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Nutrients Feb 2021Vitamin C (L-ascorbic acid) has been known as an antioxidant for most people. However, its physiological role is much larger and encompasses very different processes... (Review)
Review
Vitamin C (L-ascorbic acid) has been known as an antioxidant for most people. However, its physiological role is much larger and encompasses very different processes ranging from facilitation of iron absorption through involvement in hormones and carnitine synthesis for important roles in epigenetic processes. Contrarily, high doses act as a pro-oxidant than an anti-oxidant. This may also be the reason why plasma levels are meticulously regulated on the level of absorption and excretion in the kidney. Interestingly, most cells contain vitamin C in millimolar concentrations, which is much higher than its plasma concentrations, and compared to other vitamins. The role of vitamin C is well demonstrated by miscellaneous symptoms of its absence-scurvy. The only clinically well-documented indication for vitamin C is scurvy. The effects of vitamin C administration on cancer, cardiovascular diseases, and infections are rather minor or even debatable in the general population. Vitamin C is relatively safe, but caution should be given to the administration of high doses, which can cause overt side effects in some susceptible patients (e.g., oxalate renal stones). Lastly, analytical methods for its determination with advantages and pitfalls are also discussed in this review.
Topics: Antioxidants; Ascorbic Acid; Ascorbic Acid Deficiency; Humans; Kinetics
PubMed: 33668681
DOI: 10.3390/nu13020615 -
American Family Physician Sep 2019Acute upper respiratory tract infections are extremely common in adults and children, but only a few safe and effective treatments are available. Patients typically...
Acute upper respiratory tract infections are extremely common in adults and children, but only a few safe and effective treatments are available. Patients typically present with nasal congestion, rhinorrhea, sore throat, cough, general malaise, and/or low-grade fever. Informing patients about the self-limited nature of the common cold can help manage expectations, limit antibiotic use, and avoid over-the-counter purchases that may not help. Treatments with proven effectiveness for cold symptoms in adults include over-the-counter analgesics, zinc, nasal decongestants with or without antihistamines, and ipratropium for cough. Lower-quality evidence suggests that Lactobacillus casei may be beneficial in older adults. The only established safe and effective treatments for children are acetylcysteine, honey (for children one year and older), nasal saline irrigation, intranasal ipratropium, and topical application of ointment containing camphor, menthol, and eucalyptus oils. Over-the-counter cold medications should not be used in children younger than four years. Counseling patients about the importance of good hand hygiene is the best way to prevent transmission of cold viruses.
Topics: Adult; Ascorbic Acid; Child; Common Cold; Echinacea; Fluid Therapy; Humans; Nasal Decongestants; Nonprescription Drugs; Patient Education as Topic
PubMed: 31478634
DOI: No ID Found -
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 -
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 -
Nutrients Apr 2021Vitamin C is an essential nutrient that serves as antioxidant and plays a major role as co-factor and modulator of various pathways of the immune system. Its therapeutic... (Review)
Review
Vitamin C is an essential nutrient that serves as antioxidant and plays a major role as co-factor and modulator of various pathways of the immune system. Its therapeutic effect during infections has been a matter of debate, with conflicting results in studies of respiratory infections and in critically ill patients. This comprehensive review aimed to summarize the current evidence regarding the use of vitamin C in the prevention or treatment of patients with SARS-CoV2 infection, based on available publications between January 2020 and February 2021. Overall, 21 publications were included in this review, consisting of case-reports and case-series, observational studies, and some clinical trials. In many of the publications, data were incomplete, and in most clinical trials the results are still pending. No studies regarding prevention of COVID-19 with vitamin C supplementation were found. Although some clinical observations reported improved medical condition of patients with COVID-19 treated with vitamin C, available data from controlled studies are scarce and inconclusive. Based on the theoretical background presented in this article, and some preliminary encouraging studies, the role of vitamin C in the treatment of patients with SARS-CoV-2 infection should be further investigated.
