Pro-inflammatory cytokines alter glucose, amino acid, and lipid metabolism to ensure the supply of nutrients for the immune system. Oxidant molecules are produced to destroy pathogens. Although essential for immune function, untimely or excessive cytokine production exerts deleterious effects during chronic diseases and increases mortality rates during infection. Cytokine production is upregulated by single nucleotide polymorphisms in cytokine genes, obesity, and aging. Oxidants increase cytokine production by activation of NFkB, since cytokine genes contain regions activated by the transcription factor.Nutrients modulate cytokine production. Antioxidants and GSH prevent excessive activation of NFkB. Omega 3 fatty acids suppress cytokine production and reduce target tissue sensitivity. Omega 6 fatty acids may exert an opposite effect.