Authors' perspective: What is the optimum intake of vitamin C in humans?

Micronutrients and the Periodontium: A Narrative Review

This is a comprehensive narrative assessment of micronutrient relevance for periodontal health. The periodontium is a crucial and intricate structure that supports the tooth within the alveolar bone. Composed of four tissues with distinct embryological origins- the alveolar bone, cementum, gingiva, and periodontal ligament - the periodontium plays a fundamental role in maintaining dento-alveolar function and homeostasis. Periodontitis is gaining attention due to its widespread occurrence worldwide. This inflammatory condition disrupts the balance between the host immune response and microbial virulence factors. Connective tissue production and host defenses require proteins for periodontal health. Vegetable proteins support periodontal health by promoting tissue repair and immune function, while excessive dietary fats can exacerbate inflammation and increase the risk of periodontal disease (PD). Inflammation is further compounded due to dietary animal fats, which contribute to the risk of PD. Omega-3 fatty acids are well-known for their anti-inflammatory effects, which help reduce periodontal inflammation. Adequate intake of essential minerals and vitamins is required for maintaining periodontal health. Vitamins K, D, and A are crucial in maintaining oral epithelial integrity, facilitating bone development, and supporting overall tissue maintenance. Inadequate calcium (Ca²⁺) and magnesium (Mg²⁺) levels have been associated with severe PD. Antioxidants such as vitamin C help alleviate inflammation in periodontal tissues. As recognized by dental professionals, nutritional status plays a considerable role in an individual's risk of developing PD.

The physiological functions of ascorbate in the development of cancer

The metabolite ascorbate (vitamin C) is synthesized endogenously in most animals or, in humans and some other species, obtained from the diet. Its role in cancer development is controversial. Addition of ascorbate to cultured cells or high-dose administration in animals can inhibit growth of many cancers, but most of these effects are caused by non-physiological biochemical activities. Few experiments have tested the physiological roles of ascorbate in cancer development by depleting it in physiological settings. Ascorbate depletion inhibits the activity of ten-eleven translocation (TET) enzymes in hematopoietic and leukemia cells and accelerates myeloid leukemia development. Many clinical trials have tested ascorbate supplementation in cancers and shown little or no evidence that it has a beneficial role. I propose that depletion experiments are needed to define the cancers in which ascorbate has a physiological role, establish its cellular and molecular targets, and provide a rationale for clinical trials.

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.

Combination of inorganic nitrate and vitamin C prevents collagen-induced arthritis in rats by inhibiting pyroptosis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease characterized by synovial inflammation, cartilage damage, and bone loss. Although effective treatments are currently lacking, early interventions hold promise for alleviating RA symptoms. Inorganic nitrates and vitamin C (VC) are essential bioactive substances abundant in fruits and vegetables. Notably, nitrates and VC exhibit synergistic effects in a series of physiological and pathological conditions. In this study, we aim to examine the combination of nitrate and VC for preventing RA in a collagen-induced arthritis (CIA) rat model. Nitrate partly reduced foot swelling and arthritis scores and was more effective when combined with VC. Histopathological and radiological analyses revealed that nitrate + VC treatment alleviated synovial hyperplasia and bone loss. Additionally, nitrate + VC lowered the levels of TNF-α and IL-1β in serum as well as synovial tissue, decreased the expression of NF-κB and reduced the number of macrophages in synovial tissue. Compared to the CIA group, nitrate + VC decreased the levels of NLRP3 and GSDMD in macrophages, thus inhibiting pyroptosis. According to in vitro experiments, nitrate inhibited the activation of the NLRP3/caspase-1/GSDMD pathway in macrophages by conversion into nitrite. VC reduced the expression and phosphorylation of NF-κB in macrophages and thus reduced the expression levels of TNF-α and IL-1β. Therefore, nitrate/nitrite and VC may exert synergistic effects by blocking the interaction between NF-κB and NLRP3, further alleviating the inflammation and pyroptosis of macrophages, which provides a new strategy for RA prevention.

A Comprehensive Evaluation of Nutritional Quality and Antioxidant Capacity of Different Chinese Eggplant Varieties Based on Multivariate Statistical Analysis

Free amino acids, polyphenols, and anthocyanins were quantified in 30 Chinese eggplant varieties. Moreover, antioxidant capacity characterizations including 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric-reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) were performed. The total amino acid content of the 30 eggplant varieties ranged from 15,267.19 to 26,827.4 mg kg-1 DW. The most abundant amino acids were glutamic acid, arginine, and aspartic acid. The coefficients of variation (CV) for the 20 amino acids ranged from 5.85 to 106.14%, of which 18 free amino acids had CVs > 20%. Total polyphenol and anthocyanin contents ranged from 17,097.41 to 39,474.98 µg g-1 DW and 5.28 to 978.32 µg g-1 DW, respectively. The variability of both polyphenol and anthocyanin components was >20%, with a range of 21.25-102.89%. Chlorogenic acid was the most abundant polyphenol. The total anthocyanin content of purple eggplant varieties was significantly higher than green varieties. Of the purple eggplant varieties, V28 ('E150725'), V30 ('1952'), and V16 ('Weichangqie101') had significantly higher total anthocyanins than the other eggplant varieties. DPPH, ABTS, and FRAP assays showed peaks at V3 ('Zhengqie924'). Pearson's correlation analysis revealed that polyphenols and anthocyanins were the main contributors to the antioxidant capacity of eggplants. A classification model with principal component analysis classified 30 Chinese eggplant varieties into two categories: high and low antioxidant capacities. The top five Chinese eggplant varieties ranked for amino acids, antioxidants, and antioxidant capacity were V29 ('Zhengqie903'), V24 ('Zhengqie78'), V1 ('1871'), V3 ('Zhengqie924'), and V28 ('E150725'). These findings provide theoretical basis for high-quality breeding and producer/consumer selection of eggplants.

The Impact of Nutritional Components on Periodontal Health: A Literature Review

Periodontitis is a chronic inflammatory disease driven by the accumulation of bacterial plaque and the host's immune response, leading to the destruction of periodontal tissues. Nutrition, particularly the intake of micronutrients with anti-inflammatory and antioxidant properties, plays a crucial role in maintaining periodontal health. This review explores the impact of various micronutrients-vitamins (A, B, C, D, E), minerals (calcium, iron, zinc, potassium, copper, manganese, selenium), and omega-3 fatty acids-on periodontal disease prevention and management. Deficiencies in these nutrients can exacerbate periodontal tissue damage by impairing immune responses, promoting oxidative stress, and reducing bone and tissue regeneration capabilities. While certain populations may be more vulnerable to these deficiencies, such as those following Western diets or living in low- and middle-income countries, even in developed nations, suboptimal nutrient intake is associated with worse periodontal outcomes. Although some studies suggest that supplementation of specific micronutrients may benefit periodontal therapy, the evidence remains inconclusive, necessitating further randomized clinical trials. This review underscores the importance of considering nutritional guidance in periodontal treatment protocols and highlights the need for tailored recommendations based on recent findings.

Vitamin C intake and osteoarthritis: findings of NHANES 2003-2018 and Mendelian randomization study

Background

The role of vitamin C in osteoarthritis (OA) is still a subject of debate. Our aim was to combine the National Health and Nutrition Examination Survey (NHANES) and MR studies to explore the relationship between vitamin C intake and OA.

