Trans fatty acid isomers in Canadian human milk

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.

Facile and Green Production of Human Milk Fat Substitute through Rhodococcus opacus Fermentation

Human milk fat substitute (HMFS) is a class of structured lipids widely used in infant formulas. Herein, HMFS was prepared by Rhodococcus opacus fermentation. The substrate oils suitable for HMFS production were coconut oil (66.1-57.5%), soybean oil (17.5-26.5%), high oleic acid sunflower oil (5.4-4.5%), Antarctic krill oil (9-9.5%), and fungal oil (2%). Six HMFSs were prepared, among which HMFS V and VI were similar to human milk fat from Chinese in terms of fatty acid composition and triacylglycerol species. The sn-2 position of HMFS was occupied by palmitic acid (49.31 and 43.48% in HMFS V and VI, respectively). The major triacylglycerols were OPL, OPO, and LPL, accounting for 15.90, 9.49, and 6.84 and 17.52, 8.44, and 8.55% in HMFS V and VI, respectively. This study is the first to prepare structured lipids intended for infant formula through fermentation, providing a novel strategy for the edible oil industry.

Dietary habits of Slovenian inland and coastal primiparous women and fatty acid composition of their human milk samples

The quantity and composition of fatty acids (FAs) in milk can influence an infant's growth and development through maternal diet. Therefore, associations between maternal diet and FA composition in 74 mature human milk samples were investigated. This study aimed to obtain FA patterns in mature milk arising from different dietary habits in two geographically different areas in Slovenia: Koper (KP), a coastal area, and Pomurje (MS), an inland area. The results revealed statistically significant differences in the dietary intake of game, freshwater fish, and fresh and frozen seafood between the study areas. Among the mean percentages of 35 individual FAs in milk, 19 were higher in KP and 16 were higher in MS. In KP, despite the higher intake of fresh seafood, the levels of saturated and monounsaturated FAs were higher and the levels of PUFAs, ω-3, and ω-6 were lower compared to those in MS. The ω-6:ω-3 ratio did not differ significantly between the study areas. This finding was not expected and indicates a discrepancy between the measured and self-reported data - the latter lack reliable data on dietary supplements. Therefore, determination of FA profile is important as a promising biomarker of dietary intake in environmental health studies.

Is fatty acid composition of breast milk different in various populations? A systematic review and meta-analysis

This systematic review and meta-analysis aims to systematically review the fatty acid (FA) composition of breast milk in different populations. We systematically searched the Medline via PubMed, Scopus and Clarivate till July 2019. We initially retrieved 433 articles. Having removed duplicates, with initial searching of title and abstracts, 317 papers were excluded and 80 remained. A meta-analysis of 80 cross-sectional, cohort studies, including 8793 subjects, was conducted. Meta-regression analysis indicated that factors including maternal age (p-values of SFA: 0.03, omega-3: 0.01, trans fats:<0.001, total fatty acids: 0.02), year of conducting study (p-values of SFA: <0.001, MUFA: 0.02, omega-6: 0.04,trans fats: 0.04) and sample size (p-values of SFA: 0.03, PUFA: 0.01, omega-6: 0.01, omega-3:<0.001) contributed to the heterogeneity of meta-analysis. This study indicates the large variation of FA content in maternal milk across different populations. Special concern is necessary for both the quality and total amount of fat intake of pregnant and lactating mothers.

Trans-10, cis-12 conjugated linoleic acid reduces milk fat content and lipogenic gene expression in the mammary gland of sows without altering litter performance

Trans-10, cis-12 conjugated linoleic acid (CLA) decreases milk fat synthesis in lactating sows and involves, at least in part, the down-regulation of lipogenic genes. The objective was to evaluate the effect of CLA on milk composition and lipogenic gene expression. Twenty multiparous sows were randomly assigned to one of the two treatments for 18 d (from day 7 to day 25 of lactation): (1) control (no CLA added) and (2) 1 % of CLA mixed into the ration. CLA treatment decreased milk fat and protein content by 20 % (P = 0·004) and 11 % (P = 0·0001), respectively. However, piglet weight did not differ between treatments (P = 0·60). Dietary CLA increased the concentration of SFA in milk fat by 16 % (P < 0·0001) and decreased MUFA by 17·6 % (P < 0·0001). In the mammary gland, CLA reduced gene expression of acetyl-CoA carboxylase-α by 37 % (P = 0·003), fatty acid synthase by 64 % (P = 0·002), stearoyl-CoA desaturase 1 by 52 % (P = 0·003), lipoprotein lipase by 26 % (P = 0·03), acyl glycerol phosphate acyltransferase 6 by 15 % (P = 0·02) and diacylglycerol acyltransferase 1 by 27 % (P = 0·02), whereas the expression of fatty acid binding protein 3 was not altered by CLA treatment (P = 0·09). Mammary expression of casein-β and α-lactalbumin was reduced by CLA by 68 % (P = 0·0004) and 62 % (P = 0·005), respectively. Additionally, CLA had no effect on the expression of lipogenic genes evaluated in adipose tissue. In summary, CLA reduced milk fat content without negatively affecting litter performance and it affected mammary expression of genes involved in all lipogenic pathways studied.

Quantification of breast milk trans fatty acids and trans fat intake by Hong Kong lactating women

BACKGROUND/OBJECTIVES

Diet westernization in Hong Kong may increase trans fat intake, whereas it may decrease intake of polyunsaturated fatty acids. The present study was to determine the current breast milk fatty acid composition and trans fat intake by Hong Kong lactating mothers.

