Fish Consumption and Sustainability: A Modeling Study Evaluating the Effects of Fish and Canned Fish Consumption on Nutritional Adequacy and Selected Metrics of Environmental Impact

Background/Objectives: Although aquatic foods are recognized for their nutritional value and relatively low environmental impact, their role in healthy and sustainable dietary patterns remains poorly characterized, particularly regarding canned fish products. This study aimed to evaluate the impact of increasing fresh and/or canned fish consumption within two healthy and sustainable dietary patterns representative of the Italian context, one EAT-Lancet-based (MED_EAT-IT) and one based on Italian Food-Based Dietary Guidelines (FBDGs). Methods: Three alternative scenarios were generated for each baseline dietary pattern by increasing fish intake from three to four servings/week, replacing poultry, while varying fresh fish and canned tuna contributions. Nutrient intakes, nutritional adequacy, and environmental impact indicators were compared across scenarios. Results: Replacing poultry with fresh fish generally improved the nutrient profile of the MED_EAT-IT pattern, increasing EPA+DHA (+14%), vitamin B12 (+11%), and vitamin D (+12%) intakes while slightly reducing cholesterol. These improvements were less evident in the FBDGs pattern, likely due to its fixed portion-based structure. Compared with fresh fish, substituting canned tuna resulted in slightly lower intakes of selected micronutrients and cholesterol, while nutritional adequacy was maintained for most nutrients. Carbon and water footprints were largely unchanged, with modest reductions observed as fish intake increased, particularly when canned tuna was included (up to −6.2% CF and −5.5% WF). Conclusions: These findings suggest that increasing fresh and canned fish consumption within optimized dietary patterns may improve micronutrient intake while maintaining, or slightly reducing, environmental impact, supporting the promotion of aquatic foods, including shelf-stable products, in healthy and sustainable diets.