Human milk fatty acid composition and its association with maternal blood and adipose tissue fatty acid content in a cohort of women from Europe.

PURPOSE: Human milk (HM) composition is influenced by factors, like maternal diet and body stores, among other factors. For evaluating the influence of maternal fatty acid (FA) status on milk FA composition, the correlation between FA content in HM and in maternal plasma, erythrocytes, and adipose tissue was investigated. METHODS: 223 European women who delivered at term, provided HM samples over first four months of lactation. Venous blood and adipose tissue (only from mothers who consented and underwent a C-section delivery) were sampled at delivery. FAs were assessed in plasma, erythrocytes, adipose tissue, and HM. Evolution of HM FAs over lactation and correlations between FA content in milk and tissues and between mother's blood and cord blood were established. RESULTS: During lactation, arachidonic acid (ARA) and docosahexaenoic acid (DHA) significantly decreased, while linoleic acid (LA), alpha-linolenic acid (ALA), and eicosapentaenoic acid (EPA) remained stable. Positive correlations were observed between HM and adipose tissue for palmitic, stearic, oleic, and polyunsaturated fatty acids (PUFAs). Correlations were found between milk and plasma for oleic, LA, ARA, ALA, DHA, monounsaturated fatty acids (MUFAs), and PUFAs. No correlation was observed between erythrocytes and HM FAs. LA and ALA were more concentrated in maternal blood than in infant blood, contrary to ARA and DHA, supporting that biomagnification of LCPUFAs may have occurred during pregnancy. CONCLUSIONS: These data show that maternal adipose tissue rather than erythrocytes may serve as reservoir of PUFAs and LCPUFAs for human milk. Plasma also supplies PUFAs and LCPUFAs to maternal milk. If both, adipose tissue and plasma PUFAs, are reflection of dietary intake, it is necessary to provide PUFAs and LCPUFAs during pregnancy or even before conception and lactation to ensure availability for mothers and enough supply for the infant via HM.

Quantification of total cholesterol in human milk by gas chromatography.

Human milk provides the key nutrients necessary for infant growth and development. The objective of this study was to develop and validate a method to analyze the cholesterol content in liquid human milk samples along lactation. Direct saponification of the sample using ethanolic potassium hydroxide solution under cold conditions was applied and unsaponifiable matter was separated by centrifugation. Cholesterol was converted into its trimethylsilyl ether and the derivative analyzed by gas chromatography coupled with a flame ionization detector. Cholesterol was quantified using epicoprostanol as internal standard. The method is suitable for the determination of cholesterol in only 0.3 g of human milk. It has been validated showing good repeatability (CV(r) < 15%) and intermediate reproducibility (CV(iR) < 15%). The method was used to analyze human milk obtained from five mothers collected at day 30(±3), 60 (±3) and 120 (±3) after delivery. The cholesterol content in human milk slightly decreased from 13.1 mg/100 g at 1 month to 11.3 mg/100 g 120 days after delivery. The method can also be used to determine desmosterol, an intermediate in cholesterol synthesis.

Quantification of fatty acids in erythrocytes and plasma by fast gas chromatography.

As a result of the heterogeneous nature of lipid classes in complex biological matrices such as plasma and erythrocytes, it is imperative to have a robust and validated methodology for fatty acid quantification. The effective method presented here combines available methodology of fast gas chromatography and an improvement of the sample preparation methodology before injection into the gas chromatograph. This methodology ensures complete transesterification and quantification of total and individual fatty acids (and not only in relative amounts) by addition of internal standards. We considered sample preparation key, and we established the use of lysis buffer and ethanol for erythrocytes and plasma sample preparation, respectively. Fatty acid profile was determined by acid methylation and fast gas chromatography equipped with a flame ionization detector. The triacylglycerol 13:0, phosphatidylcholine 23:0, and methyl esters 21:0 were used as internal standards. Within the linearity of the calibration, the ratio of the peak area of each fatty acid over the peak area of the internal standard was constant (coefficient of variation ≤ 2.5). Satisfactory repeatability <15% and intermediate reproducibility < 15% were observed. Finally, this validated method was applied to a pre-clinical trial that investigated the impact of dietary fats on accretion of specific fatty acids in plasma and erythrocytes.

