Valeille, K., J. Ferezou, et al. (2006). "The natural
concentration of the conjugated linoleic acid, cis-9,trans-11, in
milk fat has antiatherogenic effects in hyperlipidemic hamsters." J
Nutr 136(5): 1305-1310.
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.
