Why Your Collagen Isn't Working Without Vitamin C
Collagen synthesis requires vitamin C as an enzymatic cofactor. Taking collagen peptides without adequate vitamin C means your body is missing a required input for building collagen. Most collagen powders contain none. ONCE pairs 5g of collagen peptides with 500mg of vitamin C and 120mg of hyaluronic acid in the same scoop.
Collagen is the most-purchased beauty supplement in the world, and an enormous share of it is being taken in a way that leaves out a required ingredient. Not a helpful ingredient. A required one.
The mechanism, in plain language
Your body does not absorb collagen and place it in your skin. It breaks the peptides down and uses them as raw material to build its own collagen. That building process runs on two enzymes — prolyl hydroxylase and lysyl hydroxylase — and both of them require vitamin C to function.
This is not a supplement-industry theory. It is the reason scurvy destroys connective tissue: without vitamin C, collagen cannot be properly formed.
What collagen has been shown to do
Hydrolysed collagen peptides have been shown to improve skin elasticity and hydration in randomized trials, with studied daily doses commonly falling between 2.5g and 10g. The endpoints in that research are elasticity and hydration measurements — not wrinkle removal, and not appearance transformation. We will describe what was measured and let you decide.
The doses that matter
| Ingredient | Role | In ONCE |
|---|---|---|
| Collagen peptides, hydrolysed | The raw material | 5g |
| Vitamin C | Required cofactor for synthesis | 500mg |
| Hyaluronic acid | Studied for skin hydration | 120mg |
| Glycine | Roughly a third of collagen's own amino acid structure | 1g |
| Biotin | Hair, skin and nails support | 500mcg |
The glycine detail
Here is a second input most people never hear about. Glycine makes up roughly a third of collagen's own amino acid sequence. ONCE carries 1g of it — partly as a synthesis input, partly because glycine is naturally sweet and earns its place in the flavour system too.
Why the biotin is deliberately low
ONCE carries 500mcg of biotin, and that number is held down on purpose. The beauty market sells 5,000 and 10,000mcg mega-doses, which are far beyond any established need — and high-dose biotin is known to interfere with laboratory blood tests, including thyroid panels and the troponin test used to assess chest pain. A supplement that skews a cardiac test is a bad trade for hair claims.
ONCE launches as a 30-serving tub. One scoop into 12 to 16 ounces of cold water, stir, drink it with breakfast. That is the entire routine, and it costs $50 a month. There is no caffeine in it, so it works at 6am or 6pm.
Nothing here requires you to stop buying collagen. It requires you to check that whatever you are taking includes the cofactor it cannot work without.
Common questions
Do you need vitamin C with collagen?
Yes. Collagen synthesis requires vitamin C as an enzymatic cofactor for prolyl hydroxylase and lysyl hydroxylase. Without adequate vitamin C the body cannot properly form collagen from the peptides you consume. Most collagen powders contain no vitamin C. ONCE includes 500mg alongside 5g of collagen peptides.
How much collagen per day is effective?
Randomized trials on hydrolysed collagen peptides commonly use 2.5g to 10g daily and have shown improvements in skin elasticity and hydration. ONCE carries 5g per serving.
Is high-dose biotin bad?
High-dose biotin, such as the 5,000 to 10,000mcg amounts common in beauty supplements, is known to interfere with laboratory blood tests including thyroid panels and the troponin test used to evaluate chest pain. ONCE deliberately holds biotin at 500mcg for this reason.
Does hyaluronic acid work orally?
Oral low-molecular-weight hyaluronic acid has been studied for skin hydration. ONCE includes 120mg of oral-grade, low-molecular-weight hyaluronic acid alongside its collagen and vitamin C.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is educational and is not medical advice; consult a physician before starting any supplement.