Monoacylglycerol-enriched oil increases EPA/DHA delivery to circulatory system in humans with induced lipid malabsorption conditions.

It was hypothesized that under induced lipid malabsorption/maldigestion conditions, an enriched sn-1(3)-monoacylglycerol (MAG) oil may be a better carrier for n-3 long-chain PUFAs (LC-PUFAs) compared with triacylglycerol (TAG) from fish oil. This monocentric double blinded clinical trial examined the accretion of EPA (500 mg/day) and DHA (300 mg/day) when consumed as TAG or MAG, into the erythrocytes, plasma, and chylomicrons of 45 obese (BMI ≥30 kg/m2 and ≤40 kg/m2) volunteers who were and were not administered Orlistat, an inhibitor of pancreatic lipases. Intake of MAG-enriched oil resulted in higher accretion of LC-PUFAs than with TAG, the concentrations of EPA and DHA in erythrocytes being, respectively, 72 and 24% higher at 21 days (P < 0.001). In addition, MAG increased the plasma concentration of EPA by 56% (P < 0.001) as compared with TAG. In chylomicrons, MAG intake yielded higher levels of EPA with the area under the curve (0-10 h) of EPA being 55% greater (P = 0.012). In conclusion, in obese human subjects with Orlistat-induced lipid maldigestion/malabsorption conditions, LC-PUFA MAG oil increased LC-PUFA levels in erythrocytes, plasma, and chylomicrons to a greater extent than TAG. These results indicate that MAG oil might require minimal enzymatic digestion prior to intestinal uptake and transfer across the epithelial barrier.

Bioavailability of bioactive food compounds: a challenging journey to bioefficacy.

Bioavailability is a key step in ensuring bioefficacy of bioactive food compounds or oral drugs. Bioavailability is a complex process involving several different stages: liberation, absorption, distribution, metabolism and elimination phases (LADME). Bioactive food compounds, whether derived from various plant or animal sources, need to be bioavailable in order to exert any beneficial effects. Through a better understanding of the digestive fate of bioactive food compounds we can impact the promotion of health and improvement of performance. Many varying factors affect bioavailability, such as bioaccessibility, food matrix effect, transporters, molecular structures and metabolizing enzymes. Bioefficacy may be improved through enhanced bioavailability. Therefore, several technologies have been developed to improve the bioavailability of xenobiotics, including structural modifications, nanotechnology and colloidal systems. Due to the complex nature of food bioactive compounds and also to the different mechanisms of absorption of hydrophilic and lipophilic bioactive compounds, unravelling the bioavailability of food constituents is challenging. Among the food sources discussed during this review, coffee, tea, citrus fruit and fish oil were included as sources of food bioactive compounds (e.g. (poly)phenols and polyunsaturated fatty acids (PUFAs)) since they are examples of important ingredients for the food industry. Although there are many studies reporting on bioavailability and bioefficacy of these bioactive food components, understanding their interactions, metabolism and mechanism of action still requires extensive work. This review focuses on some of the major factors affecting the bioavailability of the aforementioned bioactive food compounds.

Increasing Dietary alpha-linolenic acid enhances tissue levels of long-chain n-3 PUFA when linoleic acid intake is low in hamsters.

