CWeak evidence, or evidence againstVitamin
The short answer
Does not prevent colds. May marginally shorten them. One orange and a pepper get you past the reference intake without a tablet.
Who this is actually for
People with very low fruit and vegetable intake, and smokers, whose requirement is higher.
What it is legally allowed to claim
Quoted from the EU register of authorised health claims, Regulation (EU) 432/2012. A product may only make these claims if it supplies enough of the nutrient to qualify.
- Vitamin C contributes to the normal function of the immune system
- Vitamin C contributes to normal collagen formation for the normal function of blood vessels
- Vitamin C increases iron absorption
How much is too much
No EFSA upper level. Doses above about 1000 milligrams commonly cause diarrhoea.
Cautions and interactions
High doses raise the risk of oxalate kidney stones in susceptible people and interfere with some blood glucose meters.
Ask a pharmacist before you start anything. Interactions with prescribed medicines are the most common way supplements cause harm, and they are easy to check. Bring the actual packet, or a photo of the ingredients panel, because doses and forms vary enormously between products. Nothing here is a substitute for advice about your own situation.