ArticlePDF AvailableLiterature Review

Abstract

Vitamin C is an essential dietary nutrient for the biosynthesis of collagen and a co-factor in the biosynthesis of catecholamines, L-carnitine, cholesterol, amino acids, and some peptide hormones. The lack of vitamin C causes scurvy, a pathological condition leading to blood vessel fragility and connective tissue damage due to failure in producing collagen, and, finally, to death as result of a general collapse. Vitamin C is potentially involved also in cancer and cardiovascular diseases prevention. In addition, vitamin C effects on nervous system and chronically ill patients have been also documented. This review attempts to summarize recent and well established advances in vitamin C research and its clinical implications. Since vitamin C has the potential to counteract inflammation and subsequent oxidative damage that play a major role in the initiation and progression of several chronic and acute diseases, it represents a practical tool to administer for the early prevention of these pathologic conditions.
1
Post-print version, please cite this article as:
Grosso G, Bei R, Mistretta A, Marventano S, Calabrese G, Masuelli L, Giganti MG, Modesti A, Galvano F, Gazzolo D. Effects of
Vitamin C on health: a review of evidence. Front Biosci. 2013 Jun 1;18:1017-29.
Copyright © 2013 Frontiers in Bioscience. All rights reserved.
Effects of Vitamin C on health: a review of evidence
Giuseppe Grosso
1,2
, Roberto Bei
3
, Antonio Mistretta
1
, Stefano Marventano
1
, Giorgio Calabrese
4
, Laura Masuelli
5
, Maria
Gabriella Giganti
3
, Andrea Modesti
3
, Fabio Galvano
2
, Diego Gazzolo
6,7
.
1
Department of G.F. Ingrassia, Section of Hygiene and Public Health, University of Catania, Catania, Italy,
2
Department of Drug
Sciences, Section of Biochemistry, University of Catania,
3
Department of Clinical Sciences and Translational Medicine, University
of Rome "Tor Vergata", Rome, Italy,
4
Department of Biology, Piemonte Orientale University, Alessandria, Italy,
5
Department of
Experimental Medicine, University of Rome “Sapienza”, Rome, Italy.
6
Department of Maternal, Fetal and Neonatal Medicine,
Cesare Arrigo Children's Hospital, Alessandria, Italy.
7
Department of Pediatric Cardiac Surgery IRCCS, San Donato Milanese
Hospital, San Donato Milanese, Italy.
TABLE OF CONTENTS
1. Abstract
2. Introduction
3. Vitamin C in humans: adsorption, deficiency, excess
4. Mechanisms of action of Vitamin C
4.1. Collagen synthesis
4.2. Regulation of hypoxia-inducible factor 1α
4.3. Antioxidant action
4.4. Pro-oxidant action
5. Anti-carcinogenic effects of vitamin C
6. Vitamin C and cardiovascular diseases
7. The Role of vitamin C in critically ill patients
8. Vitamin C effects on nervous system
9. Vitamin C in ocular diseases
10. Conclusions
11. Acknowledgements
12.References
1. ABSTRACT
Vitamin C is an essential dietary nutrient for the biosynthesis of collagen and a co-factor in the biosynthesis of
catecholamines, L-carnitine, cholesterol, amino acids, and some peptide hormones. The lack of vitamin C causes scurvy, a
pathological condition leading to blood vessel fragility and connective tissue damage due to failure in producing collagen, and,
finally, to death as result of a general collapse. Vitamin C is potentially involved also in cancer and cardiovascular diseases
prevention. In addition, vitamin C effects on nervous system and chronically ill patients have been also documented. This review
attempts to summarize recent and well established advances in vitamin C research and its clinical implications. Since vitamin C has
the potential to counteract inflammation and subsequent oxidative damage that play a major role in the initiation and progression of
several chronic and acute diseases, it represents a practical tool to administer for the early prevention of these pathologic conditions.
2. INTRODUCTION
Vitamin C, or ascorbic acid, is an essential dietary nutrient for a variety of biological functions. Under physiological
conditions, it is fundamental in the biosynthesis of collagen through facilitating the hydroxylation of proline and lysine residues, thus
allowing proper intracellular folding of pro-collagen for export and deposition as mature collagen (1). Vitamin C serves in humans
also as a co-factor in several important hydroxylation reactions, such as the biosynthesis of catecholamines (through the conversion
of dopamine to norepinephrine), L-carnitine, cholesterol, amino acids, and some peptide hormones (2).
The growing understanding of mechanisms of vitamin C on human health led to calls for continuous updated reappraisals
regarding the dietary requirements for this nutrient. Given the potential involvement of vitamin C in cancer and cardiovascular
diseases (CVD), as well as its effects on nervous system and chronically ill patients, the aim of this review is to address the potential
effects of vitamin C at both experimental and clinical stages focusing on recent evidences supporting a potential role for vitamin C in
degenerative diseases prevention.
2
Post-print version, please cite this article as:
Grosso G, Bei R, Mistretta A, Marventano S, Calabrese G, Masuelli L, Giganti MG, Modesti A, Galvano F, Gazzolo D. Effects of
Vitamin C on health: a review of evidence. Front Biosci. 2013 Jun 1;18:1017-29.
Copyright © 2013 Frontiers in Bioscience. All rights reserved.