Methods

Clinical information on participants during NHANES 2003-2018 was collected and the relationship between vitamin C intake and OA risk was assessed using logistic regression modelling. In MR analyses, three methods were used to explore the causality of vitamin C intake with OA. Sensitivity analysis to verify the stability of the MR study.

Results

The cross-sectional study included a total of 31,527 participants, categorizing them into low (<30.2 mg), medium (30.2-93.0 mg) and high (>93.0 mg) level groups based on their vitamin C intake levels. Logistic regression models showed that vitamin C intake was not associated with OA risk (p > 0.05). Inverse-variance weighted (IVW) method of MR study showed no causality between vitamin C intake and OA (OR = 0.993, 95% CI: 0.901 ~ 1.095, p = 0.882). Sensitivity analysis indicated that the MR study was reliable.

Conclusion

Our cross-sectional and MR studies showed that vitamin C intake was not associated with OA risk. More researches are needed in the future to investigate the link between vitamin C and OA.

Cardiovascular adaptations and pathological changes induced by spaceflight: from cellular mechanisms to organ-level impacts

The advancement in extraterrestrial exploration has highlighted the crucial need for studying how the human cardiovascular system adapts to space conditions. Human development occurs under the influence of gravity, shielded from space radiation by Earth's magnetic field, and within an environment characterized by 24-hour day-night cycles resulting from Earth's rotation, thus deviating from these conditions necessitates adaptive responses for survival. With upcoming manned lunar and Martian missions approaching rapidly, it is essential to understand the impact of various stressors induced by outer-space environments on cardiovascular health. This comprehensive review integrates insights from both actual space missions and simulated experiments on Earth, to analyze how microgravity, space radiation, and disrupted circadian affect cardiovascular well-being. Prolonged exposure to microgravity induces myocardial atrophy and endothelial dysfunction, which may be exacerbated by space radiation. Mitochondrial dysfunction and oxidative stress emerge as key underlying mechanisms along with disturbances in ion channel perturbations, cytoskeletal damage, and myofibril changes. Disruptions in circadian rhythms caused by factors such as microgravity, light exposure, and irregular work schedules, could further exacerbate cardiovascular issues. However, current research tends to predominantly focus on disruptions in the core clock gene, overlooking the multifactorial nature of circadian rhythm disturbances in space. Future space missions should prioritize targeted prevention strategies and early detection methods for identifying cardiovascular risks, to preserve astronaut health and ensure mission success.

Dietary Vitamin C Intake and Changes in Frequency, Severity, and Location of Pain in Older Adults

BACKGROUND

Oral vitamin C supplementation has been associated with lower risk of chronic postsurgical pain. However, the effect of dietary vitamin C on pain in a nonsurgical setting is unknown. We aimed to investigate the association between dietary vitamin C intake and changes over time in chronic pain and its characteristics in community-dwelling adults aged 60 + years.

METHODS

We pooled data from participants of the Seniors-ENRICA-1 (n = 864) and Seniors-ENRICA-2 (n = 862) cohorts who reported pain at baseline or at follow up. Habitual diet was assessed with a face-to-face diet history and dietary vitamin C intake was estimated using standard food composition tables. Pain changes over time were the difference between scores at baseline and follow up obtained from a pain scale that considered the frequency, severity, and number of pain locations. Multivariable-adjusted relative risk ratios were obtained using multinomial logistic regression.

RESULTS

After a median follow-up of 2.6 years, pain worsened for 696 (40.3%) participants, improved for 734 (42.5%), and did not change for 296 (17.2%). Compared with the lowest tertile of energy-adjusted vitamin C intake, those in the highest tertile had a higher likelihood of overall pain improvement (RRR 1.61 [95% confidence interval 1.07-2.41], p-trend .02). Higher vitamin C intake was also associated with lower pain frequency (1.57 [1.00-2.47], p-trend = .05) and number of pain locations (1.75 [1.13-2.70], p-trend = .01).

CONCLUSIONS

Higher dietary vitamin C intake was associated with improvement of pain and with lower pain frequency and number of pain locations in older adults. Nutritional interventions to increase dietary vitamin C intake with the aim of improving pain management require clinical testing.

Micronutrient Status and Breast Cancer: A Narrative Review

Breast cancer is one of the most common cancers worldwide, at the same time being one of the most prevalent causes of women's death. Many factors such as alcohol, weight fluctuations, or hormonal replacement therapy can potentially contribute to breast cancer development and progression. Another important factor in breast cancer onset includes micronutrient status. In this narrative review, we analyzed 23 micronutrients and their possible influence on breast cancer onset and progression. Further, the aim of this study was to investigate the impact of micronutrient status on the prevention of breast cancer and its possible influence on various therapeutic pathways. We researched meta-analyses, systemic and narrative reviews, retrospective studies, as well as original studies on human and animal models. The results of these studies indicate a possible correlation between the different levels of micronutrients and a decreased risk of breast cancer as well as a better survival rate. However, further studies are necessary to establish adequate doses of supplementation of the chosen micronutrients and the exact mechanisms of micronutrient impact on breast cancer therapy.

Vitamin C, vitamin E, β-carotene and risk of Parkinson's disease: a systematic review and dose-response meta-analysis of observational studies

OBJECTIVE

This study aimed to explore the relationship between the intake of vitamin C, vitamin E and β-carotene, and the risk of Parkinson's disease (PD).

METHODS

Web of Science, Embase, PubMed, Cochrane library, CNKI, and WanFang databases were searched from inception to 29 August 2022 for observational studies reporting the odds ratios (ORs) or relative risks (RRs) or hazard ratios (HRs) and 95% confidence intervals (CIs) of PD by Vitamin C/Vitamin E/β-carotene intake. Random-effects models, publication bias assessment, subgroup, sensitivity and dose-response analyses were performed, using.Stata version 12.0.

RESULTS

A total of 13 studies were included. There was no significant association between high-dose vitamin C intake and the risk of PD compared with low-dose vitamin C intake (RR = 0.98, 95%CI:0.89,1.08). Compared with low-dose intake, high-dose intake of vitamin E can prevent the risk of PD (RR = 0.87, 95%CI:0.77,0.99). Compared with lower β-carotene intake, there was a borderline non-significant correlation between higher intake and PD risk (RR = 0.91, 95%CI:0.82,1.01), and high dose β-carotene intake was found to be associated with a lower risk of PD in women (RR = 0.78, 95%CI:0.64,0.96).

CONCLUSION

This study shows that vitamin E intake can reduce the risk of PD and play a preventive role.

Can vitamins improve periodontal wound healing/regeneration?

Periodontitis is a complex inflammatory disorder of the tooth supporting structures, associated with microbial dysbiosis, and linked to a number if systemic conditions. Untreated it can result in an irreversible damage to the periodontal structures and eventually teeth loss. Regeneration of the lost periodontium requires an orchestration of a number of biological events on cellular and molecular level. In this context, a set of vitamins have been advocated, relying their beneficial physiological effects, to endorse the biological regenerative events of the periodontium on cellular and molecular levels. The aim of the present article is to elaborate on the question whether or not vitamins improve wound healing/regeneration, summarizing the current evidence from in vitro, animal and clinical studies, thereby shedding light on the knowledge gap in this field and highlighting future research needs. Although the present review demonstrates the current heterogeneity in the available evidence and knowledge gaps, findings suggest that vitamins, especially A, B, E, and CoQ10, as well as vitamin combinations, could exert positive attributes on the periodontal outcomes in adjunct to surgical or nonsurgical periodontal therapy.

