Vitamin c and immune function
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The Role of Vitamin C in Immune Function
Vitamin C and Immune Defense Mechanisms
Vitamin C, also known as ascorbic acid, is a crucial micronutrient with multiple roles in the human body, particularly in immune function. It acts as a potent antioxidant and a cofactor for various biosynthetic and gene regulatory enzymes. Vitamin C supports the immune system by enhancing the functions of both the innate and adaptive immune responses. It strengthens the epithelial barrier against pathogens and promotes the oxidant scavenging activity of the skin, which helps protect against environmental oxidative stress1.
Vitamin C and Neutrophil Function
Neutrophils, a type of phagocytic cell, accumulate high levels of vitamin C, which enhances their chemotaxis, phagocytosis, and the generation of reactive oxygen species, ultimately leading to effective microbial killing. Vitamin C is also essential for the apoptosis and clearance of spent neutrophils from infection sites, reducing tissue damage1 2. Studies have shown that vitamin C supplementation can improve various neutrophil functions, including chemotaxis and oxidative burst activity, particularly in specific populations such as athletes and patients with myocardial infarction2.
Vitamin C and Lymphocyte Function
While the role of vitamin C in lymphocytes is less clear, it has been shown to enhance the differentiation and proliferation of B- and T-cells, likely due to its gene-regulating effects1. In elderly patients, vitamin C supplementation has been associated with improved cell-mediated immune function, including increased T-cell counts and enhanced lymphocyte proliferation3 4. Additionally, vitamin C is essential for the maturation of T-cells, influencing the selection of functional T-cell receptors and the expression of key genes involved in T-cell development8.
Vitamin C Deficiency and Immune Impairment
Vitamin C deficiency can lead to impaired immunity and increased susceptibility to infections. Infections, in turn, deplete vitamin C levels due to enhanced inflammation and metabolic demands1. In young grass carp, vitamin C deficiency was shown to decrease immune function and structural integrity, leading to increased inflammation and susceptibility to infections7.
Vitamin C Supplementation and Infection Prevention
Supplementation with vitamin C has been shown to prevent and treat respiratory and systemic infections. Prophylactic intake of vitamin C at adequate levels (100-200 mg/day) can optimize cell and tissue levels, while treatment of established infections may require higher doses to meet the increased inflammatory and metabolic demands1. In the context of COVID-19, vitamin C has been suggested to enhance antiviral immunity and reduce excessive inflammatory responses, potentially improving patient outcomes10.
Conclusion
Vitamin C plays a vital role in supporting various aspects of the immune system, from enhancing neutrophil and lymphocyte functions to maintaining epithelial barriers and reducing oxidative stress. Adequate intake of vitamin C is essential for preventing immune impairment and reducing susceptibility to infections. Supplementation may be particularly beneficial in specific populations and during periods of increased immune stress, such as infections or critical illnesses.
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Most relevant research papers on this topic
Vitamin C and Immune Function
Vitamin C contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune systems, enhancing microbial killing, and preventing and treating respiratory and systemic infections.
Very Rigorous Journal
Highly CitedVitamin C and Neutrophil Function: Findings from Randomized Controlled Trials
Vitamin C supplementation may improve neutrophil functions, but future randomized controlled trials should incorporate prescreening for low vitamin C status and appropriate dosing regimens.
Systematic ReviewVery Rigorous JournalThe effect of dietary supplementation with vitamins A, C and E on cell-mediated immune function in elderly long-stay patients: a randomized controlled trial.
Dietary supplementation with vitamins A, C, and E can improve cell-mediated immune function in elderly long-stay patients.
RCTHighly CitedEffect of vitamin C supplements on cell-mediated immunity in old people.
Vitamin C supplements can enhance T lymphocyte proliferation and tuberculin skin hypersensitivity in elderly individuals, but do not significantly affect serum IgA, IgG, and IgM levels.
RCTHighly CitedVitamin C and immune cell function in inflammation and cancer
Low vitamin C levels can negatively impact immune cell function, cell metabolism, and epigenetics, potentially affecting inflammation and cancer.
Highly CitedThe Long History of Vitamin C: From Prevention of the Common Cold to Potential Aid in the Treatment of COVID-19
Vitamin C supplementation may be beneficial for certain groups at high risk of infection, but its effectiveness in reducing respiratory infections remains unclear.
Literature ReviewHighly CitedDietary vitamin C deficiency depresses the growth, head kidney and spleen immunity and structural integrity by regulating NF-κB, TOR, Nrf2, apoptosis and MLCK signaling in young grass carp (Ctenopharyngodon idella).
Vitamin C deficiency in young grass carp decreases immunity and causes inflammation, while also affecting structural integrity and related signaling molecules.
Highly CitedVitamin C promotes maturation of T-cells.
Ascorbic acid plays a crucial role in T-cell maturation and enhances immune function through its role in lymphoid cell-intrinsic development and epigenetic mechanisms.
In Vitro StudyHighly CitedThe Role of Physiological Vitamin C Concentrations on Key Functions of Neutrophils Isolated from Healthy Individuals
Neutrophils in healthy individuals can regulate their uptake of ascorbate to maintain optimal cell functioning, but higher oral intakes may help reduce tissue damage and inflammation associated with neutrophil extracellular trap formation.
In Vitro StudyVery Rigorous JournalThe Role of Vitamin C, Vitamin D, and Selenium in Immune System against COVID-19
Vitamin C, vitamin D, and selenium supplements can enhance the immune system's response to COVID-19 by improving physical barrier, preventing cytokine storms, and enhancing T cell maturation and antibody production.
Highly Cited