METHODS

Sixty lactating women were recruited for the study. Each participant donated 15 ml of milk at week 4 and 6 after delivery. Dietary data were collected using a 3-day food record method, covering 2 weekdays and 1 weekend day. Milk fatty acids were analyzed using a gas chromatography method. Trans fat consumption was assessed using the Nutrition Data System for Research or calculating the intake based on percentage of trans fatty acids in the breast milk.

RESULTS

Linoleic acid, α-linolenic acid, arachidonic acid, and docosahexaenoic acid in breast milk were 16.23%, 1.52%, 0.59%, and 0.66% total milk lipids, respectively. Mean daily intakes of total fat, saturated fatty acids, monounsaturated fatty acids, were 79, 24, 29, and 18 g, respectively. Total trans fat intake was estimated to be 1.15-1.20 g daily and accounted for 0.50-0.52% total energy.

CONCLUSIONS

Breast milk of Hong Kong Chinese lactating women contained relatively higher contents of arachidonic and docosahexaenoic acids compared with those of Western countries. Compared with the previous study conducted in 1995, breast milk total trans fatty acids in 2018 still remained low. Total trans fat intake by Hong Kong lactating women in 2018 was a half of WHO's recommendation that total trans fat intake should be <1% total energy.

Human Milk Lipidomics: Current Techniques and Methodologies

Human milk contains a complex combination of lipids, proteins, carbohydrates, and minerals, which are essential for infant growth and development. While the lipid portion constitutes only 5% of the total human milk composition, it accounts for over 50% of the infant’s daily energy intake. Human milk lipids vary throughout a feed, day, and through different stages of lactation, resulting in difficulties in sampling standardization and, like blood, human milk is bioactive containing endogenous lipases, therefore appropriate storage is critical in order to prevent lipolysis. Suitable sample preparation, often not described in studies, must also be chosen to achieve the aims of the study. Gas chromatography methods have classically been carried out to investigate the fatty acid composition of human milk lipids, but with the advancement of other chromatographic techniques, such as liquid and supercritical fluid chromatography, as well as mass spectrometry, intact lipids can also be characterized. Despite the known importance, concise and comprehensive analysis of the human milk lipidome is limited, with gaps existing in all areas of human milk lipidomics, discussed in this review. With appropriate methodology and instrumentation, further understanding of the human milk lipidome and the influence it has on infant outcomes can be achieved.

The impact of lactation and gestational age on the composition of branched-chain fatty acids in human breast milk

Breast milk consumption reduces the incidence of necrotizing enterocolitis (NEC) in preterm infants compared to formula. Branched-chain fatty acids (BCFAs) are present in breast milk but not in most formulas intended for preterm infants. We aimed to determine the composition of BCFAs in the breast milk of mothers with preterm infants, and to understand the impact of gestational age at birth and stage of lactation on BCFA content. The main BCFAs in preterm breast milk were iso-14:0, iso-15:0, anteiso-15:0, iso-16:0, iso-17:0, and anteiso-17:0. Breast milk BCFAs as a percent of total fatty acids (g per 100 g, %) were significantly different across lactation stages, with the highest concentration in colostrum, followed by transitional and mature breast milk (median: 0.41, 0.31, and 0.28%, respectively, p < 0.05). Lower BCFAs in preterm breast milk compared to term breast milk may have been related to maternal intake, or the ability of the mammary gland to extract BCFA from plasma, or differences in mammary gland BCFA synthesis. BCFAs were mainly in the sn-2 position (52-65%), similar to palmitic acid. Overall, preterm and term breast milk BCFAs were similar and showed specific concentration patterns, resembling 16:0 with respect to sn-2 positional distribution. BCFAs were reduced with lactation stage, similar to highly unsaturated fatty acids.

A 24-year prospective study of dietary α-linolenic acid and lethal prostate cancer

Several meta-analyses have attempted to determine the relationships between intake of α-linolenic acid (ALA) and prostate cancer, but results were inconclusive. 47,885 men aged 40-75 years without prior cancer in the Health Professionals Follow-Up Study were prospectively followed from 1986 to 2010. Intake of ALA was determined from validated food frequency questionnaires every 4 years. We used multivariate Cox proportional hazards models to estimate hazard ratios (HR) with 95% confidence intervals (CIs) for lethal prostate cancer (distant metastasis or prostate cancer death). 386 lethal prostate cancers were diagnosed in the pre-PSA era (before February, 1994) and 403 cancers in the PSA era. Intake of ALA was associated with increased risk of lethal prostate cancer in the pre-PSA era (comparing top to bottom quintile of intake, multivariate-adjusted HR = 1.78; 95% CI = 1.22-2.06; p_trend  = 0.003), but not in the PSA era (HR = 0.81; 95% CI = 0.56-1.17; p_trend  = 0.53), and the difference in associations was statistically significant (p for interaction = 0.02). Mayonnaise, a primary food source of ALA intake in our cohort, was likewise only significantly associated with lethal prostate cancer in the pre-PSA era. Among many other fatty acids that are correlated with ALA due to shared food sources, none was associated with lethal prostate cancer in the pre-PSA era. In conclusion, higher intake of ALA was associated with an increased risk of lethal prostate cancer in the pre-PSA era, but not in the PSA era. Potential reasons for the differential associations warrant further investigation.