Possibilities of valorization of Gnetum spp leaves in modern gastronomy: Production and characterization of new vegetable tarts and salads

Gnetum spp is a green creeper plant abundantly found in the Central African forests. Their leaves are eaten as vegetable by inhabitants. In order to valorize this vegetable in modern gastronomy, a survey was carried out in three towns of Cameroon to evaluate its importance in the feeding habits. The leaves were also sliced in two different forms, precooked, spin-dried and used for Gnetum tarts and salads production. 50, 100 and 150 g of thin sliced precooked leaves were used to prepare three salads and three tarts, keeping the other ingredients constant. Three additional tarts were prepared similarly using thinnest sliced precooked leaves. The final products were analyzed in terms of physiochemical, nutritional and sensorial properties. More than 96.9% of people investigated eat Gnetum leafy vegetables at least once per month. The survey study indicates that the transformation of Gnetum is mostly done by people within the age of 20 to 40 years old. Results of the physicochemical analyses showed that the total protein, lipid and carbohydrate contents increased in general with the increasing of the Gnetum leaf quantities used for preparation. The crude fiber contents of salads and tarts ranged from 52.00 ± 0.68 to 62.66 ± 1.26 and 29.33 ± 0.67 to 33.66 ± 0.47 g/100 g DW respectively. They were positively correlated with the quantity of Gnetum leaves used. The total phenolic contents, also increased significantly (p < 0.05) with the quantity of Gnetum leaves, from 182.45 ± 1.69 to 493.52 ± 2.10 mg/100 g DW for the salad and from 86.69 ± 4.08 to 283.21 ± 6.79 mg/100 g DW for the tart. The calculated energy density of tarts and salads permitted to classify these food products as low and high energy density foods respectively. The nutritional densities of produced tarts oscillated from 0.27 to 0.3 and that of salads from 0.58 to 0.71. With their nutritional values and the significant amount of fibers, Gnetum tarts and salads could be good new recipes to valorize the Gnetum leafy vegetables.

Is vitamin C a booster of the effects of dietary nitrate on endothelial function? Physiologic rationale and implications for research

Endothelial dysfunction (ED) is an early marker of vascular damage linked to the loss of integrity of the endothelial lining and represents a key step in the pathogenesis of atherosclerosis and cardiovascular diseases (CVDs). ED may be reversible, hence the development and testing of effective early interventions could be beneficial for the prevention and treatment of CVDs. Recent studies have demonstrated that the consumption of dietary nitrate (NO₃^-), an inorganic anion that serves as a substrate for the gas transmitter nitric oxide (NO), can lower blood pressure, improve endothelial function and, in observational studies, reduce the risk for CVD. We hypothesize that the co-consumption of NO₃^- with vitamin C, which is a potent antioxidant, could enhance the "yield" of NO produced from a given NO₃^- dose byThis could translate into greater NO-dependent effects on endothelial function (EF) and overall vascular health (than may be experienced with NO₃^- supplementation alone). This review presents evidence to suggest that the combination of vitamin C and dietary nitrate could represent a promising and effective approach to improve EF and reduce CVD risk, and discuss opportunities for future research.

The association between vitamin C dietary intake and its serum levels with anthropometric indices: A systematic review and meta-analysis

BACKGROUND

studies showed inflammatory background of overweight and obesity. Prevalence of weight disorders has dramatically increased over the past few decades. Vitamin C is an antioxidant and may be associated with weight disorders. This study aims to systematically review the relationship between dietary and serum vitamin C levels with anthropometric indices.

METHODS

A systematic search was conducted in Medline database (PubMed), Scopus, Embase, Web of Science, Cochrane library and Google Scholar up to the end of August 2021. All observational studies that assessed the relationship between dietary or circulating vitamin C levels and body mass index (BMI) and waist circumference (WC) on adults were included. The quality of included studies was assessed using the National Institute of Health quality assessment tool.

RESULTS

Among 11,689 studies, 47 and 37 articles were included in the systematic review and meta-analysis, respectively. There was an inverse significant correlation between WC and serum vitamin C levels (r = -0.28, 95% CI: -0.35,-0.21, I² = 14.2%) and between BMI and serum vitamin C levels (r = -0.17, 95% CI: -0.25, -0.09, I² = 72.8%). Higher vitamin C consumption was significantly associated with lower BMI. There were no significant differences in serum vitamin C levels between normal-weight and overweight subjects, but serum vitamin C levels were significantly higher in obese subjects in comparison with normal-weight subjects.

CONCLUSION

Results showed that both dietary and serum vitamin C levels were inversely associated with BMI and WC. More well-designed clinical trials are needed to assess the effect of vitamin C supplementation in prevention and treatment of obesity.

Potential Properties of Natural Nutraceuticals and Antioxidants in Age-Related Eye Disorders

Eye health is crucial, and the onset of diseases can reduce vision and affect the quality of life of patients. The main causes of progressive and irreversible vision loss include various pathologies, such as cataracts, ocular atrophy, corneal opacity, age-related macular degeneration, uncorrected refractive error, posterior capsular opacification, uveitis, glaucoma, diabetic retinopathy, retinal detachment, undetermined disease and other disorders involving oxidative stress and inflammation. The eyes are constantly exposed to the external environment and, for this reason, must be protected from damage from the outside. Many drugs, including cortisonics and antinflammatory drugs have widely been used to counteract eye disorders. However, recent advances have been obtained via supplementation with natural antioxidants and nutraceuticals for patients. In particular, evidence has accumulated that polyphenols (mostly deriving from Citrus Bergamia) represent a reliable source of antioxidants able to counteract oxidative stress accompanying early stages of eye diseases. Luteolin in particular has been found to protect photoreceptors, thereby improving vision in many disease states. Moreover, a consistent anti-inflammatory response was found to occur when curcumin is used alone or in combination with other nutraceuticals. Additionally, Coenzyme Q10 has been demonstrated to produce a consistent effect in reducing ocular pressure, thereby leading to protection in patients undergoing glaucoma. Finally, both grape seed extract, rich in anthocyanosides, and polynsatured fatty acids seem to contribute to the prevention of retinal disorders. Thus, a combination of nutraceuticals and antioxidants may represent the right solution for a multi-action activity in eye protection, in association with current drug therapies, and this will be of potential interest in early stages of eye disorders.

Effect of Solid-State Fermentation on Vitamin C, Photosynthetic Pigments and Sugars in Willow Herb (Chamerion angustifolium (L.) Holub) Leaves

The goal of this investigation was to establish the impact of solid-state fermentation of different durations on the quantitative changes of vitamin C, sugars and photosynthetic pigments in the leaves of willow herbs. The tested leaves were fermented using two solid-state fermentation methods (aerobic and anaerobic) for different time periods (unfermented and fermented for 24, 48 and 72 h). The quantitative and qualitative composition of chlorophylls, carotenoids, sugars and vitamin C were determined using high performance liquid chromatography (HPLC) with UV detectors. Results indicated that aerobic and anaerobic solid-state fermentation significantly decreased the contents of vitamin C, dehydroascorbic and L-ascorbic acids in leaves compared with the unfermented leaves. The contents of total chlorophyll and chlorophyll a were the highest in unfermented leaves and after 24 h of aerobic solid-state fermentation. The maximum content of total carotenoids in leaves were after 48 and 72 h of aerobic solid-state fermentation (149.31 mg 100 g^-1 and 151.51 mg 100 g^-1, respectively). The application of anaerobic solid-state fermentation resulted in significant increase in the content of total sugars, fructose and glucose in investigated samples. In conclusion, optimization of fermentation parameters allows increasing the content of sugars and photosynthetic pigments in leaves of willow herbs.

