trans Octadecenoic acid and trans octadecadienoic acid are inversely related to long-chain polyunsaturates in human milk: results of a large birth cohort study

Optimizing ARA and DHA in infant formula: A systematic review of global trends, regional disparities, and considerations for precision nutrition

In the context of precision nutrition, the addition of ARA and DHA in infant formula needs to consider more factors. This study conducted a comprehensive literature review, including 112 relevant Chinese and English articles, to summarize and analyze the global levels of ARA, DHA, and the ARA/DHA ratio in breast milk. The data were correlated with local aquatic products intake and children's IQ. The results indicated that the average level of DHA in breast milk across regions is lower than that of ARA. Variations in DHA content were identified as a primary factor influencing ARA/DHA ratio fluctuations. Breast milk ARA and DHA levels decrease with prolonged lactation periods but increase over the past 22 years. Correlation analysis revealed a significant positive relationship between aquatic products intake and breast milk DHA levels (r = 0.64, p < 0.05). Breast milk DHA levels also showed a significant positive correlation with children's IQ (r = 0.67, p < 0.01). Stable breast milk ARA content did not exhibit significant correlations with aquatic products intake or children's IQ (r = 0, p > 0.05). Among 22 infant formula products available in China, only 5 had ARA levels within the range of breast milk. Most formula products had higher ARA levels than DHA, resulting in ARA/DHA ratios generally exceeding 1. The temporal and spatial variability in breast milk ARA and DHA levels may lead to diverse health outcomes in infants. Therefore, the addition of ARA and DHA in infant formula should consider this variability, including the molecular forms and positional isomerism of the added ARA and DHA. Additionally, considering the impact of different cognitive development tests and infant's gene expression on formula assessment results, there is a need to establish a more comprehensive infant health assessment system to guide the addition of ARA and DHA in formula.

Antibiotics and probiotics-induced effects on the total fatty acid composition of feces in a rat model

Fatty acids (FAs) play important roles as membrane components and signal transduction molecules. Changes in short chain FA (SCFA) composition are associated with gut microbiota modifications. However, the effect of bacteria-driven changes on the detailed FA spectrum has not been explored yet. We investigated the effect of antibiotics (ABx) and/or probiotics, in four treatment groups on rat stool FA composition. Principal component analysis indicated that the chromatogram profiles of the treatment groups differ, which was also observed at different time points. Linear mixed effects models showed that in the parameters compared (sampling times, treatments. and their interactions), both the weight percentage and the concentration of FAs were affected by ABx and probiotic administration. This study found that the gut microbiome defines trans and branched saturated FAs, most saturated FAs, and unsaturated FAs with less carbon atoms. These results are among the first ones to demonstrate the restoring effects of a probiotic mixture on a substantial part of the altered total FA spectrum, and also revealed a previously unknown relationship between gut bacteria and a larger group of FAs. These findings suggest that intestinal bacteria produce not only SCFAs but also other FAs that may affect the host's physiological processes.

Trans isomeric fatty acids in human milk and their role in infant health and development

It is well known that long chain polyunsaturated fatty acids (LCPUFAs) play an important role in neurodevelopment in the perinatal life. The most important source of these fatty acids is the diet, however, they can also be formed in the human body from their shorter chain precursors, the essential fatty acids. Since the WHO recommends exclusive breastfeeding for the first six months after birth, the exclusive source of these fatty acids for breastfed infants is human milk, which can be influenced by the mother's diet. Unsaturated fatty acids can have either cis or trans configuration double bond in their chain with distinct physiological effects. Cis isomeric unsaturated fatty acids have several beneficial effects, while trans isomers are mostly detrimental, because of their similar structure to saturated fatty acids. Trans fatty acids (TFAs) can be further subdivided into industrial (iTFA) and ruminant-derived trans fatty acids (rTFA). However, the physiological effects of these two TFA subgroups may differ. In adults, dietary intake of iTFA has been linked to atherosclerosis, insulin resistance, obesity, chronic inflammation, and increased development of certain cancers, among other diseases. However, iTFAs can have a negative impact on health not only in adulthood but in childhood too. Results from previous studies have shown that iTFAs have a significant negative effect on LCPUFA levels in the blood of newborns and infants. In addition, iTFAs can affect the growth and development of infants, and animal studies suggest that they might even have lasting negative effects later in life. Since the only source of TFAs in the human body is the diet, the TFA content of breast milk may determine the TFA supply of breastfed infants and thus affect the levels of LCPUFAs important for neurodevelopment and the health of infants. In this review, we aim to provide an overview of the TFA content in human milk available in the literature and their potential effects on infant health and development.

