Prior studies indicate an important role of leptin in signaling between the intestinal microbiota and the heart. Supplementation of the diet with active cultures of Lactobacillus plantarum 299v leads to significant reductions in fibrinogen and LDL-cholesterol, and leptin concentrations in smokers. These clinical studies demonstrate that a probiotic is capable of decreasing risk factors for cardiovascular disease. Note that neither leptin nor TMAO levels, per se, are recognized cardiovascular risk factor. This is currently an area with enormous potential for gaining new mechanistic insight and may lead to a therapeutic product or clinical use.