COVID-19 and nutritional deficiency: a review of existing knowledge.

COVID-19 has resulted in an ongoing global pandemic, which spread largely among people who have had close contact with the infected person. The immunopathology of the SARS-CoV-2 virus includes the production of an excess amount of pro-inflammatory cytokines "a cytokine-storm". The respiratory system (main), cardiovascular system and the gastrointestinal tract are the most affected body systems during viral infection. It has been found that most of the patients who require admission to hospital are elderly or have chronic underlying diseases. Higher cases of malnutrition and co-morbidities like diabetes mellitus and cardiovascular diseases are reported in elderly patients due to which, the immune system weakens and hence, the response to the virus is diminished in magnitude. A deficiency of micronutrients results in impaired immune responses leading to improper secretion of cytokines, alterations in secretory antibody response and antibody affinity which increases susceptibility to viral infection. The deficiency of various micronutrients in COVID-19 patient can be treated by appropriate nutritional supplements, prescribed after evaluating the patients' nutritional status. Here we aim to highlight the role of a few particular nutrients namely Vitamin D, Vitamin C, Omega-3 fatty acids, Zinc and Magnesium along with the synergistic roles they play in enhancing immunity and thus, maintaining homeostasis.

Water-Soluble Vitamins in Human Milk Factors Affecting Their Concentration and Their Physiological Significance.

Most B vitamins and vitamin C are among the nutrients in milk most strongly affected by maternal status and/or dietary intake. Recent analytical methods are more efficient and valid, revealing major differences in water-soluble vitamins across population groups. An inadequate supply in milk can be detrimental to the breastfed infant's health and development although cutoff points below which risk is increased are often uncertain, and little attention has been paid to adverse effects of low milk water-soluble vitamins on infant health and function. Concentrations change during lactation: thiamine, niacin, and pantothenic acid increase; B6, B12, and ascorbic acid gradually decrease; while riboflavin concentrations are stable, as is choline after an initial increase. Folate fluctuates until stabilizing in late lactation. Water-soluble vitamin concentrations in milk are also influenced by maternal supplementation, and, for some, by parity, preterm delivery, smoking, and maternal illness. However, there is relatively little change in concentrations during a feed nor is diurnal variation a major influence. Reported concentrations are used to set adequate intakes for infants and incremental requirements for lactation. However, the status of available data is poor due to the small number of participants in most studies, uncertainties about maternal nutritional status, and variable times of milk collection postpartum.

The role of vitamin C in epigenetic regulation.

Vitamin C (L-ascorbic acid) is a micronutrient best known for its anti-scurvy activity in humans. Vitamin C is involved in many biological processes involving enzymatic reactions that are catalyzed by members of dioxygenases which use Fe(II) and 2-oxoglutarate as a co-substrate.The article reviews recent data that suggest the involvement of ascorbate in dioxygenases catalyzed chromatin and DNA modifications which thereby contribute to epigenetic regulation. Concerning chromatin modification, the dioxygenases are involved in distinct demethylation reactions with varying specificity for the position of the lysine on the target histone. TET hydroxylases catalyse the oxidation of methyl groups in the 5 position of cytosine in DNA yielding 5-hydroxymethylcytosine, while further iterative oxidation reactions results in the formation of 5-formylcytosine and 5-carboxylcytosine. A few previous studies demonstrated that ascorbate may enhance generation of 5-hydroxymethylcytosine in cultured cells, probably acting as a cofactor of TETs during hydroxylation of 5-methylcytosine. Physiological concentrations of ascorbate in human serum (10-100 µM) may guarantee stable level of 5-hydroxymethylcytosine, a modification necessary for epigenetic function of the cell. 5-Hydroxymethylcytosine level is substantially decreased in almost all investigated cancers, what may be linked with cancer development. Therefore, it is possible that supplementation with ascorbate could contribute to better management of individual cancer patient. This issue is also discussed in our paper.

[Dual action of vitamin C versus degradation and supplementation]. / Dwukierunkowe dzialanie witaminy C a degradacja i suplementacja.

The article discusses vitamin C from the point of view of its supplementation with food and in the form of oral supplements. The dual action of vitamin C is connected with the presence of oxygen, which may reduce the amount of the vitamin in food products, influence thermal resistance, cause degradation and show an antioxidation effect. Vitamin C stimulates the immune cells and collagen synthesis. It may protect the LDL fraction against oxidation, and therefore it is interesting for cosmetology, rheumatology, immunology and dietetics. The latest research with respect to vitamin C proved that it has the ability to dissolve neurotoxic senile plaques. Equally effective in the treatment of Alzheimer's disease is the oxidised form of vitamin C, i.e. dehydroascorbic acid. Vitamin C may be used in a combined vitamin E supplementation to avoid the pro-oxidative effect and reduce the risk of diabetes mellitus type 2 complications. In the review there is a description of the types of vitamin C degradation depending on a specific factor such as pH, temperature, oxygen, enzyme and the impact of diet on the quantity of the supplied vitamin. The literature data confirmed the positive influence of vitamin C as an addition to food. The last part of the article presents the methods of vitamin C protection used in food processing technology and of determining its content in food products. Additionally, the article describes the problems related to vitamin C oxidation processes during food processing and storage. The presented research results indicate that an adequate diet contains a sufficient amount of vitamin C for healthy people. In the case of chronic patients it is better to use supplementation.

