Young women partition fatty acids towards ketone body production rather than VLDL-TAG synthesis, compared with young men

Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK.
The British journal of nutrition (Impact Factor: 3.45). 03/2011; 105(6):857-65. DOI: 10.1017/S0007114510004472
Source: PubMed


Before the menopause, women are relatively protected against CVD compared with men. The reasons for this sex difference are not completely understood, but hepatic fatty acid metabolism may play a role. The present study aimed to investigate the utilisation of plasma NEFA by the liver and to determine whether they are partitioned differently into ketone bodies and VLDL-TAG in healthy, lean young men and women. Volunteers were studied during a prolonged overnight fast (12-19 h) using an intravenous infusion of [U-¹³C]palmitate. After 12 h fasting, the women had a more advantageous metabolic profile with lower plasma glucose (P < 0·05) and TAG (P < 0·05) but higher plasma NEFA (P < 0·05) concentrations. Plasma 3-hydroxybutyrate (3-OHB) concentrations rose more in women than in men, and the transfer of ¹³C from [U-¹³C]palmitate to plasma [¹³C]3-OHB reached a plateau 6-7 h after the start of the infusion in women but was still increasing at 6 h in men. This implies a slower 3-OHB production rate and/or dilution by other precursor pools in men. In women, the high isotopic enrichment of plasma 3-OHB suggested that systemic plasma fatty acids were the major source of 3-OHB production. However, in men, this was not observed during the course of the study (P < 0·01). There were no sex differences for the incorporation of ¹³C into VLDL1- or VLDL2-TAG. The ability of young women to partition fatty acids towards ketone body production rather than VLDL-TAG may contribute to their more advantageous metabolic profile compared with young men.

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Available from: Martin Adiels, Jan 07, 2014
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    • "Hepatic fatty acid oxidation has been shown to be upregulated in obese compared with nonobese individuals in the postabsorptive state (35); however, we are unaware of available data in the postprandial state. In addition, evidence of greater hepatic partitioning of fatty acids between oxidation and VLDL-TG production has been reported recently in postabsorptive lean women than in men (36). "
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    • "Indeed, recent studies demonstrated that women exhibit higher non-oxidative FFA disposal (i.e. esterification and storage as triglycerides) [129] and after an overnight fast, they preferentially partition FFA towards hepatic oxidation to ketone bodies, rather than incorporation into VLDL-TG [130]. FFA can also be shuttled back to adipose tissue through the direct FFA uptake pathway discussed above. "
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