Metabolic aspects of trans fatty acids

The consumption of trans isomers of unsaturated fatty acids has been associated withuntoward metabolic effects. Several clinical investigations demonstrated that trans fatty acids increase plasma LDL-cholesterol and lipoprotein (a) and reduce HDL-cholesterol concentrations. These alterations of plasma lipid profiles indicate an atherogenic effect of trans fatty acids. Both in preterm infants and in healthy children aged 1-15 years, we found blood plasma arachidonic acid (C20:4omega-6) levels and the product/substrate ratios of arachidonic acid synthesis (C20:4omega-6/C18:2omega-6) inversely correlated to the level of the principal trans fatty acid, trans octadecaenoic acid (C18:1omega-9/7, trans), which is compatible with a dose-dependent inhibition of arachidonic acid synthesis by trans fatty acids. Moreover, in premature infants trans fatty acids in blood plasma correlated inversely with birth weight in an observational study, indicating that trans fatty acids may impair early human growth. It appears desirable to limit the dietary intake of trans fatty acids. The major dietary sources of trans fatty acids are partially hydrogenated vegetable and fish oils. Refinement of the industrial technology of partial hydrogenation and appropriate food labelling may lead to a considerably decrease of human exposure to trans fatty acids.     

TransFatty Acid Content of Selected New Zealand Foods

The fatty acid composition andtransfatty acid content of samples of New Zealand foods representing certain food groups have been determined by a combined gas chromatography/infrared spectroscopy method. The mean levels oftransfatty acids in the fat portion of these foods are (g/100 g fatty acids) margarine, 16.4; table spreads, 15.7; butter/margarine blends, 9.6; butter, 6.4; pastry, 6.2; potato chips (deep fried in beef dripping), 5.6; cakes, 5.3, crackers, 2.0; sweet biscuits, 1.9; potato crisps, 0.5. Expressed as a proportion of dry weight of food the meantransfatty acid content values are (g/100 g dry weight) margarine, 14.9; table spreads, 14.4; butter/margarine blends, 8.1; butter, 6.0; potato chips (deep fried in beef dripping), 1.6; pastry, 1.2; cakes, 0.9, crackers, 0.3; sweet biscuits, 0.2; potato crisps, 0.2. In contrast to North America, hydrogenated plant oils with high levels oftransfatty acids do not appear to be present in the New Zealand food supply.     

Dietary fat type influences total milk fat content in lean women

Trans fatty acids (TFA) are found naturally in some foods (e.g., dairy products) as well as many processed foods made with partially hydrogenated vegetable oils (PHVO). Data from a growing literature suggest that some TFA decrease milk fat in lactating animals. Because the physiologic effects of TFA in lactating women are unknown, this study was designed to investigate the effects of TFA consumption on human milk fat. A randomized, crossover design (n = 12) was used to study the effect of 3 dietary treatments: high PHVO (regular margarine), low PHVO (low TFA margarine), or low PHVO but high in naturally occurring TFA (butter) on milk fat. Treatments were administered for 5 d, with 7-d washout periods. Maternal adiposity was estimated by dual-energy X-ray absorptiometry. Milk and blood were collected on d 5 of each intervention period. In general, milk and serum fatty acid concentrations mirrored those of the dietary treatments. There were significant interactions between treatment and maternal adiposity on milk fat and infant milk consumption, as well as on serum glucose and nonesterified fatty acid (NEFA) concentrations. Consumption of regular margarine, compared with low TFA margarine, resulted in lower milk fat in leaner, but not in more obese women. Consumption of either regular or low TFA margarine, compared with butter, elevated serum NEFA concentrations in the more obese women. In summary, consumption of regular margarine, compared with low TFA margarine, decreased milk fat in lean women. Further studies are required to determine whether infant milk consumption might compensate for this potentially important change in milk composition.     