Dietary intake of α-linolenic acid and risk of age-related macular degeneration

Background: The relation between α-linolenic acid (ALA), a plant-derived omega-3 (n-3) fatty acid, and age-related macular degeneration (AMD) is unclear. European researchers reported that ≤40% of ALA can be present as trans forms.Objective: We aimed to evaluate the associations between intake of ALA and intermediate and advanced AMD.Design: Seventy-five thousand eight hundred eighty-nine women from the Nurses' Health Study and 38,961 men from Health Professionals Follow-Up Study were followed up from 1984 to 2012 and from 1986 to 2010, respectively. We assessed dietary intake by a validated food-frequency questionnaire at baseline and every 4 y thereafter. One thousand five hundred eighty-nine incident intermediate and 1356 advanced AMD cases (primarily neovascular AMD) were confirmed by medical record review.Results: The multivariable-adjusted HR for intermediate AMD comparing ALA intake at the top quintile to the bottom quintile was 1.28 (95% CI: 1.05, 1.56; P-trend = 0.01) in the analyses combining 2 cohorts. The HR in each cohort was in the positive direction but reached statistical significance only in the women. However, the positive association was apparent only in the pre-2002 era in each cohort and not afterward (P-time interaction = 0.003). ALA intake was not associated with advanced AMD in either time period. Using gas-liquid chromatography, we identified both cis ALA (mean ± SD: 0.13% ± 0.04%) and trans ALA isomers (0.05% ± 0.01%) in 395 erythrocyte samples collected in 1989-1990. In stepwise regression models, mayonnaise was the leading predictor of erythrocyte concentrations of cis ALA and one isomer of trans ALA. We also found trans ALA in mayonnaise samples.Conclusions: A high intake of ALA was associated with an increased risk of intermediate AMD before 2002 but not afterward. The period before 2002 coincides with the same time period when trans ALA was found in food and participants' blood; this finding deserves further study.

Essential fatty acids as functional components of foods- a review

During the recent decades, awareness towards the role of essential fatty acids in human health and disease prevention has been unremittingly increasing among people. Fish, fish oils and some vegetable oils are rich sources of essential fatty acids. Many studies have positively correlated essential fatty acids with reduction of cardiovascular morbidity and mortality, infant development, cancer prevention, optimal brain and vision functioning, arthritis, hypertension, diabetes mellitus and neurological/neuropsychiatric disorders. Beneficial effects may be mediated through several different mechanisms, including alteration in cell membrane composition, gene expression or eicosanoid production. However, the mechanisms whereby essential fatty acids affect gene expression are complex and involve multiple processes. Further understanding of the molecular aspects of essential fatty acids will be the key to devising novel approaches to the treatment and prevention of many diseases.

Mandatory trans fat labeling regulations and nationwide product reformulations to reduce trans fatty acid content in foods contributed to lowered concentrations of trans fat in Canadian women's breast milk samples collected in 2009-2011

BACKGROUND

Recent efforts in Canada to reduce industrial trans fatty acids (TFAs) in foods include mandated inclusion of TFA content on food labels and recommendations by Health Canada that encourage the food industry to voluntarily limit TFA content in all vegetable oils and soft margarines and in all other prepackaged foods to <2% and <5% of total fat, respectively.

OBJECTIVE

To assess the impact of these efforts, we measured the concentration of TFAs in human breast milk samples.

DESIGN

The TFA content in 639 breast milk samples collected in 2009, 2010, and 2011 from breastfeeding mothers in 10 major cities across Canada was analyzed by gas chromatography.

RESULTS

The mean (±SD) TFA contents were 2.7 ± 0.9% (n = 153, range: 1.4-7.2%), 2.2 ± 0.7% (n = 309, range: 1.0-6.8%), and 1.9 ± 0.5% (n = 177, range: 0.9-3.4%) of total milk fat for samples collected in 2009, 2010, and 2011, respectively. These values are considerably lower than the value of 7.2 ± 3.0% (range: 0.1-17.2%) found previously for Canadian human milk in 1992. On the basis of a linear correlation between the percentage of TFAs in the diet and human milk fat established by Craig-Schmidt et al, and assuming that 30% of energy of a lactating mother's diet is derived from fat, we estimated from the TFA human milk fat data that TFA intake of Canadian breastfeeding mothers was 0.9%, 0.5%, and 0.3% of total energy in 2009, 2010, and 2011, respectively. These estimated values are lower than the WHO's maximum recommended intake of 1% of total energy for a healthy diet.

CONCLUSIONS

The results suggest that the trans fat labeling regulations introduced in 2003 and recommendations by Health Canada in 2007 instructing the food manufacturers and restaurants to limit TFAs in foods have resulted in significant reductions in TFAs in the diets of Canadian breastfeeding mothers and their breast milk.

Early docosahexaenoic acid supplementation of mothers during lactation leads to high plasma concentrations in very preterm infants

Very preterm infants are vulnerable to deficiency in DHA. In a longitudinal study, 10 mothers who delivered ≤29 wk gestation and planned to breast-feed received DHA (1200 mg/d) until 36 wk after conception. The plasma DHA status was assessed in their 12 infants (including 2 pairs of twins) from birth to d 49. Fatty acid profiles were measured weekly in breast milk, and in plasma of mothers and infants at baseline and at d15 and 49. Plasma and breast milk fatty acid concentrations in the DHA-supplemented group at d 49 were compared with a reference group of very preterm infants (n = 24, including triplets) whose mothers (n = 22) did not receive DHA during lactation. The infants' plasma DHA concentration tended to be greater in the DHA group than in the reference group (P = 0.10) and was greater when expressed as a percentage of total fatty acids (P = 0.009). At d 49, maternal milk DHA in the DHA group (1.92 ± 1.10 mmol/L) was ~12 times higher than in the reference group (0.15 ± 0.27 mmol/L) (P < 0.001). The amount of DHA provided to the infants increased from wk 1 through wk 7 in the DHA group (P < 0.001). Although enteral intake at wk 7 did not differ between the DHA group [119 ± 51 mL/(kg·d)] and the reference group [113 ± 66 mL/(kg·d)], DHA group infants received 55 ± 38 mg/(kg·d) of DHA, and the reference group infants received 7 ± 11 mg/(kg·d) (P < 0.001). Early supplementation with DHA to lactating mothers with low dietary DHA intake successfully increased the plasma DHA status in very preterm infants.

