b.glen c serum: Can 7.5% Vitamin C Rival 15% Formulas?

When it comes to vitamin c serums, the sweet spot is usually at around 15 to 20%. That’s where most studies have shown to deliver beneficial results, and it’s also the % used by most brands, including the famous SkinCeuticals Vitamin C.

Not everyone’s skin can tolerate 15% though, so there’s definitely a market for gentler serums, but then expectations are also lower. After all, less vitamin c, less potent results, right?

At 7.5% vitamin c, the b.glen C Serum is challenging this notion, and as usual, I’ve put my skin to the test to find out.

Overview

What is it
Concentrated, yet gentle formula to brighten dark spots, reduce the appearance of acne scars, and protect the skin from free radical damage.

Best suited for
Normal to dry skin types, especially sensitive skin folks who struggle with the higher concentrations of vitamin c but still want to stick to the ascorbic acid form. While the finish isn’t oily, combo and oily skin types may not enjoy the texture.

Things to note
Alcohol free and fragrance free.

Packaging
A plastic squeeze tube bottle with a fine tip so you can easily control how much to dispense. It also features an undetectable automatic air shut off valve which helps prevent air from getting in and keeping the formula fresh for longer.

Scent
No noticeable scent.

Texture
Like a dry oil. It doesn’t feel heavy, but there’s not much slip either. Unlike an oil, it absorbs quickly into the skin.

Finish
Natural finish with no noticeable shine or stickiness.

Price & Size
$49 for 15ml on b.glen official website ($10 off if you use my link) and Amazon (20% off with code NFDBKCMR)

Product Demo

b.glen C Serum Ingredients

Ascorbic acid should need no introduction. It’s the most effective and well studied form of vitamin c, with benefits like:

• decreasing hyperpigmentation and improving skin tone
• increasing collagen production
• protecting our skin against free radicals like UV rays

It’s big downside is that it’s not very stable and prone to oxidization, especially in water based formulas. Luckily b.glen uses a water-free formula in a specially designed tube (see above), but most importantly, it uses a unique encapsulation technology that prevents the vitamin c from degrading, even after a year of using the product!

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Liposomes and QuSome Technology

Now our skin naturally is designed to keep things out, both bad and good, so figuring out how to get ingredients into the skin is a key part of skincare formulation.

A popular method is using liposomes with ingredients like lechithin. Imagine tiny bubbles made of fats, similar to the fats in our skin. These bubbles surround, protect, and stabilize the active ingredient, and because they’re so similar to our skin, they can easily pass through and go deeper, bringing the active ingredient along with them.

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QuSome Technology, developed by Dr. Brian Keller, uses nano-sized liposomes (between 70-150 nm) to deliver ingredients precisely where they are needed. While liposomes themselves aren’t anything new, QuSome improves upon the traditional methods by:

• demonstrating higher penetration capabilities
• efficiently encapsulating both water-soluble (e.g., Vitamin C) and oil-soluble (e.g., Vitamin A) ingredients
• having the versatility to either enhance or reduce skincare penetration, where the latter would be ideal in sunscreen formulas
• maintaining stability in various formulations (eg. liquid, emulsion, and cream)

Thanks to QuSome, b.glen doesn’t need stabilizing ingredients like ferulic acid and vitamin e to keep the vitamin c fresh. I’ve used my tube for more than a month and the liquid still comes out clear – proof that the vitamin c has yet to break down.

Would it be nice to see other antioxidants or humectants in the formula? It’s hard to say no because we’ve been conditioned to think more = better. But b.glen’s philosophy is to deliver the best results without overcomplicating the formula, and I respect that. It’s always nice to have a minimalist alternative to all the maximalist products out there.

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How I use my vitamin c serums

I’m a big proponent of using vitamin c in the morning to take full advantage of their fantastic antioxidant properties, which can help further protect our skin against UV rays (please do NOT skip sunscreen though).

