Heat stress poses a significant challenge in poultry production, as high temperatures disrupt physiological homeostasis, impair antioxidant defenses, and reduce productive performance. Birds under thermal stress show alterations in metabolic and endocrine regulation, with decreased feed intake and oxidative damage, which compromise cellular integrity and immune responsiveness. This review synthesizes evidence on biochemical defense mechanisms activated by heat stress and examines nutritional strategies for restoring redox equilibrium and enhancing adaptation. Focus is placed on minerals and bioactive compounds involved in antioxidant protection and osmotic regulation. Betaine maintains cellular hydration and stabilizes protein structures, supporting growth performance under thermal challenge. Selenium, through selenoproteins, reinforces antioxidant enzyme systems and improves immune competence. Insect-derived proteins provide digestible amino acids, natural antioxidants, and chitin-derived compounds that enhance intestinal functionality and stress tolerance. Sulfur-containing amino acids are essential for glutathione biosynthesis and maintaining hepatic and intestinal integrity. Additional bioactive nutrients, including vitamins A, C, and E, reinforce antioxidant defenses, while short-chain organic acids like butyric acid maintain intestinal morphology, barrier function, and microbial homeostasis. Evidence from experimental studies and meta-analyses shows that element-enriched diets can effectively alleviate heat stress effects, offering a cost-efficient alternative to mechanical cooling systems. These nutritional interventions support animal welfare, improve feed efficiency, and promote sustainable poultry production under adverse climatic conditions.