The Natural Concentration of the Conjugated Linoleic Acid, cis-9,trans-11, in Milk Fat Has Antiatherogenic Effects in Hyperlipidemic Hamsters

Abstract

Milk fat is usually considered to be proatherogenic, although its fatty acid composition can vary, due mainly to farming conditions. No study has evaluated whether such variation can modify the atherogenic properties of dairy fat. Aortic lipid deposition and related risk factors were examined in Syrian hamsters fed diets for 12 wk containing 200 g/kg of 2 commercial milk fats [high content of saturated fatty acids (HSF) and low content of saturated fatty acids (LSF)] contrasting, respectively, in total saturated fatty acids (72 vs. 67 g/100 g), 18:1, trans (4.24 vs. 7.26 g/100g), and conjugated linoleic acid (mainly cis-9,trans-11 or rumenic acid; 0.39 vs. 2.59 g/100 g). Hamsters fed the LSF-diet had 25% less aortic cholesteryl-ester deposition than those fed the HSF-diet; this was accompanied by an improved plasma cholesterol profile (lower LDL cholesterol and LDL:HDL cholesterol ratio), a lower local inflammatory status (aortic gene expression of cyclooxygenase-2), and lower aortic gene expression of vascular cell adhesion molecule-1 (all P < 0.05). Supplementation of the LSF-diet with rumenic acid (up to 9 g/kg) amplified the antiatherogenic effect of the original LSF-diet compared with the HSF-diet, i.e., less aortic cholesterol loading, increased reverse cholesterol transport potential (higher plasma HDL cholesterol concentration and ATP-binding cassette, subfamily A, transporter 1 gene expression in aorta), and decreased LDL-peroxidability index and gene expression of proinflammatory IL-1beta in the aorta (all P < 0.05). In conclusion, our results suggest that the atherogenic potential of milk fat can be greatly reduced in products with a naturally high abundance of rumenic acid, and argue for increasing this fatty acid in milk.

1H NMR metabonomics can differentiate the early atherogenic effect of dairy products in hyperlipidemic hamsters

“…Atherogenic outcome was 45 positively associated with several conventional plasma biomarkers of atherogenic risk, such 46 as total plasma cholesterol, triglycerides, or LDL cholesterol 19,30 . These results agree with 47 other observations 7,31 and validate our model of diet-induced atherogenesis. Not surprisingly, 48 these plasma lipids also corresponded to the NMR signals found positively associated with 49 the severity of atherosclerosis, which substantiates our metabonomic approach to find early 50 A c c e p t e d M a n u s c r i p t 8 8 atherogenic biomarkers.…”

“…Diet and water were available ad libitum, and the cheeses 45 were provided by Lactalis (Retiers, France). The fatty acid compositions of the various 46 products and of the basal diet are listed in Tables 1, 2 Whole aortic lipids were extracted and analyzed by gas liquid chromatography using a 11 high temperature non-polar capillary column 7,19 . Whole aortic cholesteryl esters were taken 12 as an indicator of early atherogenesis (fatty streaks) 19,20 , and expressed as a % of the tissue 13 phospholipids.…”

“…As milk fat 4 represents a rich source of saturated fatty acids, dairy products are recommended to be 5 consumed sparingly 3 , although this advice has been challenged by recent studies 4,5 . These 6 conflicting results may arise from (i) the high variation of fatty acid composition in milk fat 7 related to atherogenic risk 6,7 , (ii) the type of dairy products consumed (fermented or not) 4 , 8 and (iii) the complexity of the dairy food matrix. In fact, many foods are complex mixtures of 9 molecules that simultaneously induce chronic or subtle modifications in numerous 10 biochemical pathways.…”

“…The hyperlipidemic hamster model used in our study 21 has been previously found to be appropriate for studying atherogenesis associated with dietary 22 challenges 7,19 . A group of hamsters fed a low-fat diet was used as a non-atherogenic 23 reference to better emphasize the metabolic disruptions linked to high-fat diets and the onset 24 of the disease.…”

The protective effect of processed cheese against hyperlipidemia in rats

“…CLA has been considered anticarcinogenic and antiatherosclerotic at concentrations of 0.5-1% in the diet of animals [33]. Valeille et al [40] suggested that the atherogenic potential of milk fat can be greatly reduced in products with a naturally high content of c 9 t 11 content. Although CLA isomers have different physiological effects, ingestion of c 9 t 11 and/or t 10 c 12 CLA isomers decreased plasma lipid concentrations (cholesterol and TG) in Wistar rats [12].…”