Establishment of an evaluation model for human milk fat substitutes

Fatty acid composition and distribution of human milk fat (HMF), from mothers over different lactating periods in Guangzhou, China, were analyzed. The universal characteristics were consistent with previously reported results although the fatty acid content was within a different range and dependent on the local population (low saturated fatty acid and high oleic acid for Guangdong mothers' milk fat). Based on the composition of the total and sn-2 fatty acids of mature milk fat, an efficient evaluation model was innovatively established by adopting the "deducting score" principle. The model showed good agreement between the scores and the degree of similarity by assessing 15 samples from different sources including four samples of HMF, eight samples of human milk fat substitutes (HMFSs) and infant formulas, and three samples of fats and oils. This study would allow for the devolvement of individual human milk fat substitutes with different and specific fatty acid compositions for local infants.

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.

Branched chain fatty acids are constituents of the normal healthy newborn gastrointestinal tract

Vernix suspended in amniotic fluid is normally swallowed by the late term fetus. We hypothesized that branched chain fatty acids (BCFA), long known to be major vernix components, would be found in meconium and that the profiles would differ systematically. Vernix and meconium were collected from term newborns and analyzed. BCFA-containing lipids constituted about 12% of vernix dry weight, and were predominantly saturated, and had 11-26 carbons per BCFA. In contrast, meconium BCFA had 16-26 carbons, and were about 1% of dry weight. Meconium BCFA were mostly in the iso-configuration, whereas vernix BCFA contained dimethyl and middle chain branching, and five anteiso-BCFA. The mass of BCFA entering the fetal gut as swallowed vernix particles is estimated to be 180 mg in the last month of gestation whereas the total mass of BCFA found in meconium is estimated to be 16 mg, thus most BCFA disappear from the fetal gut. The BCFA profiles of vernix and meconium show that BCFA are major components of normal healthy term newborn gastrointestinal tract. BCFA are candidates for agents that play a role in gut colonization and should be considered a nutritional component for the fetus/newborn.

Trans fatty acids from milk of Brazilian mothers of premature infants

AIM

The presence of trans fatty acids (TFA) in human milk may be a concern because of their possible adverse nutritional effects on the infant development. TFA may interfere with the metabolism of long-chain polyunsaturated fatty acids (LC-PUFA). Marked variation in TFA of milk appears in different populations. No data have yet been reported in Brazil, particularly as regards the milk of mothers of premature infants. Because of the importance of LC-PUFA in infant growth and development, we investigated the fatty acids composition of the milk of Brazilian mothers of premature infants.

METHODS

We analysed, through gas-liquid chromatography, the content of fatty acids of 37 milk samples obtained from mothers delivering prematurely. Samples were collected from colostrum and mature milk of exclusive breastfeeding.

RESULTS

All samples contained trans isomers of C18:1 acid with trans isomers of PUFA in lower proportion. The percentage of TFA (mean +/- SD) in the colostrum was 2.34 +/- 0.75, and 2.19 +/- 0.47 in the mature milk. For the LC-PUFA these values were 0.97 +/- 0.34 in the colostrum and 0.66 +/- 0.25 in the mature milk. The contents of total essential fatty acids and PUFA n-6 were inversely correlated with TFA in colostrum and mature milk. We found a positive correlation between levels of arachidonic acid in mature milk and change in the children's height.

CONCLUSIONS

The study showed that the intake of TFA occupies an intermediate position between the values of North America and European countries, reflecting the ongoing transition to industrialised foods in Brazil.

Preferential incorporation oftrans,trans-conjugated linoleic acid isomers into the liver of suckling rats

The present study was designed to compare the conjugated linoleic acid (CLA) isomeric distribution pattern in the liver of suckling rats in relation to those in the milk and maternal diet. Silver-ion HPLC was used to separate individual CLA isomers. It was found that the isomeric distribution pattern in the milk was very similar to that in the maternal dietary fat. However, the CLA isomeric distribution patterns in the liver phospholipids (PL) and triacylglycerols were different from those in the diet and milk. In the liver PL, totalcis/transisomers accounted for 63·6–63·9 % of total CLA, which was in contrast to the values of 88·1–89·1 % in the milk and diet. In the liver PL, totaltrans/transisomers were 20·6–20·8 % of the total CLA isomers whereas they were only 2·6–3·7 % in the milk and diet. It is concluded thattrans/trans-CLA were preferentially incorporated into the liver whereas for the incorporation ofcis/trans-CLA there was partial discrimination.

Importância dos ácidos graxos essenciais e os efeitos dos ácidos graxos trans do leite materno para o desenvolvimento fetal e neonatal

A prática da amamentação tem grande impacto do ponto de vista da saúde pública, pois o leite materno é o melhor alimento a ser oferecido até o sexto mês de vida da criança. A fração lipídica do leite representa a maior fonte de energia para crianças e fornece nutrientes essenciais, tais como vitaminas lipossolúveis e ácidos graxos poliinsaturados (AGPI). Os ácidos graxos essenciais (AGE) linoléico (LA, 18:2n-6) e alfa-linolênico (ALA, 18:3n-3) são precursores dos ácidos graxos poliinsaturados de cadeia longa (AGPI-CL), incluindo os ácidos docosahexaenóico (DHA) e araquidônico (ARA). A qualidade dos lipídios no leite secretado está diretamente relacionada com a ingestão materna. Os AGPI-CL são importantes na proteção contra alergia e infecções, no processo visual e no desenvolvimento cognitivo na infância. O processamento industrial de alimentos introduziu os ácidos graxos trans (AGT) entre os nutrientes disponíveis à população. Os AGT podem interferir no metabolismo dos AGE, diminuindo a síntese de DHA e ARA. Portanto, nos parece relevante esclarecer a população sobre a importância de um aporte adequado de AGPI e reduzido de AGT durante o período de desenvolvimento pré e pós-natal.

