Purpose: The purpose of this paper is to assess the socioscientific issue (SSI) method as a way of improving seventh graders' nutrition know-how on dietary supplements (DS), and to describe how students experience learning nutritional issues through the SSI method. Design/methodology/approach: Participants were seventh graders from three different classes (n=43). Health education intervention lasted 7 h and it embodied the three-staged model: the scenario, the inquiry and the decision-making stages. The study was qualitative in nature. The data were collected through a questionnaire before and after the intervention. The data were analyzed using summative content analysis. Findings: Intervention tended to deepen students' know-how on vitamins and rational use of DS. Students' experiences of learning nutritional issues through the SSI method were generally positive. The scenario stage was considered current and authentic. The inquiry stage and decision-making stage helped in understanding the societal connections between the study task and the rational use of DS. Practical implications SSI method enhances students' knowledge about the rational use of DS. E-learning environment gave students possibilities to work collaboratively. Especially, possibilities to discuss with peers and share own experiences supported learning. Originality/value: To solve the need of dietary supplements (DS) is a complex nutritional issue for society and for individuals. Since consumption of special diets has increased among adolescents, the rational consumption of DS is relevant and interesting learning topic at secondary school.