Low docosahexaenoic acid in the diet and milk of women in New Mexico.

Because docosahexaenoic acid (DHA) is critical for the development of the nervous system, especially during the first year of life, the content of DHA in human milk is important for the well-being of exclusively breastfed infants. The aim of this study was to determine the fatty acid composition, including DHA, of the breast milk fat and serum phospholipids of women in New Mexico, and to correlate these data with dietary fatty acid content. Samples of blood and breast milk, 3-day diet records, and information on dietary supplement use were obtained from 29 women. Eligible subjects were nonsmokers, aged 18 to 40 years, lactating for 1 to 6 months, and not pregnant, taking immunosuppressive drugs, or diagnosed with diabetes. The mean fat content of the breast milk was 3.37+/-2.34 g/dL. The percentage of DHA in the milk fat was very low (0.11%) relative to international norms (0.2% to 0.4%) and could be explained by the women's low intake of DHA (33 to 58 mg/day). These data can be explained by the fact that the subjects were not taking DHA supplements or consuming foods that are good sources of DHA. Correlations were found between the percentages of DHA in the serum phospholipids and milk fat. The findings underscore the need for educating lactating women about food sources of DHA. Educational opportunities could occur in conjunction with other education postdelivery or during postnatal clinic visits.

Desaturation indices in liver, muscle, and bone of growing male and female mice fed trans-10,cis-12 conjugated linoleic acid.

trans-10,cis-12-CLA (t10,c12-CLA) inhibits lipid deposition in adipose tissue of many species, but it also enhances lipid deposition in liver. We evaluated effects of dietary t10,c12-CLA content and gender on carcass composition, FA profile of selected tissues, and expression of FA synthase (FAS) and stearoyl-CoA desaturase-1 (SCD) mRNA in adipose tissue. Male and female (63 of each) CD-1 mice were assigned a diet containing 0.0, 0.15, or 0.30% t10,c12-CLA at 4 wk of age. Seven mice per dietary group within gender were sacrificed after 2, 4, or 6 wk. The CLA isomer caused dose-dependent reductions in dry carcass weight and fat content, without altering protein content, but carcass fat and epididymal fat pad weights of males were reduced to a greater extent than carcass fat and inguinal fat pad weights of females. FAS and SCD mRNA in adipose tissue was more abundant in females than males, but expression in both genders decreased as the t10,c12-CLA content of the diet increased. Although the weight of gastrocnemius muscle was not influenced by diet, total FA content of the muscle of both genders decreased in response to dietary t10,c12-CLA content. Femur weight of male mice increased as the t10,c12-CLA content of the diet increased, but the weight increase was associated with a reduction in total FA content. The delta 9 desaturation indices for muscle and femur suggested a linear reduction in SCD activity, whereas delta 9 indices for liver indicated linear enhancement of SCD activity. Overall, results suggested that growing male mice were more susceptible than females to t10,c12-CLA inhibition of lipid deposition.

Trans fatty acids and conjugated linoleic acids in the milk of urban women and nomadic Fulani of northern Nigeria.

BACKGROUND: Trans fatty acids (TFAs) and conjugated linoleic acids (CLAs) are present in dairy products and human milk and can have detrimental and beneficial effects in humans. The content of TFAs and CLAs in milk is determined largely by the diet of the mother. METHODS: We compared the proportions of TFAs and CLAs in the milk of rural Fulani in northern Nigeria who consume dairy products to that of women living in an urban center who consume little in the way of dairy products. Lactating Fulani women (n=41) and women residing in the city of Jos, Nigeria (n=41) were recruited into the study. We predicted that the milk of the Fulani pastoralists would contain higher amounts of TFAs and CLAs compared to their urban counterparts. RESULTS: The mean total TFA proportions for the Fulani and urban women were 0.22% and 0.34%, respectively, and were not significantly different. The percentages of CLAs in milk fat were not different between rural and urban women (0.16% vs 0.14%). These TFA and CLA values were 4- to 10-fold lower than for milk of women elsewhere in the world. CONCLUSIONS: The percentages of TFAs and CLAs in milk were not different between rural and urban dwellers in northern Nigeria whose diets differ greatly in the amounts of dairy products they contain. However, the fact that the percentages of TFAs and CLAs in the milk of Nigerian women were much lower than the percentages reported from other parts of the world may have implications for the long-term growth and development of infants in the northern Nigeria and elsewhere in the Western Sahel.

Trans10,cis12-18:2 is a more potent inhibitor of de novo fatty acid synthesis and desaturation than cis9,trans11-18:2 in the mammary gland of lactating mice.

