We previously demonstrated in non-human primates (NHP) that Mediterranean diet consumption shifted the proportional abundance of Lactobacillus in the breast and gut. This data highlights a potential link about gut-breast microbiome interconnectivity. To address this question, we compared bacterial populations identified in matched breast and faecal samples from our NHP study. Dietary pattern concurrently shifted two species in both regions; Streptococcus lutetiensis and Ruminococcus torques. While we observe similar trends in Lactobacillus abundances in the breast and gut, the species identified in each region vary; Mediterranean diet increased Lactobacillus_ unspecified species in breast but regulated L. animalis and L. reuteri in the gut. We also investigated the impact of gut permeability on the breast microbiome. Regardless of dietary pattern, subjects that displayed increased physiological measures of gut permeability (elevated plasma lipopolysaccharide, decreased villi length, and decreased goblet cells) displayed a significantly different breast microbiome. Gut barrier dysfunction was associated with increased α-diversity and significant different β-diversity in the breast tissue. Taken together our data supports the presence of a breast microbiome influenced by diet that largely varies from the gut microbiome population but is, however, sensitive to gut permeability.