Trans,n-3, and n-6 fatty acids in canadian human milk

The presence oftrans fatty acids in human milk may be a concern because of their possible adverse nutritional and physiological effects on the recipient infant. The mother's diet is the source of human milktrans fatty acids, and since these fatty acids are prevalent in many common foods of the Canadian diet, thetrans fatty acid content and the fatty acid composition of Canadian human milk were measured by gas-liquid chromatography coupled with silver nitrate-thin layer chromatography. In samples obtained from 198 lactating mothers across Canada, the average percentage of totaltrans (sum oft18∶1,t18∶2, andt18∶3) was 7.2% of breast milk fatty acids with a range of 0.1–17.2%. Analysis oft18∶1 isomer distribution indicated that partially hydrogenated vegetable oils are the major source of thesetrans fatty acids in human milk, whereas contribution from dairy products appeared to be relatively minor. Linoleci and α-linolenic acid levels were inversely related to the totaltrans fatty acids, indicating that the elevation oftrans fatty acids in Canadian human milk is at the expense of n-3 and n-6 essential fatty acids. Levels of arachidonic and docosahexaenoic acids did not correlate with their parent fatty acids, indicating that it might be difficult to elevate the levels of n-6 and n-3 C_20–22 polyunsaturated fatty acids in breast milk by increasing levels of linoleic and α-linolenic acids in the mother's diet.     

Influence of triacylglycerol structure and fatty acid profile of dietary fats on milk triacylglycerols in the rat. A two-generation study

We investigated the influence of dietary fatty acid profile and triacylglycerol structure on the fatty acid profile and triacylglycerol structure of milk lipids in two generations of rats. Three groups of rats received diets containing 20% fat of which approximately 20% was n-3 fatty acids located in different positions of the triacylglycerol: a fish oil-based diet [docosahexaenoic acid (22:6n-3) predominantly in thesn-2 position], a seal oil-based diet (22:6n-3) predominantly in thesn-1/sn-3 position or a plant oil-based diet [α-linolenic acid (18:3n-3) distributed evenly between the three positions]. This design allowed us to investigate (i) the effect of the triacylglycerol structure of the dietary fat; (ii) the effect of receiving the n-3 fatty acids as long-chain derivatives or as the precursor, 18:3n-3; and (iii) the long-term effects over two generations. The fatty acid profiles of the milk lipids largely reflected the diets, but in the second generation, the level of medium-chain fatty acids was higher (P<0.05) in the milk from rats fed the fish oil diet (24%) compared with the other dietary groups (15 and 18%). This suggests an increased endogenous synthesis of fatty acids in the mammary glands of the fish oil-fed rats. The levels of long-chain n-3 fatty acids in milk were higher (P<0.05) in rats fed maire n-3 fatty acids in milk were higher (P<0.05) in rats fed marie oils (8–12%) compared with rats fed vegetable oil (1%) in both generations. The level of long-chain n-3 fatty acids was significantly higher in the milk from the fish oil-fed rats (12.3%) compared to the seal-oil fed rats (8.0%) in the first generation, but not in the second generation (8.9 vs. 9.1%). The general structure of milk triacylglycerols was maintained in the three experimental groups with 16:0 acylated in thesn-2 position and 18:1 in thesn-1/sn-3 positions. The triacylglycerol structure of mammalian milk appears to be conserved even during extreme dietary manipulation over two generations and an extensive enrichment with long-chain n-3 polyunsaturated fatty acids requires their presence in the diet.     

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.     

Temporal Changes of Phospholipids Fatty Acids and Cholesterol in Breast Milk and Relationship with Diet