BACKGROUND/AIMS: We tested whether feeding hamsters diets varying in alpha-linolenic acid (ALA) content and low in linoleic acid (LA) could increase the tissue levels of eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) to the same extent as a fish oil-supplemented diet. METHODS: For 5 weeks, 60 hamsters were fed 1 of the following 5 diets containing 2% of total dietary energy (TE) as LA and either 0.5% (diet A), 1% (diets B and E), 2% (diet C), or 4% (diet D) ALA of TE, so that the ratio of LA/ALA was 4:1, 2:1, 1:1, or 1:2. Diet E was supplemented with fish oil at the level of 0.2% of total energy intake. At the end of the study, overnight-fasted hamsters were sacrificed, and blood and tissues were collected. RESULTS: Tissue levels of ALA, EPA, DPA, and DHA rose in proportion to the increase in the dietary ALA level (p < 0.01); however, the levels of DHA reached a plateau at ALA intakes above 1% (p < 0.01). These changes were accompanied by decreases in arachidonic acid with or without increases in LA levels (p < 0.01). Hamsters fed diet D had similar or higher EPA, DPA, and DHA tissue levels to those fed diet E (p < 0.01). CONCLUSIONS: In hamsters, diets containing 4% energy as ALA and 2% energy as LA can increase the tissue levels of EPA, DPA, and DHA to the same extent as feeding 0.2% energy as fish oil.

Mineral oil hydrocarbons in foods: is the data reliable?

The contamination of foods with mineral oil hydrocarbons (MOH) is a serious concern, requiring in most cases tedious mitigation measures that span across the whole food supply chain. A major issue today is the significant variability of the results generated by laboratories. This study was therefore designed to achieve a deeper insight into the analytical procedures used by commercial laboratories, identifying possible gaps and suggesting improvements that will enhance the reliability of the MOH data, an important prerequisite for risk assessment. In total six different food matrices, i.e. infant formula (IF), cocoa butter, cocoa powder, biscuits, fruit-based baby food containing biscuit and roast and ground coffee were subjected to comparative inter-laboratory studies, as well as one vegetable oil analysed within the frame of a professionally conducted proficiency test. The results indicate that on some matrices with possibly low amounts of MOH contamination, the current methodologies cannot reliably conclude whether or not a food sample is indeed contaminated with mineral oils (<10 mg/kg food). Urgently needed are: (i) an aligned and fully validated sample preparation strategy tested on a range of different food matrices; (ii) a confirmation of positive flame ionisation detection (FID) results by confirmatory methods such as mass spectrometry - in line with the CEN Standard and the Joint Research Centre (JRC) Guidance Document, (iii) a more detailed root-cause analysis in the reports of laboratories through the use of mineral oil markers, and (iv) a fully validated official method for the concerned foods with a limit of application <10 mg/kg food.

Monoacylglycerol Form of Omega-3s Improves Its Bioavailability in Humans Compared to Other Forms.

Numerous benefits are attributed to omega-3 fatty acids (OM3) especially in cardiovascular health. However, bioavailability and clinical efficacy depend on numerous factors, including OM3 form, food matrix effects (especially the lipid content of the diet), and metabolic capacity. Here, we show in humans that a "pre-digested" OM3-sn-1(3)-monoacylglycerol lipid structure (OM3-MAG) has a significantly greater absorption at high therapeutic doses (2.9 g/day) than the most commonly OM3-ethyl ester (3.1 g/day) form (used for the treatment of hypertriglyceridemia), and a comparable profile to other pre-digested OM3 free fatty acids (OM3-FFA) structure (3.2 g/day). Nutritional supplement doses of MAG resulted in similar increases in OM3 blood level, compared to OM3 triacylglycerols (OM3-TAG) supplements in obese subjects (1.2 g/day) under low fat diet, and in children with cystic fibrosis (1.0 g/day). These results suggest that both forms of pre-digested OM3-MAG and OM3-FFA are effectively absorbed and re-incorporated effectively into triacylglycerols inside the enterocytes, before being exported into the chylomicrons lipid transport system. The pre-digested OM3-MAG might provide a more effective therapy in severe cardiovascular conditions where high doses of OM3 are required and a low-fat diet is indicated, which limited digestive lipase activity.

