Vitamin C: Evidence of its effects on the skin, whether from food or cosmetics

Vitamin C produces effects both when ingested and applied on skin

Radiance serums, detox juices, “anti-fatigue” creams… Vitamin C is everywhere in the beauty and wellness aisles. Promoted as a miracle antioxidant capable of brightening the complexion, stimulating collagen and protecting the skin from aging, it nevertheless acts differently depending on whether it is consumed through food or through the skin. Here is what scientific studies confirm on this key molecule for healthy and youthful skin.

Vitamin C, a fundamental active ingredient for the skin

Vitamin C (ascorbic acid) is essential for several biological processes:

• synthesis of collagen , which ensures the firmness and elasticity of the skin;

• neutralization of free radicals generated by UV rays, pollution or stress;

• regulation of melanogenesis , contributing to a more even skin tone;

• support for healing and local immune defenses.

But our body does not produce it : we must therefore obtain it through food... or locally.

Vitamin C from food: action from within

A diet rich in fresh fruits and vegetables (citrus fruits, kiwis, strawberries, peppers, broccoli, parsley, etc.) ensures a sufficient daily intake (around 100 mg/day).

Its proven effects:

• improvement of the structure of the dermis via the stimulation of collagen;

• reduction of signs of oxidative stress ;

• support for healing after injury;

• indirect protection against premature skin aging .

Studies show that people with high plasma levels of vitamin C have fewer deep wrinkles and better skin hydration. However, this action remains systemic and depends on many factors (absorption, metabolism, lifestyle).

Vitamin C applied to the skin: localized but technical effectiveness

Topical application of vitamin C allows the molecule to be concentrated directly in the epidermis and dermis, where collagen is formed. However, this approach is technically complex because:

• the ascorbic acid molecule is unstable (it oxidizes in light and air);

• its optimal absorption pH is acidic (around 3.5), which can irritate sensitive skin;

• only certain stabilized forms (ascorbyl glucoside, MAP, SAP) or anhydrous formulations guarantee good efficacy.

  
  

Proven effects (with regular use 6–12 weeks):

• brighter complexion ;

• reduction of pigment spots ;

• reduction of superficial fine lines ;

  
  

Food vs. cosmetics: complementary mechanisms

Shape	Mechanism	Main advantage	Limit
Dietary vitamin C	Distribution via blood	Acts globally (collagen, immunity, cellular protection)	Limited skin concentration
Topical vitamin C (serum, cream)	Penetrates the epidermis (if pH and stability are optimal)	Directly targets exposed skin cells	Instability and risk of irritation

The synergy between the two is ideal: eating a varied diet and applying a well-formulated topical treatment = double anti-aging defense.

Precautions and best practices

• Prefer stable formulas (opaque, airless bottles).

• Introduce gradually (1 day / 2 at the beginning) to avoid redness or tingling.

• Apply in the morning under sunscreen.

• Avoid oral overdoses (> 1000 mg/day unnecessary except in case of deficiency).

Conclusion

Whether it comes from a plate or a bottle, vitamin C remains one of the skin's best allies.

• Internally, it supports the production of collagen and fights against oxidative stress.

• Externally, it protects, illuminates and evens out the complexion. But like any active molecule, its effectiveness depends on its form, stability and regularity of use. The diet + cosmetics duo remains the most effective strategy for radiant and resilient skin over time.

Have you ever tried vitamin C cosmetics?

• No, I have never tried any
• Yes, and I am satisfied with the results on my skin
• Yes, but I haven't seen any improvement in my skin

Do you eat foods rich in vitamin C?

• No, I don't
• Yes, on a daily basis
• Yes, but not on a daily basis
• No, but I take vitamin C supplements