Phospholipids (PLs) and cholesterol in human milk (HM) are affected by lactation, and differential lipids are closely related to maternal diet. The contents of PLs and cholesterol in Chinese HM are quantified by gas chromatography and high performance liquid chromatography, respectively, and the relationship between differential lipids and the maternal diet is obtained by Pearson. The result shows that SFA, MUFA, and polyunsaturated fatty acid (PUFA) are not affected by lactation and geography for total fatty acids, but almost all sn‐2 fatty acids are influenced by geography and remain unchanged during lactation. Most SFAs show absolute sn‐2 selectivity and the majority of MUFAs and PUFAs are esterified at the sn‐1 position. Cholesterol (13.8–22.6 mg per 100 g milk) and 25‐hydroxycholesterol (0.45–1.01 mg per 100 g milk) increase significantly and remain constant during lactation, respectively, and they are affected by regions. In addition, the differential lipids (22:1n‐9, C9:0, trans‐PUFA, 22:4n‐6, etc.) of PLs are closely related to the maternal diet. PLs and cholesterol content differ from western research and infant formula, which will help to design an infant formula that is more suitable for Chinese babies in the future. Practical Application: Compared with PLs and cholesterol in western countries and infant formula, the specificity of Chinese HM can more accurately target the development of formulas suitable for the growth of Chinese infants. At the same time, according to the influence of the mother?s diet on the composition of HM, it is more reasonable to guide the diet of the mother.     

Current studies on relation of fat to health

An increase in the linoleic to oleic acid ratio by an increase in the percentage of the polyunsaturated ω6 family of fatty acids in culinary fats and a decrease in the consumption of cholesterol-rich food were believed necessary as a prerequisite to early intervention in coronary heart disease. A decrease in total fat consumption also has been recommended. However, a decrease in the percentage of fat in the diet may not be nutritionally sound, as it may only increase the percentage of carbohydrates consumed and, thus, the synthesis of the ω9 family of fatty acids from the surfeit calories. It may be more judicious to decrease the total number of calories through less consumption of a well balanced diet. Furthermore, as thetrans-fatty acids, which are formed during hydrogenation, are not discriminated against completely by acyl-glycerol-3-phosphoryl-choline transferase or acyl coenzyme A cholesteryl transferase, it would be, from a biological viewpoint, advantageous to eliminatetrans-fatty acids from both stick and tub type margarines. One of five papers presented at the symposium, “Status of Fat in Food and Nutrition,” AOCS Fall Meeting, Chicago, September 1973.     

Supplemental Conjugated Linoleic Acid Consumption Does Not Influence Milk Macronutrient Contents in all Healthy Lactating Women

The term “conjugated linoleic acid” (CLA) refers to a group of positional and geometric isomers that are derived from linoleic acid and are found primarily in meat and milk products from ruminant animals. Due to the array of putative benefits associated with various forms of CLA, there has been recent interest in supplementing human diets with these fatty acids especially when weight loss is desired. However, in many animal models, CLA has been shown to decrease milk fat production. There is some concern, therefore, that maternal CLA supplementation during lactation might inadvertently decrease nutrient supply to the nursing infant. However, there is only limited research on the effect of CLA consumption on milk fat content in women. Based on previously published work from our laboratory, we hypothesized that CLA supplementation would reduce the milk fat percentage in lactating women in a dose-dependent manner. Breastfeeding women (n = 12) were assigned randomly to treatments of 4 g/day safflower oil (SFO), 2 g/day CLA plus 2 g/day SFO, or 4 g/day CLA in a double blind, 3 × 3 Latin square design. Conjugated linoleic acid supplements contained approximately equal amounts of cis9,trans11–18:2 and trans10,cis12–18:2; the two most common isoforms of CLA. Milk was collected by complete breast expression on the last day (day 5) of each intervention period and analyzed for macronutrient and fatty acid composition. On day 4 of each intervention period, infant milk consumption was estimated by 24 h weighing of the infant. Washout periods were 9 days in length. We observed a dose-dependent increase in the concentrations of cis9,trans11–18:2 and trans10,cis12–18:2 in the milk fat. However, we detected neither a change in overall macronutrient composition nor infant milk consumption. These data do not support those obtained from animal models or our previous human work suggesting that consumption of CLA mixtures necessarily reduces milk fat. It is possible that either (1) the interpretation of our previously published data should be reevaluated, and/or (2) there are important intra- and inter-species differences in this regard.     

