. A total of 20 cohort studies from 13 articles were included in the final analysis. In a meta-analysis of all studies, there was no significant association between dietary or supplementary vitamin C intake and lung cancer risk (RR/HR, 0.90; 95% CI, 0.80-1.01; I2=56.4%; n=20). In the subgroup meta-analysis by the source of vitamin C, dietary vitamin C intake decreased the risk of lung cancer (RR/HR, 0.82; 95% CI, 0.73-0.92; I2=42.5%; n=14), whereas there was no association between supplementary vitamin C intake and lung cancer risk (RR/HR, 1.01; 95% CI, 0.84-1.22; n=4). The present meta-analysis of cohort studies found that dietary vitamin C intake is beneficial for preventing lung cancer, whereas its supplementary intake does not have a beneficial effect.

Prioritizing strategies for wheat biofortification: Inspiration from underutilized species

The relationship between malnutrition and climate change is still poorly understood but a comprehensive knowledge of their interactions is needed to address the global public health agenda. Limited studies have been conducted to propose robust and economic-friendly strategies to augment the food basket with underutilized species and biofortify the staples for nutritional security. Sea-buckthorn is a known "superfood" rich in vitamin C and iron content. It is found naturally in northern hemispherical temperate Eurasia and can be utilized as a model species for genetic biofortification in cash crops like wheat. This review focuses on the impacts of climate change on inorganic (iron, zinc) and organic (vitamin C) micronutrient malnutrition employing wheat as highly domesticated crop and processed food commodity. As iron and zinc are particularly stored in the outer aleurone and endosperm layers, they are prone to processing losses. Moreover, only 5% Fe and 25% Zn are bioavailable once consumed calling to enhance the bioavailability of these micronutrients. Vitamin C converts non-available iron (Fe3+) to available form (Fe2+) and helps in the synthesis of ferritin while protecting it from degradation at the same time. Similarly, reduced phytic acid content also enhances its bioavailability. This relation urges scientists to look for a common mechanism and genes underlying biosynthesis of vitamin C and uptake of Fe/Zn to biofortify these micronutrients concurrently. The study proposes to scale up the biofortification breeding strategies by focusing on all dimensions i.e., increasing micronutrient content and boosters (vitamin C) and simultaneously reducing anti-nutritional compounds (phytic acid). Mutually, this review identified that genes from the Aldo-keto reductase family are involved both in Fe/Zn uptake and vitamin C biosynthesis and can potentially be targeted for genetic biofortification in crop plants.

Genome of Phyllanthus emblica: the medicinal plant Amla with super antioxidant properties

Phyllanthus emblica or Indian gooseberry, commonly known as amla, is an important medicinal horticultural plant used in traditional and modern medicines. It bears stone fruits with immense antioxidant properties due to being one of the richest natural sources of vitamin C and numerous flavonoids. This study presents the first genome sequencing of this species performed using 10x Genomics and Oxford Nanopore Technology. The draft genome assembly was 519 Mbp in size and consisted of 4,384 contigs, N50 of 597 Kbp, 98.4% BUSCO score, and 37,858 coding sequences. This study also reports the genome-wide phylogeny of this species with 26 other plant species that resolved the phylogenetic position of P. emblica. The presence of three ascorbate biosynthesis pathways including L-galactose, galacturonate, and myo-inositol pathways was confirmed in this genome. A comprehensive comparative evolutionary genomic analysis including gene family expansion/contraction and identification of multiple signatures of adaptive evolution provided evolutionary insights into ascorbate and flavonoid biosynthesis pathways and stone fruit formation through lignin biosynthesis. The availability of this genome will be beneficial for its horticultural, medicinal, dietary, and cosmetic applications and will also help in comparative genomics analysis studies.

Free Radicals and Obesity-Related Chronic Inflammation Contrasted by Antioxidants: A New Perspective in Coronary Artery Disease

We are surrounded by factors called free radicals (FR), which attach to the molecules our body is made of, first among them the endothelium. Even though FR are to a certain extent a normal factor, nowadays we face an escalating increase in these biologically aggressive molecules. The escalating formation of FR is linked to the increased usage of man-made chemicals for personal care (toothpaste, shampoo, bubble bath, etc.), domestic laundry and dish-washer detergents, and also an ever wider usage of drugs (both prescription and over the counter), especially if they are to be used long-term (years). In addition, tobacco smoking, processed foods, pesticides, various chronic infectious microbes, nutritional deficiencies, lack of sun exposure, and, finally, with a markedly increasing impact, electromagnetic pollution (a terribly destructive factor), can increase the risk of cancer, as well as endothelial dysfunction, owing to the increased production of FR that they cause. All these factors create endothelial damage, but the organism may be able to repair such damage thanks to the intervention of the immune system supported by antioxidants. However, one other factor can perpetuate the state of inflammation, namely obesity and metabolic syndrome with associated hyperinsulinemia. In this review, the role of FR, with a special emphasis on their origin, and of antioxidants, is explored from the perspective of their role in causing atherosclerosis, in particular at the coronary level.

Cell signaling pathways based on vitamin C and their application in cancer therapy

Vitamin C, a small organic molecule, is widely found in fruits and vegetables and is an essential nutrient in the human body. Vitamin C is closely associated with some human diseases such as cancer. Many studies have shown that high doses of vitamin C have anti-tumor ability and can target tumor cells in multiple targets. This review will describe vitamin C absorption and its function in cancer treatment. We will review the cellular signaling pathways associated with vitamin C against tumors depending on the different anti-cancer mechanisms. Based on this, we will further describe some applications of the use of vitamin C for cancer treatment in preclinical and clinical trials and the possible adverse events that can occur. Finally, this review also assesses the prospective advantages of vitamin C in oncology treatment and clinical applications.