1. As with all serums, I use the b.glen C Serum after my essences and toners. If I’m pairing it with another water-based serum, I’ll use that first.
2. A dime size is the recommended amount, though I tend to use a little less because otherwise I find it doesn’t always absorb fully into my skin. You should adjust accordingly based on your face size.
3. Sometimes I’ll use a mist beforehand to help the serum better spread across my skin.
4. Once absorbed, I follow up with my moisturizer and sunscreen.

Usually with other ascorbic acid serums, I don’t use any actives in the same routine. Heck sometimes I struggle when I’ve used a strong acid or retinol the night before! But the b.glen c serum is so gentle that I’ve had no issues using it, even when my skin was a little irritated from last night’s tretinoin!

Usage Experience & Results

This isn’t my first time using a waterless vitamin c, though my experiences have been a hit or miss, and I find it really comes down to the formula.

I’ve talked about b.glen’s unique QuSome formula, and while I can’t physically measure how far deep the vitamin c goes, I’ve had no issues with pilling or feeling like the product is just sitting on my skin. It absorbs fairly fast, even faster if I mist beforehand, and has layered wonderfully under all my different moisturizers and sunscreens.

The texture does take some getting used to though. It feels like an oil but isn’t moisturizing like one, and it’s not quite a gel either. Honestly it’s not my favorite, though I don’t dislike it either. Just that if you’re big on the sensorial aspect, this may not be your cup of tea.

The good news is that despite my generally poor results with ascorbic acid, I did see some slight brightening after using the b.glen c Serum for 4 weeks. Nothing major, and I tried my best to capture the difference in photos, but I’ll let you be the judge:

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What impressed me most though was the fact that after 4 weeks, the serum remains completely clear. Not even the slightest hint of yellow. But that’s not even the most incredible part. I found my empty b.glen c serum from a year ago, opened up the tube, and the liquid was STILL 99% clear with very slight yellowing. I’ve had serums that looked worse right after opening!

Lastly let’s talk about the small tube size, at first it can feel more like an eye cream than a serum! However, for something with a shorter shelf life like vitamin c, a smaller amount isn’t a bad thing. Also the fine tip means I have control over exactly how much product comes out. Maybe Japanese brands are onto something with this design!

So can 7.5% vitamin c really rival 15+%?

To be completely honest, I have seen better results with higher % vitamin c serums. But I should also point out that all those serums also contained more than just vitamin c, which could be responsible for the improvements.

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On the other hand, I’ve also experience worse results with plenty of high % vitamin c serums, also with other beneficial ingredients. As a matter of fact if you rank the products in my Vitamin C Database (available for free to subscribers), the b.glen c Serum is actually ranked higher than most!

So yes, a lower % vitamin c can indeed work better for the skin than higher concentrations, it all really comes down to the formula.

But to be fair, in my comparison below, I will only be discussing other ascorbic acids with very few to no other supporting ingredients.

Other Ascorbic Acid Products Compared

Lixir Vitamin C Paste
The first ascorbic acid product I tried that actually delivers results! It contains 10% vitamin c and hyaluronic acid and stings a little on application, but my skin is noticeably brighter afterwards. This one is a mask though, so not as convenient to use.

MATTER OF FACT Brightening + Firming Serum
When this was first release, they made bold claims about how they could keep their 20% vitamin c fresh with their waterless formula. While this felt gentle on the skin and did brighten my skin tone, it 1) is expensive 2) still managed to oxidize after a few weeks, and I wasn’t even close to half way done.

The INKEY List Vitamin C Serum
One of my favorite ascorbic acid formulas for its efficacy and affordability if you don’t mind mixing it with one of your existing serums (ideally a soothing/hydrating one). It’s way too strong to use on its own (30%!!) and the texture isn’t the best either.

Final Verdict

Jenny Wu

Passionate about science-based skincare. Tested hundreds if not thousands of products since my 20's. Working regularly with brands like iHerb, Ulta, CurrentBody, and MedStar Health to share my knowledge and experience in all things beauty. Learn more.

Skin profile: 35+, dry/combination, focused on well-aging, hydration, and a healthy glow ✨