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Nutrients Aug 2017The primary function of the skin is to act as a barrier against insults from the environment, and its unique structure reflects this. The skin is composed of two layers:... (Review)
Review
The primary function of the skin is to act as a barrier against insults from the environment, and its unique structure reflects this. The skin is composed of two layers: the epidermal outer layer is highly cellular and provides the barrier function, and the inner dermal layer ensures strength and elasticity and gives nutritional support to the epidermis. Normal skin contains high concentrations of vitamin C, which supports important and well-known functions, stimulating collagen synthesis and assisting in antioxidant protection against UV-induced photodamage. This knowledge is often used as a rationale for the addition of vitamin C to topical applications, but the efficacy of such treatment, as opposed to optimising dietary vitamin C intake, is poorly understood. This review discusses the potential roles for vitamin C in skin health and summarises the in vitro and in vivo research to date. We compare the efficacy of nutritional intake of vitamin C versus topical application, identify the areas where lack of evidence limits our understanding of the potential benefits of vitamin C on skin health, and suggest which skin properties are most likely to benefit from improved nutritional vitamin C intake.
Topics: Ascorbic Acid; Humans; Skin; Vitamins
PubMed: 28805671
DOI: 10.3390/nu9080866 -
Oral Diseases Sep 2016Vitamin C (Ascorbic Acid), the antiscorbutic vitamin, cannot be synthesized by humans and other primates, and has to be obtained from diet. Ascorbic acid is an electron... (Review)
Review
Vitamin C (Ascorbic Acid), the antiscorbutic vitamin, cannot be synthesized by humans and other primates, and has to be obtained from diet. Ascorbic acid is an electron donor and acts as a cofactor for fifteen mammalian enzymes. Two sodium-dependent transporters are specific for ascorbic acid, and its oxidation product dehydroascorbic acid is transported by glucose transporters. Ascorbic acid is differentially accumulated by most tissues and body fluids. Plasma and tissue vitamin C concentrations are dependent on amount consumed, bioavailability, renal excretion, and utilization. To be biologically meaningful or to be clinically relevant, in vitro and in vivo studies of vitamin C actions have to take into account physiologic concentrations of the vitamin. In this paper, we review vitamin C physiology; the many phenomena involving vitamin C where new knowledge has accrued or where understanding remains limited; raise questions about the vitamin that remain to be answered; and explore lines of investigations that are likely to be fruitful.
Topics: Ascorbic Acid; Humans; In Vitro Techniques; Oral Health; Recommended Dietary Allowances
PubMed: 26808119
DOI: 10.1111/odi.12446 -
Nutrients Oct 2019The pharmacokinetics of vitamin C (vitC) is indeed complex. Regulated primarily by a family of saturable sodium dependent vitC transporters (SVCTs), the absorption and... (Review)
Review
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.
Topics: Ascorbic Acid; Ascorbic Acid Deficiency; Diffusion; Female; Homeostasis; Humans; Intestinal Absorption; Nutritional Requirements; Pregnancy; Smoking; Sodium-Coupled Vitamin C Transporters; Tissue Distribution
PubMed: 31601028
DOI: 10.3390/nu11102412 -
Journal of Experimental & Clinical... Oct 2021Mounting evidence indicates that vitamin C has the potential to be a potent anti-cancer agent when administered intravenously and in high doses (high-dose IVC). Early... (Review)
Review
Mounting evidence indicates that vitamin C has the potential to be a potent anti-cancer agent when administered intravenously and in high doses (high-dose IVC). Early phase clinical trials have confirmed safety and indicated efficacy of IVC in eradicating tumour cells of various cancer types. In recent years, the multi-targeting effects of vitamin C were unravelled, demonstrating a role as cancer-specific, pro-oxidative cytotoxic agent, anti-cancer epigenetic regulator and immune modulator, reversing epithelial-to-mesenchymal transition, inhibiting hypoxia and oncogenic kinase signalling and boosting immune response. Moreover, high-dose IVC is powerful as an adjuvant treatment for cancer, acting synergistically with many standard (chemo-) therapies, as well as a method for mitigating the toxic side-effects of chemotherapy. Despite the rationale and ample evidence, strong clinical data and phase III studies are lacking. Therefore, there is a need for more extensive awareness of the use of this highly promising, non-toxic cancer treatment in the clinical setting. In this review, we provide an elaborate overview of pre-clinical and clinical studies using high-dose IVC as anti-cancer agent, as well as a detailed evaluation of the main known molecular mechanisms involved. A special focus is put on global molecular profiling studies in this respect. In addition, an outlook on future implications of high-dose vitamin C in cancer treatment is presented and recommendations for further research are discussed.
Topics: Administration, Intravenous; Ascorbic Acid; Humans; Neoplasms
PubMed: 34717701
DOI: 10.1186/s13046-021-02134-y -
Actas Dermo-sifiliograficas Nov 2006Vitamin C or ascorbic acid is a hydrosoluble vitamin derived from glucose metabolism. It acts as a reductor agent required for synthesis of collagen fibers through... (Review)
Review
Vitamin C or ascorbic acid is a hydrosoluble vitamin derived from glucose metabolism. It acts as a reductor agent required for synthesis of collagen fibers through hydroxylation of proline and lysine. It also protects the body against damage caused by the free radicals. Humans cannot synthesize ascorbic acid as they lack an enzyme called gulonolactone oxidase. Concentrations in plasma and leukocytes reflect the levels of the diet and body deposits respectively of this vitamin. Among foods with high vitamin C levels are tomatoes, potatoes, and citrus fruits such as limes, oranges and lemons. The current recommendation of daily intake of vitamin C is 90 mg/d for men and 75 mg/d for women. Patients with chronic diseases such as cancer or diabetes or those who smoke need higher doses in their usual diet. Ascorbic acid deficiency gives rise to the appearance of scurvy. This disease is rarely seen in developed countries. The symptoms develop with plasma levels below 0.15 mg/dL. Scurvy is characterized by the presence of weakness, joint pain or skin lesions in form of petechias, gum bleeding, ease of developing bruises or delay in wound healing. The most characteristic skin manifestations are purpuric perifollicular hyperkeratotic papules and the presence of kinky hair.
