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

Abstract

Substantial research suggests that the t10,c12-18:2, but not the c9,t11-18:2, isomer of conjugated linoleic acid (CLA) reduces milk fat synthesis in lactating bovine and rodent species. Because fat is the major energy-yielding component in human milk, we were interested in whether this is true for women as well. Thus, the effects of c9,t11-18:2 and t10,c12-18:2 on milk fat were examined in breast-feeding women (n = 12) in a double-blind, placebo-controlled, crossover study with latin-square design. The study was divided into six periods: baseline (3 days), three intervention periods (5 days each), and two washout periods (9 days each). During each intervention period, women consumed 750 mg/day of a supplement containing predominantly c9,t11-18:2, t10,c12-18:2, or 18:1 (olive oil placebo). Milk was collected by complete breast expression on the final day of each period. Infant milk consumption was estimated by 24 h weighing on the penultimate day of each intervention and washout period, and maternal adiposity (% body fat) was determined at baseline using dual energy X-ray absorptiometry. Milk c9,t11-18:2 and t10,c12-18:2 concentrations were greater (P < 0.05) during the corresponding CLA treatment periods as compared to the placebo period, providing strong evidence of subject compliance. Both CLA isomers were transferred into milk fat at relatively high efficiency; average transfer efficiency was estimated to be 23.3%. Compared to the placebo treatment, milk fat content was not reduced during either CLA treatment. Data indicate that body fatness did not modify any putative effect of isomeric CLA consumption on milk fat concentration. The evidence from this study suggests that the sensitivity of lactating women's mammary tissue to an anti-lipogenic effect of the t10,c12-18:2 isoform of CLA may be less than previously hypothesized.

Elevated dairy fat intake in lactating women alters milk lipid and fatty acids without detectible changes in expression of genes related to lipid uptake or synthesis

“…The treatment effects observed on milk fatty acid profiles add more evidence that the participants adhered to the guidelines of the study. In particular, the elevation of milk c9,t11-CLA content during the full-fat dairy intervention largely verifies subjects' compliance [3,29]. The differential amounts of c9,t11-CLA in the milk lipids also suggest that the dietary intervention was successful in changing the exposure of the lactating mammary epithelial cell to this potentially biologically active fatty acid.…”

Conjugated linoleic acid (CLA): Good or bad trans fat?

“…Two human studies focused on CLA and milk fat and found no changes in milk fat or protein (Hasin et al, 2007;Mosley et al, 2002). However, since the studies only used a relatively short period (5 days), it is still not clear if longer CLA supplementation would reduce milk fat content significantly enough to affect infant nutrition.…”

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

“…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.…”