Refeeding with a high-protein diet after a 48 h fast causes acute hepatocellular injury in mice.

Elucidating the effects of refeeding a high-protein diet after fasting on disease development is of interest in relation to excessive protein ingestion and irregular eating habits in developed countries. The objective of the present study was to address the hepatic effects of refeeding a high-protein diet after fasting. Mice were fasted for 48 h and then refed with a test diet containing 3, 15, 35, 40, 45 or 50 % casein. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and liver immediate-early gene expression levels were sequentially measured for the first 24 h after initiation of refeeding. Refeeding with a 50 % casein diet after 48 h of fasting led to a rapid (within 2-3 h) and abnormal elevation in serum ALT (P = 0·006) and AST (P = 0·001) activities and a marked increase in liver Finkel-Biskis-Jinkins (FBJ) osteosarcoma oncogene (P = 0·007) and nuclear receptor subfamily 4, group A, member 1 (P = 0·002) mRNA levels. In contrast, refeeding of the 3, 15 or 35 % casein diets produced no substantial increases in serum ALT and AST activities in mice. Refeeding of 40, 45 or 50 % casein increased serum ALT and AST activities in proportion to this dietary casein content. In mice refed the 3, 15 or 35, but not 50 %, casein diets, liver heat shock protein 72 transcript levels greatly increased. We conclude from these data that the consumption of a high-protein diet after fasting causes acute hepatocellular injury in healthy animals, and propose that careful attention should be paid to the use of such diets.

Suppression of gamma-tocotrienol on UVB induced inflammation in HaCaT keratinocytes and HR-1 hairless mice via inflammatory mediators multiple signaling.

Tocopherol (Toc) such as alpha-Toc has been expected to act as photochemopreventive agent of skin, but the effect of the other vitamin E forms [tocotrienols (T3)] has not been fully understood. We evaluated the anti-inflammatory effect of T3 on UVB-induced inflammatory reaction using immortalized human keratinocytes and hairless mice. gamma-T3 suppressed UVB-induced PGE(2) production while similar alpha-Toc doses had no effect. The anti-inflammatory actions of gamma-T3 were explained by its ability to reduce UVB-induced inflammatory gene and protein expression [cyclooxgenase-2 (COX-2), interleukin (IL)-1beta, IL-6, and monocyte chemotactic protein-1]. Western blot analysis revealed gamma-T3 inhibited p38, extracellular signal-regulated kinase, and c-Jun N-terminal kinase/stress-activated protein kinase activation. In HR-1 hairless mice, oral T3 suppressed UVB-induced changes in skin thickness, COX-2 protein expression, and hyperplasia, but alpha-Toc did not. These results suggest T3 has potential use to protect against UVB-induced skin inflammation.

Effects of a high-protein diet on host resistance to Paracoccidioides brasiliensis in mice.

We investigated the effects of high protein intake on host resistance to Paracoccidioides brasiliensis. Two-d fasted mice were infected with P. brasiliensis and refed on diets with three different levels (54%, 20%, and 5%) of casein. The mice refed the 54% casein diet showed reduced antifungal activity in the spleen and liver as compared with the mice refed the 5% or the 20% casein diet. After infection, increases in spleen and liver mRNA levels of myeloperoxidase, cathepsin-G, and elastase-2 were more profound in the mice refed the 54% casein diet as compared with the mice refed the 5% or the 20% casein diet. Infected mice refed the 54% casein diet exhibited greater interferon (IFN)-gamma production in the spleen and liver and higher levels of thiobarbituric acid reactive substances (TBARSs) in the liver as compared with those refed the 5% casein diet. These results indicate that high protein intake impairs host resistance to P. brasiliensis.

Effect of dietary oils on host resistance to fungal infection in psychologically stressed mice.

Psychological stress can modulate host defense against invading pathogens. In this study, we investigated the effect of dietary oils on social isolation stress-induced modulation of host resistance to Paracoccidioides brasiliensis. In olive oil-fed mice, 3 weeks of isolation stress resulted in temporarily delayed clearance of this fungus in the liver compared with group-housed mice. By contrast, in soybean oil-fed mice, isolation stress had no significant effect on antifungal activity. The olive oil-fed mice showed greater liver interferon (IFN)-gamma and interleukin (IL)-6 production in response to infection as compared with the soybean oil-fed mice. In the olive oil-fed mice, isolation stress led to greater infection-induced IFN-gamma production in the liver compared with the group-housed animals. These results indicate that the modulatory effects of psychological stress on host resistance to P. brasiliensis can vary depending on dietary fatty acid composition.

