Multiple ecological crises present significant health threats to humans and require behaviour change that offers co-benefits for both human health and environmental sustainability. A behaviour offering these co-benefits is the consumption of whole grain products, which has significant health benefits and relieves the food industry's strain on the environment. Providing information on benefits of a behaviour has shown to be effective in promoting behaviour change in both the health and environmental context, but research on the mechanisms and effectiveness is inconclusive. Specifically, it is unclear whether framing the information (health vs. environmental benefits) differs in its effectiveness and whether this depends on individual cognitive or affective differences. To gain a better understanding of the effectiveness of information framing and its underlying mechanisms in the context of increasing whole grain consumption, we conducted a randomised controlled trial with a convenience sample of 123 individuals. Two intervention groups received an information framing (health or environmental benefits), an active control group received neutral facts on whole grain products. In a three-week Ecological Momentary Assessment study, we assessed daily intention and behaviour as well as risk perception and motivational orientation, both separately for health and environment. After a one-week baseline phase, participants received daily messages (health benefits vs. environmental benefits vs. neutral facts). The analyses showed that across all groups, participants increased their intended and actual whole grain consumption, indicating an effect of information but not framing. Potentially, any information increased the salience of whole-grain consumption and thus intentions and consumption. Interestingly, health motivational orientation significantly moderated the effect of messages on intention in the control group, with higher individual health motivational orientation at baseline being related to higher intention, but not consumption, at the later measurement points. No other significant moderations were found. Implications for further research and intervention designs will be discussed.