Tetrasodium glutamate diacetate (TGDA), also known as GLDA‑Na₄, is a chelating agent derived from the amino acid L‑glutamic acid. In cosmetic formulations, TGDA binds multivalent metal ions such as calcium, magnesium and iron, which are present in water and raw materials. Free metal ions catalyze oxidation and other degradation reactions in emulsions, surfactants and active ingredients; chelating them slows oxidation, prevents rancidity and colour change, and stabilizes pH. TGDA’s strong affinity for metal ions improves the stability and appearance of creams, lotions, gels and surfactant systems. The ingredient can also reduce water hardness and prevent mineral precipitation, thereby improving foam quality and cleansing performance in shampoos and body washes. Because metal ions on bacterial cell walls contribute to membrane integrity, TGDA weakens microbes by extracting Ca²⁺ from cell surfaces; this makes preservatives like sodium benzoate more effective and allows formulators to lower preservative concentrations without compromising microbial safety.

In hair care applications, TGDA’s ability to sequester mineral ions helps keep hair fibres free of hard‑water deposits that cause dullness and brittleness. By complexing calcium and magnesium, TGDA improves shampoo lather and reduces scale build‑up, leading to softer, more manageable hair. It is also used in hair dyes and bleach to ensure predictable colour results by controlling metal‑catalyzed peroxide decomposition. TGDA is produced from monosodium L‑glutamic acid via fermentation and is readily biodegradable; it provides a greener alternative to traditional chelants like EDTA and NTA and has been recognized as safe by the U.S. EPA’s Design for the Environment program. TGDA can be incorporated into a wide range of formulations, including facial cleansers, moisturizers, deodorants, sunscreens, hair conditioners, wipes and makeup.