Topics: Adult; Aged; Antioxidants; Ascorbic Acid; Child; Clinical Trials as Topic; Dietary Supplements; Drug Administration Routes; Female; Humans; Male; Middle Aged; SARS-CoV-2; Severity of Illness Index; Treatment Outcome; Vitamins; COVID-19 Drug Treatment
PubMed: 33916257
DOI: 10.3390/nu13041172 -
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 -
International Journal of Environmental... Nov 2020Antioxidant supplementation, including vitamin E and C supplementation, has recently received recognition among athletes as a possible method for enhancing athletic... (Review)
Review
Antioxidant supplementation, including vitamin E and C supplementation, has recently received recognition among athletes as a possible method for enhancing athletic performance. Increased oxidative stress during exercise results in the production of free radicals, which leads to muscle damage, fatigue, and impaired performance. Despite their negative effects on performance, free radicals may act as signaling molecules enhancing protection against greater physical stress. Current evidence suggests that antioxidant supplementation may impair these adaptations. Apart from athletes training at altitude and those looking for an immediate, short-term performance enhancement, supplementation with vitamin E does not appear to be beneficial. Moreover, the effectiveness of vitamin E and C alone and/or combined on muscle mass and strength have been inconsistent. Given that antioxidant supplements (e.g., vitamin E and C) tend to block anabolic signaling pathways, and thus, impair adaptations to resistance training, special caution should be taken with these supplements. It is recommended that athletes consume a diet rich in fruits and vegetables, which provides vitamins, minerals phytochemicals, and other bioactive compounds to meet the recommended intakes of vitamin E and C.
Topics: Antioxidants; Ascorbic Acid; Dietary Supplements; Exercise; Humans; Vitamin E; Vitamins
PubMed: 33203106
DOI: 10.3390/ijerph17228452 -
Nutrients Feb 2021Gout, known as "the disease of the kings", is the most frequent type of arthritis. It results from sustained hyperuricemia that leads to monosodium urate crystal... (Review)
Review
Gout, known as "the disease of the kings", is the most frequent type of arthritis. It results from sustained hyperuricemia that leads to monosodium urate crystal deposition in joint structures and soft tissue. Environmental factors such as diet affect the incidence of gout; there is a known relationship between the occurrence of an acute attack of gout and the consumption of alcohol and meat; and a low purine diet is a widely recognized nonpharmacological method of supplementing the treatment and preventing recurrence of arthritis. This review aims to summarize the current knowledge about the role of vitamin C in prevention and treatment of gout. A PubMed/Medline database search on the role of vitamin C in purine metabolism was done. Reports from in vitro and animal studies seem to be promising and to allow explanation of the physiological relationship between vitamin C and uric acid. Most epidemiological studies indicate a significant correlation between high vitamin C intake and lower serum uric acid levels. Despite promising observations, there are few observational and interventional studies, and their results do not clearly define the benefits of a high daily intake of vitamin C in preventing the development and recurrence of gout.
Topics: Ascorbic Acid; Diet; Gout; Humans; Hyperuricemia
PubMed: 33671646
DOI: 10.3390/nu13020701 -
Nutrients Oct 2020Cataracts or clouding of the lens is the leading cause of blindness in the world. Age and diabetes are major risk factors, and with an increasing aging and diabetic... (Review)
Review
Cataracts or clouding of the lens is the leading cause of blindness in the world. Age and diabetes are major risk factors, and with an increasing aging and diabetic population, the burden of cataracts will grow. Cataract surgery is an effective way to restore vision; however, alternatives to cataract surgery are required to reduce the looming cataract epidemic. Since it is well established that oxidative damage plays a major role in the etiology of cataracts, antioxidants have been promoted as therapies to delay and/or prevent cataracts. However, many antioxidant interventions including vitamin C have produced mixed results as anti-cataract therapies. Progress has been made towards our understanding of lens physiology and the mechanisms involved in the delivery and uptake of antioxidants to the lens which may guide future studies aimed at addressing some of the inconsistencies seen in previous animal and human studies. Of interest is the potential for vitamin C based supplements in delaying the onset of cataracts post vitrectomy which occurs in up to 80% of patients within two years. These targeted approaches are required to reduce the burden of cataract on hospitals and improve the quality of life of our aging and diabetic population.
Topics: Aging; Animals; Antioxidants; Ascorbic Acid; Cataract; Diabetes Complications; Dietary Supplements; Humans; Nutritional Physiological Phenomena; Oxidative Stress; Risk Factors; Vitrectomy; Vitreous Body
PubMed: 33066702
DOI: 10.3390/nu12103142