The Sum of Plasma Fatty Acids iso16:0, iso17:0, trans11-18:1, cis9, trans11-CLA, and cis6-18:1 as Biomarker of Dairy Intake Established in an Intervention Study and Validated in the EPIC Cohort of Gipuzkoa.

The questioned reliability of 15:0, 17:0, and trans9-16:1 acids as biomarkers of dairy fat intake also questions the relationship between the intake of these products and their health effects. Two studies were conducted in the same geographical region. In an intervention study, volunteers followed a diet rich in dairy products followed by a diet without dairy products. Plasma and erythrocyte fatty acids (FA) were analyzed, and their correlations with dairy product intakes were tested. The FA biomarkers selected were validated in the Gipuzkoa cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC) observational study. The correlation coefficients between plasma concentrations of iso16:0, iso17:0, trans11-18:1, cis9, trans11-18:2, and cis6-18:1 and the dairy fat ingested are similar in both studies, indicating that their concentration increases by 0.8 µmol/L per gram of dairy fat ingested. The biomarkers are positively related to plasma triglycerides (r = 0.324 and 0.204 in the intervention and observational studies, respectively) and total cholesterol (r = 0.459 and 0.382), but no correlation was found between the biomarkers and atherogenicity indexes. In conclusion, the sum of the plasma concentration of the selected FAs can be used as biomarkers of dairy product consumption. A linear relationship exists between their plasma concentrations and ruminant product intake. These biomarkers allow for obtaining consistent relationships between dairy intake and plasma biochemical parameters.

Antiproliferation Activity and Mechanism of c9, t11, c15-CLNA and t9, t11, c15-CLNA from Lactobacillus plantarum ZS2058 on Colon Cancer Cells.

Conjugated linolenic acid (CLNA) is a type of ω-3 fatty acid which has been proven to have a series of benefits. However, there is no study about the function of Lactobacillus-derived CLNA isomer. Lactobacillus plantarum ZS2058 has been proven to manifest comprehensive functions and can produce CLNA. To investigate the specific functions of CLNA produced by this probiotic bacterium, two different conjugated α-linolenic acid (CLNA) isomers were successfully isolated. These isoforms, CLNA1 (c9, t11, c15-CLNA, purity 97.48%) and CLNA2 (c9, t11, t15-CLNA, purity 99.00%), both showed the ability to inhibit the growth of three types of colon cancer cells in a time- and concentration-dependent manner. In addition, the expression of MDA in Caco-2 cells was increased by CLNA1 or CLNA2, which indicated that lipid peroxidation was related to the antiproliferation activity of CLNAs. An examination of the key protein of pyroptosis showed that CLNA1 induced the cleavage of caspase-1 and gasdermin-D, while CLNA2 induced the cleavage of caspase-4, 5 and gasdermin-D. The addition of relative inhibitors could alleviate the pyroptosis by CLNAs. CLNA1 and CLNA2 showed no effect on caspase-3, 7, 9 and PARP-1, which were key proteins associated with apoptosis. No sub-diploid apoptotic peak appeared in the result of PI single staining test. In conclusion, CLNA1 activated caspase-1 and induced Caco-2 cell pyroptosis, whereas CLNA2 induced pyroptosis through the caspase-4/5-mediated pathway. The inhibition of Caco-2 cells by the two isomers was not related to apoptosis. This is the first study on the function of Lactobacillus-derived CLNA isomer. The inhibition pathway of Lactobacillus-derived CLNA isomer on colon cancer cells were proved.

The content of conjugated linoleic acid (CLA) isomer groups in milk of two Polish sheep breeds determined by silver ion liquid chromatography (Ag(+)-HPLC).

Sheep milk is rich in CLA isomers which are biologically active components influencing human health. There are four geometric CLA isomer pairs: cis, trans; trans, cis; trans, trans and cis, cis. The aim of the present study was the analysis of CLA isomer groups content by Ag+-HPLC in milk fat of Zelaznenska (ZS) and Wrzosówka (WS) sheep breeds. The ewes of both breeds were kept under the same environmental and nutritional conditions. Milk samples were collected from 60 suckling ewes (30 from each breed), at the age of 3-4 years and in their 4th week of lactation. A higher total amount of all CLA isomer groups was obtained in milk of ZS ewes, however, this result was statistically insignificant. The percentage of the main c9, t11 isomer in total CLA was higher in Wrzosówka milk (68% vs. 74%). The content of the trans, trans isomer group in milk fat of the studied breeds was similar. The percentage of this group in total CLA in milk of WS and ZS constitutes 7.2% and 7.7%, respectively. The amount of cis,cis isomers in milk fat of ZS was higher thanWS (P < or = 0.01).

Conjugated linoleic acids (CLA) as precursors of a distinct family of PUFA.

One of the possibilities for distinct actions of c9,t11- and the t10,c12-conjugated linoleic acid (CLA) isomers may be at the level of metabolism since the conjugated diene structure gives to CLA isomers and their metabolites a distinct pattern of incorporation into the lipid fraction and metabolism. In fact, CLA appears to undergo similar transformations as linoleic acid but with subtle isomer differences, which may account for their activity in lowering linoleic acid metabolites in those tissues rich in neutral lipids where CLA is preferentially incorporated. Furthermore, c9,t11 and t10,c12 isomers are metabolized at a different rate in the peroxisomes, where the shortened metabolite from t10,c12 is formed at a much higher proportion than the metabolite from c9,t11. This may account for the lower accumulation of t10,c12 isomer into cell lipids. CLA isomers may therefore be viewed as a "new" family of polyunsaturated fatty acids (PUFA) producing a distinct range of metabolites using the same enzymatic system as the other (i.e., n-3, n-6 and n-9) PUFA families. It is likely that perturbation of PUFA metabolism by CLA will have an impact on eicosanoid formation and metabolism, closely linked to the biological activities attributed to CLA.