What is vitamin C and what is it for?

Vitamin C is an essential nutrient that your body neither produces nor stores, and its most important function is one almost nobody mentions: without vitamin C your body cannot make collagen. It isn't that it makes it worse. It cannot make it. It's a chemical requirement, not an optional extra. Here we explain what vitamin C is, what it really is for, how much you need and what it doesn't do, even though it's often said.

What is vitamin C?

Vitamin C, also called ascorbic acid, is a water-soluble vitamin: it dissolves in water and doesn't accumulate in body fat. That has two practical consequences. The first is that you need to consume it every day, because the body eliminates what it doesn't use through urine. The second is that it's hard to get poisoned by it, though not impossible at very high doses.

Unlike most mammals, human beings lost the ability to synthesize vitamin C. A dog makes its own; you don't. That's why you depend completely on what you eat.

What is vitamin C for in the body?

Vitamin C takes part in several processes, but it's worth separating them by weight of evidence:

• Collagen synthesis: it's its structural function and the best documented one. Without vitamin C there is no stable collagen.
• Antioxidant activity: it neutralizes free radicals in the body's watery medium, where fat-soluble antioxidants don't reach.
• Iron absorption: vitamin C converts plant-based iron into a form the intestine does absorb. That's why lemon on your lentils isn't just flavor.
• Wound healing: a direct consequence of the above, because a wound closes by building new collagen.
• Immune function: it takes part in the workings of several defense cells, although this is constantly misinterpreted. Further down we explain it without embellishment.

Vitamin C and collagen: why one doesn't work without the other

This is the part that almost always gets summed up in three words and deserves explaining, because it's where vitamin C stops being a generic nutrient and becomes concrete.

Collagen is made as a long chain that then has to coil around itself into a triple helix, the structure that gives it strength. For that helix to be stable, two amino acids in the chain —proline and lysine— must be chemically modified through a process called hydroxylation. The enzymes that do that work need vitamin C in order to function. Without it, the chain is produced but the helix doesn't hold and the collagen degrades before being of any use.

That's the explanation for scurvy, the disease caused by vitamin C deficiency. Bleeding gums, wounds that reopen, fragile skin, teeth that come loose: these aren't separate symptoms, they're the same symptom seen in different tissues. It's collagen the body couldn't finish building. If you want to go deeper into the protein that holds all this up, we explain it in the main proteins of the skin.

The useful conclusion: there's no point supplying collagen if the vitamin C that allows it to be assembled is missing, and there's no point in vitamin C if there's no raw material to assemble. They go together.

Which foods have vitamin C?

Vitamin C is more widely spread than the orange juice stereotype suggests. In fact, several foods clearly beat citrus:

• Raw red bell pepper: it's one of the most concentrated sources there is, far above the orange.
• Guava: a single piece more than covers a day's requirement.
• Citrus: orange, mandarin, lemon, grapefruit.
• Berries: strawberry, raspberry, blackberry, blueberry.
• Kiwi and papaya.
• Cruciferous vegetables: broccoli, cauliflower, Brussels sprouts.
• Fresh chiles and tomato.

A detail almost nobody takes into account: vitamin C is fragile. It degrades with heat, light and time. Broccoli boiled for a long time loses a good part of its vitamin C into the cooking water, and a juice squeezed hours ago has less than you think. Steam it, cut shortly before eating and drink juices freshly made.

How much vitamin C do you need a day?

The recommendation for an adult is around 75 mg a day for women and 90 mg for men. Someone who smokes needs about 35 mg more, because tobacco smoke speeds up its depletion. These are amounts covered by two or three servings of fresh fruit and vegetables a day: nothing exotic is needed.

Here a fact rarely mentioned in supplement advertising is worth noting: blood plasma becomes saturated with vitamin C at around 200 mg a day. Above that point, the percentage you absorb drops and the excess is eliminated through urine. Taking 1,000 mg doesn't leave you ten times better off than taking 100. The tolerable upper limit is set at around 2,000 mg a day; going beyond it can cause digestive discomfort and diarrhea, and in predisposed people it increases the risk of kidney stones.

What happens if you're short on vitamin C?

Outright deficiency is uncommon today, but mild deficiency isn't so much, especially in people who eat little fresh fruit and vegetables, smoke, or go through periods of a lot of physiological stress. The signs include swollen gums or gums that bleed when brushing, persistent tiredness, bruises that appear easily, dry and rough skin, and wounds that take longer than normal to close.