The Impact of Linoleic Acid on Infant Health in the Absence or Presence of DHA in Infant Formulas

Both linoleic acid (LA) and α-linolenic acid (ALA) are essential dietary fatty acids, and a balanced dietary supply of these is of the utmost importance for health. In many countries across the globe, the LA level and LA/ALA ratio in breast milk (BM) are high. For infant formula (IF), the maximum LA level set by authorities (e.g., Codex or China) is 1400 mg LA/100 kcal ≈ 28% of total fatty acid (FA) ≈ 12.6% of energy. The aims of this study are: (1) to provide an overview of polyunsaturated fatty acid (PUFA) levels in BM across the world, and (2) to determine the health impact of different LA levels and LA/ALA ratios in IF by reviewing the published literature in the context of the current regulatory framework. The lipid composition of BM from mothers living in 31 different countries was determined based on a literature review. This review also includes data from infant studies (intervention/cohort) on nutritional needs regarding LA and ALA, safety, and biological effects. The impact of various LA/ALA ratios in IF on DHA status was assessed within the context of the current worldwide regulatory framework including China and the EU. Country averages of LA and ALA in BM range from 8.5-26.9% FA and 0.3-2.65% FA, respectively. The average BM LA level across the world, including mainland China, is below the maximum 28% FA, and no toxicological or long-term safety data are available on LA levels > 28% FA. Although recommended IF LA/ALA ratios range from 5:1 to 15:1, ratios closer to 5:1 seem to promote a higher endogenous synthesis of DHA. However, even those infants fed IF with more optimal LA/ALA ratios do not reach the DHA levels observed in breastfed infants, and the levels of DHA present are not sufficient to have positive effects on vision. Current evidence suggests that there is no benefit to going beyond the maximum LA level of 28% FA in IF. To achieve the DHA levels found in BM, the addition of DHA to IF is necessary, which is in line with regulations in China and the EU. Virtually all intervention studies investigating LA levels and safety were conducted in Western countries in the absence of added DHA. Therefore, well-designed intervention trials in infants across the globe are required to obtain clarity about optimal and safe levels of LA and LA/ALA ratios in IF.

The Role of Ionic Liquid Interaction in the Separation of Fatty Acid Methyl Esters—Polyunsaturated Geometric Isomers in GC–MS

Knowledge of the type and level of saturated and unsaturated fatty acids in food and clinical matrices is of practical importance, but the wide variety of fatty acids makes analyses very complex. The discrimination of the geometric isomers of fatty acid needs proper and effective separation conditions. The efficiency of three different stationary phases was evaluated by GC–MS methods in the separation of fatty acids in their methyl ester forms. Significant differences were observed in the efficiencies of polysiloxane-based (non-polar HP-5MS and medium/high polarity DB-225MS) and ionic liquid-based (SLB-IL111) columns. Baseline separation of the geometric isomers of linoleic acid methyl ester was obtained by the extremely polar SLB-IL111 column, showing a preference over the other two columns. The optimization of the experimental conditions (response linearity, limit of detection, limit of quantification, system suitability, intraday and interday repeatability and accuracy) showed the separation power of the ionic liquid interaction in the analyses by using short (25–30 m long) columns. By deducting the general principles of the interaction, predictions can be made for the separation of other isomers. The results facilitate the precise identification of various types of fatty acids in real samples for nutritional information.