Polyunsaturated fatty acid supply with human milk

Polyunsaturated fatty acids in human milk may derive from diet, liberation from maternal body stores, or endogenous synthesis from precursor fatty acids. The contribution of each of these sources has not been studied in detail. Although maternal diet is a key factor affecting human milk composition, other factors such as gestational age, stage of lactation, nutritional status, and genetic background are known to influence the fat content and fatty acid composition in human milk. Both linoleic and α-linolenic acids, the essential fatty acids, are present in human milk, as are several other n−6 and n−3 longer chain polyunsaturated fatty acids that are required for optimal growth and development of infants. The fatty acid profile of human milk from lactating women of different countries is remarkably stable, but there is variability in some of the components, such as docosahexaenoic acid, which is mainly due to differences in dietary habits. Tracer techniques with stable isotopes have been valuable in assessing the kinetics of fatty acid metabolism during lactation and in determining the origin of fatty acids in human milk. Based on these studies, the major part of polyunsaturated fatty acids in human milk seems not to be provided directly from the diet but from maternal tissue stores.     

Cholestane as a digestibility marker in the absorption of polyunsaturated fatty acid ethyl esters in Atlantic salmon

Salmonid fish require long-chain n−3 fatty acids in their diet. The digestibility of different chemical forms of fish oil fatty acids, fed as triacylglycerols, free fatty acids or ethyl esters, was examined in 300 g farmed Atlantic salmon (Salmo salar) using cholestane as an indicator of fat absorptionin lieu of the chromium oxide (Cr₂O₃) which is commonly used as a marker in digestibility studies. It was established that the two digestibility markers gave similar results. Conveniently, cholestane does not require a separate analysis if fatty acids are to be determined by appropriate gas-liquid chromatography. The long-chain polyunsaturated fatty acids were particularly well absorbed, the apparent digestibility being 90–98% when feeding triacylglycerols or free fatty acids. However, the digestibility of monounsaturated fatty acids (75–94%) was lower, and lower still for saturated fatty acids (50–80%). Ethyl esters of fatty acids were significantly less well absorbed (P<0.05) than were the corresponding fatty acids in free acid or triacylglycerol form. Irrespective of dietary fat type, only free fatty acids were identified in feces, indicating total hydrolysis of triacylglycerols and ethyl esters. Presented in part at the World Aquaculture Society meeting, June 10–14, 1990, Halifax, Canada.     

Infant cerebellar gray and white matter fatty acids in relation to age and diet

There is little evidence as to the fatty acid composition of the cerebellum in infancy and it remains uncertain whether milk diet can influence its composition. We therefore examined cerebellar gray and white matter of infants less than 6 mon old who had died unexpectedly. The fatty acid content of 33 gray and 21 white matter specimens from infants born at term and 6 gray and 5 white matter specimens from pretern infants was assessed by gas chromatographic/mass spectrometric analysis. Infants were grouped according to whether they had received human or manufactured formula milk. Whereas cerebellar cortex docosahexaenoic acid (DHA, 22∶6n−3) concentrations were significantly lower (P<0.01) in the formula-fed than breast-fed infants, no differences existed between the term (n=10) and preterm (n=5) Scientific Milk Adaptation (SMA) formula-fed infants. Cerebellar white matter DHA concentrations were similarly lower (P<0.01) in the SMA formula-fed infants (n=8) than in an age-matched breast-fed group. Low concentrations of cerebellar white matter lignoceric (24∶0) and nervonic acid (24∶1n−9) in two 7-wk-old preterm infants appeared to correlated with postgestational rather than chronological age. Dietary long-chain polyunsaturated fatty acids particularly DHA, are probably essential for normal development of the infant cerebellum.     

Positional analyses of triacylglycerol fatty acids in the milk fat of the antarctic fur seal (Arctocephalus gazella)

The positional distribution of fatty acids has been determined for the milk triacylglycerols of the Antarctic fur seal,Arctocephalus gazella. Of particular interest was the positional distribution of the polyunsaturated n−3 fatty acids in milk triacylglycerols (TG). In adipocytes of pinnipeds, TG are synthesized with the n−3 fatty acids primarily in thesn-1,3 positions. To determine the positional distribution, extracts of enzymatically digested lipids were separated by thin-layer chromatography, and the constituent fatty acids were separated and quantified by gas-liquid chromatography. Monoenoic and saturated fatty acids comprised over 75% of the total, the ratio of monoenoic to saturated fatty acids being 2∶1. The percent content of the long-chain n−3 fatty acids, 20∶5, 22∶5 and 22∶6, ranged between 15–20%. The positional analyses revealed that at thesn-2 position of milk TG, saturated fatty acids were in excess (57%), and the content of n−3 fatty acids was less than 5%. More than 80% of the n−3 fatty acids in milk were located in thesn-1,3 positions. The data indicate that in pinnipeds TG are synthesized in the mammary gland and adipose tissue with fatty acids having similar positional distributions.     

