We examine public trust and distrust in governmental food and nutrition authorities, through analyzing 727 letters sent electronically to the Swedish National Food Agency by lay people. Using thematic analysis, four themes were developed, defining public expressions of trust and distrust in official dietary advice. Trust was expressed as (a) seeking to confirm and clarify dietary advice, or (b) seeking official arbitration between competing dietary advice. Distrust was expressed as (c) questioning and scrutinizing dietary advice, or (d) protesting and resisting dietary advice. Notably, expressions of distrust employed discursive practices that both mirrored authoritative discourses and subverted official advice, by appealing to scientific language and 'alternative' evidence. All letters positioned the agency as the ultimate authority on healthy eating; notwithstanding whether the agency’s advice was to be followed or resisted. Thus, the letters revealed how the same authoritative discourses can simultaneously be a site of public trust and distrust.