Vitamin C: The Antioxidant Powerhouse

L-Ascorbic Acid (the most potent form of vitamin C) products are so popular in the skincare industry, it may feel like brands are beating a dead horse. The reality is — it works! In fact, it’s quite the skincare multi-tasker. L-AA has decades of clinical testing to prove that it is an effective free radical quencher and skin brightener. Let’s dive in to take a closer look at this chemist favorite molecule!

How does L-Ascorbic Acid work?

chemist confessions antioxidant free radical

Free radicals leads to all sorts of unwanted aging symptoms. Enter L-ascorbic acid (L-AA), your best in class radical-quenching antioxidant here to save the day. Antioxidants like L-AA sacrifices itself to bond to the free radicals, saving your skin cells. This is why, in a nutshell, L-AA is an essential part of your long-term age prevention care. Age prevention through radical quenching isn’t L-AA’s only benefit. It has been shown to have visible skin tone, texture improvements within 4 to 12 weeks of consistent use. L-AA has also demonstrated to treat melasma and hyperpigmentation effectively either alone or used in conjunction with other brightening actives (read more here). Lastly, L-AA boosts collagen synthesis. Since collagens are the pillars of your skin structural integrity, this explains why L-AA also helps with minimizing fine lines and wrinkles. To sum up: L-AA is an age-preventing antioxidant that brightens skin and boosts collagen production.

How do I choose a good L-AA product?

Like all powerhouse actives, there's always a catch. L-AA is infamously unstable in water, and can be a pain in the butt to formulate. Trust us, we know. To get the most out of your L-AA product, you must choose one that’s formulated correctly so that it remains stable long enough for you to get all the benefits out of it. There are 3 main forms of vitamin C products you can choose from: classic water serum, anhydrous suspension, and powder vitamin C.

For water-based vitamin serums to remain stable and effectively penetrate your skin, the pH of the formula needs to be under 3.5. There should also be other antioxidants like vitamin E and ferulic acid to prevent vitamin C degradation. Because of the low pH, some people may find the products irritating. Start with a lower concentration if you’re new to the ingredient. L-AA is effective starting at 5%, and you can ramp it up all the way to ~20%. 

Another way to prevent the degradation problem is to use water-free (anhydrous) formulas. These usually consist of a finely ground vitamin C powder that is suspended in silicone or organic oils. These formulas don’t penetrate as well as their water-based counterparts, so the concentration is usually a bit higher. We are personally not huge fans of these formulas (pet peeve about the funky texture...), but they can work well for those irritated by the low pH water-based formulas.

Powdered vitamin C products are by far the most stable options on the market. But the downside is that you never know if you’re adding quite the right amount to your regimen. Not to mention the messiness.

Sold! How do I include vitamin C in my routine?

You can use L-AA products both day and night. It’s best to use it daily in the morning on cleansed skin before moisturizer and sunscreen to get the most out of its radical scavenging prowess.


  • What it does: Antioxidant protection, skin brightening, boosts collagen production.
  • Effective Concentration: at minimum 5%, but usually 10% and up.
  • Other concerns? HIGHLY. UNSTABLE. When your product gets amber colored, it's time to toss it out.
  • You can learn more about vitamin C products here
PS. There are a lot of products out there that feature vitamin C derivatives like ascorbyl palmitate, tetrahexyldecyl ascorbate, etc. None of them hold a candle to L-ascorbic acid in terms of the number of clinical tests and data that support their skincare benefits. However, they may still be good options for those who just can’t tolerate L-AA at all. Just remember, the dose makes the poison and don’t settle for a product that won’t tell you how much you’re getting.

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