Reply: "Letter to the Editor Re: Billeaud et al. Nutrients 2018, 10, 690".

We thank Bernard and colleagues for their careful reading and interest in our article Effects on Fatty Acid Metabolism of a New Powdered Human Milk Fortifier Containing Medium-Chain Triacylglycerols and Docosahexaenoic Acid in Preterm Infants [...].

Correction: Billeaud et al. "Effects on Fatty Acid Metabolism of a New Powdered Human Milk Fortifier Containing Medium-Chain Triacylglycerols and Docosahexaenoic Acid in Preterm Infants" Nutrients 2018, 10, 690.

The authors wish to make a correction to the published version of their paper [...].

Impact of dietary protein on lipid metabolism in hamsters is source-dependent and associated with changes in hepatic gene expression.

This study tested the hypothesis that protein source is a factor determining the impact of the diet on lipid metabolism in hamsters. Twenty-eight hamsters of similar body weight were assigned for a period of 8 weeks to one of the following four diets (seven per group) containing either 20 % (w/w) casein (CAS), beef protein (BF), wheat gluten (WG) or soya protein (SOY). The fat composition of the diet was the same (15.5 % w/w) in all groups and provided SFA, MUFA and PUFA representative of the average Canadian diet. After an overnight fast, blood and liver were collected for the measurement of serum lipids, fatty acid composition of liver phospholipids and mRNA levels of selected genes involved in lipid metabolism. WG resulted in lower total cholesterol, HDL-cholesterol and non-HDL-cholesterol but, along with SOY, in higher mRNA levels of cholesterol 7 alpha-hydroxylase and LDL receptor. Furthermore, both WG and SOY resulted in lower 18 : 3n-3, 20 : 4n-6, total n-6 PUFA, 18 : 1n-9 and total MUFA, but higher 22 : 6n-3, total n-3 PUFA, 22 : 6n-3/18 : 3n-3 and 22 : 5n-3/18 : 3n-3 ratios in liver phospholipids, and higher hepatic Delta6-desaturase mRNA levels. These results show that the impact of dietary protein on lipid metabolism is source-dependent and associated with changes in mRNA abundances of key hepatic enzymes and receptors.

Analysis of chemically synthesized oleoylethanolamide by gas-liquid chromatography.

Oleoylethanolamide (OEA) is known to potentially have beneficial biological effects on weight management by controlling food intake and activating lipid catabolism. In biological fluids, OEA and other endogenously biosynthesized fatty acid ethanolamides are usually analyzed by liquid chromatography-mass spectrometry (LC-MS). The present study provides analytical method to routinely assess the quality of OEA prepared for biological studies by gas-liquid chromatography (GLC). The preparation of OEA for biomedical studies can be performed by N-acylation of oleic acid/esters or using oleoyl chloride. In the present study, OEA was prepared by transamidation of triolein. The analysis of the synthesized OEA has been performed by gas-liquid chromatography of its trimethylsilyl ether (TMS) derivatives. Free OEA cannot be analyzed as such because dehydration of the ethanolamide moiety promptly happens in the GLC injection. This thermal degradation reaction gives rise to the formation of an oxazoline derivative. The TMS moiety prevents the reaction, and the structure of the formed derivative was assessed by mass spectrometry. We show here that OEA prepared for biological studies can be routinely analyzed by GLC after TMS derivative preparation.

Combining results of two GC separations partly achieves determination of all cis and trans 16:1, 18:1, 18:2 and 18:3 except CLA isomers of milk fat as demonstrated using Ag-ion SPE fractionation.

