Comparison of the postprandial metabolic fate of U-13C stearic acid and U-13C oleic acid in postmenopausal women

Authors: RODRIGUEZ-MORATO, JOSE - Hospital Del Mar Medical Research Institute; GALLUCCIO, JEAN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; DOLNIKOWSKI, GREGORY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; LICHTENSTEIN, ALICE - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; MATTHAN, NIRUPA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Arteriosclerosis Thrombosis and Vascular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2020
Publication Date: 12/1/2020
Citation: Rodriguez-Morato, J., Galluccio, J.M., Dolnikowski, G.G., Lichtenstein, A.H., Matthan, N. 2020. Comparison of the postprandial metabolic fate of U-13C stearic acid and U-13C oleic acid in postmenopausal women. Arteriosclerosis Thrombosis and Vascular Biology. https://doi.org/10.1161/ATVBAHA.120.315260.
DOI: https://doi.org/10.1161/ATVBAHA.120.315260

Interpretive Summary: Most dietary saturated fatty acids increase risk for cardiovascular disease. Hence, the Dietary Guidelines for Americans recommends that intake of all saturated fatty acids be less than 10% of the total energy intake. However, at least one of these dietary fatty acids does not appear to increase risk for cardiovascular disease and may not need to be restricted in intake. Using a novel technique that tracks the fate of this fatty acid after dietary intake, we have demonstrated how it has a neutral rather than detrimental effect on CVD risk factors. These results will contribute toward ongoing efforts to optimize dietary/nutrient-labeling guidance.

Technical Abstract: OBJECTIVE: Compare the postprandial fatty acid metabolism of isotopically labeled stearate (U-13C18:0) and oleate (U-13C18:1). APPROACH AND RESULTS: In conjunction with a randomized-controlled crossover trial, 6 hypercholesterolemic postmenopausal women (>/=50 years; body mass index: 25.6+\-3.0 kg/m2; LDL [low-density lipoprotein]-cholesterol >/=110 mg/dL) consumed isocaloric diets enriched in 18:0 or 18:1 (10%-15% E) for 5 weeks each. On day 1 of week 5, following a 12-hour fast, participants receive their experimental diet divided into 13 hourly meals beginning at 8 am. U-13C18:0 or U-13C18:1 was incorporated into the 1:00 pm meal (1.0 mg/kg body weight). Serial blood and breath samples were collected over 12 hours and fasting samples at 24 and 48 hours. Plasma and lipid subfraction fatty acid profiles were assessed by gas chromatography-flame ionization detector, isotope-enrichment by liquid chromatography time-of-flight mass spectrometry, and fatty acid oxidation rate (expired 13CO2) by isotope ratio mass spectrometry. Both diets resulted in similar plasma LDL-cholesterol concentrations. Kinetic curves showed that U-13C18:0 had a higher plasma area under the curve (66%), lower plasma clearance rate (-46%), and a lower cumulative oxidation rate (-34%) than U-13C18:1. Three labeled plasma metabolites of U-13C18:0 were detected: 13C16:0, 13C16:1, and 13C18:1. No plasma metabolites of U-13C18:1 were detected within the study time-frame. Higher incorporation of 18:0 in cholesteryl ester and triglyceride fractions was observed on the 18:0 compared with the 18:1 diet. CONCLUSIONS: The neutrality of 18:0 on plasma LDL-cholesterol concentrations is not attributable to a single factor. Compared with 18:1, 18:0 had higher plasma area under the curve because of lower clearance and oxidation rates, underwent both a direct and a multistage conversion to 18:1, and was preferentially incorporated into cholesteryl esters and triglycerides.