The Vitamin C Oxidation Problem: What’s the Next Gold Standard? A Dermatologist Explains

Division Chief, Dermatology

Dr. Arpana A Shah brings 25 years of clinical, surgical, and cosmetic dermatology to Kayura and a voice that shapes how we think, formulate, and grow.

You bought a vitamin C serum because you wanted more antioxidant protection, brighter-looking skin, and a little more support against the visible effects of environmental stress. Then, a few weeks later, you notice something has changed. The serum that was once clear or pale is now noticeably yellow, orange, or darker.

That change can be a sign that your vitamin C has begun to oxidize.

And this is one of the biggest challenges with topical vitamin C: it is a powerful antioxidant, but it is also a notoriously unstable ingredient. Exposure to oxygen, light, heat, and certain formulation conditions can accelerate its degradation.

But Why Does Vitamin C Oxidize?

Vitamin C is sensitive to oxygen, light, and heat. Over time, exposure to these can cause it to oxidize and break down, which is one of the biggest challenges with vitamin C skincare.

That’s why packaging matters. You’ll often find vitamin C in opaque bottles, pumps, or airless pumps designed to minimize exposure to air and light and help protect the formula’s stability.

Because once it begins to oxidize and degrade, you can no longer assume that the product contains the same amount of intact, active vitamin C that it did when it was freshly formulated. Research on topical vitamin C consistently identifies stability as one of the major challenges in developing effective formulations. And this is one reason the conversation around vitamin C has always focused so heavily on concentration.

The Vitamin C Percentage Game

For years, the easiest way to compare vitamin C serums was to look at the number on the front of the bottle.

The assumption was simple: more vitamin C must mean more benefits for skin, and get through its outer barrier to do its job.

That means a lower concentration that is well protected and effectively delivered may have more potential to perform than a much higher concentration that is unstable or poorly delivered. It’s not just about how much vitamin C you put in the bottle. It’s about how much of it actually gets where it needs to go.

So instead of asking only:

“How much vitamin C is in my serum?”

A better question is:

“How much of it can stay stable and actually reach my skin?”

And that's where things get more interesting.

So, What’s the Next Gold Standard?

Delivery.

Not just more vitamin C, but a smarter way to protect it and help it reach the skin. And one of the most interesting approaches is encapsulation, specifically, liposomal vitamin C.

Meet Liposomal Vitamin C

Think of liposomal vitamin C as vitamin C wrapped in a protective phospholipid shell.

This protective layer helps shield vitamin C from environmental factors that can cause it to break down, helping improve its stability. And because phospholipids are similar to the lipids naturally found in our skin, this structure can also help the vitamin C interact with the skin barrier and reach deeper layers more effectively.

So instead of simply adding more vitamin C, liposomal delivery takes a different approach: protect it, deliver it, and help get it where it needs to go.

Why Encapsulation Changes the Vitamin C Conversation

Encapsulation addresses both sides of that question: How well is that vitamin C protected, and how effectively can it be delivered?

It helps protect a sensitive ingredient

Vitamin C is vulnerable to environmental factors such as oxygen, light, and heat. Encapsulation can create a protective environment around the active, helping reduce its exposure to conditions that contribute to degradation.

It can support delivery through the skin

Your skin barrier is selective by design. Certain delivery systems can help an ingredient interact with and move through this barrier more effectively. Studies of liposomal ascorbate have demonstrated improved penetration into skin layers compared with non-encapsulated forms in experimental settings.

It shifts the focus from concentration to performance

A 20% concentration sounds impressive. But a percentage printed on a bottle does not tell you the complete story of stability, penetration, or delivery.

That doesn't mean concentration is irrelevant. It means concentration is not the whole story. And that distinction matters when you're choosing a vitamin C serum.

What I Look For in a Vitamin C Serum

When I evaluate a vitamin C product, I don't look at the percentage alone. I look at the form of vitamin C, how it is protected from degradation, and how it is delivered. Because ultimately, the goal is simple: keep the ingredient stable and help it reach the skin in a form that can do its job.

And that is exactly the approach behind Karma Boost Liposomal Vitamin C + Antioxidant Serum.