People with type 1 diabetes have immune systems that destroy their bodies’ pancreatic β cells, which are needed to produce insulin. The disease typically affects young people and children and was long thought to have genetic origins. However, in past decades, a progressive rise in the cases of type 1 diabetes has made many researchers wonder whether environmental factors such as hygiene, antibiotic use, and diet may also play a role in this disease. A team led by Charles R. Mackay and Eliana Mariño of Monash University has found that molecules produced by gut microbiomes can protect mice against the onset of type 1 diabetes. If the work holds true for humans, dietary interventions may be an effective approach for protecting insulin-producing β cells in these patients (Nat. Immunol. 2017, DOI: 10.1038/ni.3713). In particular, the researchers found that when they fed mice with type 1 diabetes a diet that increased the gut microbiome’s production of acetate and butyrate, the mice were protected from the rogue behavior of their immune system T cells. This is not the first time that short-chain fatty acids from gut microbiomes have been identified as modulators of health. For example, acetate and butyrate from mouse gut microbiomes have also been shown to impact obesity, allergies, asthma, and epigenetic modifications in the animals.