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Conjugated linolenic acid is slowly absorbed in rat intestine, but quickly converted to conjugated linoleic acid

Laboratory of Food and Biomolecular Science, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
Journal of Nutrition (Impact Factor: 4.23). 08/2006; 136(8):2153-9.
Source: PubMed

ABSTRACT We showed previously that alpha-eleostearic acid (alpha-ESA; 9Z11E13E-18:3) is converted to 9Z11E-conjugated linoleic acid (CLA) in rats through a Delta13-saturation reaction. To investigate this further, we examined the absorption and metabolism of alpha-ESA in rat intestine using a lipid absorption assay in lymph from the thoracic duct. In this study, we used 4 test oils [tung oil, perilla oil, CLA-triacylglycerol (TG), and pomegranate seed oil, containing alpha-ESA, alpha-linolenic acid (LnA; 9Z12Z15Z-18:3), CLA, and punicic acid (PA; 9Z11E13Z-18:3), respectively]. Emulsions containing the test oils were administered to rats, and lymph from the thoracic duct was collected over 24 h. The positional and geometrical isomerism of CLA produced by PA metabolism was determined using GC-electron impact (EI)-MS and (13)C-NMR, respectively; the product was confirmed to be 9Z11E-CLA. A part of alpha-ESA and PA was converted to 9Z11E-CLA 1 h after administration; therefore the lymphatic recoveries of alpha-ESA and PA were modified by the amount of recovered CLA. Cumulative recovery of CLA, alpha-ESA, and PA was lower than that of LnA only during h 1 (P < 0.05), and cumulative recovery of alpha-ESA and PA was significantly lower than that of LnA and CLA for 8 h (P < 0.05). Therefore, the absorption rate was LnA > CLA > alpha-ESA = PA. The conversion ratio of alpha-ESA to 9Z11E-CLA was higher than that of PA to 9Z11E-CLA over 24 h (P < 0.05). These results indicated that alpha-ESA and PA are slowly absorbed in rat intestine, and a portion of these fatty acids is quickly converted to 9Z11E-CLA.

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    • "Inside in vivo system however , the action of CLnAs largely depends on its permeability across GI tract which directly implies its bioavailabilty . Moreover , transport of CLnA across GI tract is very slow and involves quick conversion into conjugated linoleic acid ( CLA ) ( Tsuzuki et al . 2006 ) thereby limiting its efficacy . The absorption of CLnA can be improved significantly by converting the lipid fractions comprising them into nanoemulsions due to : i ) the presence of surfactants which enhances penetration across cellular membranes due to its amphiphilicity ( Kreilgaard 2002 ) ; ii ) uptake of hydrophobic bioactive age"
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    • "Interestingly, CLnA can be converted to CLA; e.g. c9,t11,t13-CLnA and c9,t11,c13-CLnA to c9,t11-CLA in rats [17] and c9,t11,c13-CLnA to c9,t11-CLA in humans [18]. "
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