This dataset contains untargeted proteomic measurements from H441 epithelial cells cultured under physiologic metabolic conditions. Cells were conditioned in human plasma–like medium (HPLM) and treated with or without an amino acid supplement. Proteomic profiling was performed to quantify global protein abundance changes associated with amino acid supplementation under these metabolic conditions. Pathway-level analyses were conducted to characterize cellular processes altered by supplementation. This dataset provides a resource for examining proteome-level responses to metabolic modulation in epithelial cells.