Changes in human milk fatty acid composition and maternal lifestyle-related factors over a decade: a comparison between the two Ulm Birth Cohort Studies

Human milk fatty acid composition varies during lactation and is influenced by maternal diet, maternal lifestyle-related factors and genetic background. This is one of the first studies to investigate a period effect, that is, the impact of lifestyle-related changes on human milk fatty acid composition, in two different cohorts. Lactating women were recruited from the general population a decade apart in Ulm, Germany, using similar methodology. Human milk samples collected 6 weeks postpartum were analysed (Ulm Birth Cohort Study (UBCS (2000)), n 567; Ulm SPATZ Health Study (SPATZ (2012)), n 458). Centred log ratio transformation was applied to fatty acid data. Principal component analysis was used to determine study-dependent fatty acid profiles. A general linear model was used to determine the study (or period) effect on fatty acid profiles adjusting for duration of gestation, age, education, delivery mode, smoking and pre-pregnancy BMI. Two principal components were retained (PC1 and PC2). PC1 was associated with UBCS, while PC2 was associated with SPATZ. PC1 comprised high SFA, and low MUFA, n-6 and n-3 long-chain PUFA (LCPUFA). The inverse was true for PC2. Although human milk remains a source of essential fatty acids, infants could be at risk of inadequate n-3 and n-6 LCPUFA intake through human milk. The differences in the human milk fatty acid profiles also reflect changes in maternal dietary habits in the more recent cohort, which may comprise lower intakes of dietary trans-fatty acids and SFA and higher intakes of vegetable oils.

Human milk fatty acid profile across lactational stages after term and preterm delivery: A pooled data analysis

BACKGROUND

Lipids in human milk (HM) provide the majority of energy for developing infants, as well as crucial essential fatty acids (FA). The FA composition of HM is highly variable and influenced by multiple factors. We sought to increase understanding of the variation in HMFA profiles and their development over the course of lactation, and after term and preterm delivery, using a pooled data analysis.

OBJECTIVE

To review the literature and perform a pooled data analysis to qualitatively describe an extensive FA profile (36 FAs) in term and preterm colostrum, transitional - and mature milk up to 60 days postpartum.

DESIGN

A Medline search was conducted for HMFA profile data following term or preterm delivery. The search was confined to English language papers published between January 1980 and August 2018. Studies reporting original data, extensive FA profiles in HM from healthy mothers were included. Weighted least squares (WLS) means were calculated from the pooled data using random or fixed effect models.

RESULTS

Our pooled data analysis included data from 55 studies worldwide, for a total of 4374 term milk samples and 1017 preterm milk samples, providing WLS means for 36 FAs. Patterns in both term and preterm milk were apparent throughout lactation for some FAs: The most abundant FAs (palmitic, linoleic and oleic acid) remained stable over time, whereas several long-chain polyunsaturated FAs (including ARA and DHA) seemed to decrease and short- and medium-chain FAs increased over time.

CONCLUSIONS

High heterogeneity between individual studies was observed for the reported levels of some FAs, whereas other FAs were remarkably consistent between studies. Our pooled data suggests that specific FA categories fluctuate according to distinct patterns over the course of lactation; many of these patterns are comparable between term and preterm milk.

New approach shows no association between maternal milk fatty acid composition and childhood wheeze or asthma

BACKGROUND

Previous observational studies have implied breastmilk fatty acid composition may play a role in the development of atopic eczema or atopic sensitization in breastfed infants and toddlers. However, studies investigating associations with wheeze and asthma in later childhood are scarce and did not account for inherent correlation of compositional data. Our aim was to explore the association of maternal milk fatty acid composition with childhood wheezing phenotypes and asthma up to age 13 years using a new statistical approach.

METHODS

Breastmilk was collected 6 weeks and 6 months postdelivery in the Ulm Birth Cohort Study (n=720 and n=454, respectively). Concentrations of 28 fatty acids were measured by high-resolution capillary gas-liquid chromatography. To control for constant-sum constraint, concentration data were transformed using the centered log ratio method. Compositional biplots and correlation matrices were used to group centered log ratio transformed fatty acids. Adjusted risk ratios with parent-reported wheezing phenotypes and doctor-diagnosed asthma were computed using a modified Poisson regression.

RESULTS

We observed no straightforward evidence of associations between overall breastmilk fatty acid composition and specific wheeze phenotypes or doctor-diagnosed asthma.

CONCLUSION

Using appropriate statistical methodology, we report null associations. These findings may partly be attributable to several cohort-specific factors associated with breastfeeding and breastmilk collection. Further studies could improve on ours by analyzing samples of breastmilk and formula and by including all children for whom these are exclusively or together the major source of fatty acids in the first months of life.