trans fatty acids. 4. Effects on fatty acid composition of colostrum and milk

trans Isometric fatty acids of partially hydrogenated fish oil (PHFO) consist oftrans 20∶1 andtrans 22∶1 in addition to thetrans isomers of 18∶1, which are abundant in hydrogenated vegetable oils, such as in partially hydrogenated soybean oil (PHSBO). The effects of dietarytrans fatty acids in PHFO and PHSBO on the fatty acid composition of milk were studied at 0 (colostrum) and 21 dayspostpartum in sows. The dietary fats were PHFO (28%trans), or PHSBO (36%trans) and lard. Sunflower seed oil (4%) was added to each diet. The fats were fed from three weeks of age throughout the lactation period of Experiment 1. In Experiment 2 PHFO or “fully” hydrogenated fish oil (HFO) (19%trans), in comparison with coconut oil (CF) (0%trans), was fed with two levels of dietary linoleic acid, 1 and 2.7% from conception throughout the lactation period. Feedingtrans-containing fats led to secretion oftrans fatty acids in the milk lipids. Levels oftrans 18∶1 andtrans 20∶1 in milk lipids, as percentages of totalcis+trans 18∶1 andcis+trans 20∶1, respectively, were about 60% of that of the dietary fats, with no significant differences between PHFO and PHSBO. The levels were similar for colostrum and milk. Feeding HFO gave relatively lesstrans 18∶1 andtrans 20∶1 fatty acids in milk lipids than did PHFO and PHSBO. Only low levels ofcis+trans 22∶1 were found in milk lipids. Feedingtrans-containing fat had no consistent effects on the level of polyenoic fatty acids but reduced the level of saturated fatty acids and increased the level ofcis+trans monoenoic fatty acids. Increasing the dietary level of linoleic acid had no effect on the secretion oftrans fatty acids but increased the level of linoleic acid in milk. The overall conclusion was that the effect of dietary fats containingtrans fatty acids on the fat content and the fatty acid composition of colostrum and milk in sows were moderate to minor.     

Monitoring of Fat Content,Free Fatty Acid and Fatty Acid Profile Including <Emphasis Type="Italic">trans</Emphasis> Fat in Pakistani Biscuits

The fat contents of 12 brands of biscuits were extracted and evaluated for free fatty acids (FFA) and their fatty acid composition (FAC). The oil content and FFA varied from 13.7 to 27.6% and 0.2 to 1.0%, respectively. The FAC was analyzed by gas chromatography–mass spectroscopy with particular emphasis on trans fatty acids (TFA). Total saturated, unsaturated, cis-monounsaturated and polyunsaturated fatty acids were determined in the range of 37.9–46.9, 53.0–62.0, 12.3–43.7 and 0.1–9.2%, respectively. The high amount of TFA was observed in all biscuit samples and varied from 9.3 to 34.9%. The quantity and quality of the lipid fraction of the biscuits indicated that the all analyzed biscuits are a rich source of fat, saturated fatty acids and trans fatty acids, consequently not suitable for the health of consumers. The high content of trans fatty acids and palmitic acid also indicated that blends of RBD palm oil and partially hydrogenated oil had been used in the biscuit manufacturing.     

Incorporation oftrans long-chain n−3 polyunsaturated fatty acids in rat brain structures and retina