Milk fat is a complex mixture of geometric and positional isomers of monounsaturated and polyunsaturated, including short-, long- and branch-chain fatty acids (FAs). There has been partial success to resolve this mixture of FAs using different GC temperature programs, or a combination of GC isothermal and temperature programs. To overcome the problem associated with overlapping isomers prior silver-ion separation was recommended. However, this procedure is time consuming and not practical for routine analysis. In addition, previous methods focused mainly on the trans and cis isomers of 18:1. The present method takes advantage of differences in the relative elution times between different types of FAs. The method involved analyzing each milk fat using the same highly polar 100-m capillary column and GC instrument, and conducting two separations using temperature programs that plateau at 175 and 150 degrees C. The relative shift among the geometric and positional isomers at these two temperature settings was enough to permit identification of most of the trans and cis 16:1, 18:1 and 20:1, the c/t-18:2 and the c/c/t-18:3 isomers found in milk fat. The identity of these FAs was confirmed by prior separation of the total fatty acid methyl esters (FAMEs) of milk fat using Ag(+)-SPE columns, and comparing the fractions to the total milk fat. The Ag(+)-SPE technique was modified to obtain pure saturated, trans- and cis-monounsaturated and diunsaturated FAMEs. By combining the results from these two separate GC analyses, knowing the elution order, it was possible to determine most of the geometric and positional isomers of 16:1, 18:1, 20:1, 18:2 and 18:3 without a prior silver-ion separation. Only few minor FAs could not be resolved, notable the conjugated linoleic acid isomers that still required the complimentary Ag(+)-HPLC separation. The two GC temperature programs have been successfully used to routinely analyze most FA isomers in total milk and beef fats in about 200 min without the use of prior silver-ion separations.

Biological functions and metabolism of oleoylethanolamide.

The present review is focused on the metabolism and the emerging roles of oleoylethanolamide (OEA) with emphasis on its effects on food intake control and lipid metabolism. The biological mechanism of action, including a non-genomic effect mediated through peroxisome proliferator-activated receptor alpha (PPAR-alpha) and transient receptor potential vanilloid type 1 (TRPV1) receptor, is discussed. The research related to fatty acid ethanolamides has been focused until recently on anandamide and its interaction with cannabinoid receptor subtype 1. The roles of other N-acyl ethanolamine fatty acid derivatives have been neglected until it was demonstrated that OEA can modulate food intake control through interaction with PPAR-alpha. Further investigations demonstrated that OEA modulates lipid and glucose metabolism, and recent study confirmed that OEA is an antagonist of TRVP1. It has been demonstrated that OEA has beneficial effects on health by inducing food intake control, lipid beta-oxidation, body weight loss and analgesic effects. The investigation of the mechanism of action revealed that OEA activates PPAR-alpha and stimulates the vagal nerve through the capsaicin receptor TRPV1. Pre-clinical studies showed that OEA remains active when administered orally.

Effect of CLA and other C18 unsaturated fatty acids on DGAT in bovine milk fat biosynthetic systems.

Production of dairy products with increased amounts of nutraceutic FA such as conjugated linoleic acid (CLA) represents a recent approach for dairy producers and processors to increase the value of their products. The effect of CLA and other FA on the expression of diacylglycerol acyltransferase-1 (DGAT-1) and DGAT-2, and DGAT activity were investigated in bovine mammary gland epithelial (MAC-T) cells. DGAT gene expression analyses were also conducted using bovine mammary gland tissue from dairy cows. In the studies with MAC-T cells, there were no significant effects of CLA isomers or other FA on DGAT1 expression, whereas all FA tested showed enhanced DGAT2 expression (P < 0.05 to P < 0.001), with alpha-linolenic acid (alpha-18:3) having the greatest effect. Additionally, DGAT2 expression was co-ordinated with expression of lysophosphatidic acid acyltransferase (LPAAT), an observation that was also apparent in mammary gland from lactating dairy cows. In contrast, treatment of MAC-T cells with trans-10, cis-12 18:2 or alpha-18:3 resulted in a significant (P < 0.05) decrease in overall DGAT enzyme activity, although the mechanisms resulting in these effects are unclear. Competition assays using microsomes from bovine mammary gland tissue and 1-[(14)C]oleoyl-CoA suggested that DGAT activity was more selective for oleoyl (cis-9 18:1)-CoA than cis-9, trans-11 18:2-, trans-10, cis-12 18:2- or cis-9, cis-12 18:2-CoA. Collectively, the results suggest the relationship between trans-10, cis-12 18:2 and reduced TAG production in bovine milk is not linked to the production of DGAT1 or DGAT2 transcripts, but probably involves effects of this CLA isomer at events beyond transcription, such as post-translational and/or enzyme activity effects.

