The Complete Vitamin C System
The Complete Vitamin C System
Most Vitamin C serums are already degrading before they reach your skin. We fixed that.
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Stable daily Vitamin C. Freshly activated Vitamin C. One clean, performance-led system.
No unnecessary fillers. No ingredient compromise.
Real Results. Real People. 8 Weeks.

Wendy · Advanced THD Vitamin C Serum · 8 weeks · No filters

Dale · Advanced THD Vitamin C Serum · Week 6 · No filters

Trial Participant · Advanced Vitamin C System · 8 weeks · No filters
Trial Results
8-week independent trial


What This System Does
The Intrinsic Advanced Vitamin C System combines two complementary forms of Vitamin C in one complete skincare protocol — 8% Tetrahexyldecyl Ascorbate (THD) for stable daily antioxidant support, and freshly activated L-Ascorbic Acid for targeted use.
Together, they help support collagen, brighter-looking skin, a smoother texture and a more even-looking skin tone, while helping improve the appearance of pigmentation, sun spots and fine lines over time.
What Our Trial Participants Said
"Brighter and smoother — my skin tone is so much more even and calmer. The redness I'd had for years just settled down."
Wendy
Advanced Vitamin C System · 8 weeks
"Reduced sunspots, skin feels smoother. Very happy — easy to use, and some visible results."
Dale
Advanced Vitamin C System · Week 6 (still using at Week 10)
"Fine lines have softened — jaw and neck lines have improved."
Trial Participant
Advanced Vitamin C System · 8 weeks
What's Included
- Advanced THD Vitamin C Serum — 8% stable, oil-soluble Vitamin C in a water-free lipid serum
- Vitamin C Activation Booster — the lightweight vehicle for freshly activated Vitamin C
-
Vitamin C Activation Powder — 100% L-Ascorbic Acid, kept dry until the moment of use
Why This System Is Different
Vitamin C comes in different forms, each with different formulation strengths. L-Ascorbic Acid is the most extensively studied form of Vitamin C, but it is less stable once dissolved in water. THD Vitamin C is oil-soluble and highly stable, making it particularly well suited to consistent daily use.
The Intrinsic system brings both approaches together. The 8% THD Serum provides stable daily Vitamin C and antioxidant support, while the Activation System keeps L-Ascorbic Acid dry until use so it can be freshly mixed when needed.
WHAT YOU MAY NOTICE WITH CONSISTENT USE
- Brighter, more even-looking skin tone
- Smoother-looking skin texture
- Softer appearance of fine lines
- Improved appearance of pigmentation and sun spots
- Support for collagen and firmer-looking mature skin
- Daily antioxidant support against environmental stressors
THIS IS FOR YOU IF:
- You have mature skin and want to support collagen and the appearance of fine lines
- Pigmentation, sun spots or uneven skin tone are a concern
- You want brighter, smoother and more even-looking skin
- You want Vitamin C that remains stable in the bottle
- You care deeply about the ingredients in your skincare
- You want a complete Vitamin C skincare system, rather than just another serum
WHY TWO FORMS OF VITAMIN C?
L-Ascorbic Acid is the most extensively studied form of Vitamin C in skincare — but it is notoriously unstable in water-based formulas. The moment it is mixed with water, it begins to oxidise and lose potency. Many serums are already significantly degraded by the time they reach your skin.
Tetrahexyldecyl Ascorbate (THD) is oil-soluble, highly stable and able to penetrate into the skin's lipid layers where it converts to active Vitamin C. It does not oxidise, does not irritate and does not turn orange in the bottle. The Activation Powder addresses the potency question by keeping 100% pure L-Ascorbic Acid completely dry until the moment of application — delivering Vitamin C at full potency, every time.
Two forms. One clean system. No compromise.
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Product Details
Key Ingredients
Tetrahexyldecyl Ascorbate (THD)
A highly stable, oil-soluble form of Vitamin C that penetrates into the skin's lipid layers and converts to active Vitamin C. Unlike traditional L-Ascorbic Acid, THD does not oxidise in formula, does not cause irritation and remains effective throughout the product's shelf life. Supports collagen production, protects against oxidative damage and improves skin tone and texture with consistent daily use.