During heat treatment, polyunsaturated fatty acids and specifically 18∶3n−3 can undergo geometrical isomerization. In rat tissues, 18∶3 Δ9c, 12c, 15t, one of thetrans isomers of linolenic acid, can be desaturated and elongated to givetrans isomers of eicosapentaenoic and docosahexaenoic acids. The present study was undertaken to determine whether such compounds are incorporated into brain structures that are rich in n−3 long-chain polyunsaturated fatty acids. Two fractions enriched intrans isomers of α-linolenic acid were prepared and fed to female adult rats during gestation and lactation. The pups were killed at weaning. Synaptosomes, brain microvessees and retina were shown to contain the highest levels (about 0.5% of total fatty acids) of thetrans isomer of docosahexaenoic acid (22∶6 Δ4c, 7c, 10c, 13c, 16c, 19t). This compound was also observed in myelin and sciatic nerve, but to a lesser extent (0.1% of total fatty acids). However, the ratios of 22∶6trans to 22∶6cis were similar in all the tissues studied. When the diet was deficient in α-linolenic acid, the incorporation oftrans isomers was apparently doubled. However, comparison of the ratios oftrans 18∶3n−3 tocis 18∶3n−3 in the diet revealed that thecis n−3 fatty acids were more easily desaturated and elongated to 22∶6n−3 than the correspondingtrans n−3 fatty acids. An increase in 22∶5n−6 was thus observed, as has previously been described in n−3 fatty acid deficiency. These results encourage further studies to determine whether or not incorporations of suchtrans isomers into tissues may have physiological implications. Presented in part at the 32nd International Conference on the Biochemistry of Lipids, 1991, Granada, Spain. Delta nomenclature (Δ) is used fortrans polyunsaturated fatty acids to specify the position and geometry of ethylenic bonds. Polyunsaturated fatty acids containingtrans double bonds are abbreviated giving the locations of thetrans double bonds only; e.g., 20∶5 Δ17t 20∶5 Δ5c,8c,11c,14c,17t; 22∶5 Δ19t, 22∶5 Δ7c,10c,13c,16c,19t; 22∶6 Δ19t 22∶6 Δ4c,7c,10c,13c,16c,19t.     

Evaluating the <Emphasis Type="Italic">trans</Emphasis> Fatty Acid,CLA, PUFA and Erucic Acid Diversity in Human Milk from Five Regions in China

Human milk was obtained from 97 healthy lactating women from five different regions in China. Twenty-four hour dietary questionnaire identified the foods consumed that showed distinct differences in food types between cities. The southern and central regions had higher levels of total trans fatty acids (TFA) and conjugated linoleic acids (CLA) in human milk than the northern region. The major isomers in human milk from the northern region were vaccenic and rumenic acids, whereas the other regions had a random distribution of these isomers. This was consistent with the isomer distribution in the refined vegetable oils used and their increased formation during high temperature stir-frying. The human milk composition showed little evidence that partially hydrogenated fats were consumed, except eight mothers in Guangzhou who reported eating crackers, plus four other mothers. The TFA concentration in these human milk samples was higher (2.06–3.96%). The amount of n-6 (1.70–2.24%) and n-3 (0.60–1.47%) highly unsaturated fatty acids (HUFA) in human milk and the resultant ratio (1.43–2.95) showed all mothers in China had an adequate supply of HUFA in their diet. Rapeseed oil was consumed evidenced by erucic acids in human milk. The levels of erucic acid were below internationally accepted limits for human consumption. The levels of undesirable TFA and CLA isomers in human milk are a concern. Efforts to decrease the practice of high temperature stir-frying using unsaturated oils, and a promotion to increase consumption of dairy and ruminant products should be considered in China.     

Trans fatty acid isomers in Canadian human milk

The fatty acid composition, totaltrans content (i.e., sum of all the fatty acids which may have one or moretrans double bonds) and geometric and positional isomer distribution of unsaturated fatty acids of 198 human milk samples collected in 1992 from nine provinces of Canada were determined using a combination of capillary gas-liquid chromatography and silver nitrate thin-layer chromatography. The mean totaltrans fatty acid content was 7.19±3.03% of the total milk fatty acids and ranged from 0.10 to 17.15%. Twenty-five of the 198 samples contained more than 10% totaltrans fatty acids, and thirteen samples contained less than 4%. Totaltrans isomers of linoleic acid were 0.89% of the total milk fatty acids with 18∶2Δ9c, 13t being the most prevalent isomer, followed by 18∶2Δ9c, 12t and 18∶2Δ9t, 12c. Using the totaltrans values in human milk determined in the present study, the intake of totaltrans fatty acids from various dietary sources by Canadian lactating women was estimated to be 10.6±3.7 g/person/d, and in some individuals, the intake could be as high as 20.3 g/d. The 18∶1trans isomer distribution differed from that of cow's milk fat but was remarkably similar to that in partially hydrogenated soybean and canola oils, suggesting that partially hydrogenated vegetable oils are the major source of thesetrans fatty acids.     

