Supplemental Conjugated Linoleic Acid Consumption Does Not Influence Milk Macronutrient Contents in all Healthy Lactating Women

Abstract

The term "conjugated linoleic acid" (CLA) refers to a group of positional and geometric isomers that are derived from linoleic acid and are found primarily in meat and milk products from ruminant animals. Due to the array of putative benefits associated with various forms of CLA, there has been recent interest in supplementing human diets with these fatty acids especially when weight loss is desired. However, in many animal models, CLA has been shown to decrease milk fat production. There is some concern, therefore, that maternal CLA supplementation during lactation might inadvertently decrease nutrient supply to the nursing infant. However, there is only limited research on the effect of CLA consumption on milk fat content in women. Based on previously published work from our laboratory, we hypothesized that CLA supplementation would reduce the milk fat percentage in lactating women in a dose-dependent manner. Breastfeeding women (n = 12) were assigned randomly to treatments of 4 g/day safflower oil (SFO), 2 g/day CLA plus 2 g/day SFO, or 4 g/day CLA in a double blind, 3 x 3 Latin square design. Conjugated linoleic acid supplements contained approximately equal amounts of cis9,trans11-18:2 and trans10,cis12-18:2; the two most common isoforms of CLA. Milk was collected by complete breast expression on the last day (day 5) of each intervention period and analyzed for macronutrient and fatty acid composition. On day 4 of each intervention period, infant milk consumption was estimated by 24 h weighing of the infant. Washout periods were 9 days in length. We observed a dose-dependent increase in the concentrations of cis9,trans11-18:2 and trans10,cis12-18:2 in the milk fat. However, we detected neither a change in overall macronutrient composition nor infant milk consumption. These data do not support those obtained from animal models or our previous human work suggesting that consumption of CLA mixtures necessarily reduces milk fat. It is possible that either (1) the interpretation of our previously published data should be reevaluated, and/or (2) there are important intra- and inter-species differences in this regard.

Acceleration of reflex maturation and physical development in suckling rats: effects of a maternal diet containing lipids from goat milk

“…Reflex maturation Palm grasp 6.5 (5-9) 9 (8-11) 4 (3-8)* , ** Righting reflex 4 (3-6) 5.5 (2-10) 3 (1-6)* , ** Cliff avoidance 6 (3-9) 6 (2-9) 4 (1-6)* , ** Vibrissae placing 9.5 (8-11) 10 (7-11) 9 (6-11)** Negative geotaxis 14 (7-11) 14 (8-14) 10 (7-12)* , ** Auditory startle 12 (11)(12)(13) 13 (12)(13)(14)(15) 10.5 (9-13)* , ** Free-fall righting 18 (15)(16)(17)(18)(19)(20) 17 (14)(15)(16)(17)(18) 16 (13)(14)(15)(16)(17)*…”

“…14 Analyzing breast milk from women receiving supplementation with CLA was observed in the milk the presence of CLA isomers but there were no modifications in the macronutrients composition. 15,16 Preliminary studies showed that dietary CLA offered to pregnancy and/or lactating rats are able to crossing the blood-brain barrier of the offspring and stay until a postnatal period. 17 However, it has been observed that an outcome of drinking goat milk (which CLA is included) versus cow's milk increased weight gain, length, and skeletal mineralization in rats.…”

Consumption of c9,t11–18:2 or t10,c12–18:2 Enriched Dietary Supplements Does Not Influence Milk Macronutrients in Healthy, Lactating Women

“…In fact, CLA-induced milk fat reduction has been observed in bovine, ovine, and murine species [6][7][8]. Similarly, we have reported that consumption of a preparation consisting mainly of two CLA isomers (c9,t11-and t10,c12-18:2) reduced milk fat concentration by 23% in a group of well-nourished women [9], although more recent work from our group does not appear to support this [10]. A reduction in milk fat percentage was also observed in lactating women consuming large amounts of a trans fatty acid-containing margarine in comparison to when they consumed diets containing large amounts of a low trans fatty acid margarine [11].…”

Scientific Opinion on the safety of “conjugated linoleic acid (CLA)-rich oil” (Tonalin® TG 80) as a Novel Food ingredient

“…Due to the cross over design of the human study (CLA effect was not studied during the same period of lactation) and the low number of subjects, the relevance of such a finding is unclear. More recent studies performed either with CLA mixtures (Mosley et al, 2007; 50:50 CLA 2 or 4 g per day) in 36 lactating women or with pure isomers in 12 lactating women (Hasin et al, 2005; 750 mg per day of each isomer) showed no effect on milk composition.…”