Vitamin C supplementation for diabetes management: A comprehensive narrative review

Growing evidence suggests that vitamin C supplementation may be an effective adjunct therapy in the management of people with diabetes. This paper critically reviews the current evidence on effects of vitamin C supplementation and its potential mechanisms in diabetes management. Evidence from meta-analyses of randomized controlled trials (RCTs) show favourable effects of vitamin C on glycaemic control and blood pressure that may be clinically meaningful, and mixed effects on blood lipids and endothelial function. However, evidence is mostly of low evidence certainty. Emerging evidence is promising for effects of vitamin C supplementation on some diabetes complications, particularly diabetic foot ulcers. However, there is a notable lack of robust and well-designed studies exploring effects of vitamin C as a single compound supplement on diabetes prevention and patient-important outcomes (i.e. prevention and amelioration of diabetes complications). RCTs are also required to investigate potential preventative or ameliorative effects of vitamin C on gestational diabetes outcomes. Oral vitamin C doses of 500-1000 mg per day are potentially effective, safe, and affordable for many individuals with diabetes. However, personalisation of supplementation regimens that consider factors such as vitamin C status, disease status, current glycaemic control, vitamin C intake, redox status, and genotype is important to optimize vitamin C's therapeutic effects safely. Finally, given a high prevalence of vitamin C deficiency in patients with complications, it is recommended that plasma vitamin C concentration be measured and monitored in the clinic setting.

The perils of planning strategies to increase vitamin C content in plants: Beyond the hype

Ever since the identification of vitamin C (ascorbic acid, AsA) as an essential molecule that humans cannot synthesize on their own, finding adequate dietary sources of AsA became a priority in nutrition research. Plants are the main producers of AsA for humans and other non-synthesizing animals. It was immediately clear that some plant species have more AsA than others. Further studies evidenced that AsA content varies in different plant organs, in different developmental stages/environmental conditions and even within different cell compartments. With the progressive discovery of the genes of the main (Smirnoff-Wheeler) and alternative pathways coding for the enzymes involved in AsA biosynthesis in plants, the simple overexpression of those genes appeared a suitable strategy for boosting AsA content in any plant species or organ. Unfortunately, overexpression experiments mostly resulted in limited, if any, AsA increase, apparently due to a tight regulation of the biosynthetic machinery. Attempts to identify regulatory steps in the pathways that could be manipulated to obtain unlimited AsA production were also less successful than expected, confirming the difficulties in "unleashing" AsA synthesis. A different approach to increase AsA content has been the overexpression of genes coding for enzymes catalyzing the recycling of the oxidized forms of vitamin C, namely monodehydroascorbate and dehydroascorbate reductases. Such approach proved mostly effective in making the overexpressors apparently more resistant to some forms of environmental stress, but once more did not solve the issue of producing massive AsA amounts for human diet. However, it should also be considered that a hypothetical unlimited increase in AsA content is likely to interfere with plant development, which is in many ways regulated by AsA availability itself. The present review article aims at summarizing the many attempts made so far to improve AsA production/content in plants, evidencing the most promising ones, and at providing information about the possible unexpected consequences of a pure biotechnological approach not keeping into account the peculiar features of the AsA system in plants.

Improvement of Moist Heat Resistance of Ascorbic Acid through Encapsulation in Egg Yolk–Chitosan Composite: Application for Production of Highly Nutritious Shrimp Feed Pellets

Simple Summary

Egg yolk (EY) is an excellent supplement for aquatic animals and has good food functionality. According to the high lipid content in EY, it was, for the first time, used in combination with chitosan (CS) to encapsulate the ascorbic acid (AA) to minimize the loss of AA during exposure to feed processing and seawater. The microcapsules’ production yield, EE, and moist heat resistance were evaluated. One selected encapsulated AA was fortified in shrimp feed. The AA retention in feed processing and seawater was evaluated. Both EE and production yields of the microcapsules were relatively high compared to other reports. Moist heat resistance capability of the encapsulated AA was up to 82%. EY was essential in moist heat protection, while CS significantly improved the microcapsules’ production yield, EE, and morphology. The loss of AA in feed processing and seawater was remarkably improved by 16 folds compared to the unencapsulated AA. The microcapsules showed high potential application for foods and aquatic feed to protect heat-labile and hydro-soluble substances.

Abstract

Egg yolk (EY) is an excellent supplement for aquatic animals and has good technofunctionality. Ascorbic acid (AA) is a potent bioactive substance and is essentially added to shrimp feed; however, it is drastically lost in both feed processing and in rearing environments. In this study, AA was microencapsulated in an EY–chitosan (CS) composite. The encapsulated vitamin was then mixed into a shrimp feed mixture to form pelleted feed via twin-screw extrusion. The effects of the EY/AA ratio and the amount of CS on moist heat resistance, production yield, encapsulation efficiency (EE), and morphology of microcapsules were investigated. The molecular interaction of the microcapsule components was analyzed by FTIR. The size and size distribution of the microcapsules were determined using a laser diffraction analyzer. The microstructure was evaluated by SEM. The physical properties of the microcapsule-fortified pelleted feed were determined. The AA retention at each step of feed processing and during exposure to seawater was evaluated. The results showed that the microcapsules had a spherical shape with an average diameter of ~6.0 μm. Decreasing the EY/AA ratio significantly improved the production yield, EE, and morphology of the microcapsules. EY proved to be the key component for moist heat resistance, while CS majorly improved the production yield, EE, and morphology of the microcapsules. The microcapsules showed no adverse impact on feed properties. The loss of AA in food processing and seawater was remarkably improved. The final content of the encapsulated AA remaining in shrimp feed was 16-fold higher than that of the unencapsulated AA.

