Supplementary information: Ethnic differences in postprandial fatty acid trafficking and utilisation between overweight and obese White European and Black African-Caribbean men

Black African-Caribbean (BAC) populations are at greater risk of cardiometabolic disease than White Europeans (WE), despite exhibiting lower fasting triacylglycerol (TAG) concentrations. However, limited data exist regarding postprandial fatty acid metabolism in BAC populations. This study determined ethnic differences in postprandial fatty acid metabolism between overweight and obese WE and BAC men. WE (n=10, age 33.3±1.7 years; BMI 26.8 [25.8-31.0] kg/m2) and BAC (n=9, age 27.9±1.0 years; BMI 27.5 [26.0-28.6] kg/m2) men consumed two consecutive (at 0 and 300 mins) moderate-to-high fat meals; the first labelled with U-13C palmitate. The plasma concentration and appearance of meal-derived fatty acids in very-low density lipoprotein (VLDL)-TAG, chylomicron-TAG, and NEFA were determined over an 8-hour postprandial period. Indirect calorimetry with 13CO2 enrichment determined total and meal-derived fatty acid oxidation rates, and plasma -hydroxybutyrate (3-OHB) concentration was measured to assess ketogenesis. BAC exhibited lower postprandial TAG (AUC0-480 671 [563-802] vs. 469 [354-623] mmol/L/min, P=0.022) and VLDL-TAG (AUC0-480 288±30 vs. 145±27 mmol/L/min, P=0.003) concentrations than WE. The appearance of meal-derived fatty acids in VLDL-TAG was lower in BAC than WE (AUC0-480 133±12 vs 78±13 mmol/L/min, P=0.007). Following the second meal, BAC showed a trend for lower chylomicron-TAG concentration (AUC300-480 69 [51-93] vs. 43 [28-67] mmol/L/min, P=0.057). There were no ethnic differences in the appearance of chylomicron-TAG, cumulative fatty acid oxidation and the NEFA:3-OHB ratio (P>0.05). In conclusion, BAC exhibit lower postprandial TAG concentrations compared with WE men, driven by lower VLDL-TAG concentrations and possibly lower chylomicron-TAG in the late postprandial period. These findings suggest that postprandial fatty acid trafficking may be a less important determinant of cardiometabolic risk in BAC than WE men.