Human Milk Fatty Acid Composition: Comparison of Novel Dried Milk Spot Versus Standard Liquid Extraction Methods

Accurate assessment of the long chain polyunsaturated fatty acid (LC-PUFA) content of human milk (HM) provides a powerful means to evaluate the FA nutrient status of breastfed infants. The conventional standard for FA composition analysis of HM is liquid extraction, trans-methylation, and analyte detection resolved by gas chromatography. This standard approach requires fresh or frozen samples, storage in deep freeze, organic solvents, and specialized equipment in processing and analysis. Further, HM collection is often impractical for many studies in the free living environment, particularly for studies in developing countries. In the present study, we compare a novel and more practical approach to sample collection and processing that involves the spotting and drying ~50 μL of HM on a specialized paper stored and transported at ambient temperatures until analysis. Deming regression indicated the two methods aligned very well for all LC-PUFA and the abundant HM FA. Additionally, strong correlations (r > 0.85) were observed for DHA, ARA, EPA, linoleic (LA), and alpha-linolenic acids (ALA), which are of particular interest to the health of the developing infant. Taken together, our data suggest this more practical and inexpensive method of collection, storage, and transport of HM milk samples could dramatically facilitate studies of HM, as well as understanding its lipid composition influences on human health and development.

Analysis of breast milk fatty acid composition using dried milk samples

Background

The effect of breast milk fatty acid (FA) composition, particularly levels of docosahexaenoic acid (DHA), on infant health outcomes is unclear. Part of the reason for this is difficulties in collecting, storing and shipping milk samples to the laboratory. Here we report the validation of a dried milk spot (DMS) system to measure FA composition to help overcome these obstacles.

Milk FA were measured by gas chromatography and reported as percent of total FA; the FA of primary interest in this study were DHA and industrially produced trans FA (iTFA). Experiments were carried out using pooled milk samples from US (n = 5) and Malawian women (n = 50). Experiments compared liquid vs. DMS samples (n = 55), assessed stability of FA composition under different storage conditions (n = 5), and compared the results from two different labs using the same methods (n = 5).

Results

Both % DHA and % iTFA levels in liquid and DMS samples were strongly correlated (R² = 0.99 and 0.99, respectively, P < 0.0001). The % DHA in DMS samples was stable for up to four weeks at room temperature and up to three years at -80 °C; only slight deviations from the acceptable range of variability (±15 %) occurred in the 4 °C and -20 °C conditions for % DHA. The % iTFA was stable under all conditions. All % DHA and % iTFA were within 15 % of the referent when analyzed in two laboratories.

Conclusions

Valid FA composition values can be obtained from DMS samples using this robust collection and transport system which should facilitate studies of the role of milk FA composition in infant development.

Electronic supplementary material

The online version of this article (doi:10.1186/s13006-016-0060-2) contains supplementary material, which is available to authorized users.

Contribution of n-3 long-chain polyunsaturated fatty acids to human milk is still low in Hungarian mothers

Maternal diet has decisive influence on the fatty acid composition of human milk. Fifteen years ago, we found outstandingly low contribution of docosahexaenoic acid (DHA) to human milk in a small group of Hungarian mothers. The major aim of the present study was to investigate whether DHA status in human milk in Hungary changed during the last 15 years. We aimed to examine the fatty acid composition of human milk at three different stages of lactation (3rd day, 6th week, and 6th month) in healthy Hungarian mothers. Fatty acid composition of human milk lipids was determined by gas chromatograph with flame ionization detector. Contribution of arachidonic acid to the fatty acid composition of human milk significantly decreased during lactation (0.91 [0.38] in colostrum, 0.53 [0.17] at 6th week, and 0.46 [0.13] at 6th month, p < 0.01). The contribution of DHA significantly decreased from colostrum to the 6th week of lactation (0.29 [0.12] and 0.14 [0.04], p < 0.01), without further changes by 6 months (0.12 [0.10]).

CONCLUSION

The contribution of DHA to the fatty acid composition of mature human milk in Hungarian mothers is still among the lowest values ever reported in the literature.

