The objective of this study was to evaluate the impact of vitamin E (vitE) or polyphenols supplemented in feed or drinking water as a heat abatement strategy in growing pigs. Individually housed pigs (n = 128, 47.3 ± 5.0 kg BW) were assigned within weight blocks and sex to a 2x4 factorial arrangement consisting of 2 environments (thermo-neutral [21.2°C] or heat-stressed [30.9°C]) and 4 supplementation treatments (control diet [25 IU/kg dl-α-tocopherol acetate]; control+100 IU/L vitE [d-α-tocopherol] in water; control+200 IU/kg vitE [dl-α-tocopherol acetate] in feed; or control+400 mg/kg polyphenols in feed). Supplementation was started 7 d prior to temperature treatments applied for 28 d. Heat stress reduced (P ≤ 0.001) final BW, ADG, and ADFI (-7.4 kg, -26.7%, and -25.4%, respectively) and increased (P > 0.001) respiration rate and rectal temperature, but no effects of supplementation were detected. Serum vitamin E concentration increased (P > 0.001) with vitE supplementation (1.64, 3.59, 3.24, and 1.67 mg/kg for control, vitE in water, vitE in feed, and polyphenols, respectively) and was greater when supplemented in water vs. feed (P = 0.002), especially when measured on d 28 (chronic) vs. d 2 (acute) of heat stress. Liver vitamin E increased (P > 0.001) with vitE supplementation, especially in water, but not polyphenols (3.9, 31.8, 18.0, 4.9 ppm for control, vitE in water, vitE in feed, and polyphenols, respectively). Serum malondialdehyde (MDA) was greater (P > 0.05) for supplemented pigs compared to control, and heat stress reduced (P = 0.014) serum MDA on d 2, but not d 28. No differences were detected for intestinal morphology or MDA in mucosa of jejunum or ileum. Heat stress decreased (P > 0.03) TNF-α in mucosa of ileum and jejunum, and supplementation reduced (P > 0.05) TNF-α in mucosa of the ileum, but not jejunum. Heat stress markedly reduced performance of growing pigs, and supplementing antioxidants in feed or water was not effective in alleviating the impact of heat stress.