3. VITAMIN C IN HUMANS: ADSORPTION, DEFICIENCY, EXCESS
Though most animals are able to endogenously synthesize large quantities of vitamin C, humans do not have the capability
to synthesize vitamin C due to a series of mutations of the gene encoding gulonolactone oxidase which catalyses the last enzymatic
step in ascorbate synthesis (3, 4). However, the requirement for vitamin C is satisfied by natural sources and vitamin C supplements
existing in the ordinary diet. The lack of vitamin C causes scurvy, a pathological condition leading to blood vessel fragility,
connective tissue damage, fatigue, and, finally, death. In addition to poor dietary intake of vitamin C, alcoholism (5), elderly age,
socioeconomic deprivation (6), mental illness (7), malabsorption disorders, kidney failure, hemodialysis (8), and peritoneal dialysis
(9) have been identified as risk factors for low vitamin C endogen levels and developing clinical symptoms of scurvy (10-12). Intake
of 10 mg per day of vitamin C is appropriate to prevent scurvy. This amount results in plasma concentrations of vitamin below 10
µM, already higher than that necessary to prevent scurvy (13). However, the current recommended dietary allowance (RDA) for
vitamin C for adult men and women, is set at 75 mg/day for women and 90 mg/day for men (14).
The adsorption of vitamin C from the dietary sources depends on the facilitated diffusion and a saturable-substrate transport
mechanism involving the ascorbate-specific transporters, which saturation and low expression (induced by substrate downregulation)
control the effective serum vitamin C concentration. The facilitated diffusion is mediated by the facilitative glucose transporters
(GLUT) whereas the active transport depends on the sodium vitamin C transporters (SVCT). The gradient-driven transport mediates
the absorption of oxidized form of vitamin C, dehydroascorbic acid (DHA), in an energy-independent manner especially in osteoblast
(15), muscle (16), and retinal cells (17). where the GLUT transporters are predominantly expressed. DHA and glucose share the same
GLUT transporters leading to a competitive inhibition particularly secondary to pathologies that alter serum glucose levels and
attenuate the bioavailability of vitamin C, for instance under hyperglycemic conditions caused by diabetes (18-20).
SVCT transporters, present in humans in 2 isoforms (SVCT1 and SVCT2), actively transfer ascorbate directly into the cell.
SVCT1 is subject to substrate feedback inhibition by ascorbate and its expression is attenuated by high concentrations of vitamin C in
vitro (21) and by oral ingestion (22). SVCT2 is sensitive to the changes in intracellular ascorbate levels (23), which may play a
regulatory role in maintaining ascorbate homeostasis inside the cell (22). Furthermore, age-related decline in SVCT1 expression in
rat liver cells has been observed (24), explaining why elderly individuals require higher levels of vitamin C (25). On the contrary,
unlike SVCT1, SVCT2 levels were not observed to decline with age, perhaps as a result of low abundance of this transporter in the
liver (24).
Generally, high doses of vitamin C can be toxic (26). Excess ascorbate is normally excreted harmlessly in the urine, but the
excess of formation of oxalate can accumulate in various organs in patients with renal failure or renal insufficiency (such as kidney
transplanted patients) and in patients undergoing dialysis (27, 28). Administration of high doses of vitamin C is contraindicative for
patients with oxalate kidney stones or hyperoxaluria (due to the incapacity of eliminating oxalate) and in patients with a deficiency in
glucose-6-phosphate dehydrogenase (due to the occurring of intravascular haemolysis) (26, 29).
4. MECHANISM OF ACTIONS OF VITAMIN C
4.1. Collagen synthesis
Vitamin C is required for collagen synthesis by acting as a cofactor for non-heme iron α-ketoglutarate-dependent
dioxygenases such as prolyl 4-hydroxylase. Vitamin C stimulates all types of collagen synthesis by donating electrons required for
hydroxylation of proline and lysine in procollagen by specific hydroxylase enzymes (30). In the catalytic cycle, the co-substrate, α-
ketoglutarate, undergoes oxidative decarboxylation to form succinate and a highly reactive iron-oxo (Fe+4) species. In the absence of
a substrate molecule, the enzyme becomes uncoupled and then ascorbate reduces oxo-iron back to Fe+2, restoring the enzyme's
activity. Coordination of ascorbate with enzyme-bound iron would provide the necessary electrons in uncoupled reaction cycles to
reactivate the enzyme, consistent with the observation that the role of ascorbate is to keep the non-heme iron in the catalytically
active, reduced state (31). Collagen synthesis is required for maintaining normal vascular function but also for tumor angiogenesis
(32, 33).
4.2. Regulation of hypoxia-inducible factor 1α
Ascorbate has been shown to assist prolyl and lysyl hydroxylases in the hydroxylation of hypoxia-inducible factor 1α (HIF-
1α), a transcription factor responsible for the cellular response to low oxygen conditions through activation of genes controlling
several cellular transduction pathways by regulating growth and apoptosis, cell migration, energy metabolism, angiogenesis,
vasomotor regulation, extracellular matrix and barrier functions, and transport of metal ions and glucose (34, 35). Under normoxic
3
Post-print version, please cite this article as:
Grosso G, Bei R, Mistretta A, Marventano S, Calabrese G, Masuelli L, Giganti MG, Modesti A, Galvano F, Gazzolo D. Effects of
Vitamin C on health: a review of evidence. Front Biosci. 2013 Jun 1;18:1017-29.
