Fig. 3
Gut microbiota TMAO productivity in low producer can be enhanced by carnitine supplementation. a For all the 56 subjects, the TMAO productivity showed nonsignificant change by carnitine supplementation. b For the subgroup of low-TMAO producer, TMAO productivity was significantly increased by carnitine supplementation, when it showed nonsignificant change in the subgroup of high-TMAO producer. For A and B, time reflects hours after oral challenge of carnitine. Bars represent the mean ± S.E.M for the indicated groups. c TMAO productivity represented by plasma TMAOMAX of OCCT in the low-TMAO group was also increased significantly by carnitine supplementation, whereas it showed nonsignificant change in the high-TMAO producer group. d Schematic diagram briefly showing results of carnitine supplement intervention in healthy omnivores and vegetarians with each individual’s TMAO productivity measured by OCCT before and after the intervention. Generally, 55% subjects were grouped as low-TMAO producer phenotype while 45% subjects were grouped as high-TMAO producer. The TMAO production capacity in low-TMAO producer was significantly enhanced by carnitine supplementation with some shifted to high-TMAO producer phenotype. For the high-TMAO producer group, no overall significant change of TMAO productivity was found by the intervention