There's life in the old dog yet: vitamin C as a therapeutic option in endothelial dysfunction.

The use of vitamin C against different diseases has been controversially and emotionally discussed since Linus Pauling published his cancer studies. In vitro and animal studies showed promising results and explained the impact of vitamin C, particularly in cases with endothelial dysfunction. Indeed, studies (reviewed in this issue of Critical Care by Oudemans-van Straaten and colleagues) using high-dose vitamin C and the parenteral route of application seem to be more successful than oral vitamin C delivery.

Vitamin C revisited.

This narrative review summarizes the role of vitamin C in mitigating oxidative injury-induced microcirculatory impairment and associated organ failure in ischemia/reperfusion or sepsis. Preclinical studies show that high-dose vitamin C can prevent or restore microcirculatory flow impairment by inhibiting activation of nicotinamide adenine dinucleotide phosphate-oxidase and inducible nitric oxide synthase, augmenting tetrahydrobiopterin, preventing uncoupling of oxidative phosphorylation, and decreasing the formation of superoxide and peroxynitrite, and by directly scavenging superoxide. Vitamin C can additionally restore vascular responsiveness to vasoconstrictors, preserve endothelial barrier by maintaining cyclic guanylate phosphatase and occludin phosphorylation and preventing apoptosis. Finally, high-dose vitamin C can augment antibacterial defense. These protective effects against overwhelming oxidative stress due to ischemia/reperfusion, sepsis or burn seems to mitigate organ injury and dysfunction, and promote recovery after cardiac revascularization and in critically ill patients, in the latter partially in combination with other antioxidants. Of note, several questions remain to be solved, including optimal dose, timing and combination of vitamin C with other antioxidants. The combination obviously offers a synergistic effect and seems reasonable during sustained critical illness. High-dose vitamin C, however, provides a cheap, strong and multifaceted antioxidant, especially robust for resuscitation of the circulation. Vitamin C given as early as possible after the injurious event, or before if feasible, seems most effective. The latter could be considered at the start of cardiac surgery, organ transplant or major gastrointestinal surgery. Preoperative supplementation should consider the inhibiting effect of vitamin C on ischemic preconditioning. In critically ill patients, future research should focus on the use of short-term high-dose intravenous vitamin C as a resuscitation drug, to intervene as early as possible in the oxidant cascade in order to optimize macrocirculation and microcirculation and limit cellular injury.

Role of vitamins D, E and C in immunity and inflammation.

Inflammatory responses are operationally characterized by pain, redness, heat and swelling at the site of infection and trauma. Mast cells reside near small blood vessels and, when activated, release potent mediators involved in allergy and inflammation. Vitamin D modulates contraction, inflammation and remodeling tissue. Vitamin D deficiency has been linked to multiple diseases and several data have demonstrated a strong relationship between serum vitamin D levels and tissue function. Therapy targeting vitamin D3 signaling may provide new approaches for infectious and inflammatory skin diseases by affecting both innate and adaptive immune functions. Mast cells are activated by oxidized lipoproteins, resulting in increased expression of inflammatory cytokines and suggesting that the reduction of oxidation of low density lipoprotein by vitamin E may also reduce mast cell activation. Vitamin C is also an anti-oxidant well-known as an anti-scurvy agent in humans. Vitamin C inhibits peroxidation of membrane phospholipids and acts as a scavenger of free radicals and is also required for the synthesis of several hormones and neurotransmitters. In humans, vitamin C reduces the duration of common cold symptoms, even if its effect is not clear. Supplementation of vitamin C improves the function of the human immune system, such as antimicrobial and natural killer cell activities, lymphocyte proliferation, chemotaxis and delayed-type hypersensitivity. Vitamin C depletion has been correlated with histaminemia which has been shown to damage endothelial-dependent vasodilation. However, the impact of these vitamins on allergy and inflammation is still not well understood.

The role of antioxidants in photoprotection: a critical review.

