Squalene is a hydrocarbon and a triterpene, and is a natural and vital part of the synthesis of all plant and animal sterols, including cholesterol, steroid hormones, and vitamin D in the human body.Squalene is used in cosmetics, and more recently as an immunologic adjuvant in vaccines.Squalene has been proposed to be an important part of the Mediterranean diet as it may be a chemopreventive substance that protects people from cancer.qualene is a low density compound often stored in the bodies of cartilaginous fish such as sharks, which lack a swim bladder and must therefore reduce their body density with fats and oils.