Vitamin C supports the immune system, skin and iron absorption. Most people get enough from fruit and vegetables.
Calculator Official intake Study doses Expert targets Best form Works with Safety Sources
PRI (population reference intake)
| Men | 110 mg |
|---|---|
| Women | 95 mg |
| Pregnancy | 105 mg |
| Breastfeeding | 155 mg |
Safe upper limit: not set
No safe limit set.
RDA (recommended dietary allowance)
| Men | 90 mg |
|---|---|
| Women | 75 mg |
| Pregnancy | 85 mg |
| Breastfeeding | 120 mg |
Safe upper limit: 2,000 mg a day
Smokers need 35 mg more per day (NIH).
Source: National Academies (NASEM) 2019
These are doses tested in research, not personal advice. Some exceed the upper limit because they were short courses or given under medical care.
200-2,000 mg a day
Cochrane review: taking at least 200 mg every day did not prevent colds in most people, but colds were about 8% shorter in adults and 14% shorter in children. Starting only after symptoms began showed no consistent effect.
500 mg a day
AREDS gave 500 mg vitamin C with vitamin E, beta-carotene, zinc and copper to people who already had intermediate macular degeneration. The full combination lowered the odds of advanced disease by about 28%. Vitamin C was never tested alone, and people without the disease were not shown to benefit.
These targets come from named organisations, not from EFSA or the NIH. They are listed so you can see the case for a higher intake, with the source behind each one.
400 mg a day
The Linus Pauling Institute recommends at least 400 mg vitamin C a day for adult men and women, against the EFSA value of 110 mg for men and 95 mg for women. The institute was founded by Linus Pauling, who argued for high-dose vitamin C.
Best form
Ascorbic acid
Why: Plain ascorbic acid is absorbed as well as vitamin C from food. In comparisons, Ester-C and ascorbic acid with bioflavonoids gave the same blood levels, so the NIH calls simple ascorbic acid the preferred source.
Alternatives: Buffered forms (sodium or calcium ascorbate) can be easier on a sensitive stomach.
Vitamin C helps the body absorb iron from plant foods and supplements (non-heme iron). Taking them together is a simple way to absorb more.
Peppers, kiwi, citrus, berries, broccoli, potatoes.
Increases iron absorption from plant foods and supplements.
Very high doses can cause diarrhoea and may add to kidney stone risk in men.
Pregnant, breastfeeding, on medication, or managing a health condition? Check with a doctor or pharmacist before starting a supplement.
Values checked: November 12, 2026.
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