Vitamin C
Ascorbic Acid
Also known as: L-Ascorbic Acid, Ascorbate
Vitamin C is an essential water-soluble vitamin known for its potent antioxidant properties and crucial role in immune system support.
Introduction
Vitamin C, also known as ascorbic acid, is a vital water-soluble nutrient involved in a wide range of physiological processes. It acts as a potent antioxidant, supports immune defense by enhancing various cellular functions, and plays a critical role in collagen synthesis, necessary for wound healing and maintaining healthy skin, cartilage, bones, and blood vessels. It also improves the absorption of non-heme iron, supports neurotransmitter function, and may contribute to cardiovascular and cognitive health. Since humans cannot synthesize Vitamin C endogenously, it must be consumed regularly through diet or supplementation. While scurvy due to deficiency is rare in developed nations, marginal deficiency can still impair immune function and increase oxidative stress.
Main Benefits
Contributes to the normal function of the immune system, particularly during and after intense physical exercise.
Contributes to the protection of cells from oxidative stress.
Contributes to normal collagen formation for the normal function of skin, cartilage, bones, and blood vessels.
Increases non-heme iron absorption from plant-based foods.
Mechanism of Action
Vitamin C operates primarily as an electron donor, functioning as a powerful antioxidant that neutralizes free radicals and reactive oxygen species in aqueous environments. It supports the immune system by stimulating white blood cell production and function and helps regenerate other antioxidants like vitamin E. Vitamin C is also a necessary cofactor in enzymatic reactions that produce collagen, carnitine, and several neurotransmitters. Furthermore, it enhances non-heme iron absorption by reducing iron from the ferric to ferrous form.
Natural Sources
Vitamin C is naturally abundant in fresh fruits and vegetables. Citrus fruits such as oranges and grapefruits, strawberries, kiwi, bell peppers, broccoli, Brussels sprouts, and leafy greens are especially rich sources.
Examples:
Oranges
Grapefruits
Strawberries
Kiwi
Bell peppers
Broccoli
Brussels sprouts
Spinach
A balanced diet with regular intake of fruits and vegetables typically provides sufficient Vitamin C.
Deficiency Symptoms
Vitamin C deficiency can cause scurvy, a condition marked by fatigue, inflammation of the gums, joint pain, and impaired wound healing. Early signs include irritability and general malaise. Long-term deficiency can result in severe complications if not addressed.
Common Symptoms:
Fatigue
Swollen or bleeding gums
Joint pain
Poor wound healing
Irritability
Anemia
Deficiency is rare in developed countries but more prevalent among smokers, alcoholics, and malnourished individuals.
Untreated deficiency can lead to serious outcomes like scurvy and impaired immunity.
Recommended Daily Intake
Recommended intake values for Vitamin C vary by age, sex, and physiological condition. Guidelines from institutions like the NIH and EFSA help ensure sufficient intake across populations.
Reference Values:
| Adult men | 90 mg/day |
| Adult women | 75 mg/day |
| Pregnant women | 85 mg/day |
| Lactating women | 120 mg/day |
| Children (1–3 years) | 15 mg/day |
| Children (4–8 years) | 25 mg/day |
| Children (9–13 years) | 45 mg/day |
| Adolescents (14–18 years) | 65–75 mg/day |
Sources for RDI/AI:
- https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
- https://www.efsa.europa.eu/en/efsajournal/pub/3418
These values are general recommendations. Always consult a healthcare provider for personalized guidance.
Effectiveness for Specific Focuses
Supported by multiple studies demonstrating improved immune defense and reduced cold duration.
Required for collagen synthesis, essential for skin structure and wound healing.
Its antioxidant activity may reduce oxidative stress linked to aging processes.
Longevity Impact
Vitamin C’s antioxidant capacity may help mitigate cellular damage associated with aging. While not directly proven to extend lifespan, it plays a role in cellular repair and inflammation modulation which may indirectly support longevity.
Evidence is emerging but not conclusive.
Safety Information
Potential Side Effects
Diarrhea
Nausea
Abdominal cramps
Contraindications
Individuals with a history of kidney stones
Patients with iron overload disorders (e.g., hemochromatosis)
Overdose Information
Vitamin C is generally well tolerated but high doses may cause gastrointestinal upset.
High doses can cause gastrointestinal symptoms such as diarrhea, nausea, and abdominal cramps. Kidney stone risk may increase in predisposed individuals.
Documented Overdose Symptoms:
Diarrhea
Nausea
Abdominal cramps
Kidney stones
Toxicity Thresholds: UL: 2,000 mg/day (Source: NIH)
Vitamin C has low toxicity due to renal excretion, but chronic high intake may pose risk in susceptible individuals.
Interactions
Drug Interactions:
May interfere with chemotherapy effectiveness.
May cause false readings in certain lab tests (e.g., blood glucose).
Generally low risk but context-dependent in clinical settings.
Other Supplement Interactions:
Enhances iron absorption when taken concurrently with iron supplements.
Mostly beneficial interactions, minimal risk.
Use cautiously in individuals with kidney issues or iron metabolism disorders. Always follow dosage instructions.
Forms and Bioavailability
Vitamin C is available in several forms including ascorbic acid, sodium ascorbate, calcium ascorbate, and liposomal formulations. Absorption is typically efficient, with only minor differences between standard forms.
Ascorbic Acid
The most common form, well absorbed at standard doses.
Well established in clinical research.
Can cause mild stomach upset in sensitive individuals.
Sodium Ascorbate
Buffered form that is gentler on the stomach.
Comparable to ascorbic acid with better GI tolerance.
Calcium Ascorbate
Combines Vitamin C with calcium; good for sensitive stomachs.
Offers additional calcium benefits.
Liposomal Vitamin C
Encapsulated for enhanced absorption.
Preliminary data suggests higher uptake.
Warnings & Suitability
Did You Know...?
British sailors were historically given citrus fruits to prevent scurvy.
Unlike most animals, humans cannot synthesize Vitamin C.
General Scientific Sources
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Content Verification
Last Medical Review: 5/17/2025
Reviewed by: Editorial Team