Intake of trans fatty acid isomers found in ruminant fat versus industrial sources differentially impact concentrations of fatty acids in erythrocytes (1025.17)

Abstract

Evidence suggests concentration of trans fatty acids (TFA) in erythrocyte (RBC) membranes is strongly predictive of coronary heart disease (CHD) risk. Some data suggest a direct association with industrially‐produced TFA (iTFA) and CHD risk, and an inverse or no association with naturally‐occurring TFA in ruminant fat (rTFA). Differential incorporation of TFA isomers in RBC membranes from iTFA and rTFA may account for differences in CHD risk reported between the two sources; however, controlled dietary interventions comparing iTFA and rTFA have not measured RBC TFA isomers. In a double‐blind randomized‐controlled crossover feeding trial healthy adults (N=106; 47M, 59F) were fed 4 diets for 24 days each: 0.1% en mixed isomers TFA (control), 3.0% en highly‐purified vaccenic acid (VA), 3.0% en mixed isomers iTFA, and 1.0% en c9,t11‐CLA. Total fat (34% en) and other macronutrients were matched across diets. RBC VA was highest following the VA diet (P < 0.05), while elaidic acid was highest following the iTFA diet (P < 0.05). RBC c9,t11‐CLA was highest after the CLA diet (P < 0.05), followed by the VA diet (P < 0.05), indicating some conversion of VA to c9,t11‐CLA resulting from the dietary VA. In conclusion, highly‐purified dietary VA and c9,t11‐CLA differentially impact RBC fatty acid profiles compared to iTFA. Differences in RBC fatty acids impact membrane fluidity which may explain differences of rTFA and iTFA on CHD risk.Grant Funding Source: Supported by: USDA, Nestle, National Dairy Council, Dairy Australia