The Effect of β-Carotene, Tocopherols and Ascorbic Acid as Anti-Oxidant Molecules on Human and Animal In Vitro/In Vivo Studies: A Review of Research Design and Analytical Techniques Used

Prolonged elevated oxidative stress (OS) possesses negative effect on cell structure and functioning, and is associated with the development of numerous disorders. Naturally occurred anti-oxidant compounds reduce the oxidative stress in living organisms. In this review, antioxidant properties of β-carotene, tocopherols and ascorbic acid are presented based on in vitro, in vivo and populational studies. Firstly, environmental factors contributing to the OS occurrence and intracellular sources of Reactive Oxygen Species (ROS) generation, as well as ROS-mediated cellular structure degradation, are introduced. Secondly, enzymatic and non-enzymatic mechanism of anti-oxidant defence against OS development, is presented. Furthermore, ROS-preventing mechanisms and effectiveness of β-carotene, tocopherols and ascorbic acid as anti-oxidants are summarized, based on studies where different ROS-generating (oxidizing) agents are used. Oxidative stress biomarkers, as indicators on OS level and prevention by anti-oxidant supplementation, are presented with a focus on the methods (spectrophotometric, fluorometric, chromatographic, immuno-enzymatic) of their detection. Finally, the application of Raman spectroscopy and imaging as a tool for monitoring the effect of anti-oxidant (β-carotene, ascorbic acid) on cell structure and metabolism, is proposed. Literature data gathered suggest that β-carotene, tocopherols and ascorbic acid possess potential to mitigate oxidative stress in various biological systems. Moreover, Raman spectroscopy and imaging can be a valuable technique to study the effect of oxidative stress and anti-oxidant molecules in cell studies.

Increasing vitamin C through agronomic biofortification of arugula microgreens

Vitamin C (Vit C) is an essential micronutrient and antioxidant for human health. Unfortunately, Vit C cannot be produced in humans and is ingested through diet while severe deficiencies can lead to scurvy. However, consumption is often inconsistent, and foods vary in Vit C concentrations. Biofortification, the practice of increasing micronutrient or mineral concentrations, can improve the nutritional quality of crops and allow for more consistent dietary levels of these nutrients. Of the three leading biofortification practices (i.e., conventional, transgenic, and agronomical), the least explored approach to increase Vit C in microgreens is agronomically, especially through the supplemental application of ascorbic acid. In this study, biofortification of Vit C in microgreens through supplemental ascorbic acid was attempted and proven achievable. Arugula (Eruca sativa 'Astro') microgreens were irrigated with four concentrations of ascorbic acid and a control. Total Vit C (T-AsA) and ascorbic acid increased in microgreens as supplementary concentrations increased. In conclusion, biofortification of Vit C in microgreens through supplemental ascorbic acid is achievable, and consumption of these bio-fortified microgreens could help fulfill the daily Vit C requirements for humans, thereby reducing the need for supplemental vitamins.

Biological Functions of Antioxidant Dipeptides

In the history of modern nutritional science, understanding antioxidants is one of the major topics. In many cases, food-derived antioxidants have π conjugate or thiol group in their molecular structures because π conjugate stabilizes radical by its delocalization and two thiol groups form a disulfide bond in its antioxidative process. In recent years, antioxidant peptides have received much attention because for their ability to scavenge free radicals, inhibition of lipid peroxidation, chelation of transition metal ions, as well as their additional nutritional value. Among them, dipeptides are attracting much interest as post-amino acids, which have residues in common with amino acids, but also have different physiological properties and functions from those of amino acids. Especially, dipeptides containing moieties of several amino acid (tryptophan, tyrosine, histidine, cysteine, and methionine) possess potent antioxidant activity. This review summarizes previous details of structural property, radical scavenging activity, and biological activity of antioxidant dipeptide. Hopefully, this review will help provide a new insight into the study of the biological functions of antioxidant dipeptides.

Estimation of Vitamin C Intake Requirements Based on Body Weight: Implications for Obesity

Higher body weight is known to negatively impact plasma vitamin C status. However, despite this well-documented inverse association, recommendations on daily vitamin C intakes by health authorities worldwide do not include particular reference values for people of higher body weight. This suggests that people of higher body weight and people with obesity may be receiving insufficient vitamin C in spite of ingesting the amounts recommended by their health authorities. The current preliminary investigation sought to estimate how much additional vitamin C people with higher body weights would need to consume in order to attain a comparable vitamin C status to that of a lower weight person consuming an average Western vitamin C intake. Data from two published vitamin C dose-concentration studies were used to generate the relationship: a detailed pharmacokinetic study with seven healthy non-smoking men and a multiple depletion–repletion study with 68 healthy non-smoking men of varying body weights. Our estimates suggest that an additional intake of 10 mg vitamin C/day is required for every 10 kg increase in body weight to attain a comparable plasma concentration to a 60 kg individual with a vitamin C intake of ~110 mg/day, which is the daily intake recommended by the European Food Safety Authority (EFSA). Thus, individuals weighing e.g., 80 and 90 kg will need to consume ~130 and 140 mg vitamin C/day, respectively. People with obesity will likely need even higher vitamin C intakes. As poor vitamin C status is associated with increased risk of several chronic diseases including cardiovascular disease, these findings may have important public health implications. As such, dose-finding studies are required to determine optimal vitamin C intakes for overweight and obese people.

