Some foods may cause inflammation, so you'll want to stay clear. The offenders include anything high in omega-6 fatty acids, which are found in oil made from corn, sunflower, safflower, soybean, and cottonseed. They lurk in snack foods, fried foods, margarine, meats, and egg yolks. We know they're bad for the heart, but it's not clear what affect, if any, they have on rheumatoid arthritis.