TNF and gastric cancer: (3) Improvement of oxidative stress and inflammation: Three polysaccharides (TF-1, TF-2, and TF-3) from tea were found to protect mice with gastric cancer induced by N-methyl-N’-nitro-nitrosoguanidine from oxidative stress damage and inflammation by increasing the expression of SOD, CAT, and GSH-Px; decreasing the levels of IL-6 and TNF-α; and increasing the levels of immunoglobulin A, immunoglobulin G, immunoglobulin M, IL-2, IL-4, and IL-10.