The Influence of the Addition of Rosehip Powder to Wheat Flour on the Dough Farinographic Properties and Bread Physico-Chemical Characteristics

An in-depth analysis of wheat flour (WF) substituted with 0.5–2.5% rosehip powder (Rp) concerning the proximate composition, dough farinographic properties, and bread physico-chemical characteristics was performed. The purpose of this study was to investigate whether the use of Rp as a natural alternative for synthetic ascorbic acid in breadmaking was appropriate. A sample of wheat flour with an ascorbic acid addition of 2 mg/100 g was also used. Rp showed higher ash, carbohydrates, and fibre content, as well as lower moisture and protein content compared to wheat flour, and a vitamin C content of 420 ± 16.09 mg/100 g. A proximate composition analysis revealed a decrease in moisture, protein, and wet gluten, and an increase in ash, carbohydrates, and fibres for the flour mixtures compared with WF. Farinographic properties were positively influenced by the Rp addition and the high fibre content in the flour mixtures. Water absorption increased from 58.20% (WF) to 61.90% (2.5% Rp). Dough stability increased for the 0.5–1.0% Rp addition, then slightly decreased. The physico-chemical properties of bread prepared from flour mixtures showed a significant increase in height: 100.10 ± 0.14 mm (WF)–115.50 ± 0.14 mm (1.5% Rp), specific volume: 142.82 cm3/100 g (WF)–174.46 cm3/100 g (1.5% Rp), moisture: 41.81 ± 0.40% (WF)–43.92 ± 0.15% (2.0% Rp), and porosity: 87.75 ± 1.06% (WF)–89.40 ± 0.57% (2.5% Rp). The results indicated that the Rp used in breadmaking to replace synthetic ascorbic acid could be suitable.

Effect of SunGold Kiwifruit and Vitamin C Consumption on Ameliorating Exercise-Induced Stress Response in Women

INTRODUCTION

Markers of oxidative and psychological stress are elevated during high-intensity exercise. Additionally, when energy intake does not match expenditure, women who actively participate in sports and exercise are at risk of developing menstrual dysfunction, infertility, and osteoporosis. Vitamin C is known to reduce exercise-induced stress. Here, this study investigates the efficacy of consuming vitamin C from SunGold kiwifruit compared to in isolation, in ameliorating exercise-induced stress in recreationally active women.

METHODS AND RESULTS

Ten eumenorrheic women are recruited in this crossover study and attended three exercise and one rest trial. In the exercise trials, participants consumed 300 mg vitamin C from kiwifruit or drink, or have a placebo drink, followed by 30-min exercise on a cycle ergometer at 60% power. During rest visit, participants sat quietly and consumed a placebo drink. Salivary uric acid (oxidative stress) and cortisol (psychological stress) are measured before and immediately after exercise for 2 h. Both vitamin C and kiwifruit reduced exercise-induced uric acid, immediately after exercise. Vitamin C drink continued to decrease uric acid for a further 30 min and slightly attenuated exercise-induced cortisol.

CONCLUSIONS

Consuming liquid vitamin C prior to high-intensity cycling appears more effective than eating kiwifruit, in ameliorating exercise-induced stress in recreationally active women of reproductive age.

Vitamin C-Sources, Physiological Role, Kinetics, Deficiency, Use, Toxicity, and Determination

Vitamin C (L-ascorbic acid) has been known as an antioxidant for most people. However, its physiological role is much larger and encompasses very different processes ranging from facilitation of iron absorption through involvement in hormones and carnitine synthesis for important roles in epigenetic processes. Contrarily, high doses act as a pro-oxidant than an anti-oxidant. This may also be the reason why plasma levels are meticulously regulated on the level of absorption and excretion in the kidney. Interestingly, most cells contain vitamin C in millimolar concentrations, which is much higher than its plasma concentrations, and compared to other vitamins. The role of vitamin C is well demonstrated by miscellaneous symptoms of its absence-scurvy. The only clinically well-documented indication for vitamin C is scurvy. The effects of vitamin C administration on cancer, cardiovascular diseases, and infections are rather minor or even debatable in the general population. Vitamin C is relatively safe, but caution should be given to the administration of high doses, which can cause overt side effects in some susceptible patients (e.g., oxalate renal stones). Lastly, analytical methods for its determination with advantages and pitfalls are also discussed in this review.

Preparation and Characterization of Ionic Conductive Poly(acrylic Acid)-Based Silicone Hydrogels for Smart Drug Delivery System

In this study, we developed a smart drug delivery system that can efficiently deliver the required amounts of drugs using the excellent ion conductivity of poly(acrylic acid) (PAA) and an electrical stimulus. As a result of its having carboxyl groups, PAA hydrogel can be used in drug delivery patches to release drugs by ionic conductivity. However, PAA hydrogel has low durability and poor mechanical properties. The carboxyl group of PAA was combined with a siloxane group of silicone using electron-beam irradiation to easily form a crosslinked structure. The PAA-silicone hydrogel has excellent mechanical properties. Specifically, the tensile strength increased more than 3.5 times. In addition, we observed its cell compatibility using fluorescence staining and CCK-8 assays and found good cell viability. Finally, it was possible to control the drug delivery rate efficiently using the voltage applied to the ion-conductive hydrogel. As the voltage was increased to 3, 5, and 7 V, the amount of drug released was 53, 88, and 96%, respectively. These excellent properties of the PAA-silicone hydrogel can be used not only for whitening or anti-wrinkling cosmetics but also in medical drug-delivery systems.