Divergent incorporation of dietary trans fatty acids in different serum lipid fractions

Trans fatty acids may be involved in atherosclerotic vascular diseases. We investigated the incorporation of dietary trans fatty acids and oleic acid into the serum triglycerides (TG), cholesterol esters (CE), and phospholipids (PL). Fourteen healthy female volunteers, aged 23.2±3.1 yr (mean±SD), body mass index 20.8±2.1 kg/m² participated in this study. All subjects consumed both a trans fatty acid-enriched diet (TRANS diet) and an oleic acid-enriched diet (OLEIC diet) for 4 wk according to a randomized crossover design. Both experimental diet periods were preceded by consumption of a baseline diet for 2 wk which supplied 37% of total energy (E%) as fat: 18 E% from saturated fatty acids (SFA), 12 E% from monounsaturated fatty acids, and 6 E% from polyunsaturated fatty acids. Five E% of the SFA in the baseline diet was replaced by trans fatty acids (18∶1 t and 18∶2 c,t+18∶2t,t, where c is cis and t is trans) in the TRANS diet and by oleic acid (18∶1n-9) in the OLEIC diet. After the TRANS diet, the proportions of 18∶1t and 18∶2t increased (P <0.001) in all serum lipid fractions analyzed. The increase of 18∶1 t in TG and PL (1.80±0.28 vs. 5.26±1.40; 1.07±0.34 vs. 3.39±0.76 mol% of total fatty acids, respectively) was markedly higher than that in CE (0.44±0.07 vs. 0.92±0.26), whereas that of 18∶2t was nearly the same in all three fractions. The proportions of palmitic, stearic, arachidonic, and eicosapentaenoic acids in TG, CE, and PL and that of oleic acid in TG and CE were decreased when compared with the baseline value. In contrast, the proportion of palmitoleic acid in TG and PL and that of linoleic acid in PL increased on the TRANS diet. After consumption of the OLEIC diet, the proportion of oleic acid increased in all three lipid fractions analyzed, and the percentage increase was nearly the same in all fractions. In contrast, the proportions of 18∶1 t in TG and PL and 18∶2 t in TG and CE decreased when compared with the baseline value. In conclusion, a moderate increase in dietary trans fatty acids resulted in a marked incorporation into serum lipids and decreased the conversion of linoleic acid to its more unsaturated long-chain metabolites. Analysis of 18∶1 t from serum TG and PL seems to reflect reliably the dietary intake of this fatty acid.     

Trans-18:1 acid content and profile in human milk lipids. Critical survey of data in connection with analytical methods

This study presents an in-depth, critical survey of the current knowledge about trans- 18:1 acid content and profile in human milk lipids. Emphasis is placed on the analytical methods employed to quantitate trans- 18:1 acids, most of which lead to imprecise quantitative data. It is demonstrated that data obtained by single gas-liquid chromatography (GLC) on polar capillary columns are underestimates by 25–40%. Several experiments indicate that the total content of trans-18:1 acids in human milk is directly related to the quantities ingested the previous day(s), provided no gross weight loss occurs during breast-milk feeding. Equations have been proposed to describe this relationship, and apparently the percentage of trans-18:1 isomers, relative to total fatty acids, is approximately three-fourths the quantity (in g) ingested by lactating mothers. That is, the determination of the trans-18:1 acid percentage in human milk is a convenient means to estimate trans-18:1 acid consumption by corresponding populations. Adapted methods (i.e., silver-ion thin-layer chromatography, coupled with GLC on long polar capillary columns) allow accurate quantitation of most individual trans- 18:1 acids, more particularly of the trans-Δ16 isomer. This determination, along with a knowledge of the distribution of individual isomers in ruminant fats and partially hydrogenated oils, is a convenient means to estimate the relative contribution of these two dietary sources to the distribution of individual trans-18:1 isomers in human milk lipids. A comparison of human milk and infant formulas is made with regard to trans-18:1 acid content and profile. Important differences are noted between data from European countries and from North America.     