中国市售桶装植物油脂肪酸的研究

目的对市售桶装植物油中脂肪酸进行分析,探讨其组分及含量特点。通过植物油中各类脂肪酸比例的特点,分析脂肪酸特征。方法从北京、云南、浙江、湖南、河南、哈尔滨、江苏、甘肃8个地区,选取市场普遍销售的或各地自产的品牌桶装植物油,共计8个品种,每个样品采集2个不同批号。对植物油脂进行皂化和甲酯化后,利用岛津GC2014气相色谱仪对样品进行气相色谱分析。结果市售桶装植物油主要以棕榈酸、油酸、亚油酸和α-亚麻酸为主,反式脂肪酸的平均含量为1.05g/100g。植物油的饱和脂肪酸∶单不饱和脂肪酸∶多不饱和脂肪酸的比值范围为1∶1.6～9.4∶0.9～7.4;多不饱和脂肪酸中n-6/n-3的比值范围为0.37～289.5∶1。结论市售桶装植物油反式脂肪酸含量低,但脂肪酸组成比例大多不符合中国营养学会提出的标准,并且多数缺乏n-3多不饱和脂肪酸。     

Correlation of isomeric fatty acids in human adipose tissue with clinical risk factors for cardiovascular disease

The relationships between the adipose tissue concentrations of 19 geometric and positional fatty acid isomers and 10 cardiovascular disease risk factors were determined in 76 free-living adult males. The percentages for trans isomers (total mean +/- SD 4.14 +/- 0.97%) and cis isomers (total mean +/- SD 2.91 +/- 0.34%) in adipose tissue generally agreed with dietary estimates based on the consumption of hydrogenated oils. A major exception was the percentage of 11c-18:1, which was twofold higher in adipose tissue. The total level of fatty acid isomers in adipose tissue or a factor (derived by factor analysis) that was representative of isomers of dietary origin was not significantly correlated with the cardiovascular risk factors. Only three trans isomers (11t-18:1, 12t-18:1, and 5t-14:1) and three cis isomers (11c-18:1, 13c-18:1, and 7c-16:1) were weakly correlated either positively or negatively with age, body mass index, plasma and lipoprotein cholesterol, and/or blood pressure (P less than 0.05, r greater than 0.231).     

Acute postprandial effect of hydrogenated fish oil, palm oil and lard on plasma cholesterol, triacylglycerol and non-esterified fatty acid metabolism in normocholesterolaemic males

The majority of research has focused on the association between trans unsaturated fatty acids (TUFA) from hydrogenated vegetable oils and heart disease even though TUFA are also produced from hydrogenated fish oil. We compared the acute effect of three solid fats on postprandial cholesterol, triacylglycerol (TAG) and NEFA concentrations in normocholesterolaemic males. Eight healthy male volunteers consumed each of the three 40 g fat meals (partially hydrogenated fish oil (PHFO), palm oil and lard) in random order and blood samples were drawn at 2, 4, 6 and 8 h thereafter for lipid analysis. The postprandial response in plasma TAG, TAG-rich lipoprotein-TAG (TRL-TAG), total cholesterol and plasma NEFA, measured as the area under the postprandial curve, was not significantly different between the three meals (P>0.05), which varied in MUFA, PUFA and TUFA content. There was no marked elevation of longer-chain fatty acids (C20-22, cis or trans isomers) into the TRL-TAG fraction following the PHFO meal even though they provided 40 % of the total fatty acids in the PHFO meal. The postprandial TRL-TAG response to PHFO was expected to be higher, as it is higher in TUFA, lower in PUFA and similar in saturated fatty acid composition compared with the lard and palm oil test meals. The absence of a higher postprandial response following ingestion of PHFO could be as a result of reduced absorption and increased oxidation of long-chain fatty acids (both cis and trans isomers).     

Replacement of butter on bread by rapeseed oil and rapeseed oil-containing margarine: effects on plasma fatty acid composition and serum cholesterol.