Vitamin C: historical perspectives and heart failure

Vitamin C (Vit C) is an ideal antioxidant as it is easily available, water soluble, very potent, least toxic, regenerates other antioxidants particularly Vit E, and acts as a cofactor for different enzymes. It has received much attention due to its ability in limiting reactive oxygen species, oxidative stress, and nitrosative stress, as well as it helps to maintain some of the normal metabolic functions of the cell. However, over 140 clinical trials using Vit C in different pathological conditions such as myocardial infarction, gastritis, diabetes, hypertension, stroke, and cancer have yielded inconsistent results. Such a divergence calls for new strategies to establish practical significance of Vit C in heart failure or even in its prevention. For a better understanding of Vit C functioning, it is important to revisit its transport across the cell membrane and subcellular interactions. In this review, we have highlighted some historical details of Vit C and its transporters in the heart with a particular focus on heart failure in cancer chemotherapy.

KiwiC for Vitality: Results of a Randomized Placebo-Controlled Trial Testing the Effects of Kiwifruit or Vitamin C Tablets on Vitality in Adults with Low Vitamin C Levels

Consumption of vitamin C-rich fruit and vegetables has been associated with greater feelings of vitality. However, these associations have rarely been tested in randomized controlled trials. The aim of the current study was to test the effects of eating a vitamin C-rich food (kiwifruit) on subjective vitality and whether effects are driven by vitamin C. Young adults (n = 167, 61.1% female, aged 18-35) with plasma vitamin C <40 µmol/L were randomized into three intervention conditions: kiwifruit (2 SunGold™ kiwifruit/day), vitamin C (250 mg tablet/day), placebo (1 tablet/day). The trial consisted of a two-week lead-in, four-week intervention, and two-week washout. Plasma vitamin C and vitality questionnaires (total mood disturbance, fatigue, and well-being) were measured fortnightly. Self-reported sleep quality and physical activity were measured every second day through smartphone surveys. Nutritional confounds were assessed using a three-day food diary during each study phase. Plasma vitamin C reached saturation levels within two weeks for the kiwifruit and vitamin C groups. Participants consuming kiwifruit showed significantly improved mood and well-being during the intervention period; improvements in well-being were sustained during washout. Decreased fatigue and increased well-being were observed following intake of vitamin C alone, but only for participants with consistently low vitamin C levels during lead-in. Diet records showed that participants consuming kiwifruit reduced their fat intake during the intervention period. Intervention effects remained significant when adjusting for age and ethnicity, and were not explained by sleep quality, physical activity, BMI, or other dietary patterns, including fat intake. There were no changes in plasma vitamin C status or vitality in the placebo group. Whole food consumption of kiwifruit improved subjective vitality in adults with low vitamin C status. Similar, but not identical, changes were found for vitamin C tablets suggesting that additional properties of kiwifruit may contribute to improved vitality.

Pathways of Gastric Carcinogenesis, Helicobacter pylori Virulence and Interactions with Antioxidant Systems, Vitamin C and Phytochemicals

Helicobacter pylori is a class one carcinogen which causes chronic atrophic gastritis, gastric intestinal metaplasia, dysplasia and adenocarcinoma. The mechanisms by which H. pylori interacts with other risk and protective factors, particularly vitamin C in gastric carcinogenesis are complex. Gastric carcinogenesis includes metabolic, environmental, epigenetic, genomic, infective, inflammatory and oncogenic pathways. The molecular classification of gastric cancer subtypes has revolutionized the understanding of gastric carcinogenesis. This includes the tumour microenvironment, germline mutations, and the role of Helicobacter pylori bacteria, Epstein Barr virus and epigenetics in somatic mutations. There is evidence that ascorbic acid, phytochemicals and endogenous antioxidant systems can modify the risk of gastric cancer. Gastric juice ascorbate levels depend on dietary intake of ascorbic acid but can also be decreased by H. pylori infection, H. pylori CagA secretion, tobacco smoking, achlorhydria and chronic atrophic gastritis. Ascorbic acid may be protective against gastric cancer by its antioxidant effect in gastric cytoprotection, regenerating active vitamin E and glutathione, inhibiting endogenous N-nitrosation, reducing toxic effects of ingested nitrosodimethylamines and heterocyclic amines, and preventing H. pylori infection. The effectiveness of such cytoprotection is related to H. pylori strain virulence, particularly CagA expression. The role of vitamin C in epigenetic reprogramming in gastric cancer is still evolving. Other factors in conjunction with vitamin C also play a role in gastric carcinogenesis. Eradication of H. pylori may lead to recovery of vitamin C secretion by gastric epithelium and enable regression of premalignant gastric lesions, thereby interrupting the Correa cascade of gastric carcinogenesis.

Bioavailability of Micronutrients From Nutrient-Dense Whole Foods: Zooming in on Dairy, Vegetables, and Fruits

In order to fully exploit the nutrient density concept, thorough understanding of the biological activity of single nutrients in their interaction with other nutrients and food components from whole foods is important. This review provides a narrative overview of recent insights into nutrient bioavailability from complex foods in humans, highlighting synergistic and antagonistic processes among food components for two different food groups, i.e., dairy, and vegetables and fruits. For dairy, bioavailability of vitamins A, B2, B12 and K, calcium, phosphorous, magnesium, zinc and iodine are discussed, whereas bioavailability of pro-vitamin A, folate, vitamin C and K, potassium, calcium, magnesium and iron are discussed for vegetables and fruits. Although the bioavailability of some nutrients is fairly well-understood, for other nutrients the scientific understanding of uptake, absorption, and bioavailability in humans is still at a nascent stage. Understanding the absorption and bioavailability of nutrients from whole foods in interaction with food components that influence these processes will help to come to individual diet scores that better reflect absorbable nutrient intake in epidemiologic studies that relate dietary intake to health outcomes. Moreover, such knowledge may help in the design of foods, meals, and diets that aid in the supply of bioavailable nutrients to specific target groups.

