All about Vitamin C: Is it effective in skincare?
I want to start this blog by stating that after extensive research, I have determined that Vitamin C as an ingredient in skincare is a tricky subject. I have watched endless YouTube video's, read blogs, articles, research, and academic papers. At the end of the day, it is still undetermined whether or not Vitamin C is as effective as skincare brands claim. 
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Here's what we do know about Vitamin C in the body:

Vitamin C is a water-soluble organic compound. Our bodies do not store it which means we must ingest approximately 100mg per day to maintain adequate levels (any more is simply excreted through our urine). Vitamin C is absorbed into our small intestines and is found abundantly in citrus fruits, leafy greens, and berries. 

So what does it do for our bodies? Vitamin C stimulates the production of collagen, L-carnitine, and some neurotransmitters. It helps metabolize proteins and its antioxidant activity may reduce the risk of some cancers. Excessive exposures to UV light or pollutants (e.g., cigarette smoke and ozone) may also lower vitamin C content, primarily in the epidermis (4-6)

Vitamin C in skincare:

Vitamin C is a normal skin constituent that is found at high levels in both the dermis and epidermis (1, 2). Ascorbic Acid or L-Ascorbic Acid is the only form of Vitamin C our bodies/skin can recognize. L-Ascorbic Acid is the natural form of Vitamin C, water-soluble and the most effective anti-oxidant to protect our skin from free radicals and ultraviolet light. L-Ascorbic Acid should be formulated in ingredients with a low pH from 3-3.5 - which can make products more harsh for sensitive skin. However, L-Ascorbic Acid is not very stable in skincare formulations. 

Although L-Ascorbic Acid is highly studied and proven, it loses its stability quickly when exposed to air, light, and heat, in fact, after 6 months, a product can lose 80% of its active Vitamin C. This is due to oxidization. You can tell when Vitamin C has oxidized when it starts turning orange. "Preparations with a pH below 4.0 aid in transport by promoting the uncharged form of vitamin C, ascorbic acid (11)". Typically ferulic acid is added to skincare formulations to help stabilize L-ascorbic acid. 

Because of its stability issues, many skincare companies are now using derivatives of L-Ascorbic Acid. A derivative is essentially a compound that is created from a similar compound by a chemical reaction. These derivatives work by converting into L-Ascorbic acid inside of the skin. There is no real proof that derivatives of L-Ascorbic Acid work, although they have been shown to be less effective, however more stable in skincare formulations. 

Some forms of Vitamin C derivatives include:

  • Sodium Ascorbyl Phosphate (water-soluble): soothing, good for acne-prone skin
  • Tetrahexyldecyl Ascorbate (oil-soluble): great for concentrated skin brightening, hyperpigmentation, and melasma, more of a spot treatment. 
  •  Magnesium Ascorbyl Phosphate (water-soluble): for overall skin brightening
  • Ascorbyl Glucoside (water-soluble): The least stable of the derivatives, but more stable than L-Ascorbic Acid.
  • Ethylated L-Ascorbic Acid (water-soluble): The only derivative that skin actually recognizes as L-Ascorbic Acid, is stable in water and only loses 2% active Vitamin C after 6 months. 

"Stable synthetic derivatives, such as ascorbate phosphate, are considered to have limited permeability (11) and function in the skin (13, 14). Another stable lipid-soluble derivative, ascorbyl palmitate, also has limited absorption (11), and one in vitro study with cultured skin cells found that the administration of ascorbyl palmitate had some toxic effects (15)." - Vitamin C and Skin Health Oregon State University. 

 

So does it actually work in skincare?