Squalane
A lightweight, highly stable emollient that mimics the skin's natural lipids. Supports a comfortable, non-greasy finish and enhances the delivery of active ingredients into the skin.
Tocopherol (Vitamin E)
Antioxidant support that works synergistically with Vitamin C to protect the skin against environmental stressors and oxidative damage.
L-Ascorbic Acid (Activation Powder)
100% pure L-Ascorbic Acid — the most extensively researched form of Vitamin C in skincare. Kept completely dry and separate until the moment of use, ensuring maximum potency at every application.
Propanediol (Activation Booster)
A lightweight, skin-compatible solvent that dissolves the Activation Powder efficiently and supports seamless delivery to the skin.
Why Intrinsic
Most skincare products are formulated with fillers, stabilisers and synthetic ingredients that pad out the formula and dilute results. At Intrinsic Skincare we believe you should never have to choose between clean ingredients and visible results.
Every Intrinsic formula is naturopath-developed and built on a simple principle — only ingredients that genuinely serve your skin make it into the bottle. No fillers. No compromise. No hidden nasties.
This means higher concentrations of active botanicals and clinical ingredients, products that last longer, and results you can actually see and feel.
Clean. Clinical. Uncompromising.
Directions for use
Directions for Use — Daily
- Apply Hyaluronic Acid Serum
- Apply 1–2 pumps of Advanced THD Vitamin C Serum
- Follow with moisturiser and sunscreen
Directions for Use — Booster Days (2–3 mornings per week)
- Apply Hyaluronic Acid Serum
- Mix 3 pumps of Vitamin C Activation Booster with 1 slightly rounded scoop of Vitamin C Activation Powder until fully dissolved
- Apply to face and neck
- Wait 30–60 seconds
- Apply 1–2 pumps of Advanced THD Vitamin C Serum
- Follow with moisturiser and sunscreen
Full Ingredient List
Ingredients — Advanced THD Vitamin C Serum
Coco-Caprylate/Caprate, C13-15 Alkane, Squalane, Tetrahexyldecyl Ascorbate, Tocopherol
Ingredients — Vitamin C Activation Booster
Aqua, Propanediol, Gluconolactone, Sodium Benzoate, Calcium Gluconate
Ingredients — Vitamin C Activation Powder
Ascorbic Acid
Shipping & Delivery
United Kingdom
We ship to all UK mainland addresses via Royal Mail Tracked 48. Orders are processed within 1-2 business days.
Standard tracked delivery: 2-3 business days — £4.00
Free shipping on all orders over £30.
Returns
We want you to love your Intrinsic Skincare products. If you are not completely satisfied please contact us within 14 days of receiving your order.
Contact us at info@intrinsicshop.co.uk for all shipping and returns queries.
Wow I have been using this for 3 weeks now and my skin feels amazing. Cant wait to see the results in another 3or 4 weeks time.
Thank you so much ❤️ You have supported Intrinsic for such a long time and it honestly means so much to me. I’m so pleased you’re loving the new Vitamin C System — I can’t wait to see what you think after a few more weeks! xx
My skin is starting to feel so much softer but bouncy and appears brighter too. Absolutely love all my products and look forward to seeing more benefits from the Vit C steps over the next months!
Thank you for your amazing review! It was so lovely meeting you, and I’m really pleased you’re already noticing softer, bouncier and brighter-looking skin. I’m looking forward to hearing how your skin continues to change over the next few months with the Vitamin C system.
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Wow I have been using this for 3 weeks now and my skin feels amazing. Cant wait to see the results in another 3or 4 weeks time.
Thank you so much ❤️ You have supported Intrinsic for such a long time and it honestly means so much to me. I’m so pleased you’re loving the new Vitamin C System — I can’t wait to see what you think after a few more weeks! xx
My skin is starting to feel so much softer but bouncy and appears brighter too. Absolutely love all my products and look forward to seeing more benefits from the Vit C steps over the next months!
Thank you for your amazing review! It was so lovely meeting you, and I’m really pleased you’re already noticing softer, bouncier and brighter-looking skin. I’m looking forward to hearing how your skin continues to change over the next few months with the Vitamin C system.