July 27/Ann Arbor, Mich./UPI -- More fish oil than vegetable oil in the diet decreases the formation of chemicals called prostanoids, which can increase inflammation, says a U.S. study.

William L. Smith of the University of Michigan in Ann Arbor and colleagues may help in designing new anti-inflammatory drugs with fewer side effects than the ones currently available.

"Prostanoids help control blood pressure, fight allergies and modulate inflammation, but too much of them -- especially those made from vegetable oils -- can also lead to increased pain, swelling, and redness in various tissues," Smith said in a statement.

"Our study shows that prostanoids made from fish oil are less effective at causing pain and swelling than those made from vegetable oil and that adding fish oil to the diet decreases the amount of prostanoids made from vegetable oil."

The study, published in the Journal of Biological Chemistry, looked at the mutual effects of both oils by changing their respective amounts in cultured cells and found a relative increase in fish oil lowered the amount of prostanoids from vegetable oil, although not always in the expected proportions.

From the July 30, 2007, Prepared Foods e-Flash