Free radicals have long been studied as a contributor to aging and disease processes. Endogenous production of radicals from cellular metabolism and exogenous sources from ultraviolet radiation and pollution can damage the skin on the cellular and tissue levels. Although the body possesses an elegant defense system to prevent radical damage, this innate system can be overwhelmed and lead to a state of oxidative stress or immunosuppression, and can even trigger carcinogenesis. Topical supplementation of antioxidants can provide additional protection to neutralize reactive oxygen species from both endogenous and exogenous sources. This review will discuss our current understanding of the mechanisms of free radical damage and evaluate the potential benefit of topical antioxidants in sunscreens and skin care products.

Vitamin C transport and its role in the central nervous system.

Vitamin C, or ascorbic acid, is important as an antioxidant and participates in numerous cellular functions. Although it circulates in plasma in micromolar concentrations, it reaches millimolar concentrations in most tissues. These high ascorbate cellular concentrations are thought to be generated and maintained by the SVCT2 (Slc23a2), a specific transporter for ascorbate. The vitamin is also readily recycled from its oxidized forms inside cells. Neurons in the central nervous system (CNS) contain some of the highest ascorbic acid concentrations of mammalian tissues. Intracellular ascorbate serves several functions in the CNS, including antioxidant protection, peptide amidation, myelin formation, synaptic potentiation, and protection against glutamate toxicity. The importance of the SVCT2 for CNS function is supported by the finding that its targeted deletion in mice causes widespread cerebral hemorrhage and death on post-natal day 1. Neuronal ascorbate content as maintained by this protein also has relevance for human disease, since ascorbate supplements decrease infarct size in ischemia-reperfusion injury models of stroke, and since ascorbate may protect neurons from the oxidant damage associated with neurodegenerative diseases such as Alzheimer's, Parkinson's, and Huntington's. The aim of this review is to assess the role of the SVCT2 in regulating neuronal ascorbate homeostasis and the extent to which ascorbate affects brain function and antioxidant defenses in the CNS.

Ascorbic acid: an old player with a broad impact on body physiology including oxidative stress suppression and immunomodulation: a review.

Ascorbic acid is a low molecular weight antioxidant well known as anti-scorbut acting vitamin C in humans, primates and guinea pigs. This review summarizes basic data about ascorbic acid in its physiological action point of view. It is divided into biochemistry of ascorbic acid synthesis, mechanism of antioxidant action and participation in anabolism, pharmacokinetics and excretion, exogenous ascorbic acid immunomodulatory effect and participation in infectious diseases, impact on irradiation and intoxication pathogenesis, and supplementary demands. The primary intention was to consider ascorbic acid not only as an antioxidant but also as a chemical compound affecting multiple pathways with a potential beneficial impact in many diseases and processes in human body.

Effect of vitamin C depletion on age-related hearing loss in SMP30/GNL knockout mice.

Using senescence marker protein 30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice, which cannot synthesize vitamin C (VC), we examined whether modulating VC level affects age-related hearing loss (AHL). KO and wild-type (WT) C57BL/6 mice were given water containing 1.5 g/L VC [VC(+)] or 37.5mg/L VC [VC(-)]. At 10 months of age, KO VC(-) mice showed significant reduction in VC level in the inner ear, plasma, and liver, increase in auditory brainstem response (ABR) thresholds, and decrease in the number of spiral ganglion cells compared to WT VC(-), WT VC(+), and KO VC(+) mice. There were no differences in VC level in the inner ear, ABR thresholds, or the number of spiral ganglion cells among WT VC(-), WT VC(+), and KO VC(+) mice. These findings suggest that VC depletion can accelerate AHL but that supplementing VC may not increase VC level in the inner ear or slow AHL in mice.

Vitamin C and the role of citrus juices as functional food.

The literature on the content and stability of vitamin C (ascorbic acid, AA) in citrus juices in relation to industrial practices is reviewed. The role of vitamin C from citrus juices in human diet is also reviewed. Citrus fruits and juices are rich in several types of bioactive compounds. Their antioxidant activity and related benefits derive not only from vitamin C but also from other phytochemicals, mainly flavonoids. During juice processing, temperature and oxygen are the main factors responsible for vitamin C losses. Non-thermal processed juices retain higher levels of vitamin C, but economic factors apparently delay the use of such methods in the citrus industry. Regarding packing material, vitamin C in fruit juice is quite stable when stored in metal or glass containers, whereas juice stored in plastic bottles has a much shorter shelf-life. The limiting step for vitamin C absorption in humans is transcellular active transport across the intestinal wall where AA may be oxidized to dehydroascorbic acid (DHAA), which is easily transported across the cell membrane and immediately reduced back to AA by two major pathways. AA bioavailability in the presence of flavonoids has yielded controversial results. Whereas flavonoids seem to inhibit intestinal absorption of AA, some studies have shown that AA in citrus extract was more available than synthetic ascorbic acid alone. DHAA is reported to possess equivalent biological activity to AA, so recent studies often consider the vitamin C activity in the diet as the sum of AA plus DHAA. However, this claimed equivalence should be carefully reexamined. Humans are one of the few species lacking the enzyme (L-gulonolactone oxidase, GLO) to convert glucose to vitamin C. It has been suggested that this is due to a mutation that provided a survival advantage to early primates, since GLO produces toxic H2O2. Furthermore, the high concentration of AA (and DHAA) in neural tissues could have been the key factor that caused primates (vertebrates with relative big brain) to lose the capacity to synthesize vitamin C. Oxidative damage has many pathological implications in human health, and AA may play a central role in maintaining the metabolic antioxidant response. The abundance of citrus juices in the Mediterranean diet may provide the main dietary source for natural vitamin C.