Impact of maternal diet on human milk composition and neurological development of infants

Maternal nutrition has little or no effect on many nutrients in human milk; for others, human milk may not be designed as a primary nutritional source for the infant; and for a few, maternal nutrition can lead to substantial variations in human milk quality. Human milk fatty acids are among the nutrients that show extreme sensitivity to maternal nutrition and are implicated in neurological development. Extensive development occurs in the infant brain, with growth from ∼ 350 g at birth to 925 g at 1 y, with this growth including extensive dendritic and axonal arborization. Transfer of n-6 (omega-6) and n-3 (omega-3) fatty acids from the maternal diet into human milk occurs with little interconversion of 18:2n-6 to 20:4n-6 or 18:3n-3 to docosahexaenoic acid (DHA) and little evidence of mammary gland regulation to maintain individual fatty acids constant with varying maternal fatty acid nutrition. DHA has gained attention because of its high concentrations and roles in the brain and retina. Studies addressing DHA intakes by lactating women or human milk amounts of DHA at levels above those typical in the United States and Canada on infant outcomes are inconsistent. However, separating effects of the fatty acid supply in gestation or in the weaning diet from effects on neurodevelopment solely due to human milk fatty acids is complex, particularly when neurodevelopment is assessed after the period of exclusive human milk feeding. Information on infant fatty acid intakes, including milk volume consumed and energy density, will aid in understanding of the human milk fatty acids that best support neurological development.

Inverse association between 18-carbon trans fatty acids and intelligence quotients in smoking schizophrenia patients

This study aimed to investigate polyunsaturated (PUFA) and trans isomeric fatty acid status in schizophrenia patients. Fatty acid composition of plasma phospholipids (PL) and triacylglycerols (TG) was analyzed by gas chromatography in 29 schizophrenia patients and 15 healthy controls. We found no difference in PL n-3 fatty acid status between the two groups, while the values of 22:5n-6 were significantly higher in patients with schizophrenia than in controls. In TG, values of docosatrienoic acid (20:3n-3) and docosapentaenoic acid (20:5n-3) were significantly higher in schizophrenia patients than in controls. We found no difference in the trans fatty acid status between patients and controls. In smoking schizophrenia patients significant negative correlations were detected between Wechsler adult full-scale intelligence quotients and values of total trans fatty acids in PL lipids, whereas no such correlation was seen either in non-smoking schizophrenia patients, or in healthy controls. While data obtained in the present study fail to furnish evidence for n-3 PUFA supplementation to the diet of patients with schizophrenia, they indicate that in smoking schizophrenia patients high dietary exposure to trans fatty acids is associated with lower intelligence quotients.

Can we define an infant's need from the composition of human milk?

Human milk is recommended as the optimal nutrient source for infants and is associated with several short- and long-term benefits for child health. When accepting that human milk is the optimal nutrition for healthy term infants, it should be possible to calculate the nutritional needs of these infants from the intake of human milk. These data can then be used to design the optimal composition of infant formulas. In this review we show that the composition of human milk is rather variable and is dependent on factors such as beginning or end of feeding, duration of lactation, diet and body composition of the mother, maternal genes, and possibly infant factors such as sex. In particular, the composition of fatty acids in human milk is quite variable. It therefore seems questionable to estimate the nutritional needs of an infant exclusively from the intake of human milk. The optimal intake for infants must be based, at least in part, on other information-eg, balance or stable-isotope studies. The present recommendation that the composition of infant formulas should be based on the composition of human milk needs revision.

trans Isomeric fatty acids are inversely related to the availability of long-chain PUFAs in the perinatal period

We summarize data on the potential interaction of trans isomeric fatty acids [trans fatty acids (TFAs)] with the availability of long-chain polyunsaturated fatty acids (LC-PUFAs) in the perinatal period. Today, TFA intakes in pregnant and lactating women can be estimated to be ∼1% of energy in the majority of the population. The significant inverse associations seen between TFAs and LC-PUFAs in pregnant women in 3 different European populations investigated in a recent study raise doubts about the nutritional adequacy of high TFA intakes during pregnancy. In a recent study on the TFA content of human milk in a sizable group of mothers at the sixth week of lactation, both arachidonic and docosahexaenoic acids correlated significantly inversely to 18-carbon TFAs but not to 16-carbon TFAs, and at the sixth month of lactation arachidonic acid correlated significantly inversely to 18-carbon TFAs but not to 16-carbon TFAs. Similarly, significant inverse correlations were seen between 18-carbon TFAs and arachidonic and docosahexaenoic acids in both artery and vein wall lipids in a sizable group of healthy term infants. The TFA data obtained in umbilical blood vessel wall lipids were related to the neurologic condition of healthy children at 18 mo of age: children with minimal neurologic dysfunction at age 18 mo had significantly higher cord blood vein wall trans octadecadienoic acid values than did neurologically normal children. Total TFA values as well as total 18-carbon TFA values in umbilical vein wall lipids were significantly inversely associated with neurologic optimality score. Contradictory data renders it impossible to draw firm conclusions on the role of TFAs in modifying fetal growth; however, TFA exposure may be a confounding parameter in studies that investigate the relation between fetal fatty acid supply and intrauterine growth.

