Vitamin C - Overview

We've all grown up getting told to take a Vitamin C tablets when we are trying to beat a nasty cold. But what are the benefits of Vitamin C for the skin? The antioxidant properties of Vitamin C brightens the skin, stimulates collagen growth and help prevent UV damage and recover from hyperpigmentation. The good thing about Vitamin C is that it is one of the few actives that has a significant amount of research done on its effectiveness on wrinkles, fine lines, fighting free radicals, collagen stimulation etc.

Before we start diving into Vitamin C, some points are worth noting: 

1) Vitamin C is relatively unstable

The water-based Vitamin C solution with L-Ascorbic Acid is prone to oxidation when exposed to air.  Once it becomes oxidized, it becomes ineffective and may also become harmful to the skin by potentially increasing the formation of free radicals. From anti-oxidant it becomes pro-oxidant.  So if the water based Vitamin C product has become yellow or orange in color, that has oxidized.

2) Vitamin C can cause irritations!  

By default, Vitamin C solutions have a low pH, making them highly acidic. There needs to be at least 10% of Vitamin C in formulations in order to increase collagen synthesis and reduce wrinkles, but Vitamin C formulations can become highly acidic at these levels. This is why some users will report tingling or stinging sensations during the first few applications of Vitamin C.  

Most water based Vitamin C serums sitting on store shelves are actually degrading or oxidizing as they are sitting on the shelves.  Degradation would have occurred from the time it was made, shipped to warehouses, and held as inventory on store shelves. The shelf life and efficacy of the product is shortened even before its first use as a finished product at the hands of the consumer. Yet, the advantages of Vitamin C in water results in excellent absorption.

Vitamin C is probably one of the most researched ingredients in skincare. It is an antioxidant, meaning that it will prevent and remove free radicals from the skin.

Here are different forms of Vitamin C that are widely used in serums, creams etc.

L-Ascorbic Acid (L-AA)

 L-AA is probably the most effective Vitamin C for collagen production and UV protection. Solutions containing L-AA for topical application need to have a pH of less than 3.5 for the stability of the product.

Products with L-AA are best used in the mornings and need wait times before applying other products.

Magnesium Ascorbyl Phosphate (MAP)

A stable form of Vitamin C, MAP comes in a pale yellow, powdery form and is effective as an antioxidant and skin conditioning agent. It is a water soluble derivative of Vitamin C. It acts as a skin lightener and as an antioxidant to slow deterioration caused by exposure to the air and also to control the pH of the finished product. Unlike L-AA, MAP does not readily degrade in formulas containing water. It is considered light-stable and oxygen-stable. Studies of MAP in aqueous solutions indicate it retains over 95% of its potency at 40°C without any pH adjustment. MAP is capable of suppressing skin pigmentation, making it effective in whitening dark skin, or areas of dark skin. MAP works best at a pH of 6 to 7.

MAP based products are better for those with sensitive skin. Studies have also found that MAP is better than L-AA at achieving deeper penetration into the skin.

Ascorbyl Palmitate (AP)

AP and ATIP or TA are quite similar and is fat soluble.  In order to get these penetrate into the skin, the carrier oil need to act as a delivery mechanism.  Fatty acids with triglycerides typically remain on the skin for several minutes or even hours giving the oily look. It is quite critical to get the carrier oil right otherwise penetration would not be achieved.  

AP need to be at a low pH and therefore the oil based solution's pH need to be brought down in order for the AP to be effective. There are not much studies for that prove collagen improvement using AP.

Ascorbyl Tetra-tetraisopalmitoyl (ATIP)  or Tetrahexyldecyl Ascorbate (TA)

ATIP or TA is similar to AP in that it requires pH of 5 to be stable. It is quite mild on the skin and does not have superior benefits compared to the others above.  Vitamin E performs better than ATIP or TA.

Sodium Ascorbyl Phosphate (SAP)

There are not much studies that discusses the efficacy of SAP.  SAP is stable at a pH of 7 and is water soluble.  SAP is less effective than L-AA and MAP.

Pinnell, S R, et al. “Topical L-Ascorbic Acid: Percutaneous Absorption Studies.” Advances in Pediatrics., U.S. National Library of Medicine, Feb. 2001, www.ncbi.nlm.nih.gov/pubmed/11207686.