The odd-chain fatty acids (OCFAs) pentadecanoic acid (15:0) and heptadecanoic acid (17:0), which account for only a small proportion of total saturat

Objective: Conjugated linoleic acid (CLA) showed a wide range of beneficial biological effects with relevance for cardiovascular health in animal models and humans. Most human studies used olive oil as a reference. This study assessed the effect of CLA as compared with safflower oil on endothelial function and markers of cardiovascular risk in overweight and obese men. Heated safflower oil and olive oil were given for additional descriptive control. Methods: Eighty-five overweight men (aged 45–68 years, body mass index 25–35 kg/m²) were randomized to receive 4.5 g/d of the CLA isomeric mixture, safflower oil, heated safflower oil, or olive oil in a 4-week double-blind study. Endothelial function was assessed by peripheral arterial tonometry (PAT) index determination in the fasting and postprandial state (i.e., 4 hours after consumption of a fat- and sucrose-rich meal). Results: CLA as compared with safflower oil consumption did not impair fasting or postprandial PAT index but decreased body weight. CLA as compared with safflower oil did not change total, low-density lipoprotein (LDL), or high-density lipoprotein (HDL) cholesterol; triglycerides; insulin sensitivity indices; C-reactive protein; soluble adhesion molecules; oxidized LDL; lipoprotein a (Lp[a]); paraoxonase; or platelet-activating factor acetylhydrolase (PAF-AH) activity, but significantly reduced arylesterase activity and increased concentrations of the F₂-isoprostane 8-iso-prostaglandin F (PGF)_2α. Conclusion: CLA did not impair endothelial function. Other parameters associated with metabolic syndrome and oxidative stress were not changed or were slightly improved. Results suggest that CLA does not increase cardiovascular risk. Increased F₂-isoprostane concentrations in this context may not indicate increased oxidative stress.

The importance of the postprandial state for the early stages of atherogenesis is increasingly acknowledged. We conducted assessment of association between postprandial triglycerides, insulin and glucose after ingestion of a standardized lipid-rich test meal, and soluble cellular adhesion molecules (sCAM) in young healthy subjects. Metabolic parameters and sICAM-1, sVCAM-1 and E-selectin were measured before and hourly until 6 hours after ingestion of a lipid-rich meal in 30 healthy young men with fasting triglycerides <150 mg/dl and normal fasting glucose levels. Subjects were classified as either normal responders (NR) (postprandial triglyceride maxima < 260 mg/dl) or high responders (HR) (postprandial triglyceride maxima > 260 mg/dl). Levels of CAM were compared in HR and NR, and correlation with postprandial triglyceride, insulin and glucose response was assessed. Fasting sICAM-1 and sVCAM-1 levels were significantly higher in HR as compared to NR (p = 0.046, p = 0.03). For sE-selectin there was such a trend (p = 0.05). There was a strong positive and independent correlation between sICAM-1 and postprandial insulin maxima (r = 0.70, p < 0.001). sVCAM-1 showed significant correlation with postprandial triglycerides (AUC) (r = 0.37, p = 0.047). We found no correlation between sCAMs and fasting insulin or triglyceride concentrations. This independent association of postprandial triglycerides with sICAM-1 may indicate a particular impact of postprandial lipid metabolism on endothelial reaction.

Peroxisome proliferator-activated receptor (PPAR)γ is a key regulator in adipose tissue. The rare variant Pro12Ala of PPARγ2 is associated with a decreased risk of insulin resistance. Being dietary PPARγ ligands, conjugated linoleic acids (CLAs) received considerable attention because of their effects on body composition, cancer, atherosclerosis, diabetes, obesity and inflammation, although some effects were only demonstrated in animal trials and the results in human studies were not always consistent. In the present study effects of CLA supplementation on genome wide gene expression in adipose tissue biopsies from 11 Ala12Ala and 23 Pro12Pro men were investigated. Subjects underwent four intervention periods (4 wk) in a randomized double blind cross-over design receiving 4.25 g/d of either cis-9, trans-11 CLA, trans-10,cis-12 CLA, 1:1 mixture of both isomers or a reference linoleic acid oil preparation. After each intervention biopsies were taken, whole genome expression microarrays were applied, and genes of interest were verified by realtime PCR. The following genes of lipid metabolism were regulated by CLA: LDLR, FASN, SCD, FADS1 and UCP2 were induced, while ABCA1, CD36 and CA3 were repressed. Transcription factors PPARγ, NFAT5, CREB5 and EBF1, the adipokine NAMPT, members of the insulin signaling cascade SORBS1 and IGF1 and IL6ST were repressed, while the adipokine THBS1 and GLUT4 involved in insulin signaling were induced. Compared to trans-10,cis-12 CLA and the CLA mixture the cis-9, trans-11 CLA isomer exerted weaker effects. Only CD36 (-1.2 fold) and THBS1 (1.5 fold) were regulated. The CLA effect on expression of PPARγ and leptin genes depends on the PPARγ2 genotype. The data suggest that the isomer specific influence of CLA on glucose and lipid metabolism is genotype dependent and at least in part mediated by PPARγ. http://www.controlled-trials.com : ISRCTN91188075

The present study examined the effect of milk phospholipids (milk-PL) on lipid metabolism and on other risk factors for CVD, in comparison with milk fat (control) or soya phospholipids (soya-PL), respectively. Two double-blind parallel-group intervention trials were conducted in overweight or obese male subjects. In the first trial (trial 1), sixty-two men consumed milk enriched with either 2 g milk-PL or 2 g milk fat (control) for 8 weeks. In trial 2, fifty-seven men consumed milk enriched with either 3 g milk-PL or 2·8 g soya-PL for 7 weeks. In trial 1, milk-PL as compared with control reduced waist circumference but did not affect plasma lipids (total, HDL- and LDL-cholesterol, total cholesterol:HDL-cholesterol ratio, TAG, phospholipids), apoB, apoA1, glucose, insulin, insulin sensitivity index, C-reactive protein, IL-6, soluble intracellular adhesion molecule and total homocysteine (tHcy). Serum activities of alanine transaminase and aspartate transaminase were not changed. Activity of γ-glutamyl transferase (GGT), a marker of fatty liver, increased in the control but not in the milk-PL group, with a significant intervention effect. In trial 2, milk-PL as compared with soya-PL did not affect the above-mentioned parameters, but decreased GGT. Subjects with the methylenetetrahydrofolate reductase mutations CT and TT had 11 % (P < 0·05) higher baseline tHcy concentrations than those with the wild-type CC. However, genotype did not modulate the phospholipid intervention effect on tHcy. In conclusion, supplementation with milk-PL as compared with control fat reduced waist circumference and, as compared with both control fat and soya-PL, GGT activity.