Copyright © 2013 Frontiers in Bioscience. All rights reserved.
conditions, the HIF-1α subunit is targeted for degradation by HIF-specific prolyl hydroxylases. Under hypoxic conditions, such as
those existing in fast growing tumors, HIF-1α hydroxylation is repressed with the result that HIF-dependent gene transcription
increases, thus promoting angiogenesis and tumor growth. Because HIF-1α prolyl hydroxylase is stimulated by ascorbic acid, low
vitamin C levels would reduce HIF-1α hydroxylation and thus stabilize HIF-1α, thereby promoting HIF-dependent gene transcription
and tumor growth (36).
4.3. Antioxidant action
In all of its known functions, vitamin C functions as a potent reducing agent that efficiently quenches potentially damaging
free radicals produced by normal metabolic respiration of the body (37). At physiological concentrations, vitamin C is a potent free
radical scavenger in the plasma, protecting cells against oxidative damage caused by ROS (38-41). The antioxidant property of
ascorbic acid is attributed to its ability to reduce potentially damaging ROS, forming, instead, resonance-stabilized and relatively
stable ascorbate free radical (AFR) serving as a one-electron donor (42). The AFR is reduced back to ascorbate within cells by
NADH- and NADPH-dependent reductases that have a high affinity for the low concentrations of the radical generated (43, 44). If
the AFR significantly accumulates in areas not accessible to these enzymes, or if its concentration exceeds their capacity, two
molecules of the AFR reactor dismutate to form one molecule each of ascorbate and DHA (45).
This mechanism might explain a number of cytoprotective functions of vitamin C, including prevention of DNA mutation
induced by oxidation (46-49), protection of lipids against peroxidative damage (50, 51), and repair of oxidized amino acid residues to
maintain protein integrity (50, 52, 53). Since oxidative stress is involved in the pathogenesis of many morbid conditions, vitamin C
(frequently administered in combination with other antioxidants) have been often used to prevent or treat several diseases due to its
antioxidant properties (26, 54) .
4.4. Pro-oxidant action
Vitamin C, under certain conditions such as low concentrations and/or in the presence of free transition metals such as
copper and iron, may function as a pro-oxidant (55). Metal ions are indeed reduced by ascorbate and, in turn, may react with
hydrogen peroxide leading to the formation of highly reactive and damaging hydroxyl radicals (56). The pro-oxidant activity of
vitamin C leads to the formation of ROS (57) or glycated proteins (58). On the other hand, in vitro model suggested that certain pro-
oxidant effects of ascorbate such as the capacity to promote protein thiol oxidation in rat liver microsomes (59) can also be
advantageous.
We next discuss the effects of vitamin C in preventing or treating chronic and acute pathologic conditions due to all its
properties listed above.
5. ANTI-CARCINOGENIC EFFECTS OF VITAMIN C
Since the second half of ‘90s, a growing body of literature aimed at demonstrating that vitamin C may reduce the incidence
of most malignancies in humans (60). Indeed, high-dose of intravenous vitamin C has been found to increase the average survival of
advanced cancer patients and for a small group of responders, survival was increased to up to 20 times longer than that of controls
(61-63). Other researchers reported benefits consisting of increased survival, improved well-being and reduced pain (64, 65). The
anti-inflammatory action of ascorbic acid in cellular ambient is evident in a number of cytoprotective functions under physiological
conditions, including prevention of DNA mutation induced by oxidation (39-41, 46-49). Since DNA mutation is likely a major
contributor to the age-related development of cancer, attenuation of oxidation-induced mutations by vitamin C may be considered as
a potential anti-cancer mechanism (66). Plasma vitamin C at normal to high physiological concentrations (60–100 µmol/L)
neutralizes potentially mutagenic ROS thus decreasing oxidative stress-induced DNA damage (46-49). Moreover, in vivo studies
confirmed that consumption of vitamin C-rich foods is inversely related to the level of oxidative DNA damage (67-70).
Vitamin C may also function as cancer cells killer due to its pro-oxidant capacity (56). The tumor cell-killing action is
dependent upon ascorbate incubation time and extracellular ascorbate concentration (71). The effective concentration of vitamin C
required to mediate cancer killing can be easier achieved by intravenous injection than by per os ingestion (71, 72). Regarding the
modality of cytotoxicity to cancer cells, it remains an unsolved issue. Among the possible mechanisms, stimulatory effects on
apoptotic pathways (73-75), accelerated pro-oxidant damage that cannot be repaired by tumor cells, and increased oxidation of
ascorbate to the unstable metabolite DHA, which in turn can be toxic, have been hypothesized. The killing of cancer cells is
dependent on extracellular H2O2 formation with the ascorbate radical as an intermediate. The H2O2 formed from pharmacological
ascorbate concentrations diffuses into cells (76) and tumor cells are killed by exposure to H2O2 in less than minutes (77-81). The
4
Post-print version, please cite this article as:
Grosso G, Bei R, Mistretta A, Marventano S, Calabrese G, Masuelli L, Giganti MG, Modesti A, Galvano F, Gazzolo D. Effects of
Vitamin C on health: a review of evidence. Front Biosci. 2013 Jun 1;18:1017-29.
