Can humans produce vitamin c
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Can Humans Produce Vitamin C?
Human Inability to Synthesize Vitamin C
Humans, unlike most other vertebrates, cannot synthesize vitamin C. This inability is due to the functional loss of the gene coding for L-gulonolactone oxidase, an enzyme crucial for the biosynthesis of vitamin C 237. As a result, humans must obtain this essential nutrient through their diet, primarily from fruits and vegetables 123.
Dietary Sources and Bioavailability
Vitamin C, also known as ascorbic acid, is a water-soluble micronutrient found abundantly in various plant-based foods. It is chemically identical whether derived from synthetic sources or natural foods. However, fruits and vegetables contain additional nutrients and phytochemicals that may influence the bioavailability of vitamin C 1. Despite these potential differences, studies have shown that the bioavailability of synthetic and natural vitamin C is generally equivalent in humans 1.
Physiological Roles of Vitamin C
Vitamin C plays multiple critical roles in human physiology. It acts as a potent antioxidant and a cofactor for numerous enzymes involved in various metabolic processes. These include collagen synthesis, iron absorption, immune function, and the regulation of gene transcription and epigenetics 2349. Its antioxidant properties help protect cells from oxidative stress, which is crucial for maintaining overall health and preventing chronic diseases 49.
Health Implications of Vitamin C Deficiency
A deficiency in vitamin C can lead to scurvy, a condition characterized by impaired collagen synthesis, leading to symptoms such as bleeding gums, joint pain, and anemia 5. Additionally, vitamin C deficiency can compromise immune function, making individuals more susceptible to infections 4. Adequate intake of vitamin C is essential for maintaining optimal health and preventing these adverse effects.
Optimal Intake Recommendations
The recommended dietary allowance (RDA) for vitamin C is primarily based on preventing deficiency diseases like scurvy. However, higher intakes may offer additional health benefits, such as reducing the risk of chronic diseases like cardiovascular disease and certain cancers 6. Current evidence suggests that an intake of around 200 mg per day is optimal for most adults to maximize the health benefits of vitamin C while minimizing the risk of inadequacy or adverse effects 6.
Conclusion
Humans cannot produce vitamin C due to the loss of a crucial biosynthetic enzyme. Therefore, it is essential to obtain this vital nutrient through dietary sources. Vitamin C plays numerous roles in maintaining health, from acting as an antioxidant to supporting immune function. Ensuring adequate intake through a balanced diet rich in fruits and vegetables is crucial for preventing deficiency and promoting overall well-being.
Sources and full results
Most relevant research papers on this topic
Synthetic or Food-Derived Vitamin C—Are They Equally Bioavailable?
Synthetic and food-derived vitamin C have no significant differences in bioavailability, but animal studies show differences depending on study design and body compartments.
Literature Review
Rigorous Journal
Highly CitedVitamin C: the known and the unknown and Goldilocks.
Vitamin C's role in the body is complex and dependent on physiologic concentrations, with new knowledge and questions still requiring further investigation.
Highly CitedVitamin C in Plants: From Functions to Biofortification
Increasing vitamin C content in crops can improve human health and enhance their nutritional value and stress resistance.
Highly CitedVitamin 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 CitedTopically applied vitamin C enhances the mRNA level of collagens I and III, their processing enzymes and tissue inhibitor of matrix metalloproteinase 1 in the human dermis.
Topical vitamin C stimulates collagen production and enhances dermal cell function in postmenopausal women, with the most notable effect in those with the lowest dietary intake of vitamin C.
RCTHighly CitedAuthors' Perspective: What is the Optimum Intake of Vitamin C in Humans?
200 mg per day is the optimal dietary intake of vitamin C for most adults, maximizing potential health benefits with the least risk of inadequacy or adverse effects.
Highly CitedThe biosynthetic pathway of vitamin C in higher plants
The study identifies a novel pathway for vitamin C synthesis in plants, potentially increasing their nutritional value and stress tolerance.
Highly CitedVitamin C for the treatment of sepsis: The scientific rationale
Intravenous vitamin C reduces organ injury and improves survival in sepsis models, with potential synergistic effects with corticosteroids and thiamine.
Highly CitedVitamin C in Stem Cell Reprogramming and Cancer.
Vitamin C may play a novel role as an epigenetic anticancer agent by modulating stem cell function and enhancing fibroblast reprogramming to induced pluripotent stem cells.
Highly CitedVitamins C and E: beneficial effects from a mechanistic perspective.
Vitamin C and E supplementation may help control tumor progression, infections, and inflammation by regulating tumor growth, energy metabolism, and neutrophil function.
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