Fatty acid composition in the mature milk of Bolivian forager-horticulturalists: controlled comparisons with a US sample

Breast milk fatty acid (FA) composition varies greatly among individual women, including in percentages of the long-chain polyunsaturated FAs (LCPUFA) 20:4n-6 (arachidonic acid, AA) and 22:6n-3 (docosahexaenoic acid, DHA), which are important for infant neurological development. It has been suggested that owing to wide variation in milk LCPUFA and low DHA in Western diets, standards of milk FA composition should be derived from populations consuming traditional diets. We collected breast milk samples from Tsimane women at varying lactational stages (6-82 weeks). The Tsimane are an indigenous, natural fertility, subsistence-level population living in Amazonia Bolivia. Tsimane samples were matched by lactational stage to samples from a US milk bank, and analysed concurrently for FA composition by gas-liquid chromatography. We compared milk FA composition between Tsimane (n = 35) and US (n = 35) mothers, focusing on differences in LCPUFA percentages that may be due to population-typical dietary patterns. Per total FAs, the percentages of AA, DHA, total n-3 and total n-6 LCPUFA were significantly higher among Tsimane mothers. Mean percentages of 18:2n-6 (linoleic acid) and trans FAs were significantly higher among US mothers. Tsimane mothers' higher milk n-3 and n-6 LCPUFA percentages may be due to their regular consumption of wild game and freshwater fish, as well as comparatively lower intakes of processed foods and oils that may interfere with LCPUFA synthesis.

Inverse association between trans isomeric and long-chain polyunsaturated fatty acids in pregnant women and their newborns: data from three European countries

BACKGROUND

trans unsaturated fatty acids are thought to interfere with essential fatty acid metabolism. To extend our knowledge of this phenomenon, we investigated the relationship between trans isomeric and long-chain polyunsaturated fatty acids (LCPUFA) in mothers during pregnancy and in their infants at birth.

METHODS

Fatty acid composition of erythrocyte phosphatidylcholine (PC) and phosphatidylethanolamine (PE) was determined in Spanish (n = 120), German (n = 78) and Hungarian (n = 43) women at the 20th and 30th week of gestation, at delivery and in their newborns.

RESULTS

At the 20th week of gestation, the sum of trans fatty acids in PE was significantly (p < 0.01) lower in Hungarian [0.73 (0.51), % wt/wt, median (IQR)] than in Spanish [1.42 (1.36)] and German [1.30 (1.21)] women. Docosahexaenoic acid (DHA) values in PE were significantly (p < 0.01) higher in Hungarian [5.65 (2.09)] than in Spanish [4.37 (2.60)] or German [4.39 (3.3.2)] women. The sum of trans fatty acids significantly inversely correlated to DHA in PCs in Spanish (r = -0.37, p < 0.001), German (n = -0.77, p < 0.001) and Hungarian (r = -0.35, p < 0.05) women, and in PEs in Spanish (r = -0.67, p < 0.001) and German (r = -0.71, p < 0.001), but not in Hungarian (r = -0.02) women. Significant inverse correlations were seen between trans fatty acids and DHA in PEs at the 30th week of gestation (n = 241, r = -0.52, p < 0.001), at delivery (n = 241, r = -0.40, p < 0.001) and in cord lipids (n = 218, r = -0.28, p < 0.001).

CONCLUSION

Because humans cannot synthesize trans isomeric fatty acids, the data obtained in the present study support the concept that high maternal trans isomeric fatty acid intake may interfere with the availability of LCPUFA both for the mother and the fetus.

