<i>Ex vivo</i> study on prebiotic &amp; choline combination to modulate gut bacteria, enhance choline bioavailability, and reduce TMA production

<b>Aim:</b> Choline is a universal methyl group donor, playing an essential role in DNA methylation, signaling pathways, and the transport and metabolism of lipids. The primary source of choline intake is diet, and chronic deficiency has been associated with dementia, cardiovascular disease, and liver disease. Choline bioavailability can be diminished by gut microbes that express choline trimethylamine-lyase (<i>cutC</i>), an enzyme that converts choline into trimethylamine (TMA), a precursor for TMA N-oxide (TMAO), which is associated with an increased risk of cardiovascular diseases. Gut microbiota modulation can be achieved by prebiotics such as galactooligosaccharides, inulin, and fructooligosaccharides. The aim of our study is to use choline with prebiotics to modulate the gut microbiota to enhance choline bioavailability and minimize TMA production. <b>Methods:</b> We employed an <i>ex vivo</i> microcosm system consisting of healthy human stool samples with choline and different prebiotics and measured TMA and choline levels by targeted metabolomics. Shotgun metagenomic profiling was also performed to investigate alternation in gut microbiota composition during choline and prebiotic interventions. <b>Results:</b> Our study showed that choline to TMA conversion is dependent on a choline derivative and supplementing galactooligosaccharides (GOS) reduces this conversion. Choline to TMA conversion was associated with enriched microbiota from the genus <i>Dialister</i>, whereas GOS supplementation led to an increase in <i>Blautia</i> and a reduction in <i>Clostridia</i> populations. Loss of <i>Clostridia</i> also reduced a subset of <i>Clostridium</i> species, <i>Clostridium citroniae</i>, known to encode the <i>cutC</i> gene. The abundance of <i>Dialister</i> enhanced the chorismate biosynthesis pathway, while a reduction in <i>Clostridium</i> supported tryptophan and methionine pathways. <b>Conclusion:</b> This study is the first to identify the combination of choline and GOS supplementation as a potential strategy to modulate gut microbiota and its metabolites in order to improve disease etiology.