Can vitamin C be effective against brown spots?

What are the effects of vitamin C on hyperpigmentation?

More common than one might think, hyperpigmentation is a skin concern caused by a localized or widespread increase in melanin, the pigment produced by melanocytes to protect the skin. This overproduction can be triggered by various factors: UV exposure, skin inflammation (such as after acne), hormonal fluctuations, ageing or certain medications. In these situations, the melanogenesis goes into overdrive: tyrosinase, the enzyme that enables the conversion of the amino acid tyrosine into melanin, becomes more active and promotes the appearance of darker patches on the skin. Hyperpigmentation is very difficult to fade with cosmetic solutions.

Nevertheless, some actives, such as vitamin C, can target excess melanin and reduce hyperpigmentation.

The vitamin C interacts directly with the mechanisms of melanogenesis and notably acts at the level of tyrosinase. By binding to the copper ions present at the active site of tyrosinase, vitamin C reduces its catalytic activity and thus limits melanin formation, which can gradually diminish pigment spots. Furthermore, the ability of vitamin C to neutralise reactive oxygen species reduces UV-induced inflammation, a factor often involved in the excessive stimulation of melanocytes. Taken together, these effects explain why vitamin C is an appealing active ingredient for evening the skin tone and reducing brown spots.

An interesting clinical study evaluated the efficacy of a cream containing 25% stabilised vitamin C on the melasma of 40 participants. This open-label trial was conducted over sixteen weeks. Pigmentation changes were monitored every four weeks using the MASI (Melasma Area and Severity Index) and a mexameter, while the impact of hyperpigmentation on quality of life was also assessed using the MelasQoL (Melasma Quality-of-Life) questionnaire. After sixteen weeks of application, the results show a significant reduction in pigmentation.

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22.88%

reduction in the MASI score after 16 weeks (from 15.60 to 12.03)

7.56%

decrease in mexameter measurements after 16 weeks (from 215.01 to 198.75)

The MelasQoL scores also improved by an average of 10%, suggesting a beneficial effect on skin tone perception and patients’ quality of life. Indeed, the photographs below, although in black and white, illustrate the reduction of pigmented lesions thanks to vitamin C. These data confirm that this active ingredient can contribute to reducing melasma intensity, particularly when it is stable.

Avant et 16 semaines après application d'une crème à 25% de vitamine C stabilisée. — Before and 16 weeks after application of a 25% stabilized vitamin C cream.
Source: PARK S. W. & al. Clinical efficacy of 25% L-ascorbic acid (C'ensil) in the treatment of melasma. Journal of Cutaneous Medicine and Surgery (2009).

These findings are consistent with other research conducted on ascorbic acid. A study involving sixteen women with melasma evaluated the daily application of a 5% ascorbic acid cream to one side of the face and a 4% hydroquinone cream to the other over sixteen weeks, with each participant also using a daily sun protection. Progress was assessed by colourimetry and digital photography, supplemented by subjective evaluation. The results indicate that patient-perceived improvement was more pronounced on the hydroquinone side, rated "good" or "very good" by 93% of participants, than on the vitamin C side, where 62.5% of volunteers found the improvement "good" or "very good". The colourimetric measurements, however, revealed no statistical difference between the two formulations.

Avant et 16 semaines après application d'une crème à 5% de vitamine C. — Before and 16 weeks after application of a 5% vitamin C cream.
Source: CASTANEDO-CAZARED J. P. & al. A double-blind randomized trial of 5% ascorbic acid vs. 4% hydroquinone in melasma. International Journal of Dermatology (2004).

In contrast, adverse effects were markedly more frequent with hydroquinone (68.7%, i.e. 11/16) than with the vitamin C (6.2%, i.e. 1/16). The authors conclude that, despite its lower subjective efficacy, vitamin C is an interesting option in the management of melasma, notably due to its excellent tolerability profile.

Other studies have also confirmed the depigmenting properties of vitamin C, making this active ingredient a relevant solution for reducing brown spots and improving the evenness of the complexion.

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