Human mammary gland function at the onset of lactation: medium-chain fatty acid synthesis

Medium- and Long-Chain Triacylglycerol: Preparation, Health Benefits, and Food Utilization

Medium- and long-chain triacylglycerol (MLCT) is a structured lipid with both medium- and long-chain fatty acids in one triacylglycerol molecule. Compared with long-chain triacylglycerol (LCT), which is mainly present in common edible oils, and the physical blend of medium-chain triacylglycerol with LCT (MCT/LCT), MLCT has different physicochemical properties, metabolic characteristics, and nutritional values. In this article, the recent advances in the use of MLCT in food formulations are reviewed. The natural sources and preparation of MLCT are discussed. A comprehensive summary of MLCT digestion, absorption, transport, and oxidation is provided as well as its health benefits, including reducing the risk of overweight, hypolipidemic and hypoglycemic effects, etc. The potential MLCT uses in food formulations, such as infant formulas, healthy foods for weight loss, and sports foods, are summarized. Finally, the current safety assessment and regulatory status of MLCT in food formulations are reviewed.

Triacylglycerols containing branched palmitic acid ester of hydroxystearic acid (PAHSA) are present in the breast milk and hydrolyzed by carboxyl ester lipase

Breast milk is a complex mixture containing underexplored bioactive lipids. We performed an observational case-control study to compare the impact of delivery mode: caesarean section (CS) and vaginal birth (VB); and term (preterm and term delivery) on the levels of lipokines in human milk at different stages of lactation. Metabolomic analysis of the milk identified triacylglycerol estolides as a metabolic reservoir of the anti-inflammatory lipid mediator 5-palmitic acid ester of hydroxystearic acid (5-PAHSA). We found that triacylglycerol estolides were substrates of carboxyl ester lipase and 5-PAHSA-containing lipids were the least preferred substrates among tested triacylglycerol estolide isomers. This explained exceptionally high colostrum levels of 5-PAHSA in the VB group. CS and preterm birth negatively affected colostrum lipidome, including 5-PAHSA levels, but the lipidomic profiles normalized in mature milk. Mothers delivering term babies vaginally produce colostrum rich in 5-PAHSA, which could contribute to the prevention of intestinal inflammation in newborns.

Total and sn-2 fatty acid profile of breast milk from women delivering preterm infants under the influence of maternal characteristics

Data on the total fatty acid (FA) profile and position-specific triacylglycerides (TAGs) in preterm infants' maternal milk are essential for establishing the recommended requirement of FA in preterm infants in China. We aimed to determine the composition and positional distribution of FAs in preterm infants' maternal milk in China and further investigate the effect of maternal background on the FA composition. Breast milk samples (4, 11, 30, 60, and 90 (all ±3) days post-partum) were collected from 59 healthy women delivering preterm infants. The total and sn-2 milk FA composition was determined using gas chromatography. The multivariate statistical analysis showed significant differences in the FA profiles of milk with different lactation times, gestational ages and maternal ages. In particular, the content of linoleic and linolenic acid (ALA) was much higher, whereas the content of docosahexaenoic (DHA) and arachidonic acid were lower in the preterm milk from the Wuxi district than that from America and countries in Europe. The content of sn-2 polyunsaturated FAs (ALA: p = 0.013 and DHA: p = 0.003) were lower in the preterm colostrum from women aged over 30 years. Overall, these results suggest that the European and American standards of preterm formula may not be suitable for Chinese preterm infants, and polyunsaturated FA fortification in the maternal diet or preterm formula is needed for women with advanced age.

Differences in preterm and term milk fatty acid compositions may be caused by the different hormonal milieu of early parturition

INTRODUCTION

The hormonal milieus of pregnancy and lactation are driving forces of nutrient fluxes supporting infant growth and development. The decrease of insulin sensitivity with compensatory hyperinsulinemia with advancing gestation, causes adipose tissue lipolysis and hepatic de novo lipogenesis (DNL).

SUBJECTS AND METHODS

We compared fatty acid (FA) contents and FA-indices for enzyme activities between preterm (28-36 weeks) and term (37-42) milks, and between colostrum (2-5 days), transitional (6-15) and mature (16-56) milks. We interpreted FA differences between preterm and term milks, and their changes with lactation, in terms of the well known decrease of insulin sensitivity during gestation and its subsequent postpartum restoration, respectively.