Global Vitamin C Status and Prevalence of Deficiency: A Cause for Concern?

Vitamin C is an essential nutrient that must be obtained through the diet in adequate amounts to prevent hypovitaminosis C, deficiency and its consequences-including the potentially fatal deficiency disease scurvy. Global vitamin C status and prevalence of deficiency has not previously been reported, despite vitamin C's pleiotropic roles in both non-communicable and communicable disease. This review highlights the global literature on vitamin C status and the prevalence of hypovitaminosis C and deficiency. Related dietary intake is reported if assessed in the studies. Overall, the review illustrates the shortage of high quality epidemiological studies of vitamin C status in many countries, particularly low- and middle-income countries. The available evidence indicates that vitamin C hypovitaminosis and deficiency is common in low- and middle-income countries and not uncommon in high income settings. Further epidemiological studies are required to confirm these findings, to fully assess the extent of global vitamin C insufficiency, and to understand associations with a range of disease processes. Our findings suggest a need for interventions to prevent deficiency in a range of at risk groups and regions of the world.

Factors Affecting Vitamin C Status and Prevalence of Deficiency: A Global Health Perspective

A recent review of global vitamin C status has indicated a high prevalence of deficiency, particularly in low- and middle-income countries, as well as in specific subgroups within high-income countries. Here, we provide a narrative review of potential factors influencing vitamin C status globally. The in vivo status of vitamin C is primarily affected by dietary intake and supplement use, with those who supplement having a higher mean status and a lower prevalence of deficiency. Dietary intake can be influenced by cultural aspects such as traditional cooking practices and staple foods, with many staple foods, such as grains, contributing negligible vitamin C to the diet. Environmental factors can also affect vitamin C intake and status; these include geographic region, season, and climate, as well as pollution, the latter partly due to enhanced oxidative stress. Demographic factors such as sex, age, and race are known to affect vitamin C status, as do socioeconomic factors such as deprivation, education and social class, and institutionalization. Various health aspects can affect vitamin C status; these include body weight, pregnancy and lactation, genetic variants, smoking, and disease states, including severe infections as well as various noncommunicable diseases such as cardiovascular disease and cancer. Some of these factors have changed over time; therefore, we also explore if vitamin C status has shown temporal changes. Overall, there are numerous factors that can affect vitamin C status to different extents in various regions of the world. Many of these factors are not taken into consideration during the setting of global dietary intake recommendations for vitamin C.

Discrepancies in global vitamin C recommendations: a review of RDA criteria and underlying health perspectives

The concept of a 'recommended dietary allowance' (RDA) and similar terms describing the daily intake of essential nutrients recommended for healthy individuals is widely used by various health authorities around the world. For vitamin C, however, there remain significant discrepancies in the criteria used to establish dietary recommendations and consequently, global recommendations for daily vitamin C intake vary by more than five fold. While it appears that the scientific data underlying the recommendations are more or less the same, the interpretation differs considerably. Moreover, although a number of the assumptions used in e.g. the body pool estimates of the 1960s and 1970s have later been proven wrong and give rise to significant underestimations, these data are still used as the main support of several recommendations. Aspects that modify vitamin C requirements, such as gender, age, pregnancy, lactation, and smoking, have been taken into consideration by many but not all regulatory authorities, and are thus subject of debate. In contrast, body weight, a significant predictor of vitamin C status and requirement, has not been taken into consideration with respect to vitamin C recommendations, even in the face of the looming global obesity pandemic. The present review examines the discrepancies in vitamin C dietary recommendations of international authorities and critically discusses representative examples of criteria and the underlying health perspectives used to derive current recommended intakes of vitamin C. New biological signatures of vitamin C nutriture are also explored with regard to their potential use for future updates of dietary recommendations.

Pro- and Antioxidant Effects of Vitamin C in Cancer in correspondence to Its Dietary and Pharmacological Concentrations

Vitamin C is an antioxidant that may scavenge reactive oxygen species preventing DNA damage and other effects important in cancer transformation. Dietary vitamin C from natural sources is taken with other compounds affecting its bioavailability and biological effects. High pharmacological doses of vitamin C may induce prooxidant effects, detrimental for cancer cells. An oxidized form of vitamin C, dehydroascorbate, is transported through glucose transporters, and cancer cells switch from oxidative phosphorylation to glycolysis in energy production so an excess of vitamin C may limit glucose transport and ATP production resulting in energetic crisis and cell death. Vitamin C may change the metabolomic and epigenetic profiles of cancer cells, and activation of ten-eleven translocation (TET) proteins and downregulation of pluripotency factors by the vitamin may eradicate cancer stem cells. Metastasis, the main reason of cancer-related deaths, requires breakage of anatomical barriers containing collagen, whose synthesis is promoted by vitamin C. Vitamin C induces degradation of hypoxia-inducible factor, HIF-1, essential for the survival of tumor cells in hypoxic conditions. Dietary vitamin C may stimulate the immune system through activation of NK and T cells and monocytes. Pharmacological doses of vitamin C may inhibit cancer transformation in several pathways, but further studies are needed to address both mechanistic and clinical aspects of this effect.

