This invention relates to a non-medical food additive that is an animal growth promoter containing 99% pure zeolite partially or totally exchanged with a Cm+ cation (in other words a synthetic zeolite) with the general formula I below: 1 m ⁢ yC m + ⁡ ( 1 - y ) ⁢ 1 n ⁢ M n + ⁢ AlO 2 ⁢ x ⁢ SiO 2 in which x is greater than 1 and advantageously between 1 and 15; Mn+ represents an alkaline or alkaline earth exchangeable ion, advantageously Na+, K+, Ca2+ or Li+; n is between 1 and 2; y is the exchange rate and is between 0.001 and 1; Cm+ is a metallic cation chosen from among copper Cu2+, silver Ag+ or zinc Zn2+; m is between 1 and 2. It also relates to an additive premix and a supplemented food containing it and a method of improving the growth of animals.