Dietary fish oil appears to prevent the activation of phospholipase C-gamma in lymphocytes.

Rats were fed on a low fat diet or on high fat diets which included coconut oil, olive oil, safflower oil, evening primrose oil or fish oil as the principal fat source. The level of phosphatidylinositol-4, 5-bisphosphate in spleen lymphocytes was unaffected by diet. However, the fish oil diet significantly decreased the concentration of inositol-1,4,5-trisphosphate in stimulated lymphocytes; this concentration was also reduced following olive oil feeding. Diet did not significantly affect the level of phospholipase C-gamma1 in spleen lymphocytes but the tyrosine phosphorylation state of this enzyme in stimulated lymphocytes, as well as that of a range of other proteins, was decreased following feeding the fish oil and, to a lesser extent, the olive oil diets. It is concluded that fish oil feeding appears to result in inhibition of one or more tyrosine kinases.