RESULTS

Compared with term colostrum, preterm colostrum contained higher indices of DNL in the breast (DNL-breast) and medium chain saturated-FA (MCSAFA), and lower DNL-liver and monounsaturated-FA (MUFA). Preterm milk also had higher docosahexaenoic acid (DHA) in colostrum and transitional milk and higher arachidonic acid (AA) in mature milk. Most preterm-term differences vanished with advancing lactation. In both preterm and term milks, DNL-breast and MCSAFA increased with advancing lactation, while DNL-liver, MUFA, long chain SAFA and AA decreased. DHA decreased in term milk. MUFA was inversely related to MCSAFA in all samples, correlated inversely with PUFA in colostrum and transitional milks, but positively in mature milk. MCSAFA correlated inversely with PUFA in mature milk.

CONCLUSION

Higher maternal insulin sensitivity at preterm birth may be the cause of lower MUFA (a proxy for DNL-liver) and higher MCSAFA (a proxy for DNL-breast) in preterm colostrum, compared with term colostrum. Restoring insulin sensitivity after delivery may be an important driving force for milk FA-changes in early lactation.

Milk of northern Sudanese mothers whose traditional diet is high in carbohydrate contains low docosahexaenoic acid

AIM

  The suckling neonates and infants are reliant primarily on the mother for optimal supply of docosahexaenoic acid (DHA). The richest source of preformed DHA is cold-water oily fish. Although there is paucity of data, existing evidence suggest women with restricted access to these foods have low or marginal DHA status. The aim of the study was to investigate milk fatty acids of Sudanese mothers whose traditional diet is high in carbohydrate and low in fat and gain some insight into the provision of DHA to the suckling offspring.

METHODS

Colostrum (n =26), transitional (n=20) and mature (n=14) milk samples were obtained from Northern Sudanese women (NSW) recruited prior to delivery from Ibrahim Malik and Khartoum Teaching Hospitals.

RESULTS

  The arachidonic acid content of the colostrum (0.87±0.28%) and transitional (0.89± 0.29%) and mature (0.48±0.12%) milk of the NSW were broadly comparable with published international values. In contrast, the DHA level (colostrum 0.13±0.07%, transitional 0.13±0.06% and mature milk 0.06±0.05%) was very low.

CONCLUSION

  The study reveals breast milk of NSW, whose traditional diet is almost devoid of fish and fish products, is unlikely to provide sufficient DHA to support optimal postnatal neuro-visual development.

Polyunsaturated n-3 fatty acids and the development of atopic disease

The relationship between polyunsaturated longchain fatty acids and atopy has been discussed for decades. Higher levels of the essential fatty acids linoleic acid and alpha-linolenic acid and lower levels of their longer metabolites in plasma phospholipids of atopic as compared to nonatopic individuals have been reported by several, but not all, studies. Largely similar findings have been reported in studies of cell membranes from immunological cells from atopics and non-atopics despite differences in methodology, study groups, and definitions of atopy. An imbalance in the metabolism of the n-6 fatty acids, particularly arachidonic acid and dihomo-gamma-linolenic acid, leading to an inappropriate synthesis of prostaglandin (PG) E2 and PGE1 was hypothesized early on but has not been corroborated. The fatty acid composition of human milk is dependent on the time of lactation not only during a breast meal but also the time of the day and the period of lactation. This explains the discrepancies in reported findings regarding the relationship between milk fatty acids and atopic disease in the mother. Prospective studies show disturbances in both the n-6 and n-3 fatty acid composition between milk from atopic and nonatopic mothers. Only the composition of long-chain polyunsaturated n-3 fatty acids was related to atopic development in the children, however. A relationship between lower levels of n-3 fatty acids, particularly eicosapentaenoic acid (20:5 n-3), and early development of atopic disease is hypothesized.

Fatty acid composition of human milk in Kuwaiti mothers

Kuwaiti diet is exceptionally rich in fat, carbohydrates and proteins. In addition, subjects in Kuwait are exposed to extreme heat and sun light. Fatty acid profiles of human milk obtained from 19 full breast feeding Kuwaiti mothers were analyzed. Dietary patterns for individual mothers were determined by 24 h dietary recall and food frequency questionnaire. The fatty acid content of human milk was affected by the diet consumed by the lactating mother. The content of long chain polyunsaturated fatty acids (LCP) in human milk lipids did not correlate with their parent fatty acids like linoleic and alpha-linolenic acids. However the human milk LCP were related to the of content of LCP in the maternal diet. Mothers reporting a high fish consumption showed significant amounts of C22:6, omega 3 and C20:5, omega 3 fatty acids. As a general conclusion, breast milk produced by a well nourished mother is better suited to meet the lipid requirements of infants.