Copyright © 2013 Frontiers in Bioscience. All rights reserved.
H2O2 within the cells may cause breaks in DNA and mitochondria and the mitochondria in some cancer cells may have increased
sensitivity to H2O2 (79, 81-83).
Among other mechanisms of anti-cancer action of vitamin C, it has been earlier hypothesized a possible role of ascorbic
acid in increasing collagen synthesis (84) and inhibiting hyaluronidase (85). These mechanisms are supposed to prevent cancer
spread by increasing extracellular matrix, thus walling in tumors (86-88).
In contrast with these results, other studies have reported no effects after using vitamine C as a therapeutic drug (89, 90).
Another randomized, placebo-controlled clinical study in which a high dose of vitamin C was given orally to advanced cancer
patients led to inconsistent results, ultimately casting doubt over the effectiveness of vitamin C in treating cancer (90). Due to the
controversy of results on the vitamin C-cancer correlation and lack of validated mechanistic basis for its therapeutic action, further
research is needed to determine the feasibility of using vitamin C in clinical treatment or prevention of cancer.
6. VITAMIN C AND CARDIOVASCULAR DISEASES
Reactive oxygen species (ROS) are highly reactive molecules that derive mainly from the mitochondrial electron transport
chain and that are necessary for sever normal cellular functions, ranging from their role as signaling molecules to the more
unexpected role in inducing certain cancers. However most studies have linked the excessive generation of ROS, so-called oxidative
stress, to disease states, such as cancer, insulin resistance, diabetes mellitus, cardiovascular diseases, atherosclerosis, and aging (39-
40, 91-94) and superoxide is the most biologically relevant radical in vasculature, as it is naturally produced by most vascular cells
(95). Vitamin C provides collagens synthesis, hence allowing proper folding into the triple helical collagen molecule that is then
secreted to form the extracellular matrix, or to form part of the basement membrane with regard to type IV collagen (33). By contrast,
lack of ascorbate results in friable vessels and especially capillaries that are more prone to rupture, creating the typical petechial
hemorrhages and ecchymoses observed in scurvy and in the cerebral cortex of SVCT2 knockout mice (96).
Vitamin C has been found to prevent apoptosis by blocking the activity of inflammatory cytokines and oxidized LDL both
in cultured endothelial cells (97-99) and patients with congestive heart failure in which treatment with vitamin C decreased release of
microparticles derived from endothelial cells (98).
Results of a randomized, double-blind, placebo-controlled study conducted on subjects with documented coronary artery
disease have shown that long term oral ascorbate supplements do have persistent effects on endothelial-dependent flow-mediated
brachial artery dilation (100). A possible mechanism of action has been thought to depend on the effect of vitamin C on nitric oxide
(NO) synthase. Indeed, vitamin C enhances the NO synthase activity by maintaining tetrahydrobiopterin, an essential co-factor for
the enzyme, in its reduced and active form (101-103), normally inhibited by ROS that oxidize and thus deplete the co-factor. By
increasing NO production, vitamin C may indirectly protect the vascular endothelium due to its actions, namely smooth muscle cell
relaxation, downstream vasodilatation, and inhibition the effects of pro-inflammatory cytokines and adhesion molecules important in
atherosclerosis (104-107). Moreover, due to its antioxidant properties, vitamin C directly reduces nitrite by releasing NO from
nitrosothiols, and scavenges superoxide, although relatively high ascorbate concentrations (>100 µM) are required to prevent the
reaction of superoxide with NO (108).
The role of ascorbate in preventing uncontrolled vascular smooth muscle cells (VSMC) proliferation and dedifferentiation
after acute arterial injury have been investigated in studies of coronary restenosis in pigs (109, 110) and in humans after angioplasty
showing larger luminal diameters in subjects receiving oral vitamin C supplements compared to matched controls who did not
receive ascorbate (111). The mechanism of action is still unclear, since vitamin C has been shown to paradoxically provide collagen
synthesis, necessary for VSMC migration and proliferation (112, 113) and to prevent VSMC dedifferentiation (114, 115). A possible
explanation of the protective role of vitamin C may depend on its role on protecting VSMCs (116) and mature human macrophages
(117) from apoptosis and necrosis due to injury by oxidized LDL (118). Oxidative modification of LDL by ROS, such as superoxide
and hydroxyl radicals, also initiates a sequence of atherogenic events in the sub-endothelial space. Physiological concentrations of
ascorbic acid in vitro attenuate oxidative modification of LDL induced by transition metals (119, 120), homocysteine (121), and
myeloperoxidase-derived HOCl (122, 123), as well as those naturally produced by human vascular endothelial cells (124). The
mechanisms responsible for these actions include the ascorbate capacity of quenching aqueous ROS and reactive nitrogen species
(RNS), decreasing their bioavailability in the plasma, and of reducing the affinity of LDL-bound apolipoprotein B protein for
transition metal ions, enhancing the resistance of LDL to metal ion-dependent oxidation (125).
