Functions of vitamins
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Functions of Vitamins: A Comprehensive Overview
Vitamin D: Calcium Homeostasis and Immune Modulation
Classical Functions: Calcium and Bone Health
Vitamin D is well-known for its role in regulating calcium and phosphorus homeostasis, which is crucial for maintaining bone health and metabolism 147. It facilitates the absorption of calcium and phosphate in the intestines, mobilizes calcium in bones, and aids in calcium reabsorption in the kidneys 7.
Non-Classical Functions: Immune System Regulation
Beyond its skeletal functions, vitamin D plays a significant role in modulating the immune system. It has been observed that vitamin D deficiency is linked to chronic conditions like diabetes, asthma, and rheumatoid arthritis, which are associated with increased inflammation and immune system deregulation 14. Vitamin D receptors (VDR) are present in various immune cells, including B and T lymphocytes, monocytes, macrophages, and dendritic cells, indicating its role in immune function 1. Vitamin D and VDR signaling help suppress autoimmunity and reduce inflammatory responses by promoting regulatory T-cell differentiation and decreasing Th17 cell response 1.
Vitamin C: Antioxidant and Immune Support
Antioxidant Properties
Vitamin C is a potent antioxidant that helps protect cells from oxidative stress by donating electrons 3. It supports the epithelial barrier function against pathogens and enhances the skin's oxidant scavenging activity, thereby protecting against environmental oxidative stress 3.
Immune Function Enhancement
Vitamin C is crucial for various cellular functions in both the innate and adaptive immune systems. It accumulates in phagocytic cells like neutrophils, enhancing their chemotaxis, phagocytosis, and microbial killing capabilities 3. Additionally, it aids in the apoptosis and clearance of spent neutrophils, reducing potential tissue damage 3. Vitamin C also supports the differentiation and proliferation of B- and T-cells, contributing to a robust immune response 3.
B Vitamins: Cellular Metabolism and Brain Health
Metabolic Functions
B vitamins are essential for numerous cellular functions, acting as coenzymes in various catabolic and anabolic enzymatic reactions 8. They play critical roles in energy production, DNA/RNA synthesis and repair, and the synthesis of neurochemicals and signaling molecules 89.
Brain Function and Cognitive Health
Adequate levels of B vitamins are vital for optimal brain function. They are involved in energy-yielding metabolism, oxygen transport, and neuronal functions, which are crucial for cognitive and psychological processes 810. Deficiencies in B vitamins can lead to cognitive impairments and increased mental and physical fatigue 10.
Vitamin E: Antioxidant and Cellular Signaling
Antioxidant Role
Vitamin E, particularly α-tocopherol, is known for its antioxidant properties, protecting cells from oxidative damage 6. It has been studied for its potential in preventing chronic diseases associated with oxidative stress 6.
Beyond Antioxidant Functions
Recent studies suggest that α-tocopherol has specific signaling functions in vascular smooth muscle cells that other tocopherols do not possess 6. Additionally, γ-tocopherol can trap electrophilic mutagens in lipophilic compartments, indicating roles beyond antioxidation 6.
Conclusion
Vitamins play multifaceted roles in maintaining human health, from supporting metabolic functions and immune responses to protecting against oxidative stress and enhancing cognitive functions. Understanding these diverse functions underscores the importance of adequate vitamin intake through diet or supplementation to prevent deficiencies and promote overall well-being.
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Most relevant research papers on this topic
Vitamin D: Nutrient, Hormone, and Immunomodulator
Vitamin D plays a critical role in maintaining a healthy immune system, suppressing autoimmunity and reducing inflammation in chronic conditions like diabetes, asthma, and rheumatoid arthritis.
Very Rigorous Journal
Highly CitedRevisiting food-sourced vitamins for consumer diet and health needs: a perspective review, from vitamin classification, metabolic functions, absorption, utilization, to balancing nutritional requirements
Food-sourced vitamins are essential for human metabolism and health, with their bioavailability dependent on food composition and interactions, and their toxicity from supplementation is rare.
Systematic Review
Rigorous JournalVitamin 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 JournalHighly CitedRole of Vitamin D Beyond the Skeletal Function: A Review of the Molecular and Clinical Studies
Vitamin D plays a crucial role in regulating cellular proliferation, differentiation, apoptosis, and immunity, potentially impacting various human diseases.
Literature ReviewHighly CitedVitamin E: function and metabolism
Vitamin E has antioxidant properties and may have other functions beyond just preventing chronic diseases, but its precise role and metabolism remain unclear.
Highly CitedOverview of general physiologic features and functions of vitamin D.
Vitamin D3 plays a crucial role in calcium absorption, phosphate absorption, bone mobilization, and kidney reabsorption, with new selective analogs for therapy emerging.
Highly CitedB Vitamins and the Brain: Mechanisms, Dose and Efficacy—A Review
Adequate levels of all eight B-vitamins are essential for optimal physiological and neurological functioning, and addressing deficiencies in these vitamins, rather than just homocysteine metabolism, is crucial for brain health.
Literature ReviewVery Rigorous JournalHighly CitedThiamin function, metabolism, uptake, and transport.
Thiamin plays a crucial role in energy metabolism, neuronal communication, immune system activation, and cell-membrane dynamics, with complex uptake and transport processes involving various protein families.
Highly CitedVitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence
B vitamins, vitamin C, iron, magnesium, and zinc play crucial roles in cognitive and psychological processes, and their deficiency can lead to fatigue and mental symptoms.
Literature ReviewVery Rigorous JournalHighly Cited