Jul 13, 2026

The Truth About Vitamin C: Which Form is Best for Your Skin?

By Julia Hart Electric Facialist

Vitamin C has earned its place as one of the most researched and celebrated ingredients in skincare. It's praised for brightening dull complexions, supporting collagen production, reducing the appearance of pigmentation and defending the skin against environmental damage.

But here's something many people don't realise...

Not all Vitamin C is created equal.

In fact, there are several different forms of Vitamin C used in skincare, and they all behave differently. Some are incredibly powerful but can be unstable and irritating, while others are far more stable, gentler on sensitive skin and designed to work over the long term.

If you've ever tried a Vitamin C serum that stung, caused redness or simply didn't seem to do anything, the type of Vitamin C may have been the reason.

In this guide, we'll explore the different forms of Vitamin C, explain why they matter and reveal why THD Ascorbate has become one of my favourite ingredients for achieving brighter, healthier skin.

Why Does Your Skin Need Vitamin C?

Vitamin C is much more than a brightening ingredient.

It plays an essential role in maintaining healthy, youthful skin by helping to:

Support healthy collagen production
Protect against free radical damage
Brighten uneven skin tone
Improve the appearance of pigmentation
Defend against pollution and UV-induced oxidative stress
Enhance overall skin radiance

Think of Vitamin C as one of your skin's daily bodyguards—working behind the scenes to protect against the environmental factors that contribute to premature ageing.

The Problem With Traditional Vitamin C

When most people think of Vitamin C, they're usually referring to L-Ascorbic Acid.

This is the purest and most researched form of Vitamin C, but it also has some challenges.

L-Ascorbic Acid is:

Highly unstable when exposed to air and light
Easily oxidised, reducing its effectiveness
Formulated at a low pH, which can irritate sensitive skin
Sometimes difficult for compromised skin barriers to tolerate

If your Vitamin C serum has ever turned orange or brown, that's a sign it has oxidised and is becoming less effective.

For many people with sensitive, reactive or redness-prone skin, a gentler alternative can be a much better choice.

Meet THD Ascorbate

One of the most exciting developments in modern skincare is Tetrahexyldecyl Ascorbate (THD Ascorbate).

This advanced, oil-soluble form of Vitamin C is designed to overcome many of the limitations associated with traditional Vitamin C.

THD Ascorbate is:

Highly stable
Oil-soluble for excellent skin penetration
Gentle enough for sensitive skin
Less likely to cause irritation
Effective at supporting collagen production
Excellent for improving skin radiance and uneven pigmentation

It's no surprise that many premium, medical-grade skincare brands have chosen THD Ascorbate as their preferred form of Vitamin C.

THD Ascorbate vs L-Ascorbic Acid

L-Ascorbic Acid	THD Ascorbate
Water-soluble	Oil-soluble
Can be unstable	Highly stable
Low pH	Skin-friendly formulation
May irritate sensitive skin	Better tolerated by sensitive skin
Oxidises quickly	Longer-lasting stability
Excellent antioxidant	Excellent antioxidant with enhanced skin compatibility

Both forms have their place in skincare, but if your priority is achieving healthier, brighter skin without unnecessary irritation, THD Ascorbate is an excellent choice.

Vitamin C and Collagen

Collagen is the protein that gives our skin firmness, strength and elasticity.

As we age, collagen production naturally slows, contributing to fine lines, wrinkles and loss of firmness.

Vitamin C is an essential cofactor in collagen synthesis, helping your skin produce and maintain healthy collagen fibres.

This is one reason Vitamin C is considered such an important long-term investment for healthy skin ageing.

Vitamin C and Pigmentation

Uneven pigmentation can develop for many reasons, including:

Sun exposure
Hormonal changes
Post-inflammatory pigmentation after acne
Environmental damage
Natural ageing

Vitamin C helps brighten the complexion by supporting a more even skin tone and reducing the appearance of existing pigmentation over time.

For anyone treating melasma or persistent pigmentation, Vitamin C works particularly well alongside daily sunscreen and a healthy skin barrier.

Vitamin C and Environmental Damage

Every day your skin faces challenges from:

UV radiation
Air pollution
Free radicals
Oxidative stress
Advanced Glycation End Products (AGEs)

These environmental stressors accelerate collagen breakdown and contribute to premature skin ageing.

Antioxidants like Vitamin C help neutralise free radicals before they can damage healthy skin cells, making daily antioxidant protection one of the smartest investments you can make in your skin.

Why I Love SENTE Bio Complete AOX+ Brightening Serum

When recommending a Vitamin C serum, I'm looking for far more than just a high percentage of Vitamin C.

I want a formula that also supports the skin barrier, protects against environmental damage and remains gentle enough for everyday use.

That's exactly why I love SENTE Bio Complete AOX+ Brightening Serum.

It combines:

20% THD Ascorbate for powerful antioxidant protection and skin brightening.
Patented Heparan Sulfate Analog (HSA) Technology to support hydration, strengthen the skin barrier and improve skin resilience.
An advanced antioxidant blend to defend against free radicals, UV-induced oxidative stress and Advanced Glycation End Products (AGEs).

The result is brighter, healthier-looking skin without compromising the skin barrier.

Shop My Favourite Vitamin C Products

If you're looking to introduce Vitamin C into your skincare routine, these are some of my favourite products:

SENTE Skin Defence Serum

A high-performance antioxidant serum featuring 20% THD Ascorbate and patented HSA Technology to brighten, protect and support healthy skin.

→ Shop Sente Skin defence Serum

Julia's Thoughts

One of the biggest myths in skincare is that stronger always means better.

The reality is that the best skincare is the skincare your skin can use consistently.

That's why I'm such a fan of THD Ascorbate. It delivers many of the incredible benefits we associate with Vitamin C whilst remaining beautifully compatible with sensitive skin and supporting long-term skin health.

Healthy skin isn't built overnight.

It's built through daily protection, intelligent skincare and choosing ingredients that work with your skin rather than against it.