Macrophages take up modified LDL to become the foam cells and also mediate the inflammatory response that
accompanies atherosclerosis (126). In recent studies performed on mouse peritoneal macrophages it has been found that ascorbate
loading to intracellular concentrations of 3-10 mM prevented oxidative stress induced by latex beads (127) and stimulated several
5
Post-print version, please cite this article as:
Grosso G, Bei R, Mistretta A, Marventano S, Calabrese G, Masuelli L, Giganti MG, Modesti A, Galvano F, Gazzolo D. Effects of
Vitamin C on health: a review of evidence. Front Biosci. 2013 Jun 1;18:1017-29.
Copyright © 2013 Frontiers in Bioscience. All rights reserved.
functions such as adherence, chemotaxis, phagocytosis, and superoxide production (128). Results regarding such effects of vitamin C
have not been uniformly observed and controversy is ongoing between studies assessing that ascorbate inhibits macrophage function
by decreasing uptake and degradation of oxidized human LDL (129-131) and others in which such effect has not been observed (81,
132), maybe due to different in vitro conditions (133, 134).
Regarding the hypothesis that ascorbate is required for synthesis of the collagenous framework of atherosclerotic plaques, a
study performed on apolipoprotein E (ApoE) knockout mice revealed no effect of ascorbate diet on either plaque size or lipid
content. However, plaque collagen content was found to be decreased in animals on marginal ascorbate diet, thus demonstrating that
it plays a role on stability of atherosclerotic plaques becoming capable of rupture with associated thrombosis and infarction (135).
These findings, in light of the several benefits of ascorbate on endothelial cell proliferation, function, and viability, make it plausible
that increased plasma and cell ascorbate concentration might have a preventive effect on potential endothelial dysfunction.
Recently, several studies observed a decrease in plasma vitamin C levels in both type I and type II diabetes, and the effects
of vitamin C administered in different ways, in addition to various combinations of different anti-diabetic drugs and other
antioxidants, have been assessed (136-142). However, at present, no comprehensive agreement regarding its therapeutic effectiveness
for these conditions has been reached.
7. THE ROLE OF VITAMIN C IN CRITICALLY ILL PATIENTS
Vitamin C concentrations in plasma and leukocytes have been reported to be commonly subnormal in critically ill patients
(143), inversely correlating with multiple organs failure (144) and directly with survival (145). Since sepsis is associated with
increased production of ROS and peroxynitrite that deplete antioxidant molecules and oxidize proteins and lipids, potential
therapeutic implication of vitamin C in the treatment of various infections has been studied for a long time. Indeed, enteral
administration of vitamin C and other antioxidants in patients with sepsis has been shown to affect faster recovery (146) whereas
parenteral administration decreased morbidity and mortality (147-149). In vitro and in animal experimental sepsis vitamin C
prevented hypotension and edema in LPS-injected animals (150-152) and improved capillary blood flow, arteriolar responsiveness,
arterial blood pressure, liver function, and survival (153-158). A possible mechanism of such effects may depend on the role of
ascorbate in both inhibiting apoptosis in endothelial cells and stimulating their proliferation preventing the loss of barrier function in
sepsis condition (97-99, 159). Moreover, vitamin C improves arteriolar responsiveness to vasoconstrictors (norepinephrine,
angiotensin, vasopressin) (160, 161) and prevents inhibition of endothelium- dependent vasodilation responses to acetylcholine (162,
163) in human subjects who have inflammatory disease or have been injected with LPS, thus preventing hypotension in sepsis and,
consequently, edema. Another action of ascorbate on endothelial permeability may involve its scavenging action on superoxide and
inhibition of nitric oxide and peroxynitrite formation, as well as its property of reducing the oxidation products formed by reaction of
peroxynitrite with cell proteins (164). These actions of ascorbate may account for its effectiveness in preventing edema in critically
ill patients and experimental models.
8. VITAMIN C EFFECTS ON NERVOUS SYSTEM
Several effects produced by ascorbate have been explored on nervous system (165). Vitamin C can in fact efflux from
various types of cells (166, 167), including neurons (168), because of its hydrophilic nature and negative charge at physiologic pH.
Vitamin C appears to be allowed to enter into several brain cell lines, improving neurotransmission (169) and leading to a number of
effects on behaviors such as learning, memory and locomotion. Experimental animal models have been shown that intraperitoneal
administration of ascorbate reversed memory deficits in mice (170, 171) whereas oral administration, in conjunction with vitamin E,
improved performance on a passive avoidance task in 15 months mice but not in 3-month old mice or when ascorbate was
administered alone (172). In addiction, ascorbate treatments either intraperitoneally for 14 days or orally for 30 days improved both
acquisition and retention in this passive avoidance task (173), contrasting an earlier study in which five days of acute pre-test
ascorbate dosing led to poorer performance (174).
Oral intake of vitamin C has been shown to reduce the fear response in Japanese quail chicks tested in a less stressful light-dark
emergence paradigm (175). Moreover, long-term low levels of dietary ascorbate did not lead to impairments in learning and memory
or anxiety in knockout mice unable to synthesize their own vitamin C (176). However, due to lack of agreement between results
within these experiments and lack of correlation between different dosing regimens used and a clear pattern of results, it’s hard to
identify the exact mechanism through which vitamin C influence memory, although it appears reasonable to consider it a mediator
especially of stress-related learning.