Dietary supplementation with 11trans- and 12trans-18:1 and oxidative stress in humans

BACKGROUND

High consumption of trans fat has been associated with high oxidative stress in humans, which could increase the risk of the development or acceleration of several diseases, such as atherosclerosis, cancer, and type 2 diabetes.

OBJECTIVE

Several urinary and blood biomarkers of oxidative stress [8-iso-prostaglandin-F(2alpha) (PGF(2alpha)), 15-keto-dihydro-PGF(2alpha), and 7,8-dihydro-8-oxo-2'-deoxy-guanosine in urine and alpha-,beta-,gamma-,delta-tocopherol, and retinol in plasma] were monitored to evaluate the oxidative stress induced by dietary supplementation of 11trans- and 12trans-18:1 isomers in humans during a 6-wk intervention.

DESIGN

After a 14-d adaptation period free of trans fatty acid supplementation (baseline), the test group (n = 12) received 3.0 g 11trans-18:1/d and 3.0 g 12trans-18:1/d (Sigma 6.0 g/d), and the control group (n = 12) consumed a control oil free of trans fatty acids and conjugated linoleic acids for 6 wk.

RESULTS

The postintervention concentration of urinary 8-iso-PGF(2alpha) (free radical-induced lipid peroxidation) in the test group was significantly higher than baseline and significantly higher than that observed in the control group. The concentrations of 15-keto-dihydro-PGF(2alpha) (cyclooxygenase-mediated inflammatory response indicator) and 7,8-dihydro-8-oxo-2'-deoxy-guanosine (oxidative DNA damage) were not affected by the 11trans- and 12trans-18:1 supplementation.

CONCLUSIONS

Although an increase in urinary 8-iso-PGF(2alpha) was observed and the effects of prolonged high (ie, >5.0 g/d) consumption of trans fat could be relevant to the development of disease, the mean intakes of 11trans- and 12trans-18:1 in Europeans are estimated to be significantly below the amounts administered in this study (ie, 6.0 g/d); such low intakes could minimize the possible risk of detrimental effects on human health.

Trans fatty acids in human milk in Canada declined with the introduction of trans fat food labeling

Trans fatty acids in human milk have raised concerns because of possible adverse effects on infant growth and development. Analyses of human milk in the late 1990s in Canada showed high amounts of trans fatty acids from partially hydrogenated oils. Canada introduced labeling of trans fatty acids on retail foods in 2003. We analyzed trans and cis unsaturated and saturated fatty acids in human milk collected from 87 women in 2004-2006 and compared the levels to those in milk collected from 103 women in 1998 and analyzed using similar methods. The total trans fatty acids (mean +/- SEM, g/100 g fatty acids) in human milk in Canada decreased significantly, from 7.1 +/- 0.32 in 1998 to 6.2 +/- 0.48, 5.3 +/- 0.49, and 4.6 +/- 0.32 over 3 consecutive 5-mo periods from November 2004 to January 2006. The milk total trans fatty acids were significantly and inversely related to 16:0, 18:2(n-6), 18:3(n-3), 20:4(n-6), 22:4(n-6), and 22:5(n-6) and positively related to 18:0 and conjugated linolenic acids (P < 0.05, n = 190). The estimated exposures of exclusively breast-fed infants to trans fatty acids decreased from a mean and 95th percentile intake of 2.0 and 4.4 g x infant(-1) x d(-1) in 1998 to 1.33 and 2.41 g x infant(-1) x d(-1), respectively, in late 2005. The estimated intake of the mothers was 4.0 (range 0.51-12.3) and 2.2 (0.56-7.65) g x person(-1) x d(-1) in 1998 and late 2005, respectively. Our studies show trans fatty acids have decreased in human milk in Canada, which suggests a concomitant decrease in trans fatty acid intake among lactating women and breast-fed infants.

Trans fatty intakes during pregnancy, infancy and early childhood

All of the essential n-6 and n-3 fatty acids accumulated by the fetus must be derived by transfer from the maternal circulation, and ultimately must originate from the maternal diet. After birth, the breast-fed infant receives essential fatty acids via mother's milk, or human milk substitutes and later complementary foods. Trans fatty acids (TFA) may have adverse effects on growth and development through interfering with essential fatty acid metabolism, direct effects on membrane structures or metabolism, or secondary to reducing the intakes of the cis essential fatty acids in either mother or child. TFA are transported across the placenta and secreted in human milk in amounts that depend on the maternal dietary intake. Inverse associations have been shown between TFA and the essential n-6 and n-3 fatty acids in newborn infants, human milk and preschool children. This support the need to reduce industrially produced trans fatty acids (IP-TFA) and improve dietary fat quality, particularly by increasing intake of n-3 fatty acids.

trans Fatty acids in milk produced by women in the United States

BACKGROUND

trans Fatty acids (FAs) have been identified as negatively affecting human health. The trans FA composition of human milk fat must be examined to establish its influence on the nutritional quality of milk consumed by infants.

OBJECTIVE

We sought to ascertain the individual and total trans FA isomers (sum of FAs containing at least one trans double bond) in human milk and to identify relations between individual FAs and milk fat concentration (% by wt).