Beneficial effects of a low-protein diet on host resistance to Paracoccidioides brasiliensis in mice.

OBJECTIVE: Although protein malnutrition impairs immune functions, several studies have recently shown that protein restriction without malnutrition is beneficial to host defenses against invading pathogens and cancer. In an effort to establish the optimum diet for host resistance, we investigated the effect of different dietary protein levels on host resistance to Paracoccidioides brasiliensis. METHODS: Mice were fasted for 2 days and then infected with P. brasiliensis. Immediately after challenge with this fungus, mice were refed on diets with three different levels (0%, 1.5%, or 20%) of casein. On days 0-7 after infection, antifungal activity and levels of proinflammatory mediators in the spleen and liver were measured. RESULTS: Mice refed on the 1.5% casein diet showed higher antifungal activity in the spleen and liver compared with mice on the 20% casein diet. The antifungal activity in the spleens of mice refed on the 0% casein diet was intermediate between the antifungal activities of those refed the 1.5% and 20% casein diets. After infection, increases in spleen and liver levels of interleukin-6 and interferon-gamma, liver mRNA levels of antimicrobial proteins (myeloperoxidase, cathepsin-G, and elastase-2), and liver mRNA levels of proinflammatory mediators (interleukin-18, chemokine C-X-C motif ligand 10, nuclear factor-kappaB, inducible nitric oxide synthase, and granulocyte-macrophage colony-stimulating factor) were less profound in mice on the 1.5% or 0% casein diet compared with mice refed the 20% casein diet. CONCLUSION: The present results suggest that protein restriction without malnutrition could be beneficial to host resistance to P. brasiliensis.

Validation of an ion trap tandem mass spectrometric analysis of mulberry 1-deoxynojirimycin in human plasma: application to pharmacokinetic studies.

Mulberry 1-deoxynojirimycin (DNJ) is a potent alpha-glucosidase inhibitor. Although it is useful for the treatment of diabetes, the human absorption and metabolism of DNJ have never been characterized. We developed a method using hydrophilic interaction chromatography coupled with ion trap tandem mass spectrometry, and found that orally administered DNJ was absorbed into the blood and then excreted into the urine.

Tumor anti-angiogenic effect and mechanism of action of delta-tocotrienol.

Anti-angiogenic therapy mediated by drugs and food components is an established strategy for cancer prevention. Our previous cell-culture studies identified a food-derived anti-angiogenic compound, tocotrienol (T3, an unsaturated vitamin E), as a potential angiogenic inhibitor. Among T3 isomers, delta-T3 is considered as the most potent compound. The purpose of this study was therefore to evaluate the inhibitory effect of delta-T3 on tumor angiogenesis. As growth factors (e.g., vascular endothelial growth factor and fibroblast growth factor) play critical roles in tumor angiogenesis, a conditioned medium rich in these growth factors from human colorectal adenocarcinoma cells (DLD-1-CM) was used as an angiogenic stimulus. Delta-T3 (2.5-5 microM) significantly suppressed DLD-1-CM-induced tube formation, migration, and adhesion on human umbilical vein endothelial cells. These effects were partly associated with reactive oxygen species generation by delta-T3. Western blot analysis revealed that the anti-angiogenic effect of delta-T3 is attributable to regulation of growth factor-dependent phosphatidylinositol-3 kinase (PI3K)/phosphoinositide-dependent protein kinase (PDK)/Akt signaling as well as to induction stress response in endothelial cells. Moreover, we conducted an in vivo mouse Matrigel plug angiogenesis assay, and found that delta-T3 (10-20 microg) exhibits dose-dependent inhibition of DLD-1-induced vessel formation. These results suggest that T3 has potential use as a therapeutic dietary supplement for minimizing tumor angiogenesis.

Anti-angiogenic function of tocotrienol.