The effects of zero-erucic acid rapeseed oil and rapeseed oil-containing margarine on plasma fatty acid composition and serum cholesterol were studied in butter users (n 43). Compliance to the substitution was followed by fatty acid analysis of total plasma and plasma phospholipids. The amount of substitute fats represented, on average, 21% of total fat and 8% of total energy intake. Changes in the relative fatty acid composition of plasma phospholipids indicated further fatty acid metabolism, and were closely related to the serum cholesterol level. The reduction in saturated fatty acids led to a significant increase in the proportion of n-3 and n-6 polyunsaturated fatty acids (PUFA) with the rapeseed oil diet, whereas the margarine caused a significant rise in n-6 PUFA only. The increase in the proportions of the two PUFA families occurred in accordance with their competitive order, most completely with the rapeseed oil diet. When butter was replaced by rapeseed oil, low-density-lipoprotein-cholesterol decreased by an average of 9.1% without a reduction in high-density-lipoprotein-cholesterol. During margarine substitution the reduction was 5.2%, on average. Of the plasma phospholipids, alpha-linolenic acid and the linoleic:stearic acid ratio, but not oleic acid, were the components most significantly correlated with serum cholesterol levels or the decrease in these levels. The results show that rapeseed oil can act primarily as a source of essential fatty acids, rather than that of monoenes, in the diet of butter users.     

Trans fatty acids: are the effects only marginal?

In the process of converting vegetable oils into solid fats, a process known as partial hydrogenation, some unsaturated bonds are converted to an unnatural trans position. In humans, trans fatty acids increase low-density lipoprotein cholesterol and decrease high-density lipoprotein cholesterol. In addition, positive associations between intake of trans fatty acids and coronary heart disease have been observed in epidemiological studies. The combined results of metabolic and epidemiological studies provide strong evidence that trans fatty acid intake is causally related to risk of coronary disease. Because the consumption of partially hydrogenated fats is almost universal in the United States, the number of deaths attributable to such fats is likely to be substantial. Federal regulations should require manufacturers to include trans fatty acid content in food labels and should aim to greatly reduce or eliminate the use of partially hydrogenated vegetable fats.     

Dietary trans fatty acids alter diaphragm phospholipid fatty acid composition, triacylglycerol content and glucose transport in rats

The present study evaluates the effect of dietary trans fatty acids on diaphragm phospholipid fatty acid composition, intramyocellular triacylglycerol content and insulin-stimulated glucose uptake in comparison with dietary saturated fatty acids. Male weanling WNIN rats were divided into three groups and fed for 3 months on one of the following diets containing 10 % oil differing in fatty acid composition: control diet, saturated fatty acid diet and trans fatty acid diet. Dietary trans fatty acids increased the intramyocellular triacylglycerols and decreased the ratio of 20 : 4n-6 to 18 : 2n-6 and long-chain PUFA levels (20 %) in diaphragm phospholipids, indicating inhibition of PUFA biosynthesis. However, saturated fatty acids decreased both 18 : 2n-6 and 20 : 4n-6 without change in the ratio. Trans fatty acid-induced alterations in diaphragm phospholipid fatty acid composition and intramyocellular triacylglycerol content were associated with decreased insulin-stimulated glucose transport in the diaphragm. These observations suggest that dietary trans fatty acids decrease diaphragm insulin sensitivity, possibly due to increased intramyocellular triacylglycerol accumulation and decreased long-chain PUFA in phospholipids.     

trans Fatty acids in human milk are inversely associated with concentrations of essential all-cis n-6 and n-3 fatty acids and determine trans, but not n-6 and n-3, fatty acids in plasma lipids of breast-fed infants.

