Many people consume food without having enough information about its nutritional value, environmental impact, or how it aligns with their personal preferences, health, and sustainability goals. With increasing concerns about human health and sustainability, there is a growing need for tools that help individuals make better-informed food choices. This paper introduces the SustainHealthyFood ontology to be used as a reference model for sustainable and healthy food consumption. The ontology serves two key purposes: (1) helping users make informed decisions by providing insights into food nutrients and Eco-Scores, enabling them to assess both health and environmental impact; and (2) facilitating personalized food recommendations, such as recipe suggestions, tailored to individual preferences, personal attributes, dietary needs, health conditions, and goals. The SustainHealthyFood ontology consists of four OntoUML conceptual models focusing on: (1) Food Nutrition, (2) Health Status and Diet, (3) Environmental Sustainability, and (4) Explainable Recommendations. The operational ontology is implemented in OWL, with instances populated from existing datasets in the domains of food and environmental sustainability. For ontology testing, SPARQL queries are used to assess whether the ontology meets the competency questions. This paper describes and evaluates the SustainHealthyFood ontology, presents related work, and discusses benefits, limitations, and future work.