Objective: The purpose of the present study was to examine the effects of food label nutrition colouring schemes in interaction with food category healthiness on consumers' perceptions of food healthiness. Three streams of colour theory (colour attention, colour association and colour approach-avoidance) in interaction with heuristic processing theory provide consonant predictions and explanations for the underlying psychological processes. Design: A 2 (food category healthiness: healthy v. unhealthy) × 3 (food label nutrient colouring schemes: healthy = green, unhealthy = red (HGUR) v. healthy = red, unhealthy = green (HRUG) v. no colour (control)) between-subjects design was used. Setting: The research setting was a randomised-controlled experiment using varying formats of food packages and nutritional information colouring. Subjects: Respondents (n 196) sourced from a national consumer panel, USA. Results: The findings suggest that, for healthy foods, the nutritional colouring schemes reduced perceived healthiness, irrespective of which nutrients were coloured red or green (healthiness control = 4·86; healthiness HGUR = 4·10; healthiness HRUG = 3·70). In contrast, for unhealthy foods, there was no significant difference in perceptions of food healthiness when comparing different colouring schemes against the control. Conclusions: The results make an important qualification to the common belief that colour coding can enhance the correct interpretation of nutrition information and suggest that this incentive may not necessarily support healthier food choices in all situations.