Vitamin C Deficiency Exacerbates Dysfunction of Atherosclerotic Coronary Arteries in Guinea Pigs Fed a High-Fat Diet

Vitamin C (vitC) deficiency has been associated with an increased risk of cardiovascular disease; while several putative mechanistic links have been proposed, functional evidence supporting a causal relationship is scarce. In this study, we investigated how vitC deficiency affects coronary artery vasomotor function and the development of coronary atherosclerotic plaques in guinea pigs subjected to chronic dyslipidemia by a high-fat diet regime. Female Hartley guinea pigs were fed either a control (low-fat diet and sufficient vitC) (N = 8) or a high-fat diet with either sufficient (N = 8) or deficient (N = 10) vitC for 32 weeks. Guinea pigs subjected to the high-fat diet developed significant atherosclerotic plaques in their coronary arteries, with no quantitative effect of vitC deficiency. In isolated coronary arteries, vasomotor responses to potassium, carbachol, nitric oxide, or bradykinin were studied in a wire myograph. Carbachol, bradykinin, and nitric oxide mediated relaxation in the coronary arteries of the control group. While vasorelaxation to carbachol and nitric oxide was preserved in the two high-fat diet groups, bradykinin-induced vasorelaxation was abolished. Interestingly, bradykinin induced a significant contraction in coronary arteries from vitC-deficient guinea pigs (p < 0.05). The bradykinin-induced contraction was unaffected by L-NAME but significantly inhibited by both indomethacin and vitC, suggesting that, during vitC deficiency, increased release of arachidonic acid metabolites and vascular oxidative stress are involved in the constrictor effects mediated by bradykinin. In conclusion, the present study shows supporting evidence that poor vitC status negatively affects coronary artery function.

Differences in the Pro/Antioxidative Status and Cellular Stress Response in Elderly Women after 6 Weeks of Exercise Training Supported by 1000 mg of Vitamin C Supplementation

Vitamin C supplementation and exercise influence pro/antioxidative status and the cellular stress response. We tested the effects of exercise training for 6 weeks, supported by 1000 mg of vitamin C supplementation in elderly women. Thirty-six women were divided into two groups: a control group (CON) (n = 18, age 69.4 ± 6.4 years, 70.4 ±10.4 kg body mass) and a supplemented group (SUPP) (n = 18, aged 67.7 ± 5.6 years, body mass 71.46 ± 5.39 kg). Blood samples were taken twice (at baseline and 24 h after the whole period of training), in order to determine vitamin C concentration, the total oxidative status/capacity (TOS/TOC), total antioxidant status/capacity (TAS/TAC), and gene expression associated with cellular stress response: encoding heat shock factor (HSF1), heat shock protein 70 (HSPA1A), heat shock protein 27 (HSPB1), and tumor necrosis factor alpha (TNF-α). We observed a significant increase in TOS/TOC, TAS/TAC, and prooxidant/antioxidant balance in the SUPP group. There was a significant decrease in HSPA1A in the CON group and a different tendency in the expression of HSF1 and TNF-α between groups. In conclusion, vitamin C supplementation enhanced the pro-oxidation in elderly women with a normal plasma vitamin C concentration and influenced minor changes in training adaptation gene expression.

A Comprehensive Evaluation of Effects on Water-Level Deficits on Tomato Polyphenol Composition, Nutritional Quality and Antioxidant Capacity

Tomatoes have high nutritional value and abundant bioactive compounds. Moderate water deficit irrigation alters metabolic levels of fruits, improving composition and quality. We investigated the effects of water deficit (T1, T2, T3, and T4) treatments and adequate irrigation (CK) on tomato polyphenol composition, antioxidant capacity, and nutritional quality. Compared with CK, the total flavonoid content increased by 33.66% and 44.73% in T1 and T2, and total phenols increased by 57.64%, 72.22%, and 55.78% in T1, T2, and T3, respectively. The T2 treatment significantly enhanced antioxidant’ capacities (ABTS, HSRA, FRAP, and DPPH). There were multiple groups of significant or extremely significant positive correlations between polyphenol components and antioxidant activity. For polyphenols and antioxidant capacity, the classification models divided the treatments: CK and T4 and T1−T3. The contents of soluble solids, soluble protein, vitamin C, and soluble sugar of the treatment groups were higher than those of CK. The soluble sugar positively correlated with sugar−acid ratios. In the PCA-based model, T3 in the first quadrant indicated the best treatment in terms of nutritional quality. Overall, comprehensive rankings using principal component analysis (PCA) revealed T2 > T1 > T3 > T4 > CK. Therefore, the T2 treatment is a suitable for improving quality and antioxidant capacity. This study provides novel insights into improving water-use efficiency and quality in the context of water scarcity worldwide.

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.

Vitamin C Intake and Ischemic Stroke

Vitamin C is an essential micronutrient with important antioxidant properties. Ischemic stroke is a major public health problem worldwide. Extensive evidence demonstrates that vitamin C has protective effects against cardiovascular disease, and there is a close relationship between vitamin C intake and ischemic stroke risk. Based on the evidence, we conducted this umbrella review to clarify the relationship between vitamin C intake and ischemic stroke risk from four perspectives: cellular mechanisms, animal experiments, clinical trials, and cohort studies.

A Narrative Review on Pediatric Scurvy: The Last Twenty Years

Scurvy is a well-known clinical condition caused by vitamin C deficiency. Although considered a rare disease in high-income countries, it has been recently increasingly reported in children, especially in those with abnormal dietary habits, mental or physical disabilities. We performed an extensive review of the literature analyzing studies published in the last 20 years focusing on clinical features, differential diagnosis and diagnostic delay. Fifteen articles were selected, collectively reporting a total of 166 children. Because of the wide clinical spectrum (musculoskeletal complaints and/or mucocutaneous lesions or systemic symptoms), scurvy can mimic several conditions, including autoimmune diseases, infections, and neoplasia. In addition, frequent findings such as normal nutritional status, anemia or elevated inflammatory markers may guide clinicians towards the abovementioned misdiagnoses. Scurvy should be considered in patients presenting with musculoskeletal complaints, not only in those with risk factors but also in healthy children. A focused dietary history and a careful physical examination, assessing other signs of vitamin C deficiency, are mandatory in these patients. When suspected, the dosage of serum vitamin C is the diagnostic gold standard; furthermore, imaging studies, performed by an expert radiologist, can reveal the typical features of scurvy. Only early diagnosis can avoid unnecessary investigations and potentially fatal complications of the disease.