Angiogenesis means the formation of new blood vessels from preexisting vascular, is of fundamental importance in several pathological states such as tumor growth, rheumatoid arthritis, and diabetic retinopathy. Angiogenesis involves a set of steps, including activation and movement of endothelial cells and tube formation. Control of these steps by drugs or dietary food components is a hopeful approach for the prevention of angiogenic disorders. Based on these backgrounds, we searched the anti-angiogenic food components. As a result, we found that tocotrienol (T3), especially delta, beta, and gamma-T3 has the potent anti-angiogenic activity in vitro and in vivo experiments. T3, which is rich in rice bran and palm oil, inhibited growth factor-induced proliferation, migration and tube formation in human umbilical vein endothelial cells. T3 showed inhibition of tumor cell-induced angiogenesis in mouse dorsal air sac (DOS) assay. These results indicated that T3 is a potent anti-angiogenesis compound. Tocopherol (Toc) did not inhibit angiogenesis. The anti-angiogenic mechanism of T3 and Toc was evaluated by western blotting. T3 inhibited activation of growth factor-induced extracellular signal-regulated kinase, Akt (protein kinase B), and endothelial nitric oxide synthase (eNOS), which are located downstream of the various growth factor receptors. T3 suppressed phosphorylation of vascular endothelial growth factor (VEGF) receptor 2. These effects were dose-dependent manner. Anti-angiogenic mechanism of T3 mediates inhibition of growth factor induced survival, migration and angiogenesis signals. These findings suggested that T3 may have potential for preventing angiogenic disorders in humans.

Tumor angiogenesis suppression by alpha-eleostearic acid, a linolenic acid isomer with a conjugated triene system, via peroxisome proliferator-activated receptor gamma.

We have shown previously that alpha-eleostearic acid (ESA), a linolenic acid isomer with a conjugated triene system, suppresses tumor growth in vivo. In our earlier study, blood vessels were observed at the tumor surface in control mice, whereas in ESA-treated mice no such vessels were observed and the inner part of the tumor was discolored. These observations suggested that ESA might suppress cancer cell growth through malnutrition via a suppressive effect on tumor angiogenesis. In the current study, the antiangiogenic effects of ESA were investigated in vivo and in vitro. Tumor cell-induced vessel formation was clearly suppressed in mice orally administered ESA at doses of 50 and 100 mg/kg/day in a dose-dependent manner. ESA also inhibited the formation of capillary-like networks by human umbilical vein endothelial cells (HUVEC) and moderately inhibited HUVEC proliferation and migration in a dose-dependent manner. The mechanism by which ESA inhibited angiogenesis was through suppression of the expression of vascular endothelial growth factor receptors 1 and 2, activation of peroxisome proliferator-activated receptor gamma (PPARgamma) and induction of apoptosis in HUVEC. We thus demonstrated that, like troglitazone, ESA is a PPARgamma ligand and that it activates PPARgamma, induces apoptosis in HUVEC and inhibits angiogenesis. Our findings suggest that ESA has potential use as a therapeutic dietary supplement and medicine for minimizing tumor angiogenesis.

Effects of dietary fish oil on lipid peroxidation and serum triacylglycerol levels in psychologically stressed mice.

OBJECTIVE: The intake of omega-3 polyunsaturated fatty acids and psychological stress can each induce tissue lipid peroxidation. In our present study, we investigated their combined effects on the oxidative status of mouse tissues. METHODS: Mice were group-housed (four mice/cage) and fed a diet containing fish oil (as a source of omega-3 polyunsaturated fatty acids), soybean oil, or olive oil for 3 wk. These animals were then 1) housed under the same conditions (four per cage, control group) or 2) individually housed to generate psychological stress conditions (isolation stress). After 2 wk of isolation stress, the levels of thiobarbituric acid-reactive substances (an index of lipid peroxidation) and antioxidants in the liver and kidney and the serum levels of triacylglycerol were measured. RESULTS: Fish oil-fed mice showed increased levels of thiobarbituric acid-reactive substances in their livers and kidneys compared with soybean oil- or olive oil-fed mice. These increases in thiobarbituric acid-reactive substance levels in the fish oil-fed mice were less profound under isolation stress conditions when compared with the group-housed animals on the same diet. In the fish oil-fed mice, isolation stress led to an increase in liver vitamin E levels when compared with their group-housed counterparts. The fish oil-fed mice exhibited lower serum triacylglycerol levels compared with the soybean oil- or olive oil-fed mice, and this decrease was more profound under conditions of isolation stress when compared with group-housing conditions. CONCLUSION: Dietary fish oil combined with isolation stress results in lower levels of lipid peroxidation in the liver and kidney compared with dietary fish oil alone.