Genetic variants in the FADS gene cluster are associated with arachidonic acid concentrations of human breast milk at 1.5 and 6 mo postpartum and influence the course of milk dodecanoic, tetracosenoic, and trans-9-octadecenoic acid concentrations over the duration of lactation

BACKGROUND

Breastfeeding is considered an optimal nutritional source of n-6 (omega-6) and n-3 (omega-3) fatty acids (FAs) for the proper visual and cognitive development of newborn children. In addition to maternal nutrition as an important regulator of FA concentrations, first results exist on an association of breast-milk FAs with single nucleotide polymorphisms (SNPs) in the FADS gene cluster, which encodes the rate-limiting enzymes in the elongation-desaturation pathway of long-chain polyunsaturated fatty acids (LC-PUFAs).

OBJECTIVE

We analyzed the influence of FADS SNPs on breast-milk FA concentrations and their time course during lactation in the Ulm Birth Cohort study, which comprised 772 nursing mothers at 1.5 mo after giving birth, and in a subset of 463 mothers who were still breastfeeding at 6 mo postpartum.

DESIGN

We conducted linear regression analysis of 8 FADS SNPs with FA concentrations at both time points separately and assessed the genotype effect over time in a longitudinal analysis by using a generalized estimating equation regression model.

RESULTS

We observed significant associations of FADS genotypes with arachidonic acid (AA) concentrations and the 20:4n-6/20:3n-6 ratio at both time points but no association of FADS SNPs with the time course of AA concentrations. A longitudinal analysis of FAs other than LC-PUFAs by genotype over time showed associations for dodecanoic acid, cis-15-tetracosenoic acid, and trans-9-octadecenoic acid.

CONCLUSIONS

Maternal FADS genotypes are associated with breast-milk AA concentrations and might therefore influence the supply of this FA for children. Furthermore, our data indicate an interrelation between the LC-PUFA pathway and saturated and monounsaturated FAs.

Neonatal and fetal exposure to trans-fatty acids retards early growth and adiposity while adversely affecting glucose in mice

Industrially produced trans-fatty acids (TFAs) consumed in Western diets are incorporated into maternal and fetal tissues and are passed linearly to offspring via breast milk. We hypothesized that TFA exposure in utero and during lactation in infants would promote obesity and poor glycemic control as compared with unmodified fatty acids. We further hypothesized that in utero exposure alone may program for these outcomes in adulthood. To test this hypothesis, we fed female C57/BL6 mice identical Western diets that differed only in cis- or trans-isomers of C18:1 and then aimed to determine whether maternal transfer of TFAs through pregnancy and lactation alters growth, body composition, and glucose metabolism. Mice were unexposed, exposed during pregnancy, during lactation, or throughout pregnancy and lactation to TFA. Body weight and composition (by computed tomography) and glucose metabolism were assessed at weaning and adulthood. Trans-fatty acid exposure through breast milk caused significant early growth retardation (P < .001) and higher fasting glucose (P = .01), but insulin sensitivity was not different. Elevated plasma insulin-like growth factor-1 in mice consuming TFA-enriched milk (P = .02) may contribute to later catch-up growth and leanness and preserved peripheral insulin sensitivity observed in these mice. Mice exposed to TFA in utero underwent rapid early neonatal growth with TFA-free breast milk and had significantly impaired insulin sensitivity (P < .05) and greater abdominal fat (P = .01). We conclude that very early catch-up growth resulted in impaired peripheral insulin sensitivity in this model of diet-related fetal and neonatal programming. Trans-fatty acid surprisingly retarded growth and adiposity while still adversely affecting glucose metabolism.

Fatty acid profile comparisons in human milk sampled from the same mothers at the sixth week and the sixth month of lactation

OBJECTIVES

To compare fatty acid composition of human milk at 2 different stages of lactation and investigate the relation between trans isomeric and long-chain polyunsaturated fatty acids (LCPUFAs) in human milk at the sixth month of lactation.

SUBJECTS AND METHODS

We investigated human milk samples obtained at the sixth week and sixth month of lactation from 462 mothers who participated in a large birth cohort study. Fatty acid composition of human milk lipids was determined by high-resolution capillary gas-liquid chromatography.