BACKGROUND: Human milk fatty acids vary with maternal dietary fat composition. Hydrogenated dietary oils with trans fatty acids may displace cis n-6 and n-3 unsaturated fatty acids or have adverse effects on their metabolism. The effects of milk trans, n-6, and n-3 fatty acids in breast-fed infants are unclear, although n-6 and n-3 fatty acids are important in infant growth and development. OBJECTIVE: We sought to determine the relations between trans and cis unsaturated fatty acids in milk and plasma phospholipids and triacylglycerols of breast-fed infants, and to identify the major maternal dietary sources of trans fatty acids. DESIGN: We collected milk from 103 mothers with exclusively breast-fed 2-mo-old infants, blood from 62 infants, and 3-d dietary records from 21 mothers. RESULTS: Mean (+/-SEM) percentages of trans fatty acids were as follows: milk, 7.1 +/- 0.32%; infants' triacylglycerols, 6.5 +/- 0. 33%; and infants' phospholipids, 3.7 +/- 0.16%. Milk trans fatty acids, alpha-linolenic acid (18:3n-3), arachidonic acid (20:4n-6), docosahexaenoic acid (22:6n-3) (P < 0.001), and linoleic acid (18:2n-6) (P = 0.007) were each related to the same fatty acid in infant plasma phospholipids. Milk trans fatty acids were inversely related to milk 18:2n-6 and 18:3n-3, but not to milk or infant plasma 20:4n-6 or 22:6n-3. trans Fatty acids represented 7.7% of maternal total fat intake (2.5% of total energy); the major dietary sources were bakery products and breads (32%), snacks (14%), fast foods (11%), and margarines and shortenings (11%). CONCLUSIONS: There were comparable concentrations of trans fatty acids in the maternal diet, breast milk, and plasma triacylglycerols of breast-fed infants. Prepared foods were the major dietary source of trans fatty acids.     

Effect of dietary alpha-linolenic acid on thrombotic risk factors in vegetarian men

BACKGROUND: Vegetarians have lower platelet and plasma concentrations of n-3 polyunsaturated fatty acids (PUFAs) than do omnivores. We recently showed that male vegetarians have higher platelet aggregability than do omnivores. OBJECTIVE: We investigated whether male vegetarians (n = 17) who consumed an increased amount of dietary alpha-linolenic acid (ALA) showed any changes in their tissue profile of PUFAs, plasma thromboxane concentrations, platelet aggregability, or hemostatic factors. DESIGN: During the study, all subjects maintained their habitual vegetarian diets except that a proportion of dietary fat was replaced with vegetable oils and margarines that were provided. Initially, all subjects consumed a low-ALA diet (containing safflower oil and safflower oil-based margarine) for 14 d; they then consumed either a moderate-ALA diet (containing canola oil and canola oil-based margarine) or a high-ALA diet (containing linseed oil and linseed oil-based margarine) for 28 d. Blood samples were collected at day 0 (baseline), day 14, and day 42. RESULTS: Eicosapentaenoic acid, docosapentaenoic acid, total n-3 PUFAs, and the ratio of n-3 to n-6 PUFAs were significantly increased (P < 0.05), whereas the ratio of arachidonic acid to eicosapentaenoic acid was decreased (P < 0.05), in platelet phospholipids, plasma phospholipids, and triacylglycerols after either the moderate-ALA or high-ALA diet compared with the low-ALA diet. No significant differences were observed in thrombotic risk factors. CONCLUSION: ALA from vegetable oils (canola and linseed) has a beneficial effect on n-3 PUFA concentrations of platelet phospholipids and plasma lipids in vegetarian males.     

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.     

Dietary modeling shows that the substitution of canola oil for fats commonly used in the United States would increase compliance with dietary recommendations for fatty acids

