Pollution increases compounds called free radicals in the body. Too many free radicals in the body cause oxidative stress. Oxidative stress can increase the risk for cancer and other chronic diseases because cells are damaged more easily and do not repair themselves as well. Pollution in the environment cannot always be avoided. However, eating for good health may help reduce the effects of pollution in the body. Choosing more nutritious foods, such as those high in phytonutrients, may reduce oxidative stress and protect the body from the negative health effects of pollution.