Fatty acid profile of Canadian dairy products with special attention to the trans-octadecenoic acid and conjugated linoleic acid isomers.

Current scientific evidence indicates that consumption of industrial trans fatty acids (TFA) produced via partial hydrogenation of vegetable oils increases the risk of coronary heart disease. However, some studies have suggested that ruminant TFA, especially vaccenic acid (VA or 11t-18:1) and rumenic acid (RA or 9c,11t-18:2), which is a conjugated linoleic acid (CLA) isomer, may have potential beneficial health effects for humans. To date, no concerted effort has been made to provide detailed isomer composition of ruminant TFA and CLA of Canadian dairy products, information that is required to properly assess their nutritional impacts. To this end, we analyzed the fatty acid profile of popular brands of commercial cheese (n = 17), butter (n = 12), milk (n = 8), and cream (n = 4) sold in retail stores in Ottawa, Canada, in 2006-2007 by silver nitrate thin-layer chromatography and gas liquid chromatography. The average total TFA content of cheese, butter, milk, and cream samples were 5.6, 5.8, 5.8, and 5.5% of total fatty acids, respectively. VA was the major trans-octadecenoic acid (18:1) isomer in all the Canadian dairy samples with average levels of (as % total trans-18:1) 33.9% in cheese, 35.6% in butter, 31.0% milk, and 30.1% in cream. The different dairy products contained very similar levels of CLA, which ranged from 0.5 to 0.9% of total fat. RA was the major CLA isomer of all the dairy products, accounting for 82.4-83.2% of total CLA. There were no significant differences (P > 0.05) in the fatty acid profile between the 4 different dairy groups, which suggests lack of processing effects on the fatty acid profile of dairy fat.

Comparison of the Incorporation of DHA in Circulatory and Neural Tissue When Provided as Triacylglycerol (TAG), Monoacylglycerol (MAG) or Phospholipids (PL) Provides New Insight into Fatty Acid Bioavailability.

Phospholipids (PL) or partial acylglycerols such as sn-1(3)-monoacylglycerol (MAG) are potent dietary carriers of long-chain polyunsaturated fatty acids (LC-PUFA) and have been reported to provide superior bioavailability when compared to conventional triacylglycerol (TAG). The main objective of the present study was to compare the incorporation of docosahexaenoic acid (DHA) in plasma, erythrocytes, retina and brain tissues in adult rats when provided as PL (PL-DHA) and MAG (MAG-DHA). Conventional dietary DHA oil containing TAG (TAG-DHA) as well as control chow diet were used to evaluate the potency of the two alternative DHA carriers over a 60-day feeding period. Fatty acid profiles were determined in erythrocytes and plasma lipids at time 0, 7, 14, 28, 35 and 49 days of the experimental period and in retina, cortex, hypothalamus, and hippocampus at 60 days. The assessment of the longitudinal evolution of DHA in erythrocyte and plasma lipids suggest that PL-DHA and MAG-DHA are efficient carriers of dietary DHA when compared to conventional DHA oil (TAG-DHA). Under these experimental conditions, both PL-DHA and MAG-DHA led to higher incorporations of DHA erythrocytes lipids compared to TAG-DHA group. After 60 days of supplementation, statistically significant increase in DHA level incorporated in neural tissues analyzed were observed in the DHA groups compared with the control. The mechanism explaining hypothetically the difference observed in circulatory lipids is discussed.