Occurrence of orally administered mulberry 1-deoxynojirimycin in rat plasma.

1-deoxynojirimycin (DNJ), a potent glucosidase inhibitor, is a characteristic constituent of the mulberry leaf. Dietary mulberry DNJ may be beneficial for the suppression of abnormally high blood glucose levels, thereby preventing diabetes mellitus. Although there is considerable interest in the effects of mulberry DNJ, the intestinal absorption and pharmacokinetic profile of orally administered mulberry DNJ have never been characterized. In this study, we developed a method for determining the level of plasma DNJ by hydrophilic interaction chromatography coupled to a mass spectrometric detector (HILIC-MS) to investigate the absorption and metabolism of orally administered mulberry DNJ in rats. DNJ was separated from plasma extract on a TSK gel Amide-80 column, a representative column for HILIC. At postcolumn, DNJ was concurrently detected and identified by MS. The plasma DNJ concentration in fasted rats was below the detection limit [<1 microg (6 nmol)/mL]; however, the concentration reached a maximum [15 microg (92 nmol)/mL] 30 min after the administration of mulberry DNJ (110 mg/kg of body weight), and the DNJ concentration decreased rapidly thereafter. When the rats received different amounts of mulberry DNJ (1.1, 11, and 110 mg/kg of body weight), dose-dependent incorporation of DNJ into the plasma was confirmed. We did not detect any DNJ metabolites in the plasma. These findings indicate that orally administered mulberry DNJ is absorbed as an intact form from the alimentary tract and then is quickly excreted from the body. The developed HILIC-MS method could be applied in determining levels of DNJ in urine and tissues, and therefore, the method would be a powerful tool for studying the metabolic fate of mulberry DNJ as well as its bioavailability.

Slow absorption of conjugated linoleic acid in rat intestines, and similar absorption rates of 9c,11t-conjugated linoleic acid and 10t,12c-conjugated linoleic acid.

We have previously shown that the 9c,11t-conjugated linoleic acid (CLA) concentration was always significantly higher than the 10t,12c-CLA concentration following the administration of these compounds to mice and rats, and considered that structural differences between the conjugated double bonds in these isomers affected absorption in the small intestine. This study investigates the absorption of CLA in the rat intestine by a lipid absorption assay of lymph from the thoracic duct. In Study 1, we used safflower oil and a triacylglycerol form of CLA (CLA-TG), while in Study 2, we used 9c,11t-CLA and 10t,12c-CLA. The cumulative recovery of CLA was lower than that of linoleic acid until two hours after sample administration. There was no difference in the extent of lymphatic recovery of 9c,11t-CLA and 10t,12c-CLA after the administration of CLA-TG, 9c,11t-CLA, and 10t,12c-CLA to the rats, suggesting that geometrical and positional isomerism of the conjugated double bonds did not influence the absorption.

Anti-angiogenic effects of conjugated docosahexaenoic acid in vitro and in vivo.

The anti-angiogenic effects of conjugated docosahexaenoic acid (CDHA), which was prepared by an alkaline treatment of docosahexaenoic acid and contained conjugated double bonds, were investigated in vitro and in vivo. CDHA inhibited tube formation by the bovine aortic endothelial cell (BAEC), and also inhibited the proliferation of BAEC at a concentration of CDHA that suppressed tube formation, but did not influence cell migration. The inhibition of BAEC growth caused by CDHA was accompanied by a marked change in cellular morphology. Nuclear condensation and brightness were observed in Hoechst 33342-stained cells treated with CDHA, indicating that CDHA induced apoptosis in BAEC. We also evaluated the angiogenesis inhibition of CDHA in vivo. The vessel formation which was triggered by tumor cells was clearly suppressed in mice orally given CDHA. Our findings suggest that CDHA has potential use as a therapeutic dietary supplement for minimizing tumor angiogenesis.

In vivo angiogenesis is suppressed by unsaturated vitamin E, tocotrienol.

