Noncommunicable diseases (NCDs, e.g., type 2 diabetes) are a burden to humanity and hence addressed in the Sustainable Development Goals (SDGs) (target 3.4). One way of tackling NCDs is by health education as part of science education. Yet, the role of knowledge for health-promoting actions, and thus, the role of science teaching in health education, is not sufficiently clarified. Therefore, the author proposes to differentiate three knowledge types: System Health Knowledge (SK), Action-related Health Knowledge (AK), and Effectiveness Health Knowledge (EK). Accordingly, we designed a questionnaire that asked students to evaluate different questions about sugar consumption and type 2 diabetes according to their relevance for deciding their future sugar consumption. We found that students considered all questions as rather important (3-4.3, out of 5) with an assigned mean importance for SK with a mean of 3.8, for AK with a mean of 4.0, and for EK with a mean of 3.9. This research indicates that knowledge is important for decision-making and that all three types of knowledge should be recognized in health education.Sustainability 2020, 12, 3396 2 of 12 sugar (e.g., in sugar-sweetened beverages [7]) and alcohol. On the one hand, the reasons for these behaviors are conditioned by the environment or setting and socioeconomic status. On the other hand, individual motivational factors (e.g., attitudes, needs, values) and, in many places, the role of knowledge, are discussed as potential causes for (un)healthy behavior [8] (Figure 1). Sustainability 2020, 12, x FOR PEER REVIEW 2 of 12 factors (e.g., attitudes, needs, values) and, in many places, the role of knowledge, are discussed as potential causes for (un)healthy behavior [8] (Figure 1).