Abstract: The substance naturally present in milk (referred to as Milk Factor or MF) which is capable of inhibiting mammalian synthesis of cholesterol is produced by a fermentation process using a culture of Pseudomonas fluorescens loitokitok or other Milk Factor--producing strain of P. fluorescens in a culture medium containing glutaconic acid. The process may be used to increase the Milk Factor content of milk, yogurt, or similar dairy product, or the Milk Factor may be recovered from a culture medium and concentrated, crystallized and used as a food additive.