Antiangiogenic therapy using drugs and food components is a recognized strategy for the prevention of various angiogenesis-mediated disorders such as tumor growth, diabetic retinopathy, and rheumatoid arthritis. Our preliminary cell culture studies, using both bovine aortic endothelial cells and human umbilical vein endothelial cells (HUVEC) on screening for food-derived antiangiogenic compounds, showed tocotrienol (T3), an unsaturated version of vitamin E, to be a potential angiogenic inhibitor. We therefore investigaged the in vivo antiangiogenic properties of T3 using 2 well-characterized angiogenic models [mouse dorsal air sac (DAS) assay and the chick embryo chorioallantoic membrane (CAM) assay]. In the DAS assay, the increased neovascularization (angiogenesis index, 4.8 +/- 0.6) in tumor cell-implanted mice was suppressed (angiogenesis index, 2.7 +/- 0.6) by dietary supplementation of 10 mg T3-rich oil/d (equivalent to 4.4 mg T3/d). In the CAM assay, T3 (500-1000 microg/egg) inhibited new blood vessel formation on the growing CAM and increased the frequency of avascular zone (36-50%). To evaluate the antiangiogenic mechanism, we conducted cell-culture studies and found that T3 significantly reduced fibroblast growth factor -induced proliferation, migration, and tube formation in HUVEC (P < 0.05), with delta-T3 having the highest activity. Western blot analysis revealed that delta-T3 suppressed the phosphorylation of phosophoinositide-dependent protein kinase (PDK) and Akt, and increased the phosphorylation of apoptosis signal-regulating kinase and p38 in fibroblast growth factor-treated HUVEC, indicating that the antiangiogenic effects of T3 are associated with changes in growth factor-dependent phosphatidylinositol-3 kinase /PDK/Akt signaling as well as induction of apoptosis in endothelial cells. Our findings suggest that T3 has potential as a therapeutic dietary supplement for preventing angiogenic disorders, and therefore future clinical study will be required to evaluate the efficacy and safety of T3.

Mechanism of cell cycle arrest and apoptosis induction by conjugated eicosapentaenoic acid, which is a mammalian DNA polymerase and topoisomerase inhibitor.

Conjugated eicosapentaenoic acid (cEPA) selectively inhibited the activities of mammalian DNA polymerases (pols) and human DNA topoisomerases (topos). cEPA inhibited the cell growth of two human leukemia cell lines, NALM-6, which is a p53-wild type, and HL-60, which is a p53-null mutant, with LD50 values of 37.5 and 12.5 microM, respectively. In both cell lines, cEPA arrested in the G1 phase, and increased cyclin E protein levels, indicating that it blocks the primary step of in vivo DNA replication by inhibiting the activity of replicative pols rather than topos. DNA replication-related proteins such as RPA70, ATR and phosphorylated-Chk1/2 were increased by cEPA treatment in the cell lines, suggesting that cEPA led to DNA replication fork stress inhibiting the activities of pols and topos, and the ATR-dependent DNA damage response pathway could respond to the inhibitor of DNA replication. The compound induced cell apoptosis through both p53-dependent and p53-independent pathways in cell lines NALM-6 and HL-60, respectively. These results suggested the therapeutic potential of cEPA as a leading anti-cancer compound that inhibited activities of pols and topos.

Conjugated eicosapentaenoic acid inhibits vascular endothelial growth factor-induced angiogenesis by suppressing the migration of human umbilical vein endothelial cells.

We have previously shown that conjugated eicosapentaenoic acid (CEPA), which is prepared by alkaline treatment of eicosapentaenoic acid and contains conjugated double bonds, suppresses tumor growth in vivo. In this earlier study, blood vessels were observed on the tumor surface in control mice, whereas in CEPA-treated mice, no such vessels were observed and the inner part of the tumor was discolored. These observations suggest that CEPA might suppress cancer cell growth through malnutrition due to a suppressive effect on tumor angiogenesis. In this study, the antiangiogenic effects of CEPA were investigated in vitro. CEPA at 5 micromol/L inhibited vascular endothelial growth factor (VEGF)-stimulated tube formation by human umbilical vein endothelial cells (HUVEC) (P < 0.05) and also inhibited VEGF-stimulated migration of HUVEC at a concentration of CEPA that suppressed tube formation (P < 0.05) but did not influence cell proliferation. The antiangiogenic mechanism of CEPA was investigated in vitro by measuring the secretion and expression of well-characterized angiogenic factors associated with cell migration, such as matrix metalloproteinases (MMP). CEPA at a concentration that suppressed tube formation inhibited secretion and mRNA expression of MMP2 and MMP9 in VEGF-stimulated HUVEC (P < 0.05). Our findings suggest that CEPA has potential use as a therapeutic dietary supplement for minimizing tumor angiogenesis.

