Do AI Chatbots Give Nutrition Advice Aligned with the Dietary Guidelines for the Brazilian Population? An Exploratory Analysis Informed by the Commercial Determinants of Health

Background: AI chatbots are increasingly used to access health and nutrition information, but the quality and alignment of their responses with evidence-based dietary guidance remain uncertain. This study evaluated whether healthy eating recommendations generated by four AI chatbots aligned with the Dietary Guidelines for the Brazilian Population (DGBP) and whether their responses included content consistent with food corporations’ narratives. Methods: Between February and March 2026, ChatGPT, Gemini, DeepSeek, and Grok were evaluated using two questionnaires: a validated instrument developed to assess health professionals’ knowledge of the DGBP (GAB-1) and a second questionnaire simulating a citizen’s interaction based on DGBP recommendations. Responses were assessed using the GAB-1 scoring system and two author-developed instruments assessing alignment with the DGBP and food corporations’ narratives. Results: All AI chatbots provided information consistent with the DGBP in the GAB-1 assessment. However, in the citizens’ interaction, they produced at least one response containing content misaligned with the DGBP or consistent with food corporations’ narratives. Total alignment scores ranged from 42.9% (ChatGPT) to 71.4% (Grok) of the maximum, and no AI chatbot achieved full alignment on more than 42.9% of the indicators. Scores differed across chatbots (Friedman p = 0.011), but no pairwise difference remained significant after Holm adjustment. Conclusions: Although AI chatbots performed well when assessed with a structured true/false knowledge test, their nutrition advice to citizens included content inconsistent with the DGBP or consistent with food corporations’ narratives.