Vitamin C

Also known as: ascorbic acid, liposomal vitamin C, L-ascorbate

Grade A — Strong Evidencevitaminantioxidant
500–2000 mgSplit doses throughout day with meals

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.

🛡️Immunity✨Skin & Hair🧬Longevity
Last reviewed: 2026-03-12

Quick Facts

Evidence

Grade A

Studies

2

Interactions

3

Forms

1

Evidence Rating: Grade A — Strong Evidence

Multiple high-quality RCTs, systematic reviews, or meta-analyses with consistent findings.

Interaction Warnings

Chemotherapy drugsModerate

May interfere with certain chemo agents. Consult oncologist.

Iron supplementsLow

Dramatically increases non-heme iron absorption — take together for deficiency

WarfarinLow

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 PubMed

Vitamin C and immune function

Carr AC & Maggini S (2017) — Nutrients

Supports various cellular functions of both innate and adaptive immunity

View on PubMed

Alternatives to Consider

These supplements target similar goals and may be worth considering alongside or instead of Vitamin C.

Selenium

Grade B

Essential trace mineral for thyroid function (T4→T3 conversion) and antioxidant defense. Reduces Hashimoto's antibodies.

🛡️ Immunity🧬 Longevity✨ Skin & Hair

Vitamin D3

Grade A

Essential hormone precursor. Most people in northern latitudes are deficient. Strong evidence for immunity, bone health, and mood.

🛡️ Immunity🧬 Longevity

Vitamin A

Grade A

Fat-soluble vitamin essential for immunity, vision, skin, and reproduction. Most people with varied diets are not deficient. Preformed vitamin A is teratogenic at high doses — use beta-carotene in pregnancy.

🛡️ Immunity✨ Skin & Hair

Related Supplements

Selenium

Grade B — Moderate Evidence

Essential trace mineral for thyroid function (T4→T3 conversion) and antioxidant defense. Reduces Hashimoto's antibodies.

Vitamin E

Grade B — Moderate Evidence

Fat-soluble antioxidant important for cell membrane protection, immune function, and skin health. Moderate doses (200-400 IU) appear safe and beneficial. High doses (>400 IU) linked to increased mortality risk in meta-analyses. Choose mixed tocopherols and natural forms.

Vitamin D3

Grade A — Strong Evidence

Essential hormone precursor. Most people in northern latitudes are deficient. Strong evidence for immunity, bone health, and mood.

NAC (N-Acetyl Cysteine)

Grade B — Moderate Evidence

Precursor to glutathione (master antioxidant). Strong evidence for respiratory health, liver support, and psychiatric conditions.

🧪 Get Your Personalized Stack

See how Vitamin C fits with your goals and current supplements — AI-powered, evidence-graded recommendations.

⚕️ 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.

DoseGrade does not sell supplements and has no affiliate relationships with supplement manufacturers.