The Epigenetic Role of Vitamin C in Neurodevelopment

The maternal diet during pregnancy is a key determinant of offspring health. Early studies have linked poor maternal nutrition during gestation with a propensity for the development of chronic conditions in offspring. These conditions include cardiovascular disease, type 2 diabetes and even compromised mental health. While multiple factors may contribute to these outcomes, disturbed epigenetic programming during early development is one potential biological mechanism. The epigenome is programmed primarily in utero, and during this time, the developing fetus is highly susceptible to environmental factors such as nutritional insults. During neurodevelopment, epigenetic programming coordinates the formation of primitive central nervous system structures, neurogenesis, and neuroplasticity. Dysregulated epigenetic programming has been implicated in the aetiology of several neurodevelopmental disorders such as Tatton-Brown-Rahman syndrome. Accordingly, there is great interest in determining how maternal nutrient availability in pregnancy might affect the epigenetic status of offspring, and how such influences may present phenotypically. In recent years, a number of epigenetic enzymes that are active during embryonic development have been found to require vitamin C as a cofactor. These enzymes include the ten-eleven translocation methylcytosine dioxygenases (TETs) and the Jumonji C domain-containing histone lysine demethylases that catalyse the oxidative removal of methyl groups on cytosines and histone lysine residues, respectively. These enzymes are integral to epigenetic regulation and have fundamental roles in cellular differentiation, the maintenance of pluripotency and development. The dependence of these enzymes on vitamin C for optimal catalytic activity illustrates a potentially critical contribution of the nutrient during mammalian development. These insights also highlight a potential risk associated with vitamin C insufficiency during pregnancy. The link between vitamin C insufficiency and development is particularly apparent in the context of neurodevelopment and high vitamin C concentrations in the brain are indicative of important functional requirements in this organ. Accordingly, this review considers the evidence for the potential impact of maternal vitamin C status on neurodevelopmental epigenetics.

The Role of Vitamin Deficiency in Liver Disease: To Supplement or Not Supplement?

Over the past few years, growing interest has been shown for the impact of dietary requirements and nutritional factors on chronic diseases. As a result, nutritional programs have been reinforced by public health policies. The precise role of micronutrients in chronic liver disease is currently receiving particular attention since abnormalities in vitamin levels are often detected. At present, treatment programs are focused on correcting vitamin deficiencies, which are frequently correlated to higher rates of comorbidities with poor outcomes. The literature reviewed here indicates that liver diseases are often related to vitamin disorders, due to both liver impairment and abnormal intake. More specific knowledge about the role of vitamins in liver disease is currently emerging from various results and recent evidence. The most significant benefits in this area may be observed when improved vitamin intake is combined with a pharmacological treatment that may also affect the progression of the liver disease, especially in the case of liver tumors. However, further studies are needed.

Antioxidant and Bone; Protect Your Future: A Brief Review

The global campaign of osteoporosis has been organized by the International Osteoporosis Foundation (IOF) and them introducing World Osteoporosis Day (WOD) in 1997. The day is celebrated on October 20^th each year and aimed to improve the awareness of the population about disease prevention. We present some aspects of bone health and the prevention of osteoporosis related to the use of vitamins. The presenting mini-review covers a variety of sources including PubMed, Embase, Scopus, and directory of open access journals (DOAJ) from 10 years ago (Oct 2009 to Oct 2019) for recent developments in the prevention of bone loss. The search was performed by using combinations of the following keywords and or their equivalents; osteoporosis, bones health, bone loss, and vitamin to find related articles about the prevention of osteoporosis by nutritional factors. The factors affecting bone are various and could begin from fetal periods to the end of life. Some of them are not changeable including age, and genetic; however, it is possible to modify some others such as poor nutrition and vitamin deficiency. Beyond vitamin D deficiency, consumption of other vitamins also is beneficial to maintain bone health. By considering the nutritional factors especially vitamins that affect bones, it is possible to have stronger bones to enjoy life in the elderly and protect your future.

Insufficient Vitamin C Levels among Adults in the United States: Results from the NHANES Surveys, 2003-2006

Vitamin C, well-established in immune function and a key factor in epigenetic inflammatory modifications, is only obtained through consistent dietary intake. Identifying individuals at risk for Vitamin C insufficiency may guide prevention and treatment, however, national surveillance has not been evaluated in the United States since 2006. A descriptive, cross-sectional secondary analysis was performed utilizing data from the 2003-2006 National Health and Nutrition Examination Surveys (NHANES) assessing non-institutionalized adults. Five categories of plasma Vitamin C were delineated: deficiency (<11 μmol/L), hypovitaminosis (11-23 μmol/L), inadequate (23-49 μmol/L), adequate (50-69 μmol/L), and saturating (≥70 μmol/L). Results indicated 41.8% of the population possessed insufficient levels (deficiency, hypovitaminosis, and inadequate) of Vitamin C. Males, adults aged 20-59, Black and Mexican Americans, smokers, individuals with increased BMI, middle and high poverty to income ratio and food insecurity were significantly associated with insufficient Vitamin C plasma levels. Plasma Vitamin C levels reveal a large proportion of the population still at risk for inflammatory driven disease with little to no symptoms of Vitamin C hypovitaminosis. Recognition and regulation of the health impact of Vitamin C support the goal of Nutrition and Healthy Eating as part of the Healthy People 2030.

Higher doses of ascorbic acid may have the potential to promote nutrient delivery via intestinal paracellular absorption

The significance of plasma ascorbic acid (AA) is underscored by its enzymatic and antioxidant properties as well as involvement in many aspects of health including the synthesis of biomolecules during acute illness, trauma and chronic health conditions. Dietary intake supports maintenance of optimal levels with supplementation at higher doses more likely pursued. Transient increased intestinal paracellular permeability following high dose AA may be utilised to enhance delivery of other micronutrients across the intestinal lumen. The potential mechanism following dietary intake however needs further study but may provide an avenue to increase small intestinal nutrient co transport and absorption, including in acute and chronic illness.

The role of vitamin C in epigenetic cancer therapy

The role of vitamin C in the treatment of cancer has been subject to controversy for decades. Within the past 10 years, mechanistic insight into the importance of vitamin C in epigenetic regulation has provided a new rationale for its potential anti-cancer effects. At physiological concentrations, vitamin C is a potent antioxidant and thereby co-factor for a range of enzymes including the Fe(II)- and α-ketoglutarate-dependent dioxygenases that represent some of the most important epigenetic regulators; the ten-eleven translocation (TET) methylcytosine dioxygenases and the Jumonji-C domain-containing histone demethylases. Epigenetic deregulation is a hallmark of many cancers and reduced activity of these enzymes or somatic loss-of-function mutations in the genes encoding them, are observed in many cancer types. The present review outlines the growing literature on the role of vitamin C in epigenetic therapy of cancer. In the vast majority of in vitro, animal and clinical studies included in this review, vitamin C showed ability across cancer types to increase the hydroxylation of 5-methylcytosine to 5-hydroxymethylcytosine catalyzed by the TET enzymes - the first step in DNA demethylation. Most consistently, vitamin C in combination with the class of epigenetic drugs, DNA methyltransferase inhibitors, has demonstrated efficacy in the treatment of hematological malignancies in both preclinical and the limited number of available clinical studies. Yet, the pertinent question of what is the optimal dose of vitamin C in cancer studies remains to be answered. High-quality randomized placebo-controlled trials are needed to determine whether supplementation with vitamin C may benefit subgroups of patients with (pre-)cancer.

