Glycolic acid in food: ingestion safety

(People-specific data is limited; this page draws from human adult context.) Glycolic acid (hydroxyacetic acid; CAS 79-14-1) is the simplest and smallest alpha-hydroxy acid (AHA), naturally found in sugarcane, beet sugar, unripe grapes, and pineapple. It is one of the most widely used cosmetic active ingredients globally — present in anti-aging serums, exfoliating toners, chemical peels, moisturizers, body lotions, and acne treatments at concentrations ranging from as low as 2–5% (over-the-counter cosmetics) to 20–70% (professional and medical chemical peels). Glycolic acid's cosmetic mechanism involves weakening the intercellular adhesion between corneocytes (skin cells in the outermost stratum corneum), accelerating shedding of dead skin cells and promoting epidermal renewal; at the dermal level, it can stimulate collagen synthesis. Its small molecular size (MW 76 g/mol) gives it superior skin penetration compared to larger AHAs (lactic, citric, malic acids). FDA reviewed cosmetic AHA products and issued safety guidelines in 2005, recommending maximum 10% concentration with product pH ≥3.5 for consumer products; concentrations above 10% or pH below 3.5 significantly increase irritation risk. Professional peels at 30–70% are applied by trained professionals under controlled conditions with neutralization. The primary safety concerns at cosmetic concentrations are (1) skin irritation (burning, erythema, stinging, particularly in sensitive or compromised skin), (2) increased photosensitivity from stratum corneum thinning (FDA recommends sunscreen use concurrent with AHA cosmetics), and (3) exacerbation of rosacea or eczema at higher concentrations. Carcinogenicity has not been established for glycolic acid.