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Vitamin C

Vitamin C

Best for

Catch fewer colds and infections

Proven strong benefit for 8–14 weeks · 4 meta-analyses , n=36.9k

64 papers · 4 claims · 129 outcomes scored · 4 positive

Outcomes

What vitamin c actually does, by outcome

Each row is one outcome with effect size, evidence base, the dose that worked in trials, and time to first effect. Magnitude tiers come from native-unit MCID where available, Cohen's d otherwise.

Outcome Effect Evidence Dose Weeks Rank
Catch fewer colds and infections Proven strong benefit
large 		5 meta-analyses n=37k Meta-analyzed 0.05–2000 g 8–14 wk #1/17
Raise antioxidant vitamin levels Promising early signal
moderate 		12 meta-analyses n=711 Meta-analyzed 52–1500 mg 0–16 wk #1/4
Recover from colds faster Faint early signal
small 		6 meta-analyses n=126 Meta-analyzed 1–8000 mg 1–8 wk #5/10
Ease cold and flu severity Not enough research
trivial 		6 meta-analyses n=862 Meta-analyzed 1–8000 g 1–8 wk #5/17
Buy well

Recommended Vitamin C products

Real products that dose Vitamin C where the research does, in a clean formulation, from brands we've audited. We only list ones we'd stand behind.

Chosen for adequate Vitamin C dosing vs. the studied range, a clean formulation (grade A–C), and independent brand-quality audits. Not sponsored.

Risk profile

Adverse events and known drug interactions

Safety events

oxalate nephropathy severe
skin rash severe
Oxalate nephropathy leading to end-stage renal disease severe
kidney stones severe
hypokalemia severe
acute kidney injury severe
oxalate crystal deposition severe
Haemolysis severe

Drug interactions

Bortezomib major decreases effect
Doxorubicin major decreases effect
Warfarin moderate increases effect
Warfarin moderate unknown
Antineoplastic Agents moderate increases effect
Aspirin minor decreases concentration
Atorvastatin minor additive

Co-studied with

Supplements that share evidence with vitamin c

Sources

  1. 1. Vitamin C treatment reduces elevated C-reactive protein. (2009) ↑
  2. 2. Cross-over study of influence of oral vitamin C supplementation on inflammatory status in maintenance hemodialysis patients. (2013) ↑
  3. 3. Vitamin C supplementation for pregnant smoking women and pulmonary function in their newborn infants: a randomized clinical trial. (2014) ↑
  4. 4. Vitamin C supplementation slightly improves physical activity levels and reduces cold incidence in men with marginal vitamin C status: a randomized controlled trial. (2014) ↑
  5. 5. Determination of plasma and leukocyte vitamin C concentrations in a randomized, double-blind, placebo-controlled trial with Ester-C(®). (2016) ↑
  6. 6. Comparative effects of vitamin D and vitamin C supplementations with and without endurance physical activity on metabolic syndrome patients: a randomized controlled trial. (2018) ↑
  7. 7. Association between vitamin B group supplementation with changes in % flow-mediated dilatation and plasma homocysteine levels: a randomized controlled trial. (2019) ↑
  8. 8. Vitamin C supplementation promotes mental vitality in healthy young adults: results from a cross-sectional analysis and a randomized, double-blind, placebo-controlled trial. (2022) ↑
  9. 9. Effects of Oral Vitamin C Supplementation on Liver Health and Associated Parameters in Patients With Non-Alcoholic Fatty Liver Disease: A Randomized Clinical Trial. (2021) ↑
  10. 10. Efficacy of Vitamin C Supplementation on Chronic Obstructive Pulmonary Disease (COPD): A Systematic Review and Meta-Analysis. (2022) ↑

Generated August 14, 2026

Related

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