Which Form of Topical Vitamin C is the Best?

You’ve probably heard that vitamin C is one of the best ingredients to look for in a skincare product due to its ability to brighten and firm the skin. But did you know that there are many different forms of vitamin C that can be used to formulate products? Below we are going over the most commonly used forms of topical vitamin C and how they differ in stability and efficacy. So which form of topical vitamin C is the best? Keep reading to find out!

Vitamin C on graphing paper


Vitamin C

Vitamin C is a naturally occurring water-soluble antioxidant that is synthesized by most plants and animals from glucose. Unfortunately, humans lack the enzyme required for the synthesis of vitamin C, therefore it must be acquired from natural sources such as citrus fruits, green leafy vegetables, strawberries, papaya and broccoli.

 Fruits with high vitamin C content

After oral intake of vitamin C, the absorption in the gut is limited by an active transport mechanism, which means that no matter how much vitamin C you ingest only a finite amount can be absorbed. Furthermore, bioavailability of vitamin C in the skin is inadequate when it is administered orally. Thus, the use of topical forms of vitamin C is important to reap all of the skin benefits that vitamin C has to offer.

Like other antioxidants, vitamin C is capable of protecting the skin from free radicals and reactive oxygen species (ROS). Specifically, vitamin C donates electrons to neutralize ROS such as the superoxide ion and peroxide that are generated when the skin is exposed to UV light. This is important because the harmful effects of ROS occur as direct chemical alterations of the cellular DNA, the cell membrane and the cellular proteins, including collagen. Damaged collagen manifests as signs of premature aging of the skin, including wrinkles, lines, and sagging skin. Thus, vitamin C’s ability to protect collagen within skin makes it an ideal ingredient to include in anti-aging skincare products.

Forms of topical vitamin C

There are many different forms of topical vitamin C that can be used in topical skincare products, including the following:

  • L-ascorbic acid
  • Magnesium ascorbyl phosphate
  • Ascorbyl palmitate
  • Ascorbic acid polypeptide
  • Ascorbyl glucosamine
  • Ascorbyl glucoside
  • Ester-C
  • Sodium ascorbyl palmitate
  • Sodium ascorbyl phosphate

The various forms of topical vitamin C differ mostly in regards to stability, side effects, and ability to penetrate the stratum corneum. Below we are going over the most commonly used forms of topical vitamin C to determine which is the best.

L-ascorbic acid

L-ascorbic acid is the most chemically active form of vitamin C. But does that make it the best form of topical vitamin C? Not quite. L-ascorbic acid is actually the least stable form of vitamin C and also causes the most skin irritation.

When we say L-ascorbic acid is the least stable form of topical vitamin C, we mean that it is oxidizes the easiest. The oxidation of L-ascorbic acid is brought about by the loss of two hydrogen atoms as the vitamin is converted to dehydro-L-ascorbic acid (DHAA). If further oxidized, the ring will open, rendering the molecule completely useless. Sunlight, heat, air, water, and time can all lead to the oxidation of L-ascorbic acid. When vitamin C becomes oxidized it loses its potency and ultimately becomes ineffective. To the visible eye, a topical product will turn yellow or orange.

Chemical reaction of an antioxidant

Furthermore, L-ascorbic acid is an acidic molecule and can only penetrate the skin at a pH of 3.5 or less. This is much lower than the skin’s pH of 5.5. The low pH of topical products with L-ascorbic acid is the reason why they cause the most irritation out of all the forms of topical vitamin C; this low pH is very harsh on the skin.

Considering all of these issues with L-ascorbic acid, we’ve decided that this is not the best form of topical vitamin C.

Magnesium ascorbyl phosphate

Magnesium ascorbyl phosphate is more stable than L-ascorbic acid and can also penetrate the skin better. At a pH of 7, this water-soluble form of vitamin C is easily absorbed into the skin, and the rate-limiting step for absorption is its release from the vehicle, and not the rate of diffusion across the stratum corneum.

This form of vitamin C is also known to have a hydrating effect on the skin and decreases transepidermal water loss.  According to the Indian Dermatology Online Journal, magnesium ascorbyl phosphate is also a free radical scavenger that is photoprotective and increases collagen production under laboratory test conditions.

Sodium Ascorbyl Phosphate

Sodium ascorbyl phosphate is a precursor of ascorbic acid that is generated by the introduction of a phosphate group into the second position of the cyclic ring. Like magnesium ascorbyl phosphate, this form of vitamin C is much more gentle than L-ascorbic acid since it can be formulated at a pH of 7. Formulations containing sodium ascorbyl phosphate have been variously described as having no side effects.

Sodium ascorbyl phosphate has been proven to be more stable than both L-ascorbic acid and magnesium ascorbyl phosphate. A 2013 study by the Journal of the Chemical Society of Pakistan performed a chemical analysis on these forms of topical vitamin C and found that the formulation with sodium ascorbyl phosphate was more stable than those with magnesium ascorbyl phosphate and L-ascorbic acid.

Additionally, sodium ascorbyl phosphate not only provides antioxidant protection once converted to ascorbic acid within the skin but this form of vitamin C is also effective against Propionibacterium acnes, the bacteria that causes acne.

For all of these reasons, we chose to use sodium ascorbyl phosphate in the PharmWerks products because we believe it is the best form of topical vitamin C. You’ll be able to reap the benefits of sodium ascorbyl phosphate by using the ImmacuDerm Ageless Facial Serum, the Daily Use Skin Hydrator, or the Luminosity Reviving Cream.