Vitamin C
Also known as: ascorbic acid, liposomal vitamin C, L-ascorbate
Recommended Dosage
500–2000 mg
Vitamin C (ascorbic acid) is an essential water-soluble vitamin that humans cannot synthesize — we lost this ability through a genetic mutation millions of years ago. Beyond its well-known immune support role, vitamin C is critical for collagen synthesis (skin, joints, blood vessels), serves as a major antioxidant, and enhances iron absorption. While severe deficiency (scurvy) is rare today, suboptimal levels are common and associated with impaired immunity.
TL;DR: Essential antioxidant vitamin. Supports immune function, collagen synthesis, and antioxidant defense. 50% infection reduction in athletes.
Evidence Rating: Grade A — Strong Evidence
Multiple high-quality RCTs, systematic reviews, or meta-analyses with consistent findings.
Interaction Warnings
May interfere with certain chemo agents. Consult oncologist.
Dramatically increases non-heme iron absorption — take together for deficiency
High doses (>1g/day) may alter INR in some individuals
⚠️ Important Notes
- Bowel tolerance indicates max useful dose
- Liposomal form has better absorption
- High doses: kidney stone risk in susceptible individuals
Clinical Evidence (2 studies)
Vitamin C for prevention and treatment of the common cold
Hemilä H, Chalker E (2013) — Cochrane Database Syst Rev
8% duration reduction in adults; 50% incidence reduction in extreme-stress populations (29 RCTs)
View on PubMedVitamin C and immune function
Carr AC & Maggini S (2017) — Nutrients
Supports various cellular functions of both innate and adaptive immunity
View on PubMedRelated Supplements
Selenium
Grade B — Moderate EvidenceEssential trace mineral for thyroid function (T4→T3 conversion) and antioxidant defense. Reduces Hashimoto's antibodies.
Vitamin D3
Grade A — Strong EvidenceEssential hormone precursor. Most people in northern latitudes are deficient. Strong evidence for immunity, bone health, and mood.
NAC (N-Acetyl Cysteine)
Grade B — Moderate EvidencePrecursor to glutathione (master antioxidant). Strong evidence for respiratory health, liver support, and psychiatric conditions.
Astaxanthin
Grade C — PreliminaryExtremely potent antioxidant carotenoid. Promising for skin health and exercise recovery. Still building human evidence.
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⚕️ Important Disclaimer
This information is for educational purposes only. It is not medical advice. Always consult a healthcare provider before starting any supplement regimen, especially if you take medications or have health conditions.
Evidence Stack does not sell supplements and has no affiliate relationships with supplement manufacturers.