Your genome is the same right now as it was yesterday, last week, last year, or the day you were born. But your microbiomes—the combined genes of all the trillions of microbes that share your body—have shifted since the sun came up this morning. And they will change again before the next sunrise.
Elinav says that the health implications of the study are still unclear—a necessary caveat, especially given the fashionable tendency to ascribe everything to the microbiome. Many studies have shown that people who work variable shifts, or who suffer from disturbed sleep or repeated jet lag, are more prone to various health problems, including obesity, diabetes, and even some types of cancer. This study suggests that microbes (or rather, diet via microbes) might be involved in some of these connections. But how big a role do they play, compared to other possible factors? No one knows.