Geographical discrimination of uvaia (Eugenia pyriformis Cambess) by principal component analysis

BACKGROUND

The international marketing of native Brazilian fruits may benefit from research into discrimination between plants with particular properties. Plants with certain characteristics have strong potential for use in agroindustry and for the development of new processed products. In the current study, 12 uvaia plants (Eugenia pyriformis Cambess), native to Brazil, were geographically discriminated by chemometric methods, using nutritional composition, physicochemical characterization, bioactive compounds, and antioxidant capacity data.

RESULTS

Uvaia fruits presented good nutritional value, with a high moisture and carbohydrate content. All fruits presented a pH value lower than 4, being classified as highly acidic, and the total soluble solids (°Brix) ranged between 2.90 and 9.80. Some plants had a higher vitamin C content, and all the plants had a high bioactive compound content (phenolic and flavonoids) and antioxidant capacity in 1,1-difenil-2-picrilhidrazil (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) assays. Hydroethanolic solution was the best extraction solvent tested when compared with water and ethanol. Using principal component analysis, it was possible to discriminate among the plants in five different groups; however, just one group was responsible for higher antioxidant compound content.

CONCLUSION

In this work, 12 native uvaia plants were discriminated by their geographical origin using a chemometric approach. Genetic improvement based on natural selection could be accomplished with some of the plants to improve the quality of uvaia pulp and to develop new cultivars. © 2019 Society of Chemical Industry.

The Impact of Organic vs. Conventional Agricultural Practices on Selected Quality Features of Eight Potato Cultivars

An organic agricultural system based on natural methods and means of production is an alternative to intensive agriculture. The available research suggests that organic crops, in comparison to the conventional ones, are richer in phenolics and other antioxidants while containing less undesirable pesticide residues and nitrates. The aim of this study was to determine concentrations of polyphenols, lutein, vitamin C, and nitrates in eight potato cultivars (Mazur, Justa, Lawenda, Lech, Tacja, Laskana, Otolia, Magnolia) grown organically and conventionally in a controlled field experiment in Poland. Significant differences between potato tubers of the tested cultivars coming from organic and conventional production were identified for the majority of parameters. Higher concentrations of nitrates and lutein were found in conventional compared to the organic tubers, while organic potatoes were, on average, richer in phenolic compounds. Among the tested cultivars, Magnolia, Otolia, and Laskara were richest in vitamin C and phenolics. Otolia and Laskara also accumulated the highest levels of nitrates. If further confirmed, these observations might be of importance for the producers and consumers, who increasingly search for foods from sustainable and well-controlled agricultural systems.

Vitamin C in Plants: From Functions to Biofortification

Vitamin C (l-ascorbic acid) is an excellent free radical scavenger, not only for its capability to donate reducing equivalents but also for the relative stability of the derived monodehydroascorbate radical. However, vitamin C is not only an antioxidant, since it is also a cofactor for numerous enzymes involved in plant and human metabolism. In humans, vitamin C takes part in various physiological processes, such as iron absorption, collagen synthesis, immune stimulation, and epigenetic regulation. Due to the functional loss of the gene coding for l-gulonolactone oxidase, humans cannot synthesize vitamin C; thus, they principally utilize plant-based foods for their needs. For this reason, increasing the vitamin C content of crops could have helpful effects on human health. To achieve this objective, exhaustive knowledge of the metabolism and functions of vitamin C in plants is needed. In this review, the multiple roles of vitamin C in plant physiology as well as the regulation of its content, through biosynthetic or recycling pathways, are analyzed. Finally, attention is paid to the strategies that have been used to increase the content of vitamin C in crops, emphasizing not only the improvement of nutritional value of the crops but also the acquisition of plant stress resistance.

Vitamin C and Neutrophil Function: Findings from Randomized Controlled Trials

Vitamin C is known to support immune function and is accumulated by neutrophils to millimolar intracellular concentrations suggesting an important role for the vitamin in these cells. In this review, the effects of vitamin C, as a mono- or multi-supplement therapy, on neutrophil function were assessed by conducting a systematic review of randomized controlled trials (RCTs). Specifically, trials which assessed neutrophil migration (chemotaxis), phagocytosis, oxidative burst, enzyme activity, or cell death (apoptosis) as primary or secondary outcomes were assessed. A systematic literature search was conducted using the Cochrane Central Register of Controlled Trials, EMBASE, Embase Classic, Joanna Briggs Institute EBP, Ovid MEDLINE®, Ovid MEDLINE® In-Process & Other Non-Indexed Citations, Ovid Nursing Database, CINAHL and PubMed database, which identified 16 eligible RCTs. Quality appraisal of the included studies was carried out using the Cochrane Risk of Bias tool. Three of the studies assessed neutrophil chemotaxis in hospitalised patients or outpatients, two of which showed improved neutrophil function following intravenous vitamin C administration. Ten RCTs assessed neutrophil phagocytosis and/or oxidative burst activity; five were exercise studies, one in smokers, one in myocardial infarction patients and three in healthy volunteers. Two of the multi-supplement studies showed a difference between the intervention and control groups: increased oxidative burst activity in athletes post-exercise and decreased oxidant generation in myocardial infarction patients. Two studies assessed neutrophil enzyme activity; one showed deceased antioxidant enzyme activity in divers and the other showed increased antioxidant enzyme activity in athletes. One final study showed decreased neutrophil apoptosis in septic surgical patients following intravenous vitamin C administration. Overall, 44% of the RCTs assessed in this review showed effects of vitamin C supplementation on neutrophil functions. However, the studies were very heterogeneous, comprising different participant cohorts and different dosing regimens. There were also a number of limitations inherent in the design of many of these RCTs. Future RCTs should incorporate prescreening of potential participants for low vitamin C status or utilize cohorts known to have low vitamin status, such as hospitalized patients, and should also comprise appropriate vitamin C dosing for the cohort under investigation.