6
Post-print version, please cite this article as:
Grosso G, Bei R, Mistretta A, Marventano S, Calabrese G, Masuelli L, Giganti MG, Modesti A, Galvano F, Gazzolo D. Effects of
Vitamin C on health: a review of evidence. Front Biosci. 2013 Jun 1;18:1017-29.
Copyright © 2013 Frontiers in Bioscience. All rights reserved.
Regarding neurodegenerative diseases, a positive relationships has been shown between ascorbate supplement use and
reduced incidence of Alzheimer's disease (177, 178) that is known to be caused by a combination of genetic and lifestyle factors and
in part by oxidative stress (179), although these beneficial results are not universal (180, 181). Orally administered ascorbate
protected the CA1 area of the hippocampus in rats against oxidative stress and cytokine release induced by injection of fibrillar β-
amyloid (182). It also protected SH-SY5Y neuroblastoma cells from β-amyloid induced apoptosis (183).
Finally, it has been observed that intake of ascorbate as a pharmacological agent may be of benefit in protecting against
Parkinson's disease improving the bioavailability of levodopa (184) although population studies revealed no effects of ascorbate
intake in preventing the development of the disease (185).
9. VITAMIN C IN OCULAR DISEASES
The role of Vitamin C in preventing ocular disease has been evaluated, demonstrating that the development of cataract is
influenced by ascorbate (186) and that a combination of ascorbate with other antioxidant vitamins and minerals slows down the
progression of advanced age-related macular degeneration and loss of visual acuity in people with signs of this disease (187, 188).
The effectiveness of vitamin C as a treatment of diabetic retinopathy has also been examined, but further studies are required to prove
that it has a significant impact on its progress (189).
10. CONCLUSIONS
This review attempts to summarize recent and well established advances in vitamin C research and its clinical implications.
Since vitamin C has the potential to counteract inflammation and subsequent oxidative damage that play a major role in the initiation
and progression of several chronic and acute diseases, it represents a practical tool to administer in humans for the early prevention
of such pathologic conditions. However, many of such well-known beneficial effects of vitamin C intake are still only understood at
the phenomenological level and further research is needed to explore the precise effects of ascorbate in physiological systems and in
the pathology of diseases at the molecular level. A better understanding of the mechanisms of its action is of major importance in
order to define novel potential therapeutic implications regarding vitamin C.
11. ACKNOWLEDGEMENTS
This study was supported by a grant from PRIN 2009 (R.B).
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Post-print version, please cite this article as:
Grosso G, Bei R, Mistretta A, Marventano S, Calabrese G, Masuelli L, Giganti MG, Modesti A, Galvano F, Gazzolo D. Effects of
Vitamin C on health: a review of evidence. Front Biosci. 2013 Jun 1;18:1017-29.
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Grosso G, Bei R, Mistretta A, Marventano S, Calabrese G, Masuelli L, Giganti MG, Modesti A, Galvano F, Gazzolo D. Effects of
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Grosso G, Bei R, Mistretta A, Marventano S, Calabrese G, Masuelli L, Giganti MG, Modesti A, Galvano F, Gazzolo D. Effects of
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Grosso G, Bei R, Mistretta A, Marventano S, Calabrese G, Masuelli L, Giganti MG, Modesti A, Galvano F, Gazzolo D. Effects of
Vitamin C on health: a review of evidence. Front Biosci. 2013 Jun 1;18:1017-29.
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Key Words: vitamin C, ascorbic acid, cardiovascular disease, cancer, anti-inflammation, antioxidant
Send correspondence to: Roberto Bei, MD PhD Associate Professor of General Pathology, Department of Clinical Sciences and
Translational Medicine, Faculty of Medicine, University of Rome "Tor Vergata" Via Montpellier 1, 00133 Rome, Building F Sud,
2nd floor, Room 222 phone: + 39 06-72596522, Fax: + 39 06-72596506, E-mail: bei@med.uniroma2.it
Running title: Vitamin C effects on health
... In the treatment of patients with congestive heart failure, vitamin C decreases the release of endothelial cell-derived microparticles. In cultured endothelial cells, vitamin C treatment prevented apoptosis by blocking the oxidized low-density lipoprotein (LDL) and inflammatory cytokines [71]. Moreover, vitamin C may protect against heart disease by preventing free radicals and plaque formation in the arteries [72]. ...
... Over the past few years, various studies have established that millimolar concentrations of vitamin C may kill cancer cells [13]. Due to its pro-oxidant capacity, vitamin C may function as a killer of cancer cells [71]. A study showed that ascorbate concentrations in plasma higher than 1 mM appeared to have pro-oxidant-like activities, and with the association of metals such as iron and copper, highly reactive hydroxyl radicals were generated that destroyed or damaged the tumor cells [82]. ...
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Vitamin C, also known as L-ascorbic acid, is an essential vitamin with pleiotropic functions, ranging from antioxidant to anti-microbial functions. Evidence suggests that vitamin C acts against inflammation, oxidative stress, autophagy chaos, and immune dysfunction. The ability to activate and enhance the immune system makes this versatile vitamin a prospective therapeutic agent amid the current situation of coronavirus disease 2019 (COVID-19). Being highly effective against the influenza virus, causing the common cold, vitamin C may also function against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and its associated complications. Severe infections need higher doses of the vitamin to compensate for the augmented inflammatory response and metabolic demand that commonly occur during COVID-19. Compelling evidence also suggests that a high dose of vitamin C (1.5 g/kg body weight) in inflammatory conditions can result in effective clinical outcomes and thus can be employed to combat COVID-19. However, further studies are crucial to delineate the mechanism underlying the action of vitamin C against COVID-19. The current review aims to reposition vitamin C as an alternative approach for alleviating COVID-19-associated complications.