To investigate the effects of 2 conjugated linoleic acid (CLA) isomers and trans11-18:1 (TVA) on de novo lipogenesis and desaturation in liver and mammary gland, lactating mice were fed diets containing 3% canola oil (control) or 2% canola oil plus 1% stearic acid (SA), TVA, cis9,trans11 CLA (c9t11), or trans10,cis12 CLA (t10c12). In mammary tissue, TVA and CLA isomers reduced mRNA for acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) compared with control, but only c9t11 and t10c12 reduced mammary ACC activity. Of the 2 CLA isomers, t10c12 caused a greater reduction in mammary ACC activity. Hepatic ACC or FAS activity and mRNA abundance were not affected by dietary treatments. Feeding TVA, c9t11, or t10c12 reduced mammary stearoyl-CoA desaturase 1 (SCD) mRNA and activity. Reduction was greater due to feeding t10c12 compared with c9t11. Hepatic SCD mRNA was not affected by dietary treatments, but both CLA isomers depressed hepatic SCD activity. Results indicated that t10c12 is a more potent inhibitor of mammary lipogenesis and desaturation than is c9t11. A net gain of 77 and 1690 micro g of c9t11 in liver and mammary tissue, respectively, was found in the TVA-fed group over the control and SA-fed group. However, reduced mammary SCD mRNA or activity due to feeding TVA may indicate a limited capacity for desaturation of dietary TVA to c9t11 in vivo.

Effects of dietary cis 9, trans 11-18:2, trans 10, cis 12-18:2, or vaccenic acid (trans 11-18:1) during lactation on body composition, tissue fatty acid profiles, and litter growth in mice.

Cis 9, trans 11 (c 9, t11)-18:2 and trans 10, cis 12 (t10, c12)-18:2 are the major conjugated linoleic acid (CLA) isomers in dietary supplements which reduce milk fat content in nursing women. The present study evaluated the effects of each CLA isomer or vaccenic acid on body composition and tissue fatty acids during lactation in mice. Dams were fed 30 g rapeseed oil (control)/kg diet or 20 g control plus 10 g 18:0, trans 11-18:1 (t11-18:1), c 9, t11-18:2, or t10, c12-18:2. Dietary t10, c12-18:2 reduced food intake by 18 % and carcass fat weight of the dams by 49 % compared with the other treatments. Milk fat percentage ranked by treatment was 18:0>t11-18:1=c 9, t11-18:2>t10, c12-18:2. The sum of saturated 12:0 to 16:0 in milk fat was lower when c 9, t11-18:2 was fed compared with the control, 18:0, or t11-18:1 treatments. Dietary t10, c12-18:2 caused further reductions in milk fat 12:0 to 16:0. The proportion of CLA isomers was 3-fold greater in milk fat than in the carcasses of the dams. The pups nursing from the dams fed t10, c12-18:2 had the lowest body weights and carcass fat, protein, and ash contents. Nursing from the dams fed c 9, t11-18:2 also resulted in lower carcass fat compared with the 18:0 or t11-18:1 treatments. The ratios of cis 9-16:1:16:0 or cis 9-18:1:18:0, proxies for Delta(9)-desaturase activity, were markedly lower in the carcasses of the dams and pups fed t10, c12-18:2. The ratio of 20:4n-6:18 : 2n-6, a proxy for Delta(6)- and Delta(5)-desaturase and elongase activity, in the liver of the dams and pups fed t10, c12-18:2 also was lower. Dietary t11-18:1 enhanced the content of c 9, t11-18:2 in milk fat and carcasses. As in previous studies, the reduction in food intake by t10, c12-18:2 could not entirely account for the marked decrease in carcass fat content and milk fat concentration. T10, c12-18:2 probably had a negative effect on Delta(9)-desaturase and mammary de novo fatty acid synthesis. Although these effects need to be confirmed in lactating women, the results suggest that the consumption of supplements containing t10, c12-18:2 should be avoided during the nursing period.

Dietary trans-vaccenic acid (trans11-18:1) increases concentration of cis9,transll-conjugated linoleic acid (rumenic acid) in tissues of lactating mice and suckling pups.

Lactating mice were fed trans-vaccenic acid (trans 11-18:1, TVA) to assess desaturation of TVA to cis9,trans11-conjugated linoleic acid (9/11CLA). Diets contained 30 g x kg(-1) 18:2n-6 (LA) or 20 g LA plus 10 g 18:0 (SA), TVA, or a CLA mixture (MCLA). Compared with SA, feeding TVA increased 9/11CLA concentrations in blood plasma phospholipid, triglyceride, and free fatty acid fractions. However, concentrations of 9/11CLA in plasma fractions were greater when MCLA was fed compared with SA or TVA. No 9/11CLA was detected in liver of mice fed SA, and it was only 1 mg x g(-1) of total fatty acids in the carcass. In contrast, 9/11CLA content of liver (5 mg x g(-1)) and carcass (6 mg x g(-1)) of mice fed TVA was similar to liver (5 mg x g(-1)) and carcass (7 mg x g(-1)) of mice fed MCLA. Mammary tissue of SA-fed mice had no detectable 9/11 CLA, compared with 5 or 14 mg x g(-1) for TVA or MCLA-fed mice. Stearoyl-CoA desaturase activity in mammary tissue from TVA-fed dams was 14% greater compared with SA. Activity of this enzyme in liver tissue was similar among treatments. In pups nursing TVA-fed dams, 9/1 ICLA accounted for 3 mg x g(-1) in liver but no 9/11CLA was detected in the carcass. In pups nursing MCLA-fed dams, however, 9/11CLA accounted for 8 and 6 mg x g(-1) in liver and carcass. Results indicated TVA desaturation enhanced 9/11CLA in tissues and milk fat.