Trans-Vaccenic acid (TVA) is a naturally occurring trans-fatty acid found in ruminant fats and dairy products that has antitumor activity by regulating CD8+ T cell proliferation through the GPCR-CREB pathway.Trans-Vaccenic acid can be synthesized as a saturated fatty acid in the rumen, and conjugated linoleic acid is synthesized at the tissue level Trans-Vaccenic acid can synthesize saturated fatty acids in rumen and conjugated linoleic acid at tissue level.