Ingredient evidence
Vitamin C
A nutrient with important, unglamorous jobs, sold at doses ten times higher than your body can use.
Also sold as: ascorbic acid.
Our read of the evidence
Good evidence
Multiple decent human trials point the same way.
Genuinely important nutrient, rarely deficient in the UK. Useful with iron; wasted at megadoses.
What the evidence actually shows
Vitamin C is an essential cofactor in collagen synthesis, which is why it appears alongside collagen supplements with a real rationale rather than a marketing one. It also converts dietary iron into a more absorbable form, which is its most practically useful supplement role for women managing low iron.
For colds, the honest summary is that routine supplementation does not prevent them in the general population, but regular intake may slightly shorten how long they last. That is a very small return for a daily habit.
Absorption is saturable. As doses rise past a few hundred milligrams, the fraction absorbed drops sharply and the rest is excreted. A 1,000mg tablet mostly produces expensive urine, and past that point the main effect is loose stools.
How to take it.
- Typical dose
- 40mg daily is the UK requirement; 100-200mg is a sensible supplemental ceiling
- Form
- Plain ascorbic acid is fine; buffered forms are gentler on the stomach
- Timing
- With iron supplements, to improve absorption
- Worth knowing
- Doses above 1,000mg daily commonly cause stomach pain and diarrhoea, and may increase kidney stone risk in susceptible people.
What it will not do.
- It will not prevent colds
- It will not boost immunity if your intake is already adequate
- It will not be absorbed in any useful quantity above a few hundred milligrams at once
Who should avoid it.
- You have a history of oxalate kidney stones and are considering high doses
- You have haemochromatosis - vitamin C increases iron absorption
Raise with a prescriber
- Increases iron absorption, which is usually desirable but not in iron overload
- Very high doses can interfere with some blood glucose meter readings
Products containing vitamin c.
Everything below is stocked in the UK. Compare on the active dose and the cost per day rather than the size of the pack.
| Product | Key actives | Form | Price | Per day | Best for |
|---|---|---|---|---|---|
| The Collagen ElixirWelleCo | Marine collagen | Powder | £49 | £1.63 | Skin elasticity and hydration, Perimenopausal skin changes, Anyone already eating enough protein |
| Wild Nutrition Food-Grown Iron PlusWild Nutrition | Iron (food-grown), Vitamin C | Capsule | £20.00 | 67p | Confirmed low ferritin, Heavy periods, after testing, Taking alongside iron |
| Perfectil OriginalVitabiotics | Biotin, Zinc, Selenium | Tablet | ~£12 | - | General hair, skin and nail nutrient cover |
| Liquid Iron FormulaFloradix | Iron, Vitamin C, B12 | Liquid | ~£15 | - | Heavy periods and low iron intake, Anyone who cannot tolerate iron tablets |
| Wild Nutrition Collagen 500 PlusWild Nutrition | Collagen peptides, Vitamin C | Capsule | £42.50 | £1.42 | Adding protein simply, Joint comfort alongside strength work, Taking alongside iron |
| Ultra WomanHolland & Barrett | Iron, B vitamins, Zinc | Tablet | ~£10 | - | Everyday nutritional cover, Budget-conscious buyers |
| Wild Nutrition Women's Daily Multi NutrientWild Nutrition | Multivitamin, Iron, Vitamin D | Capsule | £44.00 | £1.47 | UK winter, Low sun exposure, Confirmed low ferritin |
| DR.VEGAN Gentle Iron & Vitamin CDR.VEGAN | Iron bisglycinate, Vitamin C | Capsule | £11.99 | 20p | Confirmed low ferritin, Heavy periods, after testing, Taking alongside iron |
| ARTAH Essential Iron ComplexARTAH | Iron, Vitamin C, B12, Folate | Capsule | £20.00 | 33p | Confirmed low ferritin, Heavy periods, after testing, Taking alongside iron |
Prices are the brand's UK list price at the time of writing and change often. Cost per day is calculated from pack size and the label's daily serving, and is shown only where both are published.
Common questions.
How much vitamin C do I actually need?
40mg a day in the UK, which an ordinary diet with some fruit and vegetables provides. Supplemental doses above 200mg give diminishing returns.
Should I take vitamin C with iron?
Yes, this is its most useful supplement role. Taking iron with a vitamin C source meaningfully improves absorption.
Can you take too much vitamin C?
Above about 1,000mg daily most people get stomach pain and diarrhoea, and people prone to kidney stones should be cautious.
Where this comes from.
A supplement is not clinical care.
If symptoms are affecting your work, your sleep or your relationships, the useful next step is an assessment rather than another purchase. Our check-in takes three minutes and points you to the right kind of clinician.
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Other ingredients
Good evidence. Highly effective when you are deficient. Potentially harmful when you are not. Get tested.
Reasonable evidence. Real but small skin effects. If your total protein intake is low, plain protein and vitamin C matter more.
Good evidence. Vitamin D is a genuine UK public health recommendation. K2 is reasonable, optional and oversold.
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Food supplements are not medicines and are not intended to diagnose, treat or cure any condition. They should not replace a varied diet or prescribed treatment. If you are pregnant, breastfeeding, taking medication or managing a diagnosed condition, check with a pharmacist or clinician before starting anything on this page. We do not accept payment for inclusion or placement. Where a link earns us a commission we say so on the product page. Last reviewed 27 August 2026.