Vitamin C Deficiency in the Young Brain-Findings from Experimental Animal Models

Severe and long-term vitamin C deficiency can lead to fatal scurvy, which is fortunately considered rare today. However, a moderate state of vitamin C (vitC) deficiency (hypovitaminosis C)-defined as a plasma concentration below 23 μM-is estimated to affect up to 10% of the population in the Western world, albeit clinical hallmarks in addition to scurvy have not been linked to vitC deficiency. The brain maintains a high vitC content and uniquely high levels during deficiency, supporting vitC's importance in the brain. Actions include both antioxidant and co-factor functions, rendering vitamin C deficiency likely to affect several targets in the brain, and it could be particularly significant during development where a high cellular metabolism and an immature antioxidant system might increase sensitivity. However, investigations of a non-scorbutic state of vitC deficiency and effects on the developing young brain are scarce. This narrative review provides a comprehensive overview of the complex mechanisms that regulate vitC homeostasis in vivo and in the brain in particular. Functions of vitC in the brain and the potential consequences of deficiency during brain development are highlighted, based primarily on findings from experimental animal models. Perspectives for future investigations of vitC are outlined.

Effect of Botanical Extracts on the Growth and Nutritional Quality of Field-Grown White Head Cabbage (Brassica oleracea var. capitata)

Nutraceuticals and functional foods are gaining more attention amongst consumers interested in nutritious food. The consumption of foodstuffs with a high content of phytochemicals has been proven to provide various health benefits. The application of biostimulants is a potential strategy to fortify cultivated plants with beneficial bioactive compounds. Nevertheless, it has not yet been established whether the proposed higher plants (St. John’s wort, giant goldenrod, common dandelion, red clover, nettle, and valerian) are appropriate for the production of potential bio-products enhancing the nutritional value of white cabbage. Therefore, this research examines the impact of botanical extracts on the growth and nutritional quality of cabbage grown under field conditions. Two extraction methods were used for the production of water-based bio-products, namely: ultrasound-assisted extraction and mechanical homogenisation. Bio-products were applied as foliar sprays to evaluate their impact on total yield, dry weight, photosynthetic pigments, polyphenols, antioxidant activity, vitamin C, nitrates, micro- and macroelements, volatile compounds, fatty acids, sterols, and sugars. Botanical extracts showed different effects on the examined parameters. The best results in terms of physiological and biochemical properties of cabbage were obtained for extracts from common dandelion, valerian, nettle, and giant goldenrod. When enriched with nutrients, vegetables can constitute a valuable component of functional food.

Antioxidant Therapeutics in Parkinson's Disease: Current Challenges and Opportunities

Oxidative stress is considered one of the pathological mechanisms that cause Parkinson’s disease (PD), which has led to the investigation of several antioxidants molecules as a potential therapeutic treatment against the disease. Although preclinical studies have demonstrated the efficacy of these compounds to maintain neuronal survival and activity in PD models, these results have not been reflected in clinical trials, antioxidants have not been able to act as disease modifiers in terms of clinical symptoms. Translational medicine currently faces the challenge of redesigning clinical trials to standardize criteria when testing molecules to reduce responses’ variability. Herein, we discuss current challenges and opportunities regarding several non-enzymatic antioxidants’ therapeutic molecules for PD patients’ potential treatment.

The coronavirus disease (COVID-19) - A supportive approach with selected micronutrients

Worldwide the pandemic of COVID-19 spreads rapidly and has had an enormous public health impact with substantial morbidity and mortality especially in high-risk groups, such as older people and patients with comorbidities like diabetes, dementia or cancer. In the absence of a vaccine against COVID-19 there is an urgent need to find supportive therapies that can stabilize the immune system and can help to deal with the infection, especially for vulnerable groups such as the elderly. This is especially relevant for our geriatric institutions and nursing homes. A major potential contributing factor for elderly is due to their high incidence of malnutrition: up to 80% among the hospitalized elderly. Malnutrition results when adequate macronutrients and micronutrients are lacking in the diet. Often missing in public health discussions around preventing and treating COVID-19 patients are nutritional strategies to support optimal function of their immune system. This is surprising, given the importance that nutrients play a significant role for immune function. Several micronutrients, such as vitamin D, retinol, vitamin C, selenium and zinc are of special importance supporting both the adaptive and innate immune systems. As suboptimal status or deficiencies in these immune-relevant micronutrients impair immune function and reduces the resistance to infections, micronutrient deficiencies should therefore be corrected as soon as possible, especially in the elderly and other vulnerable groups. According to epidemiological, experimental and observational studies, some case reports and a few intervention studies the supplementation of vitamin D and/or zinc are promising. The multiple anti-inflammatory and immunomodulatory effects of Vitamin D could explain its protective role against immune hyper reaction and cytokine storm in patients with severe COVID-19. A randomized, placebo-controlled intervention study even shows that high dose vitamin D supplementation promotes viral clearance in asymptomatic and mildly symptomatic SARS-CoV-2 positive individuals. Besides, the data of a recent prospective study with COVID-19 patients reveal that a significant number of them were zinc deficient. The zinc deficient patients had more complications and the deficiency was associated with a prolonged hospital stay and increased mortality. Thus, immune-relevant micronutrients may help to increase the physiological resilience against COVID-19.

Efficacy of vitamin C supplementation as an adjunct in the non-surgical management of periodontitis: a systematic review

BACKGROUND AND OBJECTIVE

The antioxidant potential of vitamin C is useful in reducing oxidative stress, free radicals, and reactive oxygen species, which may assist in the improved outcomes of periodontal therapy. This systematic review was aimed to evaluate the effectiveness of vitamin C supplementation as an adjunct to non-surgical periodontal therapy, in the management of periodontitis.

DATA SOURCES

PubMed, EMBASE, Cochrane Library, and Web of Science.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials published between January 1990 and March 2020.

PARTICIPANTS

People 18 years and older with periodontitis.

STUDY APPRAISAL AND SYNTHESIS METHODS

The Critical Appraisal Skills Programme (CASP) quality appraisal tool.

RESULTS

The initial search yielded 441 articles out of which six studies fulfilled the inclusion criteria. Vitamin C supplementation helped improve bleeding indices in gingivitis but did not significantly lead to reduction of probing depths or clinical attachment gain for periodontitis.

CONCLUSION

Administration of vitamin C as an adjunct to non-surgical periodontal therapy did not result in clinically significant improvements in pocket probing depths at 3 months in periodontitis patients. With the limited evidence available, no recommendation can be made for supplementation of vitamin C in conjunction with initial periodontal therapy for subjects with periodontitis to improve primary treatment outcome measures.

Antioxidant supplements in age-related macular degeneration: are they actually beneficial?

Age-related macular degeneration (ARMD) is one of the prominent causes of central visual loss in the older age group in the urbanized, industrialized world. In recent years, many epidemiological studies and clinical trials have evaluated the role of antioxidants and micronutrients to prevent the progression of ARMD. In this article, we review some of these major studies. In addition, we review the absorption and bioavailability and possible undesirable effects of these nutrients after ingestion. The role of genotypes and inappropriate use of these supplements are also discussed. From all the above evidence, we conclude that it may not be prudent to prescribe these formulations without a proper assessment of the individual's health and dietary status. The effectiveness of all the components in antioxidant formulations is controversial. Thus, these supplements should not be prescribed just for the purpose of providing patients some kind of therapy, which may give a false sense of mental satisfaction.