... The potential benefits of vitamin C on mortality have been previously reported [43] and several potential mechanisms proposed, including a protective effect on the vascular endothelium, preventing uncontrolled proliferation of vascular smooth muscle cells and inhibition of pro-inflammatory cytokines and adhesion molecules central to the atherogenic processes [44]. Previous studies have also reported associations between higher carotenoid concentrations and lower cancer [7,45], dementia [46] and CVD risk [5][6][7][8][9][10] and between carotenoids and markers of inflammation and oxidative stress [13]. ...
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Background The main underlying risk factors associated with coronary heart disease (CHD) are modifiable and oxidative injury and systemic inflammatory damage represent key aetiological factors associated with the development and progression of CHD and premature mortality. Objective To examine associations of plasma antioxidant status with all-cause mortality and fatal or non-fatal cardiovascular events. Design The PRIME study prospectively evaluated 9709 men aged 50–59 years between 1991 and 1993 in Northern Ireland and France who were free of CHD at recruitment and followed annually for deaths and cardiovascular events for 10 years. Serum concentrations of vitamin C, retinol, two forms of vitamin E (α- and γ-tocopherol) and six carotenoids were quantified by high-performance liquid chromatography. Baseline conventional risk factors were considered, as well as socioeconomic differences and lifestyle behaviours including diet, smoking habit, physical activity, and alcohol consumption through Cox regression analyses. Results At 10 years, there were 538 deaths from any cause and 440 fatal or non-fatal cardiovascular events. After adjustment for country, age, systolic blood pressure, diabetes, body mass index, cholesterol, high density lipoprotein cholesterol, triglycerides, height, total physical activity, alcohol consumption and smoking habit, higher levels of all antioxidants were associated with significantly lower risk of all-cause mortality, with the exception of γ-tocopherol. Only retinol was significantly associated with decreased risk of cardiovascular events in a fully adjusted model. Conclusions Low antioxidant levels contribute to the gradient of all-cause mortality and cardiovascular incidence independent of lifestyle behaviours and traditional cardiovascular and socioeconomic risk factors.
... To reap the benefits of pharmacodynamic relevance, we have demonstrated microenvironmental pH regulation/stabilization of curcumin microspheres using ascorbic acid [42]. Since, ascorbic acid has complementary pharmacological activities (antioxidant, anti-inflammatory, anti-Alzheimer's, anticancer, etc.) to curcumin, pharmacological relevance coupled with stabilization of curcumin in an acidic milieu could outweigh the work reported till date [43][44][45][46]. Ascorbic acid, due to the possibility of structural interactions, may enhance solubility and dissolution of curcumin. ...
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The present investigation aims to develop novel curcumin-ascorbic acid cocrystal for enhancing the solubility, stability, and complementary biological activities for curcumin. Based on in silico approach to screen ascorbic acid as a coformer for curcumin, cocrystals were prepared by the solvent evaporation method, and further evaluated for saturation solubility, cocrystal propensity, physicochemical interactions (FTIR and DSC), XRD, drug dissolution, etc. In silico findings confirmed the suitability (H_ex, G_mix) of ascorbic acid for the cocrystallization of curcumin. The DSC and XRD data of the solvent evaporated curcumin-ascorbic acid mixture confirmed the formation of cocrystal, eutectic, and binary mixture with an excess of coformer. The binary phase diagram implied 0.5 to the 0.65-mole fraction of curcumin, essential for cocrystallization with ascorbic acid. The novel curcumin ascorbic acid cocrystals revealed extraordinary improvement in aqueous solubility of curcumin, especially, 576 fold in distilled water, 10 fold in the buffer pH 1.2, and 9 fold in the buffer pH 6.8. The curcumin-ascorbic acid cocrystal system exhibited a superior dissolution profile compared to neat curcumin. Thus, ascorbic acid has enunciated its role as a coformer for curcumin in cocrystal formation, which has been complemented by predicted complementary biological activities, and stability (acidic milieu).
... At normal concentrations, Vitamin C reduces ROS to form stable ascorbate free radicals that are single electron donors. The free ascorbate radicals either (1) further reduced to ascorbate through reductase enzymes, or (2) combine with each other to form a molecule each of ascorbate and DHA (Grosso et al. 2013 (Brewer 2011). The tocopheroxyl radical can also be reduced by ascorbic acid during the lipid peroxidation chain reaction. ...