Fatty acid composition of French infant formulas with emphasis on the content and detailed profile oftrans fatty acids

The aim of the present study was to identify and quantitatetrans isomers of C18 fatty acids in some French infant formulas. Twenty powdered infant formulas were purchased in pharmacies and supermarkets in order to assess theirtrans mono- and poly-unsaturated fatty acids content. The fatty acid profiles were examined using methyl and isopropyl ester derivatives. The combination of gas-liquid chromatography, high-performance liquid chromatography, and silver nitrate thin-layer chromatography was needed to describe the detailed fatty acid compositions of the samples, includingtrans isomers of unsaturated C18 fatty acids. All the samples containedtrans isomers of C18∶1 acid (mean level 1.97±0.28% of total fatty acids), with vaccenic acid being generally the major isomer (15 out of 20 samples), thus indicating the origin from bovine milk. All the formulas also contained various isomers of linoleic and α-linolenic acids, but at lower levels.Trans PUFA isomers are the same as those present in deodorized oils. In conclusion, all the infant formulas analyzed in this study contained sometrans fatty acids, including isomers of essential fatty acids. This should be taken into account in the dietary intake of the newborn.     

<Emphasis Type="Italic">Trans</Emphasis>-18∶1 isomers in rat milk fat as effective biomarkers for the determination of individual isomeric <Emphasis Type="Italic">trans</Emphasis>-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): Δ4, 0.5; Δ5, 1.0;Δ6–Δ8, 18∶0; Δ9 (elaidic), 13.5; Δ10, 22.2;Δ11 (vaccenic), 16.0; Δ12, 11.3; Δ13–Δ14, 12.8; Δ15, 2.5; and Δ16, 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):Δ6, Δ8, 2.1; Δ9 (oleics), 70.9; Δ10, 6.1; Δ11, 8.3; Δ12, 4.0; Δ13, 2.8; Δ14, 4.6, and Δ15, 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): Δ4, 0.3; Δ5, 1.1; Δ6–Δ8, 16.8; Δ9, 15.3; Δ10, 22.0; Δ11, 16.7; Δ12, 11.8; Δ13–14, 11.8; Δ15, 2.5, and Δ16, 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): Δ6–Δ8, 4.7; Δ9, 72.5; Δ10, 4.0; Δ11, 8.0; Δ12, 7.1; Δ13, 1.9; Δ14, 1.0, and Δ15, 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 ingestiona nd 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 ot 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-Δ9 (oleic) and the cis-Δ11 (asclepic) isomers, which can be synthesized by the mother. However, there seems to be a significant positive selectivity for the group cis-Δ6–Δ8, and for the cis-Δ12 isomer, whereas a negative selectivity occurs for the Δ10 and Δ13 to Δ15 cis isomers. Dr. Robert L. Wolff Robert Wolff passed away at the age of 53 on the 10th of November, 2002. His know-how in the field of lipids was recognized internationally. He had the ability to lead his research projects in both the animal and vegetal worlds. His scientific achievement, more than 100 publications to his name in the field of trans fatty acids, made him highly esteemed by his colleagues. He was Conference Master at Bordeaux 1 University (France) up until 2001, at which time he joined the Nutritional Lipid Unit in I.N.R.A., Dijon (France). His mission there was to develop a research program on plasmalogens and their role in brain and muscle function, for which his analytical and biochemical skills were a guarantee of success. Unfortunately, his state of health did not allow him to complete this project. This publication is his final one.     

Fatty acid composition of danish margarines and shortenings,with special emphasis ontrans fatty acids

Trans fatty acids from hydrogenated vegetable and marine oils could be as hypercholesterolemic and atherogenic as saturated fatty acids. Hence, it is important to know the fatty acid composition in major food contributors, e.g., margarines and shortenings. In 1992 margarines were examined, and in 1995 brands covering the entire Danish market were examined. Significant amounts oftrans-18∶1 were found only in hard margarines (mean: 4.2±2.8%) and shortenings (mean: 6.8 ±3.1%), whereas the semisoft and soft margarines contained substantially lesstrans-18∶1 in 1995 than in 1992. Where marine oils had been used to a larger degree the meantrans-monoenoic content was about 15%, of which close to 50% was made up of long-chain (C₂₀ and C₂₂)trans fatty acids. A note-worthy decrease in the content oftrans-18∶1 had occurred for the semisoft margarines, from 9.8±6.1% in 1992 to 1.2±2.2% in 1995. Calculated from sales figures, the supply oftrans-18∶1 plus saturated fatty acids from margarines had decreased over this three-year period by 1.4 g/day, which has been replaced bycis monounsaturated and polyunsaturated fatty acids.