DESIGN

The FA composition of milk samples (n = 81) from women living in the southwestern United States was ascertained. The individual 18:1t isomers were separated. Correlations between each FA, total trans FAs, groups of similar FAs, and milk fat concentrations were examined.

RESULTS

The mean total trans FA concentration was 7.0 +/- 2.3% (range: 2.5-13.8%). The concentration of total 18:1t was 5.1 +/- 2.0% (range: 1.5-11.6%), and Delta10t (range: Delta9-12t) was the most abundant isomer.

CONCLUSIONS

Milk fat from women living in the United States contains concentrations of trans FAs similar to those in milk from Canadian women but greater than those reported in milk from women in other countries. In decreasing order of concentration, the Delta10t, Delta11t, Delta9t, and Delta12t isomers represented 78.9% of the total 18:1t. These FAs generally originate from partially hydrogenated vegetable oils and ruminant fat in the diet. No relation was found between the concentration of total trans FAs and milk fat concentration.

Long-chain polyunsaturated fatty acids in Chinese and Swedish mothers: diet, breast milk and infant growth

Long-chain polyunsaturated fatty acids (LC-PUFAs) are essential dietary nutrients required for the optimal growth and development of infants, particularly of the brain and retina. It is important for exclusively breastfed infants to receive milk of a correct balance between omega-6 and omega-3 fatty acids. In this study, we compared the composition of LC-PUFAs in the diet and milk of mothers and their infants' growth between Chinese and Swedish. Twenty-three and 19 mother-term infant pairs from a rural area of northern Beijing, China, and Stockholm, Sweden, who were 3 mo old and exclusively breastfed, were studied. The Chinese diet was higher in carbohydrate (17% of energy) but lower in protein (4% of energy) and fat (12% of energy) than the Swedish diet. The intake of Chinese mothers contained more linoleic acid (LA, C(18 ratio 2 omega-6)) and less arachidonic acid (AA, C(20 ratio 4 omega-6)), eicosapentaenoic acid (EPA, C(20 ratio 5 omega-3)) and docosahexaenoic acid (DHA, C(22 ratio 6 omega-3)) than that of Swedish mothers. The breast milk of the Chinese mothers had significantly higher LA and lower EPA and DHA levels than that of the Swedish mothers. However, in Chinese breast milk the AA level was significantly higher than that in Swedish breast milk. The recommended ranges of the ratios of LA to alpha-linolenic acid (LNA, C(18 ratio 3 omega-3)) and of AA to DHA in human milk are 5-10 and 0.5-1 compared with 23.0 and 3.1 in the Chinese breast milk, and 7.5 and 1.6 in the Swedish breast milk, respectively.

CONCLUSION

The diet of the studied Chinese mothers is less balanced with regard to the levels of omega-6 and omega-3 polyunsaturated fatty acids (PUFAs) than that of the Swedish mothers, which is also mirrored in the breast milk of these mothers. The clinical relevance of the difference between the levels of LC-PUFAs in the breast milk of Chinese and Swedish mothers may be elucidated by a follow-up study of the cognitive and visual functions of the infants involved.

Fatty acid composition of human milk in Western Iran

OBJECTIVE

To investigate the fatty acid composition of mature human milk in Western Iran with special focus on trans fatty acids.

DESIGN

Observational study.

METHODS

Milk samples were collected from 52 lactating mothers aging 19-39 y, from Western Iran. Subjects were asked to complete a diet questionnaire. Milk fatty acids were measured as 2-nitrophenylhydrazide derivatives by high-performance liquid chromatography.

RESULTS

Saturated fatty acids were the main fraction of human milk (41.3%). Medium-chain fatty acids (C8:0-C14:0) constituted 24%, oleic acid (C18:1omega9) accounted for 30.9% and elaidic acid (C18:1T), the trans isomer of oleic acid, comprised 11.3% of the total milk fatty acids. Linoleic (C18:2omega6) and linolenic (C18:3omega3) acid contents were 13.8 and 1.1%, respectively. The level of the polyunsaturated fatty acids was 1.4% for arachidonic (C20:4omega6) and 0.2% for eicosapentaenoic (C20:5omega3) acid.

CONCLUSIONS

The milk from Iranian lactating mothers, as compared to that from the American or European mothers, contained high levels of medium-chain and trans fatty acids. This difference may be attributed to the maternal diet with low animal protein and animal fat but with high carbohydrate and partially hydrogenated vegetable oils that carry large amounts of trans fatty acids. As the detrimental effects of trans fatty acids on blood lipids and cardiovascular diseases have been emphasized in the literature, a reduction of trans fatty acid content in the diet of Iranian mothers is suggested.

SPONSORSHIP

Kermanshah University of Medical Sciences.

Triacylglycerol markers of mature human milk

OBJECTIVES

To determine which triacylglycerol (TAG) species in mature human milk are less affected by external factors and may thus be considered as TAG markers, as well as to determine which species are most influenced by these external conditions. Furthermore, we examine the correlation between the TAG markers and their fatty acids (FAs).

SETTING AND SUBJECTS

Six healthy women from Barcelona (Catalonia, Spain).

DESIGN AND INTERVENTIONS

In order to obtain the maximum variability of sampling conditions, 40 mature human milk samples were collected from different mothers, on different days, at different times of the day, and from different breasts during and after both the baby's and mother's meal. TAG and FA profiles were determined and correlated. The TAG composition was determined by high-performance liquid chromatography with an evaporative light-scattering detector, and also with atmospheric pressure chemical ionisation mass spectrometry. FAs compositions were determined by gas chromatography.

