Up until now we have been pretty much treating our intestinal bacteria as something we needed to nurture and care for through consumption of some rather specialized foods. Yogurt, miso soup, sauerkraut, kefir, sour pickles, and tempeh were among the exotic and not-so-exotic. Now, following the recent publication of a new study out of The Netherlands, we know that everything we eat or drink affects our intestinal bacteria and is likely to have an impact on our health. The study was led by geneticist Cisca Wijmenga, and was published in the research journal Science.

In this study researchers collected stool samples from more than 1,100 people taking part in the LifeLines Cohort Study & Biobank, which is monitoring the health of 165,000 residents of the Northern Netherlands. The samples were used to analyze the DNA of the bacteria and other organisms that live in the gut. In addition to stools, the study collected information on the participants' diet, medicine-use and health.

This study is unique in that it focused on a group of normal people whereas previous research was frequently focused on patients with a specific illness. Further, the study covered an exceptionally large group of people and studied their gut DNA in detail.

This DNA analysis made it possible to examine which factors impact the diversity of the microbiome -- the intestinal bacterial community unique to each of us. And that appears to be many. People who regularly consume yogurt or buttermilk have a greater diversity of gut bacteria. Coffee and wine can increase the diversity as well, while whole milk or a high-calorie diet can decrease it.

"In total we found 60 dietary factors that influence the diversity. What these mean exactly is still hard to say," explains researcher Alexandra Zhernakova, the first author of the Science article. "But there is a good correlation between diversity and health: greater diversity is better."

Beyond diet, at least 19 different kinds of medicine -- some of which are widely used – have an impact on microbiome diversity. An earlier study by researchers has shown that antacids decrease this diversity, while antibiotics and the diabetes drug metformin also have an effect. These are important findings, Wijmenga stresses: "Disease often occurs as the result of many factors. Most of these factors, like your genes or your age, are not things you can change. But you can change the diversity of your microbiome through adapting your diet or medication. When we understand how this works, it will open up new possibilities."