Ingredient guide
Vitamin C: evidence, dose and safety
Vitamin C (ascorbic acid) is a water-soluble vitamin found in fruit and vegetables. People cannot make it, so it must come from food or supplements.
At a glance
- Strongest evidence
- B Good
- Dose in our plans
- 250 mg a day for adults
- Adult upper limit
- 1800 mg a day from food and supplements together
- Safety checks
- 3 situations and 0 medicine or supplement interactions, checked against your answers in every plan
- Reviewed
- Atrum Labs clinical team (MD, PhD), November 2026
Authorised EU health claim
Vitamin C contributes to normal collagen formation for the normal function of skin.
What the research looked at
Each line is one body of research, graded A (strong) to D (weak). How we grade evidence. What each study measured is explained in your personal plan.
| Grade | Who was studied | References |
|---|---|---|
| B | People supplementing iron |
|
| B | Smokers |
|
How much
- Our plans usually use 250 mg a day for adults. The exact dose depends on your lab results, age and medicines.
- Adult upper limit: 1800 mg a day from food and supplements together. Source: IOM 2000 vitamin C UL.
- Children's doses are set by age, and some ingredients are for adults only.
Who should not take it, or should check first
- Not suitable. Vitamin C increases iron absorption.
- A lower dose is used. High-dose vitamin C increases oxalate stone risk.
- Not suitable. Vitamin C is broken down to oxalate; risk of oxalate kidney stones and kidney damage when kidneys work poorly or with past stones.
Written and reviewed by the Atrum Labs clinical team (physician-scientists, MD, PhD) from our clinical knowledge base, version 0.2.0-draft. This page is general information, not medical advice. Food supplements are not a substitute for a varied, balanced diet and a healthy lifestyle.
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