Vitamin C

VITAMIN C – PERCENTAGES, USAGE, AND OTHER CONCERNS

Vitamin C is one of the most well-researched ingredients, and its effectiveness has been proven.
How do you choose vitamin C, how do you combine it with other ingredients, and when should you use it?

EFFECTS: MORE COLLAGEN, FEWER SKIN SPOTS

Antioxidant – protection from photoaging

UV radiation induces the formation of free radicals in the skin (oxidative stress), which causes damage to the cells—their membrane, proteins, and DNA. Vitamin C protects against oxidative stress.

Collagen synthesis – fewer wrinkles - Besides increasing the activity of fibroblasts, the cells that produce collagen, vitamin C prevents the formation of enzymes that break down collagen. More collagen, fewer wrinkles!

Fewer skin spots - Vitamin C disrupts the activity of enzymes involved in the formation of the melanin pigment—less melanin, fewer spots.

Anti-inflammatory action - Vitamin C reduces inflammation in tissues, thus promoting healing and having a beneficial effect on inflammatory conditions (acne, rosacea).

HOW TO CHOOSE A PRODUCT?

"Pure vitamin C" refers to the biologically active form, L-ascorbic acid, which is the most effective but also the least stable, requiring special packaging to protect it from light and air (dark bottles, pumps, pipettes).
For it to be absorbed into the skin, the product’s pH value must be 3.5, which is lower than the skin's pH (more acidic). Other forms—derivatives—are generally less effective but have a lower capacity for irritation, making them better tolerated by sensitive skin. They are also more stable in products. Some are particularly effective against spots, and oil-soluble derivatives penetrate the skin more deeply and easily than L-ascorbic acid.

Pure vitamin C – L-ascorbic acid

The most effective form of vitamin C works in concentrations of 10-20%. Concentrations above 20% can irritate. With pure vitamin C, initial irritation like tingling and redness may occur, which usually subsides after two to three weeks as the skin adapts.

Since it’s water-soluble, pure vitamin C creates aqueous serums with a short shelf life. One way to ensure the stability of vitamin C is to have it in powder form, which is mixed with an emulsion or serum before use. This solution is chosen by The Ordinary in two products: powder and a suspension that contains fine powder in oil spheres.

The Ordinary Vitamin C powder – 100% pure vitamin C powder. Be careful with dosing to avoid irritation from high concentrations. The brand also warns about possible tingling and initial irritation with Vitamin C Suspension 23% + HA Spheres 2%.

Other reliable forms of vitamin C - Ascorbyl glucoside and 3-O-ethyl ascorbic acid are two newer-generation vitamin C derivatives that are highly stable and particularly effective in lightening spots. If you are prone to spots or have sensitive skin, try The Ordinary Ascorbyl Glucoside 12% or Susanne Kaufmann Vitamin C Complex. If you prefer vitamin C in cream form, a great choice is Institut Esthederm Vitamin C Cream with ascorbyl glucoside.

Tetrahexyldecyl ascorbate, or “pro-vitamin C,” is another exceptionally stable form of vitamin C. It is oil-soluble, making it highly effective in penetrating the skin down to the dermis. This form of vitamin C, in an ideal combination with vitamin E and numerous botanical ingredients, is found in the luxurious capsules Darphin Ideal Resource Renewing Pro-Vitamin C and E.

A blend of multiple forms of vitamin C is available in the excellent Institut Esthederm Vitamin C Concentrated serum, which combines ascorbic acid and ascorbyl glucoside. Use it for an intensive two-week treatment several times a year. Clinically proven results in brightening the skin.

WHEN TO USE IT? HOW TO COMBINE IT?

Vitamin C can be used during the day or at night, depending on your preference and other ingredients in your skincare routine.
Vitamin C does not increase the skin’s sensitivity to the sun, so you can use it during the summer.
Do not use vitamin C in the same routine as retinol, niacinamide, acid serums, or peptides.

If you use retinol or acids in your evening routine, use vitamin C during the day. Alternatively, use these active ingredients on alternate nights. Not only can they irritate in combination, but they are absorbed at different pH levels, which can neutralize the effects of the ingredients.

Vitamin C protects against oxidative stress caused by UV rays, and when combined with vitamin E, this protective effect is significantly enhanced. That’s why it’s a good idea to include vitamins C and E in your summer skincare routine.