Innovative management programme reduces environmental impacts in Chinese vegetable production

China produces half of the world's vegetables. The production uses 1.7% of the global harvest area of crops but accounts for 7.8% of the chemical fertilizers and 6.6% of crop-sourced greenhouse gas (GHG) emissions worldwide. Using an innovative management programme, the integrated knowledge and products strategy (IKPS), we demonstrate opportunities for producing more vegetables with lower environmental impacts in China's vegetable production systems. Combining soil-crop system management practices with enhanced-efficiency fertilizer products, IKPS was tested through 54 site-year field experiments in China's major agro-ecological zones by a national research network over 12 years. Compared with current farming practices, the adoption of IKPS decreased the nitrogen (N) application rate by 38%, N surplus by 65% and GHG emissions by 28%, while increasing yield by 17%. Scenario analyses showed that adoption of IKPS in China's vegetable production could mitigate resource and environmental burdens while enhancing food and nutrition security.

Vitamins B-12 and C Supplementation Improves Arterial Reactivity and Structure in Passive Smokers: Implication in Prevention of Smoking-Related Atherosclerosis

BACKGROUND

Atherosclerosis is an important medical problem of modern society. High environmental tobacco smoke in casino is associated with an accelerated atherogenic process. We have previously shown vitamin B12 and C supplementation improves vascular reactivity and may be beneficial in vascular protection.

OBJECTIVE

To evaluate the impact of vitamin supplementation on atherosclerosis (brachial artery reactivity FMD and carotid intima-media thickness IMT) in subjects exposed to high environmental tobacco smoke.

DESIGN

Double-blind 2x2 factorial design fashion.

SETTING

Computer randomization in 4 treatment groups: placebo (n=24), vitamin B12 (n=21), vitamin C (n=23) and vitamin B12+C (n=23) groups.

PARTICIPANTS

91 passive-smoking casino employees (19.2% male, mean age 45.0±8.2 years).

INTERVENTION

Subjects were randomized to receive vitamin B12 (500µg daily), vitamin C (200mg daily), vitamin B12+C or image-matched placebo capsules for 1 year.

MEASUREMENT

Brachial FMD and carotid IMT (surrogate atherosclerotic markers) were measured by ultrasound at baseline and on completion at 12 months.

METHODS

91 passive smoking casino employees (19.2% male, mean age 45.0±8.2 years) were randomized to receive vitamin B12 (500µg daily), vitamin C (200mg daily), vitamin B12+C or image-matched placebo capsules in double-blind 2 x 2 factorial design fashion for 1 year. Brachial FMD and carotid IMT (surrogate atherosclerotic markers) were measured by ultrasound at baseline and 12 months.

RESULTS

Of the 78 (85.7%) passive-smoking employees completed the study, 11.5% had hypertension, 5.1% diabetes mellitus and 15.4% hypercholesterolemia. There were no significant changes in their blood pressures, lipid profiles, glucose and body mass index after supplementation for 1 year, but mild decrease in DBP (p<0.001) and blood creatinine (p<0.01) after combined vitamin B12 and C, and significant increase in blood B12 after vitamin B12 (p<0.01) and vitamin B12+C supplementations (p<0.001). Brachial FMD and cartotid IMT improved after the 3 vitamin supplementations (p<0.001), but not after placebo, being more significant after combined vitamin supplementations (p<0.0001). No adverse effects were reported.

CONCLUSION

Vitamin B12 or C supplementation in passive smokers improved vascular reactivity and structures at 1 year, with implication in long term atherosclerosis prevention.

(Ascorb)ing Pb Neurotoxicity in the Developing Brain

Lead (Pb) neurotoxicity is a major concern, particularly in children. Developmental exposure to Pb can alter neurodevelopmental trajectory and has permanent neuropathological consequences, including an increased vulnerability to further stressors. Ascorbic acid is among most researched antioxidant nutrients and has a special role in maintaining redox homeostasis in physiological and physio-pathological brain states. Furthermore, because of its capacity to chelate metal ions, ascorbic acid may particularly serve as a potent therapeutic agent in Pb poisoning. The present review first discusses the major consequences of Pb exposure in children and then proceeds to present evidence from human and animal studies for ascorbic acid as an efficient ameliorative supplemental nutrient in Pb poisoning, with a particular focus on developmental Pb neurotoxicity. In doing so, it is hoped that there is a revitalization for further research on understanding the brain functions of this essential, safe, and readily available vitamin in physiological states, as well to justify and establish it as an effective neuroprotective and modulatory factor in the pathologies of the nervous system, including developmental neuropathologies.

Multiple Effects of Ascorbic Acid against Chronic Diseases: Updated Evidence from Preclinical and Clinical Studies

Severe disease commonly manifests as a systemic inflammatory process. Inflammation is associated withthe enhanced production of reactive oxygen and nitrogen species and with a marked reduction in the plasma concentrations of protective antioxidant molecules. This imbalance gives rise to oxidative stress, which is greater in patients with more severe conditions such as sepsis, cancer, cardiovascular disease, acute respiratory distress syndrome, and burns. In these patients, oxidative stress can trigger cell, tissue, and organ damage, thus increasing morbidity and mortality. Ascorbic acid (ASC) is a key nutrient thatserves as an antioxidant and a cofactor for numerous enzymatic reactions. However, humans, unlike most mammals, are unable to synthesize it. Consequently, ASC must be obtained through dietary sources, especially fresh fruit and vegetables. The value of administering exogenous micronutrients, to reestablish antioxidant concentrations in patients with severe disease, has been recognized for decades. Despite the suggestion that ASC supplementation may reduce oxidative stress and prevent several chronic conditions, few large, randomized clinical trials have tested it in patients with severe illness. This article reviews the recent literature on the pharmacological profile of ASC and the role of its supplementation in critically ill patients.

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

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

Safety and efficacy of supplements in pregnancy

Pregnancy is a time where expectant mothers often focus on their diet to improve their own health and to preserve the future health of their children. There is much conflicting information in the public domain about the safety and/or efficacy of nutritional supplements during pregnancy. Despite this, the market for supplements is growing. This review discusses the roles of critical nutrients in pregnancy and the available evidence on the use of supplements to reduce risks and improve maternal and fetal outcomes. Recommendations are made for pregnant women, taking into account safety data and tolerable upper intakes set for pregnant women. It is important for dieticians, nutritionists, physicians, and other healthcare providers to be able to offer accurate and evidence-based advice on supplement use in pregnancy. Routine supplementation may not be necessary for all, but individuals at risk are identified.

Prophylactic and therapeutic effects of different doses of vitamin C on high-fat-diet-induced non-alcoholic fatty liver disease in mice

Epidemiological studies support the association between inadequate vitamin C (Vc) intake and non-alcoholic fatty liver disease (NAFLD). However, the intervention dose of Vc, and the prophylactic and therapeutic effects on NAFLD are unclear. This study aimed to investigate the prophylactic and therapeutic effects of low (LVc), medium (MVc) and high (HVc) doses of Vc on NAFLD. C57BL/6 mice were randomly assigned to prophylactic groups (mice received a high-fat diet (HFD) concomitant with different doses of Vc) and therapeutic groups (HFD-induced NAFLD mice treated with different doses of Vc). Results showed that prophylactic LVc and MVc administration reduced the risk of NAFLD development in HFD-fed mice, as evidenced by significantly lowered body weight, perirenal adipose tissue mass, and steatosis, whereas prophylactic HVc administration did not prevent HFD-induced NAFLD development. Furthermore, therapeutic MVc administration significantly ameliorated HFD-induced increase in body weight, perirenal adipose tissue mass and steatosis, whereas therapeutic LVc and HVc administration did not ameliorate NAFLD symptoms. In fact, therapeutic HVc administration significantly increased body weight, perirenal adipose tissue mass, and lobular inflammation. Moreover, prophylactic LVc administration was more effective than therapeutic LVc administration as evidenced by significantly lower body weight, perirenal adipose tissue mass, steatosis, ballooned hepatocytes, and lobular inflammation in prophylactic LVc administration. The same trends were observed between prophylactic HVc administration and therapeutic HVc administration. In addition, all Vc-administered mice exhibited low blood glucose, triglycerides and homeostasis model assessment of insulin resistance values and high adiponectin levels compared to HFD-fed mice. Our study suggested that MVc was beneficial for HFD-induced NAFLD prophylaxis and therapy. LVc prevented HFD-induced NAFLD development, while HVc for NAFLD management was risky. This study offers valuable insight into the effect of various Vc doses on NAFLD management.

