Vitamin C serum — how it works, how to use it, what to pair it with

What vitamin C does in your skin

Vitamin C (L-ascorbic acid) is the most thoroughly studied antioxidant in cosmetic science. In the skin it works on four fronts:

1. Neutralises free radicals — protects cells from UV and pollution damage. 2. Stimulates collagen synthesis — it is a cofactor for prolyl hydroxylase. Just like inside the body, so on the skin from the outside. 3. Inhibits tyrosinase — the enzyme that produces melanin. Result: lightening of sun-induced and post-inflammatory pigmentation. 4. Boosts SPF performance — daily use enhances UV protection.

Stability and concentration — what actually works

Stability is the biggest challenge. Pure ascorbic acid oxidises on contact with air and light, turns brown and loses potency.

The JuniKa Natur Vitamin C Serum contains a stable form of vitamin C (Ascorbyl Glucoside) and aloe leaf juice. Store it at room temperature, away from sunlight, and use within 6 months of opening.

Vitamin C concentration in cosmetic serum should sit in the 10–20% range. Below that — the effect is barely visible. Above that — risk of irritation without additional benefit.

How to add the serum to your routine (step by step)

Morning (after cleansing): 1. Toner (optional). 2. Vitamin C serum — 3–5 drops, gentle pressing. 3. Moisturiser. 4. SPF 30+ (mandatory, no exceptions).

Do not use vitamin C in the evening — niacinamide, retinol or AHA/BHA acids work better there.

Key point: SPF in the morning. Without SPF vitamin C generates oxidation products on the skin that can cause pigmentation rather than fade it.

Why vitamin C alone sometimes is not enough

Skin is the external picture of what happens inside the body. The most common reasons a vitamin C serum does not work despite consistent use:

• Ferritin (iron) deficiency — if you have symptoms of iron deficiency (fatigue, pallor), take a home ferritin test and discuss the result with a doctor. • Diet — a varied diet rich in vegetables and fruit is the foundation; the serum works locally, as a cosmetic. • No SPF — UV destroys more collagen in a day than the serum can rebuild in a week.

Skincare is one part of a daily routine — alongside a varied diet, sleep and sun protection.

Related product

• Ferritin (Iron Deficiency) Test 20.00 PLN

Frequently asked questions

Does stabilised vitamin C work better than the classic form?

Yes — it is the gold standard. Vitamin C as L-ascorbic acid is fully stable at low pH (≤3.5). If the formula does not change colour after opening, it is properly stabilised.

How can I tell whether a vitamin C serum is still fresh?

Stable vitamin C is a light orange colour. If your serum turns dark amber or brown — it is oxidised and loses effectiveness. Store in a cool, dark place away from heat.

Can I combine vitamin C with niacinamide or retinol?

Yes, but not in the same step. Morning: vitamin C → SPF. Evening: niacinamide or retinol. Used together at once they may reduce each other's effectiveness.