Conjugated Linolenic Acid Is Slowly Absorbed in Rat Intestine, but Quickly Converted to Conjugated Linoleic Acid

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.

Effect of dietary pomegranate seed oil and linseed oil on broiler chickens performance and meat fatty acid profile

“…The data obtained by these authors suggest that punicic acid is slowly absorbed in the rat and mice intestine, but it can be converted into 9c,11t-C18:2n-6 in various tissues, e.g., liver, adipose, kidney and brain. Moreover, punicic acid can be incorporated into plasma and red blood cells, and partially metabolized into CLA in humans (Tsuzuki et al, 2006). These authors found that punicic acid was incorporated into plasma (0.47% total fatty acids (FA)) and red blood cell membranes (RBCM) (0.37% total FA) in humans after supplementation with 3 g punicic acid per day for 28 days.…”

“…The in vivo mechanism of punicic acid conversion into CLA is not clear. Some studies suggest that conjugated linolenic acid (CLnA) isomers may be converted into 9c,11t-C18:2n-6 via Δ13-saturation reaction (Tsuzuki et al, 2006;Yuan et al, 2009a). However, the enzyme that catalyses the reaction of Δ13-saturation in animals and humans has not been identified yet.…”

“…However, the enzyme that catalyses the reaction of Δ13-saturation in animals and humans has not been identified yet. It was suggested that a nicotinamide adenine dinucleotide phosphate-dependent enzyme which is either a novel enzyme recognizing CLnA or the enzyme that is active in the leukotriene B4 reductive pathway could have carried this Δ13-saturation reaction in rats and mice (Tsuzuki et al, 2006;Yuan et al, 2009c).…”

“…Conversion of CLnA into CLA was observed in rats fed jacaric acid (Tsuzuki et al, 2006), and also in mice, rats (Koba et al, 2007;Yuan et al, 2009b,c) and humans fed punicic acid (Yuan et al, 2014). In view of the above-mentioned healthrelated effects of conjugated fatty acids (CLA), it seems desirable to provide CLnA-and CLA-enriched products for human consumption.…”

Hatice Asli Bedel, Nur Tukel Turgut, Aysegul Ugur Kurtoglu, Coskun Usta

“…It has been shown that PA can be converted into cis 9, trans 11-18:2 in various rat tissues, such as liver, adipose tissue, plasma and brain [14,15] . Also, Yuan et al have shown that PA can be incorporated into plasma and erythrocytes and a part of PA can also be metabolized into cis 9, trans 11-18:2 in humans.…”