Exfoliating acids
Other fruit acids (tartaric, malic)
Also listed as tartaric acid, malic acid, AHA, fruit acids
Grape and apple acids, usually minor parts of acid blends. Weaker exfoliants than glycolic or lactic acid, with little evidence on their own.
What it is
Tartaric acid (from grapes) and malic acid (from apples) are alpha-hydroxy acids that turn up in multi-acid blends and 'fruit extract' complexes. They are larger and weaker than glycolic and lactic acid, and in many formulas they mainly adjust pH rather than exfoliate much.
When a label says just AHA, it rarely states which acids or how much; judge the product by its full ingredient list and stated pH, if any.
How strong is the evidence?
Weak evidenceNearly all clinical AHA evidence is for glycolic and lactic acid. Tartaric and malic acid have lab data and appear in combination products, but trials testing them alone are scarce, so their contribution to a blend is uncertain.
What it's used for, checked
Exfoliation in acid blends
MixedThey add some acid activity, but blends are rarely tested ingredient by ingredient.
Brightening
UnprovenNo good trials of these acids alone.
Who should be careful
- Like all AHAs they can sting and increase sun sensitivity; use sunscreen.
- Layering several acid products raises irritation without clear extra benefit.
The studies
Every citation is checked against its PubMed record.
- Applications of hydroxy acids: classification, mechanisms, and photoactivity. Kornhauser A, Coelho SG, Hearing VJ · Clinical, Cosmetic and Investigational Dermatology · 2010 · Review
Reviews alpha-hydroxy, beta-hydroxy and polyhydroxy acids, their uses for photoaging, acne and pigmentation, and their effects on sun sensitivity, noting that their mechanisms of action still need clarification.