During periods of active inflammation, stress or following surgery there is an increase in levels of iron in the gut. While most constituents of the gastrointestinal microbiome are able to grow under conditions of increased iron availability, lactobacilli and bifidobacteria, frequently employed as probiotics, are rapidly out-competed and cannot have a beneficial effect. Thus, in order for a bacterial product to be functional during periods of active inflammation, stress or following surgery, it must be able to thrive in iron-rich environments by increasing growth rate in order to compete with the resident microbiome. Through a rational selection process, we have identified a strain of Streptococcus thermophilus (designated FX856) which is able to increase growth rate in response to iron and has anti-inflammatory properties in standard models of gastrointestinal inflammatory disease.