[Vitamin C and immune function]. / Vitamin C und Immunfunktion.

The immune system is strongly influenced by the intake of nutrients. For a long time there has been a controversy whether vitamin C can contribute to the prevention and therapy of the common cold. Several cells of the immune system can indeed accumulate vitamin C and need the vitamin to perform their task, especially phagocytes and t-cells. Thus a vitamin C deficiency results in a reduced resistance against certain pathogens whilst a higher supply enhances several immune system parameters. With regard to the common cold different studies including meta-analyses underline that the prophylactic intake of vitamin C may slightly reduce the duration of the illness in healthy persons but does not affect its incidence and severity. Supplementation of vitamin C is most effective in cases of physical strain or insufficient intake of the vitamin. With regard to the therapy of the common cold the application of vitamin C alone is without clinical effects.

Attitudes and practices of dentists with respect to nutrition and periodontal health.

OBJECTIVE: To determine the opinions and attitudes of general dental practitioners and hygienists towards the role of nutrition in periodontal health. SETTING: The study was completed by general dental practitioners and dental hygienists throughout the UK. METHOD: A questionnaire was sent out with the British Dental Journal and BDA News together with explanatory information about the study. Postage was pre-paid for replies. RESULTS: Eight hundred and seventy-nine questionnaires were completed. Sixty-six percent of respondents believed nutrition plays a role in periodontal health. Dietary factors that were considered most important were vitamin C (70%), fruit and vegetables (64%) and antioxidant vitamins (45%). Forty-four percent had recommended nutrition supplements to their patients, with multivitamin and mineral supplements (37%) and vitamin C (30%) the most popular. Eighty-two percent of respondents sourced information from dental journals. Qualitative data highlighted uncertainty amongst respondents about the evidence base around nutrition and periodontal health and a lack of training opportunities. CONCLUSIONS: A majority of dentists consider that nutrition and dietary factors play a role in maintaining periodontal health. However, there was a need to increase awareness of the current state of the evidence for a role of nutrition in maintaining periodontal health. Concern regarding lack of an evidence base for the role of nutrition in the treatment of periodontal diseases suggests a need for further research into the therapeutic role of nutrition in periodontal disease management.

Nutritional support for patients with infected wounds.

Many factors affect wound healing, including nutritional status and recent nutritional intake. Patients with infected wounds have increased requirements for nutrients and often have a reduced food intake. It is therefore important that nutritional status is carefully considered, and all patients should be screened for malnutrition using a nutrition screening tool. Nutrition plans should aim to provide sufficient energy while maintaining good glycaemic control, adequate protein and hydration, and a minimum of 100% reference nutrient intake for micronutrients. Measures required to achieve this will vary, as all patients should be assessed on an individual basis.

Protecting antioxidative effects of vitamins E and C in experimental physical stress

Like every redox-active compound vitamin E may exert pro-oxidative and antioxidativeeffects depending on the reaction partners present. In this work we evaluatedthe intensity of oxidative stress produced by a physical exercise through swimmingas well as of protecting action of antioxidant vitamins E and C. Antioxidantsystems include antioxidant enzymes: superoxide-dismutase (SOD), catalase (CAT),glutathion peroxidase (GSH-Px), as well as of components with an antioxidant actionof the reduced glutathion type (GSH) and vitamins E and C. We determine the activitiesof these enzymes in the erythrocytes and heart homogenate. Our results pointsout a protective effect against oxidative stress produced by swimming in animalstreated with vitamins E and C, which are expressed through the diminution of themalondialdehyde (MDA) quantity both in erythrocytes and in the heart, and throughthe conservation of GSH content in both products. CAT and GSH-Px activitiesdecrease while that of SOD increases on both tissues, but with different intensities inaccordance with the variation of protection degree performed by the vitamin coupleon these tissues. The obtained data underline the necessity of intensifying the meansof endogenous antiradical defence with exogenous antioxidant vitamins C and E.This study highlights the need of a proper vitamin supplement in organism understress (AU)

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