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Walnuts had been known for their explicable taste and undebatable health benefits since ancient times. Modern techniques have added evidence to this long-perceived notion by identifying and characterizing the compounds which are responsible for the varied health benefits to human health. Walnuts contain variety of nutritional and non-nutritional components which exhibit antioxidant properties. The polyphenol and flavonoid content of walnuts is higher than many popular nuts. These enclose 10% of their energy as alpha-linolenic acid (ALA). The benefits of walnuts are not achieved through single nutrient, but rather is the outcome of the functional synergy of the phytochemicals enclosed in a complex matrix acting at various metabolic and physiological levels in human body. ALA can be metabolized into several bioactive compounds like oxylipins, which protect microglial cells from inflammation and are effective against cardiovascular diseases; phytomelatonin, known for its anticancer effect; ellagitannins, metabolize into urolithin A and B and protect against obesity, diabetes, and cardiovascular diseases (CVD). Phytosterols are associated with cholesterol-lowering impact through several proposed mechanisms. Non-sodium minerals are associated with better cardiometabolic health. Present chapter highlights the antioxidant potential of walnuts and characterize the compounds exhibiting antioxidant properties. Health benefits of walnut consumption are also covered.
... Vitamin C plays a vital role in tissue growth, synthesis of vasoactive agents, immune regulation, and many other metabolic functions [50,51]. Decreased vitamin C levels are known to support the pathophysiology of various diseases, such as cancer, endocrinopathies, and neurological disorders [52]. The biological significance of vitamin C in the brain is related to the development of neurons, their functional maturation, and antioxidant responses. ...
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Autism spectrum disorders (ASD) are a group of neurodevelopmental syndromes with both genetic and environmental origins. Several recent studies have shown that inflammation and oxidative stress may play a key role in supporting the pathogenesis and the severity of ASD. Thus, the administration of anti-inflammatory and antioxidant molecules may represent a promising strategy to counteract pathological behaviors in ASD patients. In the current review, results from recent literature showing how natural antioxidants may be beneficial in the context of ASD will be discussed. Interestingly, many antioxidant molecules available in nature show anti-inflammatory activity. Thus, after introducing ASD and the role of the vitamin E/vitamin C/glutathione network in scavenging intracellular reactive oxygen species (ROS) and the impairments observed with ASD, we discuss the concept of functional food and nutraceutical compounds. Furthermore, the effects of well-known nutraceutical compounds on ASD individuals and animal models of ASD are summarized. Finally, the importance of nutraceutical compounds as support therapy useful in reducing the symptoms in autistic people is discussed.
... According to the Brazilian law, the recommended daily intake (DIR) of vitamin C is 45 µg per day (Anvisa, 2005), then, the high content of vitamin C in jams indicated that they are a good source of it, and that they can be an important food to meet the daily requirements of this vitamin. Vitamin C is known for its potential to neutralize oxidative damage and, consequently, it acts in the beginning of the progression of several chronic and acute diseases (Grosso et al., 2013). ...
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The objective of this work was to optimize formulations of guabiroba (Campomanesia xanthocarpa) jam by central composite design (CCD), to evaluate the addition of pectin (P), citric acid (CA), and fructo-oligosaccharides (FOS). The responses were pH, titratable acidity, and hardness. The CCRD showed that CA and FOS were meaningful for titratable acidity, while P was meaningful for jam hardness. The optimized formulations were F2 (0% FOS, 0.5% P, and 1.5% CA), F6 (15% FOS, 0.5% P, and 1.5% CA), and F9 (7.5% FOS, 1% P, and 1% CA), which were subjected to chemical composition and sensory analyses. No differences were observed between jam samples for ashes, protein, and lipids. Guabiroba jams showed at least 35% of the original bioactive compounds from fruit, even after the thermal processing. Formulation F9 containing 7.5% FOS shows the best taste, overall impression, and purchase intention.
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The ameliorative antioxidant effect of vitamin C, E, and garlic on tramadol induced toxicity was studied in Wistar rats. Thirty-five (35) rats were used and divided into five study groups with seven rats each. There was a significant decrease in the bodyweight of the negative control group compared with the positive control group. Also, there was a significant increase in the body weight indices of antioxidant vitamins C, E and garlic treated groups when compared with the negative control at (P < 0.05). The organ weight of the liver in the negative control group increased significantly when compared to the weight of the liver in the positive control group. This reveals the metabolic changes in the liver as the site of drug metabolism which resulted in the inflammation of the liver. The weights of the heart and kidney also showed similar differences in the graphs. There was significant decrease in the Na + , K + , level of the negative control compared to the positive control group at (P<0.05). The total level of antioxidants vitamin C, E and garlic increased significantly when compared to the negative control group (P<0.05). The level of K + in the negative control group reduced significantly when compared to the positive control group at (P<0.05) but HCO 3-increased significantly in the negative control compared to the positive control at (P<0.05), in other groups (TmVC, TmVE, TmG), HCO 3-elevated significantly compared to the control group at (P<0.05). The serum activities of female hormones; LH and Estrogen group showed a significant decrease in the negative control group at (P<0.05) when compared to the positive control group at (P<0.05) but in the TmVC, TmVE, TmG group, LH and estrogen showed a significant increase but not as the positive control group.
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Existing data on the kinetics of ascorbate radical decay, together with some new data on the effects of temperature, ionic strength, and presence of phosphate buffers, suggest a mechanism in which the ascorbate radical ion is in equilibrium with a dimer. This dimer reacts with hydrogen ion, or with other proton donors present including water and buffers (at rates depending upon their acid strengths), to form the disproportionation products ascorbate ion and dehydroascorbate acid.