3/5
Moderate
evidence
Immune support evidence brief
Vitamin C
Vitamin C is important when intake is low, but routine high-dose use has limited evidence for preventing colds or improving training adaptation.
Headline Finding
Cochrane: routine vitamin C did not prevent colds in the general population, but shortened duration modestly and helped some high-stress groups.
Dose Context
Meet dietary needs first. Research doses vary widely; megadosing is not needed for most users and can cause gastrointestinal side effects.
Important Caveat
It should not be framed as a general immune shield or recovery upgrade. Very high antioxidant dosing may not suit every training context.
Source Drawer
Linked Research
- Review Cochrane common cold review
- Review Cochrane plain-language summary
- Review NIH ODS vitamin C fact sheet
- Review Exercise antioxidant adaptation review
- Review Vitamin C and exercise review
How To Read This Rating
The score reflects evidence that the supplement does its stated job. Some jobs are direct, such as strength, endurance, or recovery; others are indirect, such as sleep, mood, appetite, or health support. A real effect can still receive a cautious practical rating when dose, safety, product quality, or audience fit remain uncertain.
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