RESULTS

The results were analysed using the SPSS statistical package and proved to be more variable than might have been found in a more restrictive sample design. Nevertheless, despite these conditions, some TAG species were found in relatively constant levels in mature human milk, and could thus be considered as markers of the mature milk TAG profile. TAG species that we can classify in this group were: LaMO, CaPO, LaCaO, LaPCa, LaOL, MPLn, LLO, LaOO, MPL, and MOL. The names do not indicate the location of fatty acids in the glycerol molecule. On the other hand, concentrations of other TAG species vary considerably between samples and consequently these may be understood to be especially affected by the external factors. TAGs like PaLS, MPO, PaOO, PPP, MPS, SPP, LOO, PPO, MOS, SSP, POL, and SOS are in this second group. Correlation between the TAG markers and their FAs was examined by Pearson's test and a significant correlation was found for some FAs.

CONCLUSIONS

The TAG species present in mature human milk are affected in different ways by external factors such as dietary intake, nutritional status, length of lactation, time of the day, etc. Some TAGs may be considered as markers of mature human milk as they are relatively constant under a wide range of sampling conditions and do not depend on the factors mentioned.

SPONSORSHIP

This study was supported by the Fundació Mestres Jané.

Trans fatty acids in hydrogenated fat inhibited the synthesis of the polyunsaturated fatty acids in the phospholipid of arterial cells

Our hypothesis that the trans fatty acids in hydrogenated fat inhibited the synthesis of polyunsaturated fatty acids in the phospholipid of arterial cells was tested with five groups each with six pregnant porcine fed from d 35 of gestation and during lactation. The basal diet contained 2% corn oil (control). The other four diets included the control + 10% butter or 10% hydrogenated fat plus two levels of Mg. Plasma, milk and aortic phospholipid fatty acids, phospholipid composition and calcium content of the aorta from the piglets were determined. At 48 +/- 2 d of age, the aorta phospholipid of piglets from porcine fed hydrogenated fat contained a significantly higher concentration of linoleic acid, less arachidonic acid, and less long chain polyunsaturated fatty acid (PUFA) than did piglets from porcine fed either butterfat or the control diet. Mg had no effect. These changes in composition in piglets from porcine fed hydrogenated fat indicate that trans fat inhibits the metabolic conversion of linoleic acid to arachidonic acid and to other n-6 PUFA. The aortic calcium content data showed a significant interaction of calcium concentration with age. We concluded: 1) that dietary trans fat perturbed essential fatty acid (EFA) metabolism which led to changes in the phospholipid fatty acid composition in the aorta, the target tissue of atherogenesis, 2) this inhibition of EFA to PUFA by the isomeric fatty acids in hydrogenated fat is a risk factor in the development of coronary heart disease.

Polyunsaturated Fatty Acids in Human Milk

The n-6 and n-3 fatty acids are essential dietary nutrients required for optimal growth and development, particularly of the brain and retina. Large amounts of the n-3 fatty acid docosahexaenoic acid (DHA) is accumulated in the brain grey matter and the visual elements of the retina during development, and reduced DHA in these tissues can result in decreased visual and psychomotor development. Although the possible importance of differences in n-6 and n-3 fatty acids, particularly DHA, between human milk and infant formulas has been the subject of intense clinical research, the variability in the essential fatty acid content of milk within and among different populations of women and implications of this to infant growth and development have received much less attention. Considerable research has shown that the DHA content of the maternal diet is the most important determinant of the amount of DHA secreted in milk, and thus the dietary intake of the breastfed infant. The DHA content of human milk varies over 10-fold, being lowest in women with no intake of DHA and highest in women with high intakes of DHA, which is found predominantly in fatty fish. The requirement for n-3 fatty acids, and the balance of n-6 and n-3 fatty acids for optimal growth and development of the brain and retina, and long-term minimization of risk of chronic disease remains as one of the most important questions in infant nutrition. Dietary recommendations to modifying dietary fat with the aim of reducing risk of chronic disease, including obesity and cardiovascular disease in adults, need to consider that when followed by pregnant women, these recommendations can have a marked effect on the amount and balance of n-6 and n-3 fatty acids secreted in milk.

Trans-18∶1 isomers in rat milk fat as effective biomarkers for the determination of individual isomeric trans-18∶1 acids in the dams' diet