Some studies have shown that vitamin C may help prevent and treat ultraviolet (UV)-induced photodamage. However, the effects of vitamin C in the skin are not well understood due to limited research. Below is some information collected from an article written in 2011 from Oregon State University about Vitamin C and Skin Health. In combination, Vitamin C and E do work better synergistically nd have show results topically for some human studies:
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Topical application of vitamin C, alone or in combination with other compounds, may result in greater photoprotection than oral supplementation because of the more direct route of administration. Topically applied combinations of vitamin C and vitamin E are more effective in preventing photodamage than either vitamin alone. In particular, this combination of antioxidant vitamins decreased the immunosuppressive effects of UV exposure (43), increased MED, and decreased cell damage (16, 18, 44). - Vitamin C and Skin Health Oregon State University. 
Limited human studies are available on photoprotection by topical application of vitamin C. Although topical ascorbic acid reduces radicals in UV-exposed human skin (45), only one study examined its effect on UV-induced erythemal response; this study reported no significant benefit of topical vitamin C (24). Like animal research, human studies using combinations of vitamin C and vitamin E have documented UV protective effects (17, 19, 24). Vitamin C and Skin Health Oregon State University. 
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Human studies often assess skin health by changes in depth or number of wrinkles and by the individual’s perception of skin health. Two observational studies found that higher intakes of vitamin C from the diet were associated with better skin appearance, with notable decreases in skin wrinkling (51, 52). The use of vitamin C (3-10%) in topical applications for at least 12 weeks has been shown to decrease wrinkling (21, 23, 25, 27), reduce protein fiber damage (25), decrease apparent roughness of skin (21), and increase production of collagen (26, 27). Topical vitamin C has also been shown to reverse some of the age-related structural changes in the interface between the dermis and the epidermis (22). However, the effects of topical vitamin C are not apparent in all individuals, and interestingly, one study found that individuals with high dietary intakes of vitamin C showed no or little effect of a topical administration (26).
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Here are our final thoughts on Vitamin C in skincare

It is so easy to claim that Vitamin C is incredible for the skin based on what we know to be true about the ingredient itself and what it does for the body when you consume it. However, like all non-drug ingredients, Vitamin C as a skincare ingredient is unregulated. This means any brand can make any claim about it. 

Some users of Vitamin C have indeed seen visible and life-changing results from using skincare with Vitamin C, however, some have seen little to no results. At the end of the day, we want to encourage you to not simply rely on your skincare to work its magic on your skin. Eating enough Vitamin C in your diet is maybe more important for your body than applying it on your skin. 

If you are going to use a skincare product with L-Ascorbic Acid in it, ensure you store it in a cool dark place and use the product within 2-3 months ( if you are using the product every single day this should be no issue). Let this be a reminder to only purchase what you need, use it up (unless it is irritating your skin). 

You may still feel a bit unclear about Vitamin C, and to be truthful so are we. We will not know until more studies are done on the ingredient. In the meantime, using formulations with L-Ascorbic Acid may benefit the skin by brightening, lightening and helping promote collage - but keep eating those leafy greens and citrus fruits. 

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RESOURCES:
1.  Shindo Y, Witt E, Han D, Epstein W, Packer L. Enzymic and non-enzymic antioxidants in epidermis and dermis of human skin. J Invest Dermatol 1994;102:122-124.  (PubMed)
2.  Rhie G, Shin MH, Seo JY, et al. Aging- and photoaging-dependent changes of enzymic and nonenzymic antioxidants in the epidermis and dermis of human skin in vivo. J Invest Dermatol 2001;117:1212-1217.  (PubMed)
4.  Shindo Y, Witt E, Packer L. Antioxidant defense mechanisms in murine epidermis and dermis and their responses to ultraviolet light. J Invest Dermatol 1993;100:260-265.  (PubMed)
5.  Thiele JJ, Traber MG, Tsang K, Cross CE, Packer L. In vivo exposure to ozone depletes vitamins C and E and induces lipid peroxidation in epidermal layers of murine skin. Free Radic Biol Med 1997;23:385-391.  (PubMed)
6.  Podda M, Traber MG, Weber C, Yan LJ, Packer L. UV-irradiation depletes antioxidants and causes oxidative damage in a model of human skin. Free Radic Biol Med 1998;24:55-65.  (PubMed)
11.  Pinnell SR, Yang H, Omar M, et al. Topical L-ascorbic acid: percutaneous absorption studies. Dermatol Surg 2001;27:137-142.  (PubMed)
September 24, 2019 by Jacqueline Parker

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