Topics: Antioxidants; Ascorbic Acid; Clinical Trials as Topic; Humans; Scurvy
PubMed: 17173758
DOI: 10.1016/s0001-7310(06)73466-4 -
Nanomedicine : Nanotechnology, Biology,... Feb 2020Vitamin C (Vit C) is a potent antioxidant with several applications in the cosmetic and pharmaceutical fields. However, the biggest challenge in the utilization of Vit C... (Review)
Review
Vitamin C (Vit C) is a potent antioxidant with several applications in the cosmetic and pharmaceutical fields. However, the biggest challenge in the utilization of Vit C is to maintain its stability and improve its delivery to the active site. Several strategies have been developed such as: controlling the oxygen levels during formulation and storage, low pH, reduction of water content in the formulation and the addition of preservative agents. Additionally, the utilization of derivatives of Vit C and the development of micro and nanoencapsulated delivery systems have been highlighted. In this article, the multiple applications and mechanisms of action of vitamin C will be reviewed and discussed, as well as the new possibilities of delivery and improvement of stability.
Topics: Antioxidants; Ascorbic Acid; Chemistry, Pharmaceutical; Drug Delivery Systems; Drug Stability; Nanostructures; Vitamins
PubMed: 31676375
DOI: 10.1016/j.nano.2019.102117 -
Nature Reviews. Cancer May 2019Over the past century, the notion that vitamin C can be used to treat cancer has generated much controversy. However, new knowledge regarding the pharmacokinetic... (Review)
Review
Over the past century, the notion that vitamin C can be used to treat cancer has generated much controversy. However, new knowledge regarding the pharmacokinetic properties of vitamin C and recent high-profile preclinical studies have revived interest in the utilization of high-dose vitamin C for cancer treatment. Studies have shown that pharmacological vitamin C targets many of the mechanisms that cancer cells utilize for their survival and growth. In this Opinion article, we discuss how vitamin C can target three vulnerabilities many cancer cells share: redox imbalance, epigenetic reprogramming and oxygen-sensing regulation. Although the mechanisms and predictive biomarkers that we discuss need to be validated in well-controlled clinical trials, these new discoveries regarding the anticancer properties of vitamin C are promising to help identify patient populations that may benefit the most from high-dose vitamin C therapy, developing effective combination strategies and improving the overall design of future vitamin C clinical trials for various types of cancer.
Topics: Animals; Antineoplastic Agents; Ascorbic Acid; Epigenesis, Genetic; Humans; Neoplasms; Oxidation-Reduction
PubMed: 30967651
DOI: 10.1038/s41568-019-0135-7 -
Science Translational Medicine Feb 2020Vitamin C (VitC) is known to directly impair cancer cell growth in preclinical models, but there is little clinical evidence on its antitumoral efficacy. In addition,...
Vitamin C (VitC) is known to directly impair cancer cell growth in preclinical models, but there is little clinical evidence on its antitumoral efficacy. In addition, whether and how VitC modulates anticancer immune responses is mostly unknown. Here, we show that a fully competent immune system is required to maximize the antiproliferative effect of VitC in breast, colorectal, melanoma, and pancreatic murine tumors. High-dose VitC modulates infiltration of the tumor microenvironment by cells of the immune system and delays cancer growth in a T cell-dependent manner. VitC not only enhances the cytotoxic activity of adoptively transferred CD8 T cells but also cooperates with immune checkpoint therapy (ICT) in several cancer types. Combination of VitC and ICT can be curative in models of mismatch repair-deficient tumors with high mutational burden. This work provides a rationale for clinical trials combining ICT with high doses of VitC.
Topics: Animals; Antineoplastic Agents; Ascorbic Acid; Immunotherapy; Melanoma; Mice; Tumor Microenvironment
PubMed: 32102933
DOI: 10.1126/scitranslmed.aay8707 -
Current Opinion in Anaesthesiology Feb 2018This narrative review summarizes recent insights into the role of vitamin C in sepsis. (Review)
Review
PURPOSE OF REVIEW
This narrative review summarizes recent insights into the role of vitamin C in sepsis.
RECENT FINDINGS
Septic shock remains a major source of morbidity and mortality in critically ill patients. Although many nutritional supplements have previously been tested unsuccessfully, vitamins are still being explored as a therapeutic option in septic patients. In particular, vitamin C-containing regimens as adjunctive therapy in sepsis have received much attention.
SUMMARY
In-vitro evidence supports a critical role for vitamin C in cellular mechanisms relevant to the pathophysiology of sepsis. However, whether this justifies therapeutic use of vitamin C in septic patients remains uncertain.
Topics: Ascorbic Acid; Critical Illness; Humans; Sepsis
PubMed: 29176375
DOI: 10.1097/ACO.0000000000000549 -
Advances in Nutrition (Bethesda, Md.) Jan 2014
Topics: Ascorbic Acid; Ascorbic Acid Deficiency; Diet; Evidence-Based Practice; Health Promotion; Humans; Recommended Dietary Allowances
PubMed: 24425716
DOI: 10.3945/an.113.005157