Female rats were fed a diet containing by weight 10% partially hydrogenated sunflower oil, 2% sunflower oil, and 1% rapeseed oil during gestation and lactation. The trans-18:1 isomer profile of the fat supplement was (in % of total trans 18:1 acids in the fat supplement): delta4, 0.5; delta5, 1.0; delta6-delta8, 18.0; delta9 (elaidic), 13.5; delta10, 22.2; delta11 (vaccenic), 16.0; delta12, 11.3; delta13-delta14, 12.8; delta15, 2.5; and delta16, 2.2 (total trans 18:1 acids in the fat supplement: 40.6%). The cis 18:1 isomer profile was (in % of total cis-18:1 isomers): delta6-delta8, 2.1; delta9 (oleic), 70.9; delta10, 6.1; delta11, 8.3; delta12, 4.0; delta13, 2.8; delta14, 4.6, and delta15, 1.2 (total cis-18:1 acids in the fat supplement: 32.6%). Suckling rats from four litters were sacrificed at day 17 or 18 after birth, and their stomach content (milk) was analyzed. The trans-18:1 isomer profile of milk was (relative proportions, in % of total): delta4, 0.3; delta5, 1.1; delta6-delta8, 16.8; delta9, 15.3; delta10, 22.0; delta11, 16.7; delta12, 11.8; delta13-14, 11.8; delta15, 2.5, and delta16, 1.9 (total trans 18:1 acids in milk: %). That of cis-18:1 isomers was (proportions in % relative to total cis-18:1 isomers): delta6-delta8, 4.7; delta9, 72.5; delta10, 4.0; delta11, 8.0; delta12, 7.1; delta13, 1.9; delta14, 1.0, and delta15, 0.7 (total cis-18:1 acids in milk: %). These results demonstrate that all isomeric acids, independent of the geometry and the position of the ethylenic bond, are incorporated into milk lipids. With regard to trans-18:1 isomers, the distribution profile in milk is identical to that in the dams' diet, i.e., there is no discrimination against any positional isomer between their ingestion and their deposition into milk lipids. As a consequence, this study indicates that the trans-18:1 isomer profile of milk reflects that in the dams' diet and supports our earlier hypothesis that the profile of trans-18:1 isomers in milk can be used to deduce the relative contribution of ruminant fats and partially hydrogenated oils in the diet to the total intake of trans-18:1 isomers. On the other hand, the cis-18:1 isomer profile in milk shows significant differences when compared to that in the dams' diet. Surprisingly, there are no major differences for the cis-delta9 (oleic) and the cis-delta11 (asclepic) isomers, which can be synthesized by the mother. However, there seems to be a significant positive selectivity for the group cis-delta6-delta8, and for the cis-delta12 isomer, whereas a negative selectivity occurs for the delta10 and delta13 to delta15 cis isomers.

Maternal and infant essential fatty acid status in Havana, Cuba

BACKGROUND

Adequate intake of essential fatty acids (EFAs) is required for optimal development of the central nervous system and visual acuity in infants. Little information exists regarding the EFA status of vulnerable populations living in Southern regions.

OBJECTIVE

We examined the adequacy of EFA status in Cuban breast-feeding mothers and their infants.

DESIGN

Blood and breast-milk samples were obtained from a cross-sectional sample of mothers and term infants in Havana at 2 mo postpartum. We determined the fatty acid profiles of total lipids in breast milk, plasma, and erythrocytes and assessed infant visual acuity by using Teller acuity cards.

RESULTS

Of the 56 mothers and infants examined, none showed biochemical signs of poor EFA status. Compared with values reported in the literature, mothers had an adequate EFA profile in their breast milk, plasma, and erythrocytes. The docosahexaenoic acid (DHA) concentration in breast milk was 0.43 +/- 0.26% of total fatty acids. It appeared that these breast-fed infants had an adequate dietary supply of DHA, as reflected by the mean plasma and erythrocyte DHA concentrations (2.82 +/- 0.84% and 7.41 +/- 1.16% of total fatty acids, respectively). Infant visual acuity testing showed a mean of 2.00 +/- 0.68 cycles/degree, which is within the normal range of mean binocular acuities for 2-mo-old term infants. The data did not show any relation between EFA concentrations and visual acuity.

CONCLUSION

The results suggest that n-3 fatty acid deficiency and potential related deficits in early visual neural development are rare, if they exist at all, in breast-feeding women and their infants in Havana.

Trans fatty acids in subcutaneous fat of pregnant women and in human milk in the Czech Republic

Using capillary gas chromatography, we determined total content of trans fatty acids (TFA) and C18:1 trans fatty acids in human milk and subcutaneous fat in 35 healthy Prague women. The average content of TFA in human milk fat was 4.22% (SD = 1.87%) of all fatty acids, and the value of trans C18:1 isomers was 3.63% (SD = 1.81%). The average concentration of total trans fatty acids in subcutaneous fat was 4.41% (SD = 0.79%) and the average content of C18:1 trans isomers was 2.81% (SD = 0.61%).

The composition of bovine milk lipids: January 1995 to December 2000

Data from recent publications on bovine milk lipids are presented and discussed. This includes extraction of lipids, triacylglycerols, phospholipids, other complex lipids, sterols, isoflavones, and fatty acids. Improved gas-liquid and high performance liquid chromatography were used. Data on the trans and cis isomers of fatty acid and of conjugated linoleic acids are given, and the analyses are described. Papers about the lipids in milks and dairy products from the United States are few; where with the exception of trans-fatty acid isomers and conjugated linoleic acids, almost no research has been reported.

Dietary trans fatty acids in early life: a review

Trans fatty acids are unsaturated fatty acids with at least a double trans configuration, resulting in a more rigid molecule close to a saturated fatty acid. These appear in dairy fat because of ruminal activity, and in hydrogenated oils; margarines, shortenings and baked goods contain relatively high levels of trans fatty acids. These fatty acids can be incorporated into both fetal and adult tissues, although the transfer rate through the placenta continues to be a contradictory subject. In preterm infants and healthy term babies, trans isomers have been inversely correlated to infantile birth weight. However, in multigenerational studies using animals, there is no correlation between birth weight, growth, and dietary trans fatty acids. Maternal milk reflects precisely the daily dietary intake of trans fatty acids, from 2% to 5% of the total fatty acids in human milk. The level of linoleic acid in human milk is increased by a high trans diet, but long-chain polyunsaturated fatty acids remain mostly unaffected. Likewise, infant tissues incorporate trans fatty acids from maternal milk, raising the level of linoleic acid and relatively decreasing arachidonic and docosahexaenoic acids. This suggests an inhibitory effect of trans fatty acid on liver Delta-6 fatty-acid desaturase activity. As opposed to blood and liver, the brain appears to be protected from the trans fatty-acid accumulation in experimental animals, but no data have yet been reported for human newborns. Further investigations in humans are needed to definitively establish the potential physiological consequences of trans fatty-acid intake during the neonatal period.