Reviewed by Souad Charifi Hadj, licensed pharmacist no. 2676.
Much is said about vitamin C, and a good part of it is unfounded. This article is about the vitamin C you consume: from food and from supplements. If you're looking for the type applied to the face in serum form, you'll find it in our guide to vitamin C for the skin. These are two different things and should not be confused.
What it does do
Vitamin C is one of the few substances for which the European Union has approved specific claims, because there is evidence to support them. These are the claims that can be made, using these exact words and no others.
Aids in collagen formation. It contributes to normal collagen formation for the normal function of skin, as well as blood vessels, bones, and gums. Collagen is the structural protein for all of these, and without vitamin C, the body does not assemble it properly. This is where its reputation regarding skin comes from, and in that respect, the reputation is well-deserved.
Helps absorb iron. It increases the absorption of iron from plant sources, which is less efficiently utilized. This is why squeezing half a lemon over lentils or spinach is not just an old wive's tale: it works.
Helps reduce tiredness and fatigue and contributes to normal energy metabolism. Note the nuance: this doesn't mean it acts as a stimulant or gives you a boost. It means that without enough vitamin C, this metabolism doesn't function as it should.
Protects cells from oxidative damage and contributes to the normal function of the immune system. It also helps regenerate the active form of vitamin E, which is one of the reasons why the two often appear together in formulas.
Vitamin C and sun: this is where most people get confused
You'll read out there that vitamin C is a "natural sunscreen." It is not, and it's important to state this clearly because the confusion has consequences.
A sunscreen filters or reflects ultraviolet radiation before it enters the skin, which is why it's measured in SPF. Vitamin C does none of that: it has no SPF and cannot be measured in SPF. What it does is act afterwards, neutralizing some of the oxidative damage that radiation leaves in its wake. It is a complement to sunscreen, never a substitute.
In other words: vitamin C cleans up some of the mess, but it doesn't prevent it from happening. The only way to prevent it is with sunscreen, shade, and clothing.
What it doesn't do, no matter how often it's repeated
Here, we need to be honest, even if it's less marketable.
It doesn't erase wrinkles. It contributes to normal collagen formation, which is not the same thing. An established wrinkle will not disappear with vitamin C, whether taken or applied.
It doesn't heal wounds or scars. Collagen is part of the tissue repair process, yes, but to say that vitamin C heals cuts, bruises, or acne scars is a leap that cannot be made. If you have a wound that won't heal or scars that worry you, a healthcare professional should examine them.
It doesn't make hair grow or nails harder. There are no approved claims for vitamin C in this regard. What can happen is that, if you have low iron and it shows in your hair, improving iron absorption can indirectly help. But the main player there is iron, not vitamin C.
It doesn't prevent colds. It contributes to the normal functioning of the immune system, which is different from preventing you from catching a cold.
How much you need and where to get it
The reference value you'll see on European labels is 80 mg per day for an adult. This amount is easily covered with food: one kiwi, half a raw red pepper, a medium orange, or a handful of strawberries will get you there or close. Red pepper, by the way, contains significantly more vitamin C than an orange, even though the orange has gotten all the fame.
Two things worth knowing. Vitamin C is sensitive to heat and water, so a raw pepper provides more than one cooked for a long time. And smokers need significantly more than others, because tobacco accelerates its consumption in the body.
Regarding supplements: it's not a vitamin that accumulates, because excess is eliminated through urine. This doesn't mean that more is better. Above one gram per day, digestive discomfort is common, and if you have a history of kidney stones or are taking medication, consult your doctor or pharmacist first.
Frequently asked questions
Does vitamin C replace sunscreen?
No. It does not filter ultraviolet radiation or have SPF. It acts as an antioxidant against some of the damage caused by the sun, but it does not prevent that damage. Sunscreen remains non-negotiable.
Is it better to take it orally or apply it to the skin?
They are different things and do not compete. The one you take supports collagen formation and other bodily functions. The one you apply acts on the skin's surface as a topical antioxidant. We explain it in depth in the vitamin C guide for skin.
How much vitamin C do I need per day?
The reference value on European labels is 80 mg daily for an adult. This is easily covered with a diet that includes fresh fruit and vegetables daily.
Can I take too much?
Excess is eliminated through urine, but exceeding one gram daily usually results in digestive discomfort. If you are taking medication or have a history of kidney stones, consult first.
Is orange the best source?
It's good, but not the best. Raw red pepper, kiwi, parsley, and cabbages often surpass it. And since heat degrades it, raw wins over cooked.
And for the skin, what do I use?
If you're interested in applied vitamin C, with its concentrations, forms, and typical mistakes, you can find it developed in vitamin C for skin. And if you want to see what we have, start with facial serums and sunscreen, which is the pair that truly works together.
This article is for informational purposes only and does not replace the advice, diagnosis, or treatment of a healthcare professional. Food supplements are not a substitute for a balanced diet.