Effects on Fatty Acid Metabolism of a New Powdered Human Milk Fortifier Containing Medium-Chain Triacylglycerols and Docosahexaenoic Acid in Preterm Infants.

Preterm infants require fortification of human milk (HM) with essential fatty acids (FA) to ensure adequate post-natal development. As part of a larger randomized controlled study, we investigated FA metabolism in a subset of 47 clinically stable preterm infants (birth weight ≤1500 g or gestational age ≤32 weeks). Infants were randomized to receive HM supplemented with either a new HM fortifier (nHMF; n = 26) containing 12.5 g medium-chain FA (MCFA), 958 mg linoleic acid (LA), 417 mg α-linolenic acid (ALA), and 157 mg docosahexaenoic acid (DHA) per 100 g of powder (in compliance with the latest guidelines) or a fat-free HMF (cHMF; n = 21). Plasma phospholipid (PL) and triacylglycerol (TAG), and red blood cell phosphatidylcholine (RBC-PC) and phosphatidylethanolamine (RBC-PE) FA profiles were assessed before and after 21 days of feeding. In the nHMF group, significantly increased levels of n-9 monounsaturated fatty acids were observed, formed most likely by elongation and desaturation of dietary saturated fatty acids present in HM. ALA fortification increased ALA assimilation into plasma TAG. Similarly, DHA fortification enriched the DHA content in RBC-PE, which, in this compartment, was not associated with lower arachidonic acid levels as observed in plasma TAG and phospholipids. RBC-PE, a reliable indicator of FA metabolism and accretion, was the most sensitive compartment in this study.

Fast analysis by gas-liquid chromatography. Perspective on the resolution of complex fatty acid compositions.

Separation of fatty acids as methyl ester (FAME) derivatives has been carried out using short and highly polar capillary column developed for fast gas-liquid chromatography (GLC) applications. The GLC parameters have been optimized in order to achieve separation of FAME ranging from 4:0 (butyric acid) to 24:1 in less than 5 min. Milk fat that has by far the most complex fatty acid composition among edible fats and oils has been used to optimize the method. The volume of the oven has been reduced in order to allow for a heating rate of 120 degrees C/min and to rapidly cool-down to the initial temperature (50 degrees C) of the GLC program. The GLC conditions developed are not suitable to achieve separation of positional and geometrical isomers of octadecenoic acid but are useful to perform separation of major fatty acids in milk fat. The conditions developed could be used to analyze edible fats and oils or biological samples such as plasma or red blood cell lipids. The results confirmed that short and highly polar fast columns operating under optimal conditions could be used to separate the fatty acids in various matrices.

Temporal Changes of Human Breast Milk Lipids of Chinese Mothers.

Fatty acids (FA), phospholipids (PL), and gangliosides (GD) play a central role in infant growth, immune and inflammatory responses. The aim of this study was to determine FA, PL, and GD compositional changes in human milk (HM) during lactation in a large group of Chinese lactating mothers (540 volunteers) residing in Beijing, Guangzhou, and Suzhou. HM samples were collected after full expression from one breast and while the baby was fed on the other breast. FA were assessed by direct methylation followed by gas chromatography (GC) analysis. PL and GD were extracted using chloroform and methanol. A methodology employing liquid chromatography coupled with an evaporative light scattering detector (ELSD) and with time of flight (TOF) mass spectrometry was used to quantify PL and GD classes in HM, respectively. Saturated FA (SFA), mono-unsaturated FA (MUFA), and PL content decreased during lactation, while polyunsaturated FA (PUFA) and GD content increased. Among different cities, over the lactation time, HM from Beijing showed the highest SFA content, HM from Guangzhou the highest MUFA content and HM from Suzhou the highest n-3PUFA content. The highest total PL and GD contents were observed in HM from Suzhou. In order to investigate the influence of the diet on maternal milk composition, a careful analyses of dietary habits of these population needs to be performed in the future.