Bifidobacteria are beneficial microbes in the guts of humans, especially early in life, when the gut microbiome is just beginning to take shape. Among the nutrients that Bifidobacteria feed on are certain sugars found in breast milk. To understand how these sugars influence Bifidobacteria metabolism, researchers monitored the effects of the sugar 2'-fucosyllactose (2'-FL) in the guts of mice. Mice were either given a specific Bifidobacterium strain alone or in combination with 2'-FL, and their gut and systemic metabolic profiles were compared. Interestingly, mice given both the bacteria and 2'-FL showed significant differences in their gut microbial diversity and metabolite profiles. These changes were indicative of healthier gut and systemic metabolic function. The rise in beneficial metabolites was proportional to the density of Bifidobacterium populations in the gut. However, without 2'-FL, the Bifidobacteria were unable to outcompete existing gut bacteria, causing the gut to return to its normal state after attempted colonization. While more work is needed to understand the implications for human health, this study underscores that microbes alone do not dictate health outcomes and points to ways of pairing microbes with the right nutrients to ensure health benefits for their host.