Japanese Quince (Chaenomeles japonica) as a Potential Source of Phenols: Optimization of the Extraction Parameters and Assessment of Antiradical and Antimicrobial Activities

The value of fruits is determined by the quantity and variety of biologically active compounds they contain, and their benefits on human health. This work presents the first study of the biochemical composition and antibacterial activity of the new Japanese quince (JQ) cultivars 'Darius', 'Rondo', and 'Rasa' fruits. The total phenolic content (TPC) was determined using the Folin-Ciocalteu method and each compound was identified by HPLC High Performance Liquid Chromatography. The antimicrobial activity against three Gram-positive and three Gram-negative bacteria, and one yeast strain, was evaluated by the agar well diffusion method using three different concentrations. The free radical scavenging activity was determined using DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid) methods and ranged from 99.1 to 115.9 μmolTE/100 g, and from 372 to 682 μmolTE/100 g, respectively. TPC ranged from 3906 to 4550 mgGAE/100 g, and five compounds, isoquercitrin, rutin, (+)-catechin, (-)-epicatechin, and chlorogenic acid were identified. All JQ extracts possessed antimicrobial activity against Gram-positive and Gram-negative bacteria, and Enterococcus faecalis (ATCC 29212) was the most sensitive strain. These results indicate that JQ fruits are a significant source of bio-compounds, which can enrich the diet with strong antioxidants, and they are very promising as a substitute for chemical preservatives in the food and cosmetic industry.

On the effect of vitamin C intake on human health: How to (mis)interprete the clinical evidence

For decades, the potential beneficial effect of vitamin C on human health-beyond that of preventing scurvy-has been subject of much controversy. Hundreds of articles have appeared either in support of increased vitamin C intake through diet or supplements or rejecting the hypothesis that increased intake of vitamin C or supplementation may influence morbidity and mortality. The chemistry and pharmacology of vitamin C is complex and has unfortunately rarely been taken into account when designing clinical studies testing its effect on human health. However, ignoring its chemical lability, dose-dependent absorption and elimination kinetics, distribution via active transport, or complex dose-concentration-response relationships inevitably leads to poor study designs, inadequate inclusion and exclusion criteria and misinterpretation of results. The present review outlines the differences in vitamin C pharmacokinetics compared to normal low molecular weight drugs, focusses on potential pitfalls in study design and data interpretation, and re-examines major clinical studies of vitamin C in light of these.

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

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

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.

Multiple genome analyses reveal key genes in Vitamin C and Vitamin D synthesis and transport pathways are shared

Vitamin C (VC) and vitamin D (VD) have been widely used as the dietary supplements and in treatment of diseases both independently and in combination. Whether there is a connection between their pathways is critical for their therapeutic applications. Using whole-genome expression profiles, we performed multiple measures of associations, networks, eQTL mappings and expressions of key genes of interest in VC and VD functions. Several key genes in their pathways were found to be associated. Gc and Rgn play important roles connecting VC and VD pathways in mice. The r values of expression levels between Gc and Rgn in mouse spleen, liver, lung, and kidney are 0.937, 0.558, 0.901, and 0.617, respectively. The expression QTLs of Gc and Rgn are mapped onto the same locations, i.e., 68-76 MB in chromosome 7 and 26-36 MB in chromosome 9. In humans, there are positive correlations between CYP27B1 and SLC23A1 expression levels in kidney (r = 0.733) and spleen (r = 0.424). SLC23A2 and RXRA are minimally associated in both mouse and human. These data indicate that pathways of VC and VD are not independent but affect each other, and this effect is different between mice and humans during VC and VD synthesis and transportation.

The Pharmacokinetics of Vitamin C

The pharmacokinetics of vitamin C (vitC) is indeed complex. Regulated primarily by a family of saturable sodium dependent vitC transporters (SVCTs), the absorption and elimination are highly dose-dependent. Moreover, the tissue specific expression levels and subtypes of these SVCTs result in a compartmentalized distribution pattern with a diverse range of organ concentrations of vitC at homeostasis ranging from about 0.2 mM in the muscle and heart, and up to 10 mM in the brain and adrenal gland. The homeostasis of vitC is influenced by several factors, including genetic polymorphisms and environmental and lifestyle factors such as smoking and diet, as well as diseases. Going from physiological to pharmacological doses, vitC pharmacokinetics change from zero to first order, rendering the precise calculation of dosing regimens in, for example, cancer and sepsis treatment possible. Unfortunately, the complex pharmacokinetics of vitC has often been overlooked in the design of intervention studies, giving rise to misinterpretations and erroneous conclusions. The present review outlines the diverse aspects of vitC pharmacokinetics and examines how they affect vitC homeostasis under a variety of conditions.

Activation of the hypoxia pathway in breast cancer tissue and patient survival are inversely associated with tumor ascorbate levels

Background

The transcription factor hypoxia inducible factor (HIF) -1 drives tumor growth and metastasis and is associated with poor prognosis in breast cancer. Ascorbate can moderate HIF-1 activity in vitro and is associated with HIF pathway activation in a number of cancer types, but whether tissue ascorbate levels influence the HIF pathway in breast cancer is unknown. In this study we investigated the association between tumor ascorbate levels and HIF-1 activation and patient survival in human breast cancer.

Methods

In a retrospective analysis of human breast cancer tissue, we analysed primary tumor and adjacent uninvolved tissue from 52 women with invasive ductal carcinoma. We measured HIF-1α, HIF-1 gene targets CAIX, BNIP-3 and VEGF, and ascorbate content. Patient clinical outcomes were evaluated against these parameters.

Results

HIF-1 pathway proteins were upregulated in tumor tissue and increased HIF-1 activation was associated with higher tumor grade and stage, with increased vascular invasion and necrosis, and with decreased disease-free and disease-specific survival. Grade 1 tumors had higher ascorbate levels than did grade 2 or 3 tumors. Higher ascorbate levels were associated with less tumor necrosis, with lower HIF-1 pathway activity and with increased disease-free and disease-specific survival.

Conclusions

Our findings indicate that there is a direct correlation between intracellular ascorbate levels, activation of the HIF-1 pathway and patient survival in breast cancer. This is consistent with the known capacity of ascorbate to stimulate the activity of the regulatory HIF hydroxylases and suggests that optimisation of tumor ascorbate could have clinical benefit via modulation of the hypoxic response.

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

OBJECTIVE

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

DESIGN

Systematic review and meta-analysis.

SETTING

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

RESULTS

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

CONCLUSIONS

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