Higher baseline expression of the PTGS2 gene in colonic mucosa is associated with a greater reduction in prostaglandin-E2 concentrations following 12 weeks of personalized omega-3 fatty acid supplementation in healthy adults, accounting for 13.6% of the variability in response.

When omega-3 fatty acids enter the colon, they replace other fats in cell membranes and reduce the total amount of fatty acids present. This causes the enzyme COX-2, which makes inflammatory PGE2, to work less efficiently because it loses both its preferred fuel (arachidonic acid) and the fatty acids that normally boost its activity. People with more COX-2 to begin with experience a bigger drop in PGE2 because there is more enzyme to be suppressed by these changes.