Distribution of tocotrienols in rats fed a rice bran tocotrienol concentrate.

To examine the distribution of rice bran tocotrienol (T3), we gave rice bran T3 to rats after considering an acceptable daily intake of vitamin E for humans. Male SD rats (5 weeks of age) were fed for 3 weeks on a commercial diet containing 6.4 mg of vitamin E per 100 g wt and additively received vitamin E or the vehicle (vitamin E-free corn oil) by oral intubation. The animals were randomly divided into 4 groups depending on the type of test diet: control (vehicle), non-T3 (no T3 + 4.3 mg of tocopherol (TOC)/kg body weight (b.w.)/day), low-T3 (0.8 mg T3 + 3.5 mg TOC/kg b.w./day), and high-T3 (3.2 mg T3 + 1.1 mg TOC/kg b.w./day). The control rats and rats in the non-T3, low-T3, and high-T3 groups took 4.3 and 8.6 mg of vitamin E/kg b.w./day, respectively. Rice bran gamma-T3 was significantly distributed to the adipose tissue and increased from 1.1 to 10.2 nmol/g of adipose tissue according to the rice bran T3 intake.

Effect of dietary oils on lymphocyte immunological activity in psychologically stressed mice.

Psychological stress has been shown to modulate immune functions. In this study, we investigated the effect of dietary oils (olive oil, soybean oil, and fish oil) on the social isolation stress-induced modulation of lymphocyte immunological activities in mice. In olive oil-fed, but not soybean oil- or fish oil-fed, mice, a 2-week isolation stress decreased the lymphocyte proliferative response, reduced the interferon-gamma and interleukin (IL)-10 secretions and increased the IL-4 secretion by lymphocytes. The isolation stress reduced the arachidonic acid content of lymphocytes markedly, moderately, and not at all in the olive oil-, soybean oil-, and fish oil-fed mice, respectively. In the olive oil-fed, but not soybean oil- or fish oil-fed, mice, the isolation stress up-regulated the expression level of mRNA for splenic heat-shock protein 70 and increased lymphocyte sensitivity to the antiproliferative effect of corticosterone. This is the first demonstration that effect of psychological stress on lymphocyte immunological activities can vary depending upon the dietary fatty acid composition.

Conjugated EPA activates mutant p53 via lipid peroxidation and induces p53-dependent apoptosis in DLD-1 colorectal adenocarcinoma human cells.

Both conjugated linoleic acid (CLA), which contains conjugated double bonds, and eicosapentaenoic acid (EPA), an n-3 polyunsaturated fatty acid, have antitumor effects. Hence, we hypothesized that a combination of conjugated double bonds and an n-3 highly unsaturated fatty acid may produce a stronger antitumor effect, and we have previously shown that conjugated EPA (CEPA), prepared by alkaline treatment of EPA, induces strong and selective apoptosis in vitro and in vivo, with the mechanism proceeding via lipid peroxidation. In this study, we examined CEPA-induced gene expression in DLD-1 colorectal adenocarcinoma human cells carrying a mutant p53, in order to understand the details of CEPA-induced apoptosis via lipid peroxidation. DNA microarray analysis of 9970 genes was performed by comparison of CEPA-treated DLD-1 cells with untreated DLD-1 cells, thereby allowing determination of the differential gene expression profile induced by CEPA in these cells. CEPA treatment caused up-regulation of expression of genes induced by p53 and activation of the mitochondrial apoptosis pathway via Bax and the death pathway via TRAIL, leading to apoptosis of DLD-1 cells. In addition, activation of the mutant p53 was also induced by CEPA, and these effects showed lipid-peroxidation dependency. This is the first such gene expression analysis of the effects of CEPA, and our results confirm that CEPA induces lipid peroxidation, activates mutant p53, and causes p53-dependent apoptosis in DLD-1 cells.

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

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.