Conjugated Linoleic Acid–Enriched Butter Fat Alters Mammary Gland Morphogenesis and Reduces Cancer Risk in Rats

Abstract

Conjugated linoleic acid (CLA) is a potent cancer preventive agent in animal models. To date, all of the in vivo work with CLA has been done with a commercial free fatty acid preparation containing a mixture of c9,t11-, t10,c12- and c11,t13-isomers, although CLA in food is predominantly (80-90%) the c9,t11-isomer present in triacylglycerols. The objective of this study was to determine whether a high CLA butter fat has biological activities similar to those of the mixture of free fatty acid CLA isomers. The following four different endpoints were evaluated in rat mammary gland: 1) digitized image analysis of epithelial mass in mammary whole mount; 2) terminal end bud (TEB) density; 3) proliferative activity of TEB cells as determined by proliferating cell nuclear antigen immunohistochemistry; and 4) mammary cancer prevention bioassay in the methylnitrosourea model. It should be noted that TEB cells are the target cells for mammary chemical carcinogenesis. Feeding butter fat CLA to rats during the time of pubescent mammary gland development reduced mammary epithelial mass by 22%, decreased the size of the TEB population by 30%, suppressed the proliferation of TEB cells by 30% and inhibited mammary tumor yield by 53% (P < 0.05). Furthermore, all of the above variables responded with the same magnitude of change to both butter fat CLA and the mixture of CLA isomers at the level of CLA (0.8%) present in the diet. Interestingly, there appeared to be some selectivity in the uptake or incorporation of c9,t11-CLA over t10,c12-CLA in the tissues of rats given the mixture of CLA isomers. Rats consuming the CLA-enriched butter fat also consistently accumulated more total CLA in the mammary gland and other tissues (four- to sixfold increases) compared with those consuming free fatty acid CLA (threefold increases) at the same dietary level of intake. We hypothesize that the availability of vaccenic acid (t11-18:1) in butter fat may serve as the precursor for the endogenous synthesis of CLA via the Delta9-desaturase reaction. Further studies will be conducted to investigate other attributes of this novel dairy product.

Effects of dietary sources of vegetable fats on performance of dairy ewes and conjugated linoleic acid (CLA) in milk

“…Abbreviations: ADF, acid detergent fibre; CLA, conjugated linoleic acid; CP, crude protein; DM, dry matter; EE, ether extract; FAMEs, fatty acid methyl esters; NDF, neutral detergent fibre; OM, organic matter; SO, sunfloweroil; HPO, hydrogenated palm oil; LCFA, long-chain fatty acids; PUFA, polyunsaturated fatty acids; TMR, total mixed ration; VA, vaccenic acid.most abundant CLA, is considered to have anticarcinogenic properties (Ip et al, 1999), while frans-10, cis-12 CLA is capable of lowering body fat and increasing lean body mass (Park et al, 1999). trans-10, cis-12 CLA also decreases the concentration of fat in cow milk (Peterson et al, 2002) and of ewe milk (Lock et al, 2006).…”

Conjugated Linoleic Acid (CLA) content of meat from three muscles of Massese suckling lambs slaughtered at different weights

“…Numerous health benefits have been attributed to single CLA isomers in experimental animal models, including actions to reduce carcinogenesis, atherosclerosis, onset of diabetes, and body fat mass (Belury, 2002, Ip et al, 1999, Lee et al, 1994and Parodi, 1997. Major dietary sources of CLA are foods from ruminants, especially dairy products, where cis-9, trans-11 18:2, also named rumenic acid (RA) is the predominant CLA isomer.…”

Production of trans C18:1 and conjugated linoleic acid in continuous culture fermenters fed diets containing fish oil and sunflower oil with decreasing levels of forage

“…The c9t11 CLA isomer has been shown to be anti-carcinogenic (Ip et al, 1999), while the t10c12 CLA isomer has been shown capable of decreasing body fat and increasing lean body mass (Park et al, 1999). The t10c12 CLA isomer also decreases fat concentration in dairy cows' milk in a dose-dependent fashion (Peterson et al, 2002).…”