COUI Skincare Super C Serum
Phenoxyethanol, Epidermal Growth Factor (EGF) has unknown safety
- May help with anti-aging although this serum contains a derivative of Vitamin C NOT the well-studied ascorbic acid
- Dermatologist approved, skincare serum with vitamin C, vitamin E, Epidermal Growth Factor (EGF), collagen, ferulic acid, and hyaluronic acid
- Promotes younger-looking skin
- Suitable for all skin types
- Recommended for mature skin, aging skin, sensitive, and damaged skin (e.g. acne, itchy, dry skin)
- Exfoliating ingredients penetrate deep below the surface of the skin
- May help with collagen production which restores skin elasticity and structure
- Firms, tightens, revives, and brightens the skin
- Natural active ingredients
- Can be used day or night
- Scientifically-formulated by world-renowned biochemist and medical experts
Ingredients Concern: Phenoxyethanol,(in low amounts this is considered safe), Epidermal Growth Factor (EGF) has unknown safety
Contains a derivative of Vitamin C (Magnesium Ascorbyl Phosphate) and NOT the L ascorbic acid which has been shown in scientific studies to produce anti-aging benefits
It is unclear whether the Magnesium Ascorbyl Phosphate in this serum will convert into ascorbic acid in the body and produce the same results that Vitamin C is known for.
There is not sufficient scientific evidence in human studies to prove that this serum will yield the same positive results that has already been shown with other Vitamin C serums.
Should be refrigerated to improve outcomes and shelf life
Phenoxyethanol has an EWG score between 2-4, depending on its usage
This serum does not contain Vitamin C "ascorbic acid" which is the ingredient that has been proven in human studies to have anti-aging benefits. It contains magnesium ascorbyl phosphate which is a derivative of Vitamin C. On a positive note, This derivative has been found to be more stable than Vitamin C ascorbic acid, and some studies in mice showed that it does convert to L ascorbic acid in the body.
However, many scientists believe that you must have ascorbic acid in a serum to be effective in providing anti-aging benefits.
For example, one study stated that "It should also be mentioned that there is an increasing number of ascorbic acid-based topical cosmetics available on the market, and it seems that not all preparations of topical ascorbic acid are effective. Many of these products use derivatives, esters, and analogs of ascorbic acid that do not penetrate the skin, do not chemically convert to L-ascorbic acid (the only form that can be used by the body), and/or are not delivered in adequate concentration. These ascorbic acid substitutes include ascorbyl palmitate, magnesium ascorbyl phosphate, ascorbic acid sulfate, ascorbyl stearate, ascorbyl dipalmitate, and ascorbic acid magnesium phosphate, which are easily stabilized but must be converted to L-ascorbate to be effectively useful. There is no direct evidence that ascorbic acid derivatives enter the skin in appreciable amounts, and it seems that their conversion to L-ascorbate is largely inefficient, thus precluding effective concentration delivery. 
Another study also states that "Formulations containing derivatives of ascorbic acid have been found to be more stable, but they DO NOT produce the same effect as that of the parent compound." 
If this form of Vitamin C derivative in this serum does effectively convert into ascorbic acid and work, then we may consider looking at the results that have been shown for ascorbic acid. Topical ascorbic acid has been shown to stimulate collagen growth and protect skin from erythema, the redness caused by UV rays from the sun.  It has also been shown to help reduce fine wrinkles, improve skin firmness and tone, improve yellowness and sallowness. 
As for the other ingredients in this serum, Marine kelp is a good source of vitamin C that further supports the production of collagen in the skin. Kelp is also a rich source of zinc, which demonstrates anti-inflammatory activity that is linked to its ability to target skin problems such as acne and it also speeds up the body's natural wound healing capabilities [4-7]. Hydrolyzed collagen supplementation safely enhances the body's production of collagen and research shows that this structural protein has positive health-enhancing properties on the skin [8, 9]. Hyaluronic acid has moisturizing properties that are beneficial for the skin . Epidermal growth factor (EGF) plays a major role in wound healing, and it is one of several growth factors that support the proper healing of wounds .
Key Ingredients: Kelp Ferment Filtrate, Magnesium Ascorbyl Phosphate (Vitamin C), Hydrolyzed Collagen, Hyaluronic Acid, Epidermal Growth Factor (EGF) (% were not listed)
All Ingredients: Distilled Water, Kelp Ferment Filtrate, Glycerol, Sodium PCA, Magnesium Ascorbyl Phosphate (Vitamin C), Hydrolyzed Collagen, Hyaluronic Acid, Carnosine (L-), Epidermal Growth Factor (EGF), Niacinamide (Vitamin B3), Centella asiatica Extract, Xanthan Gum, Thioredoxin, N-Acetyl-D-Glucosamine, Betulinic Acid, Glutathione, Citric Acid, Lemon Extract, Optiphen Plus (Phenoxyethanol (and) Caprylyl Glycol (and) Sorbic Acid)