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Antioxidants

Ferulic acid

A plant antioxidant used mainly to stabilize vitamins C and E. In that trio it doubled protection against UV damage in lab skin tests.

Limited evidenceTypical strength: About 0.5%

What it is

Ferulic acid is a polyphenol found in bran, seeds and many plants. Its best-known role in skincare is as a helper: added to a serum of 15% L-ascorbic acid and 1% vitamin E, it slowed the vitamin C from breaking down and doubled the formula's protection against UV-induced redness and sunburn cells, from about 4-fold to 8-fold.

On its own it has antioxidant and mild pigment-lightening activity in lab studies, but few human trials test it alone.

How strong is the evidence?

Limited evidence

The key evidence is one lab-and-skin study from a single research group showing ferulic acid stabilized and strengthened a vitamin C + E serum. Evidence for ferulic acid alone on wrinkles or spots in people is sparse; reviews rely mainly on lab work.

What it's used for, checked

Stabilizing vitamin C and E serums

Holds up

Improved the chemical stability of a 15% vitamin C + 1% vitamin E solution.

Extra protection against sun damage

Mixed

In the vitamin C + E combination it doubled UV protection on lab measures; it still provides no SPF.

Brightening on its own

Unproven

Inhibits pigment production in lab studies; not tested well in people.

Works well with

  • L-ascorbic acid and vitamin E

Who should be careful

  • Low irritation on its own; the stinging people notice usually comes from the acidic vitamin C it is paired with.

The studies

Every citation is checked against its PubMed record.

  1. Ferulic acid stabilizes a solution of vitamins C and E and doubles its photoprotection of skin.
    Lin FH, Lin JY, Gupta RD, Tournas JA, Burch JA, Selim MA, et al. · Journal of Investigative Dermatology · 2005 · Experimental (skin irradiation)

    Adding ferulic acid to a 15% L-ascorbic acid + 1% alpha-tocopherol solution improved its chemical stability and doubled its protection of skin against solar-simulated UV (from about 4-fold to about 8-fold), measured by redness and sunburn cells; thymine dimer formation was also reduced.

  2. Antioxidant Properties of Ferulic Acid and Its Possible Application.
    Zduńska K, Dana A, Kolodziejczak A, Rotsztejn H · Skin Pharmacology and Physiology · 2018 · Review

    Reviews ferulic acid's antioxidant, anti-inflammatory and anti-pigment properties and its use as a photoprotective and brightening ingredient, noting that its tendency to oxidize limits formulation.