None of those signs is exclusive to a lack of vitamin C. If you have them consistently, the right thing is a medical consultation and, if needed, a test. Don't solve it by assuming.

What vitamin C does NOT do

This section matters as much as the previous ones, because a mythology that doesn't hold up has been built around vitamin C:

• It doesn't prevent colds. The review of the available evidence is fairly clear: taking vitamin C regularly doesn't reduce the likelihood of catching a cold in the general population. It may shorten the duration modestly, and that's all.
• It doesn't cure, treat or prevent diseases. It's an essential nutrient, not a medication.
• More isn't better. Past the saturation point, the excess goes out in the urine. Megadoses are expensive and not very useful.
• It doesn't replace collagen. Vitamin C allows it to be assembled; it doesn't supply it.
• Topical vitamin C and ingested vitamin C are not the same thing. A serum acts on the surface of the skin; dietary vitamin C works from within. They're different things and they don't replace each other.

Saying this doesn't weaken the argument: it makes it usable. A nutrient that does three proven things is more valuable than one credited with twenty without backing.

How you absorb it also counts

With vitamin C, and with any supplement, the question isn't only how much you take but how much gets through. It's the same principle that makes the difference with collagen.

A supplement that goes through the digestive system loses an important part along the way: collagen in capsule or powder form is used at around 25%. The routes that avoid digestion perform much better. The sublingual route reaches 80%, the transdermal route of a patch also 80%, and the vaginal route reaches 99% in the local tissue. Eighty against twenty-five is more than three times what your body gets, with the same amount in the package.

Route	Approximate absorption
Capsule or powder (digestive)	25%
Sublingual	80%
Transdermal patch	80%
Vaginal (local tissue)	99%

At The Everyday Lab we work each active through the route that suits it. Vitamin C is best covered from the diet —it's the easiest and it's exactly what this article recommends—; the rest of the daily vitamin intake, on the other hand, goes in the Multi-Vitamin Patch, a transdermal patch with 11 vitamins (A, B1, B2, B3, B5, B6, B12, folic acid, D, E and K) and 80% absorption, without going through the stomach. Collagen goes by the sublingual route in the Liquid Collagen Boost, with 150 mg of hydrolyzed collagen per 1.5 mL serving (30 drops), biotin, hyaluronic acid and zinc: the sublingual route —small peptides that pass into the blood without crossing digestion— is what explains its 80% absorption, up to 3 times a capsule, with visible results in 6 weeks. If you want complete care for skin and tissues, the Collagen Bundle combines the sublingual one with the vaginal one.

You can review the detail of each route in science and absorption and the direct comparison in sublingual collagen vs. capsule.

How to make better use of vitamin C every day

Three simple habits pay off more than any megadose:

• Spread it out. Since the body doesn't store it, two separate servings do more than one big one.
• Combine it with plant iron. Lemon on your lentils, tomato with your beans, bell pepper in your chickpea salad.
• Protect it from heat. Raw or steamed preserves far more vitamin C than boiled.

And protect what you already have: excess sugar, tobacco and sun exposure without protection degrade collagen faster than any nutrient can replace it. We break it down in what destroys collagen and in why skin loses elasticity. If you're interested in the antioxidant role, we expand on it in what an antioxidant compound is, and if you want to understand the sublingual route, start with what sublingual means.

When to consult a doctor

Go to a consultation if you have frequent bleeding gums, bruises with no apparent cause, wounds that don't close, or tiredness that doesn't improve with rest. Also before starting any supplement if you're pregnant or breastfeeding, take medication regularly, or have a history of kidney stones or iron absorption problems. The information in this article is for guidance and does not replace assessment by a health professional.

In summary

Vitamin C is an essential nutrient you must consume daily because your body neither produces nor stores it. Its central function is to allow the building of stable collagen, and from that follow wound healing, skin firmness and gum health. You cover the requirement with fresh fruit and vegetables; megadoses don't provide more. And if you're going to supplement, the route it comes in through determines how much you get: 80% by the sublingual or transdermal route versus the 25% of a capsule.

About The Everyday Lab: get to know the story, the absorption technology and the full product range in The Everyday Lab's coverage in the media.

This content is for informational purposes and does not replace consultation with a health professional. Food supplements are not medications and do not cure, treat or prevent diseases.