For a while now I' ve been linking to articles about how recent medical research is indicating that inflammation and bad gut bacteria are the sources of many chronic health problems. This piece, from Harvard Magazine, is probably the most forceful yet.
Evidence has been mounting that these common chronic conditions—including Alzheimer’s, cancer, arthritis, asthma, gout, psoriasis, anemia, Parkinson’s disease, multiple sclerosis, diabetes, and depression among them—are indeed triggered by low-grade, long-term inflammation. But it took that large-scale human clinical trial to dispel any lingering doubt: the immune system’s inflammatory response is killing people by degrees.
And there's some good news here, too. A simple blood test--for "CRP"--can measure your inflammation level and there are foods you can eat that should reduce your level if its too high. (Google "anti-inflammatory foods".)