A systematic literature review on dietary intake and nutrition-related adaptations across isolation and confinement

Maintaining adequate nutritional intake and body mass is critical in spaceflight and its terrestrial analogs; however, comprehensive evidence on dietary intake patterns and nutritional adaptations during long-term isolation and confinement remains limited. Following PRISMA guidelines, this systematic review synthesizes evidence on dietary intake and nutrition-related adaptations in isolated and confined environments. Across 184 studies, dietary structure ranged from highly standardized to highly variable. Energy intake differed substantially across habitats, whereas macronutrient distributions remained within recommended ranges, characterized by stable protein intake across habitats and more variable carbohydrate and fat contributions. Body mass generally decreased, with the greatest heterogeneity observed in terrestrial isolated, confined, and extreme environments. Vitamin D insufficiency was consistently reported but could be effectively prevented through supplementation. Overall, isolated and confined environments challenge nutritionally adequate food systems, and current evidence is insufficient to draw firm conclusions on optimal strategies, particularly for longer-duration space missions.