The present invention is related to a method for purifying diatomaceous earth wherein the natural colloidal structure of the material is retained, which comprises preparing a suspension of diatomaceous earth in a liquid wherein diatomaceous earth is insoluble, separating diatomaceous earth from the suspension, treating diatomaceous earth with an inorganic or organic acid, heat-treating the thus obtained product at a temperature not higher than 300°C, subjecting the product obtained to oxidative treatment and drying the purified product. The invention also relates to a product obtainable by the above-mentioned method.