The more polyunsaturated fatty acids are contained in the oil, the more susceptible it is to environmental influences such as heat, UV light and oxygen. If such oils are heated up too much or for too long, this can result in a damaging decomposition and in conversion products such as trans-fatty acids. As a result, e.g. our Flaxseed Oil and other Vital Oils are filled into light-protected bottles in a protective atmosphere (free from oxygen). These oils should be stored in the fridge after opening.