RESULTS

Fat contents of human milk increased significantly between the sixth week and sixth month of lactation (1.63 [2.06] and 3.19 [3.14], g/100 mL; median [interquartile range], P < 0.001). Percentage contributions to human milk fatty acid composition of nearly all polyunsaturated fatty acids also increased significantly (linoleic acid: 10.09 [4.41] and 11.01 [4.53], arachidonic acid: 0.46 [0.32] and 0.48 [0.23], alpha-linolenic acid: 0.69 [0.42] and 0.75 [0.41], and docosahexaenoic acid: 0.17 [0.23] and 0.23 [0.15], % wt/wt, P < 0.001). Values of the 18-carbon trans octadecenoic acid (C18:1n-7/9t) significantly inversely correlated to linoleic acid (r = -0.24, P < 0.001), alpha-linolenic acid (r = -0.19, P < 0.001), and arachidonic acid (r = -0.43, P < 0.001). In contrast, we found no correlation between the 16-carbon trans hexadecenoic acid (C16:1n-7t) and the same LCPUFAs.

CONCLUSIONS

Data obtained in the present study indicate increasing fat contents with stable or increasing percentage contribution of LCPUFAs in human milk samples between the sixth week and at the sixth month of lactation, and the availability of 18-carbon trans isomeric fatty acids is inversely associated to the availability of several LCPUFAs in human milk at the sixth month of lactation.

Trans isomeric and LCPUFA are inversely correlated in erythrocyte membrane lipids at mid-gestation

Fatty acid composition of erythrocyte phosphatidylcholines was determined by high-resolution capillary gas chromatography in Spanish (n = 120), German (n = 78) and Hungarian (n = 43) expectant women at the 20th week of gestation. The sum of trans isomeric fatty acids was significantly (p < 0.05) lower in Hungarian (0.68 [0.43]% wt/wt, median [IQR]) than in Spanish (0.82 [0.53]) expectant women. There were no significant correlations between the sum of trans isomers and linoleic acid or alpha-linolenic acid in either of the three groups. In contrast, there were significant inverse correlations between the sum of trans fatty acids and arachidonic acid and docosahexaenoic acid in all the three groups. These data raise the possibility that maternal trans isomeric fatty acid status may be inversely associated to the essential fatty acid status of the foetus.

Trans fatty acids and fatty acid composition of mature breast milk in turkish women and their association with maternal diet's

The aim of this study was to determine the fatty acid composition and trans fatty acid and fatty acid contents of breast milk in Turkish women and to find the effect of breastfeeding mothers' diet on trans fatty acid and fatty acid composition. Mature milk samples obtained from 50 Turkish nursing women were analyzed. Total milk lipids extracts were transmethylated and analyzed by using gas liquid chromatography to determine fatty acids contents. A questionnaire was applied to observe eating habits and 3 days dietary records from mothers were obtained. Daily dietary intake of total energy and nutrients were estimated by using nutrient database. The mean total trans fatty acids contents was 2.13 +/- 1.03%. The major sources of trans fatty acids in mothers' diets were margarines-butter (37.0%), bakery products and confectionery (29.6%). Mothers who had high level of trans isomers in their milk consumed significantly higher amounts of these products. Saturated fatty acids, polyunsaturated fatty acids and monounsaturated fatty acids of human milk constituted 40.7 +/- 4.7%, 26.9 +/- 4.2% and 30.8 +/- 0.6% of the total fatty acids, respectively. The levels of fatty acids in human milk may reflect the current diet of the mother as well as the diet consumed early in pregnancy. Margarines, bakery products and confectionery are a major source of trans fatty acids in maternal diet in Turkey.

Fatty acid composition of adipose tissue and blood in humans and its use as a biomarker of dietary intake

Accurate assessment of fat intake is essential to examine the relationships between diet and disease risk but the process of estimating individual intakes of fat quality by dietary assessment is difficult. Tissue and blood fatty acids, because they are mainly derived from the diet, have been used as biomarkers of dietary intake for a number of years. We review evidence from a wide variety of cross-sectional and intervention studies and summarise typical values for fatty acid composition in adipose tissue and blood lipids and changes that can be expected in response to varying dietary intake. Studies in which dietary intake was strictly controlled confirm that fatty acid biomarkers can complement dietary assessment methodologies and have the potential to be used more quantitatively. Factors affecting adipose tissue and blood lipid composition are discussed, such as the physical properties of triacylglycerol, total dietary fat intake and endogenous fatty acid synthesis. The relationship between plasma lipoprotein concentrations and total plasma fatty acid composition, and the use of fatty acid ratios as indices of enzyme activity are also addressed.