Vitamin C
Research indicates vitamin C supplementation may support immune function and antioxidant defense, with established evidence for preventing deficiency-related conditions.
Human Trials
150
12,500 participants
Risk Level
Monthly Cost
Basic ascorbic acid supplements are cheapest; liposomal and time-release formulations cost more
Quick Facts
- Category
- Supplement
- Research Field
- Supplements
- Evidence Grade
- B+ – Good
- Risk Level
- Low
- Monthly Cost
- $5 – $30
- Human Trials
- 150
Typical Dose
500–1000 mg/day
Range
250–2000 mg/day
For informational purposes only – not medical advice. See disclaimer
Research Velocity
Mechanism of Action
Vitamin C functions as a potent antioxidant, neutralizing reactive oxygen species and supporting collagen synthesis through its role as a cofactor for prolyl and lysyl hydroxylases. Research indicates it enhances immune cell function by supporting neutrophil chemotaxis and lymphocyte proliferation. Studies suggest vitamin C also regenerates other antioxidants like vitamin E and may influence gene expression related to inflammatory pathways.
Overview
Vitamin C (ascorbic acid) is a water-soluble vitamin essential for collagen synthesis, immune function, and antioxidant defense. Research indicates that while most people obtain adequate vitamin C from diet, supplementation may provide additional benefits for immune support, particularly during periods of physical stress or illness. Large-scale studies suggest that vitamin C supplementation can reduce the duration and severity of common cold symptoms, though it appears less effective for prevention in the general population.
Studies examining vitamin C's antioxidant properties indicate it may help protect against oxidative stress and support cardiovascular health, though evidence for preventing major diseases remains mixed. The vitamin shows promise in wound healing and may support exercise recovery through its anti-inflammatory effects. Research suggests that vitamin C's bioavailability is limited at high doses, with the body maintaining tight regulation of plasma levels, making moderate dosing strategies potentially more effective than megadoses.
Safety research indicates vitamin C supplementation is generally well-tolerated, with gastrointestinal upset being the most common side effect at higher doses. The tolerable upper limit is set at 2000mg daily for adults. Studies suggest that individuals with certain genetic variations, smokers, and those under physical stress may have higher vitamin C requirements, potentially benefiting more from supplementation.
Known Interactions
- May enhance iron absorption when taken together
- High doses may interfere with certain laboratory tests including glucose and stool occult blood tests
- May reduce effectiveness of some chemotherapy drugs
- Can increase aluminum absorption from antacids
- May interact with warfarin by affecting INR levels
Legal Status by Country
Your country (United States)
Available without prescription in:
Australia, Brazil, Canada, China, Colombia, Germany, India, Israel, Japan, Mexico, Netherlands, Panama, Russia, South Korea, Switzerland, Thailand, Turkey, UAE, United Kingdom, United States
📍 = your selected country · ✈️ = medical tourism destination · Always verify current local regulations before travel.
Key Research
- 2017
Comprehensive review of vitamin C's role in immune system support
- 2019
Meta-analysis of cardiovascular outcomes with vitamin C supplementation
- 2017
Overview of vitamin C's therapeutic and preventive applications
- 2013
Cochrane review examining vitamin C's effects on common cold prevention and treatment
Related Interventions
Acetyl-L-Carnitine (ALCAR)
Research suggests acetyl-L-carnitine may support mitochondrial function, cognitive performance, and cellular energy metabolism.
Alpha-Lipoic Acid
A potent antioxidant supplement that research indicates may improve insulin sensitivity and reduce oxidative stress.
Apigenin
Research suggests apigenin, a flavonoid found in chamomile and parsley, may support cellular longevity through multiple anti-aging pathways.
Ashwagandha (KSM-66)
Adaptogenic herb showing promise for stress reduction, cortisol management, and cognitive function in multiple human trials.
Last verified: 2026-03-16