Knowledge about dietary supplements and trust in advertising them: Development and validation of the questionnaires and preliminary results of the association between the constructs

BACKGROUND

Despite offering little overall benefit and emerging concerns about their safety, dietary supplements have become increasingly popular. Trust in advertising them may contribute to high confidence in dietary supplements in public opinion.

AIM

To develop and validate a screening questionnaire intended for the general public regarding knowledge about dietary supplements and a questionnaire on trust in advertising dietary supplements, and to identify the association between these constructs.

MATERIALS AND METHODS

The development and validation of the measures was overseen by the panels of experts. The conceptual frameworks of the constructs were scientifically well grounded. A set of semi-structured interviews and anonymous web-based surveys was performed. The final questionnaire was applied to 220 non-medically educated people and 121 medically educated people.

RESULTS

A 17-item questionnaire on knowledge about dietary supplements and eight-item questionnaire on trust in advertising dietary supplements were developed. The measures presented satisfactory proof of validity, however, the psychometric properties of the questionnaire on knowledge were modest. Both the knowledge about dietary supplements in the study group and trust in advertising them were low. A significant negative relationship was found between knowledge about dietary supplements and trust in advertising them among the general public (Pearson's r = -0.42, 95%CI: -0.52 to -0.30, p<0.0001). This association was especially pronounced in people who reported not taking dietary supplements (Pearson's r = -0.61, 95%CI: -0.76 to -0.39, p<0.0001).

CONCLUSIONS

The extensive advertising of dietary supplements appears to be in conflict with promoting evidence-based knowledge about them, which raises substantial concerns for the public health. The results of the study are only preliminary and require further confirmation and exploration.

Pigments and vitamins from plants as functional ingredients: Current trends and perspectives

The food manufacturing industry has increasingly focused in the development of wholesome and safer products, including certified labeled "super foods," "healthy foods" and "functional foods," which are currently under great demand worldwide. Plant pigments and vitamins are amidst the most common additives incorporated to foodstuff, not only for improving their nutritional status but also for coloration, preservation, and even therapeutic purposes. The recovery of pigments from agro industrial wastes using green emerging approaches is a current trend and clearly the best alternative to ensure their sustainable obtainment and make these ingredients more popular, although still full of challenging aspects. Stability and bioavailability limitations of these active molecules in food matrices have been increasingly studied, and a number of methods have been proposed to minimize these issues, among which the incorporation of a co-pigment, exclusion of O₂ during processing and storage, and above all, microencapsulation and nanoencapsulation techniques. The most recent advances and challenges in the application of natural pigments and vitamins in functional foods, considering only reports of the last 5 years, were the focus of this chapter.

Vitamin C Content in Fruits: Biosynthesis and Regulation

Throughout evolution, a number of animals including humans have lost the ability to synthesize ascorbic acid (ascorbate, vitamin C), an essential molecule in the physiology of animals and plants. In addition to its main role as an antioxidant and cofactor in redox reactions, recent reports have shown an important role of ascorbate in the activation of epigenetic mechanisms controlling cell differentiation, dysregulation of which can lead to the development of certain types of cancer. Although fruits and vegetables constitute the main source of ascorbate in the human diet, rising its content has not been a major breeding goal, despite the large inter- and intraspecific variation in ascorbate content in fruit crops. Nowadays, there is an increasing interest to boost ascorbate content, not only to improve fruit quality but also to generate crops with elevated stress tolerance. Several attempts to increase ascorbate in fruits have achieved fairly good results but, in some cases, detrimental effects in fruit development also occur, likely due to the interaction between the biosynthesis of ascorbate and components of the cell wall. Plants synthesize ascorbate de novo mainly through the Smirnoff-Wheeler pathway, the dominant pathway in photosynthetic tissues. Two intermediates of the Smirnoff-Wheeler pathway, GDP-D-mannose and GDP-L-galactose, are also precursors of the non-cellulosic components of the plant cell wall. Therefore, a better understanding of ascorbate biosynthesis and regulation is essential for generation of improved fruits without developmental side effects. This is likely to involve a yet unknown tight regulation enabling plant growth and development, without impairing the cell redox state modulated by ascorbate pool. In certain fruits and developmental conditions, an alternative pathway from D-galacturonate might be also relevant. We here review the regulation of ascorbate synthesis, its close connection with the cell wall, as well as different strategies to increase its content in plants, with a special focus on fruits.

Co-Loading of Ascorbic Acid and Tocopherol in Eudragit-Nutriosomes to Counteract Intestinal Oxidative Stress

The present study aimed at developing a new vesicular formulation capable of promoting the protective effect of ascorbic acid and tocopherol against intestinal oxidative stress damage, and their efficacy in intestinal wound healing upon oral administration. A pH-dependent copolymer (Eudragit^® L100), a water-soluble prebiotic fibre (Nutriose^® FM06), a phospholipid mixture (Lipoid S75), and two natural antioxidants (ascorbic acid and tocopherol) were combined to fabricate eudragit-nutriosomes by a simple, solvent-free procedure. The vesicles were spherical and oligolamellar, with some multicompartment structures in Eudragit-nutriosomes, small in size (~100 nm), with highly negative zeta potential. The effect of Eudragit^® and Nutriose^® on the stability on storage and in simulated gastrointestinal fluids were confirmed by the Turbiscan^® technology and in vitro studies, respectively. Eudragit-nutriosomes exhibited a protective effect against H₂O₂-induced oxidative stress, and a proliferative effect in Caco-2 cells, as they provided the closure of the scratched area after 96 h of incubation.