OBJECTIVE: To examine the effect of substituting canola oil for selected vegetable oils and canola oil-based margarine for other spreads on energy, fatty acid, and cholesterol intakes among US adults. DESIGN: Twenty-four-hour food recall data from the 1999-2002 National Health and Nutrition Examination Survey (NHANES) were used to calculate the effect of substituting canola oil for dietary corn, cottonseed, safflower, soybean, and vegetable oils described as "not further specified" and of canola oil-based margarine for other spreads at 25%, 50%, and 100% replacement levels. SUBJECTS: Adult participants aged>or=20 years (n=8,983) of the 1999-2002 NHANES. STATISTICAL ANALYSIS: Sample-weighted mean daily intake values and the percentage of subjects meeting dietary recommendations were estimated at the various replacement levels. Standard errors of the means and percentages were estimated by the linearization method of SUDAAN. RESULTS: Significant (P<0.05) changes compared to estimated actual intakes included: saturated fatty acid intake decreased by 4.7% and 9.4% with 50% and 100% substitution, respectively. Complete substitution increased monounsaturated fatty acid and alpha-linolenic acid intakes by 27.6% and 73.0%, respectively, and decreased n-6 polyunsaturated fatty acid and linoleic acid intakes by 32.4% and 44.9%, respectively. The ratio of n-6 to n-3 fatty acids decreased from 9.8:1 to 3.1:1 with 100% replacement. Energy, total fat, and cholesterol intakes did not change. CONCLUSIONS: Substitution of canola oil and canola oil-based margarine for most other vegetable oils and spreads increases compliance with dietary recommendations for saturated fatty acid, monounsaturated fatty acid, and alpha-linolenic acid, but not for linoleic acid, among US adults.     

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.     

Ischaemic heart disease and consumption of hydrogenated marine oils in England and Wales.

STUDY OBJECTIVE--The aim was to examine the hypothesis that hydrogenated fats, particularly those obtained from marine oils, may present a health hazard. DESIGN--Storage fat specimens obtained at necropsy were collected from several areas in England and Wales during 1975-1978. Cases (n = 136 samples) consisted of males dying of ischaemic heart disease, male deaths from unrelated causes acting as controls (n = 95 samples). The fatty acid compositions of the specimens were determined, and analysis included those acids--16:1 trans and "higher" C-20 plus C-22 (H)--highly characteristic of partially hydrogenated marine oils. MEASUREMENTS AND MAIN RESULTS--The case samples, which had been shown to be the richer in 16:1 trans (p less than 0.005), were now found to have a significantly higher value of the ratio 16:1 trans to H (p less than 0.002), arising from consumption of differing hydrogenated marine oil types. CONCLUSIONS--It is concluded that the cases had consumed a greater amount (p less than 0.001) of hydrogenated marine oils of a certain type, ie, that manufactured from certain highly unsaturated raw oils. The process of partial hydrogenation results in conversion to a product containing large amounts of polyunsaturated acids (PUFA) which are no longer in the natural all-cis methylene interrupted configuration. Such isomeric PUFA may obstruct or compete with utilisation of natural PUFA. It is further concluded that the case excess did not rise from medical advice favouring margarine or from any difference in social class status, but rather from fortuitous selection of margarine brand.     

Comparison of fatty acid profile in plasma phospholipids in women from Granada (southern Spain) and Malmö (southern Sweden)

We conducted a first pilot study on healthy women living in two countries with different dietary habits, Granada in the south of Spain and Malm? in the south of Sweden, in order to compare their levels of plasma phospholipid fatty acids, and to examine the relationship between the differences in food consumption. This study is part of a pilot study which is nested in the European Prospective Investigation into Cancer and Nutrition, a multi-centre prospective cohort study on diet, plasma concentrations of antioxidants and fatty acids, and markers of oxidative stress. Thirty-nine women in Granada and thirty-eight women in Malm?, aged 45-50 years (all pre-menopausal) were selected among the female participants in the cohorts from these two countries. Individual measurements of the women's habitual diet were obtained by a food frequency questionnaire. 24-hour diet recalls were used for the standardised measurement of diet at group level. Plasma phospholipid fatty acid composition was determined by capillary gas chromatography. We found a different fatty acid profile in plasma between the two populations, with higher mean levels of palmitic acid (16:0), palmitoleic acid (16:1) (n-7), oleic acid (18:1), alpha-linolenic acid (18:3) (n-3) and eicosapentaenoic acid (20:5) (n-3), and lower mean levels of stearic acid (18:0) in Malm? compared to Granada. Women in Malm? consumed more meat, alcoholic beverages and sugar, and less fish and shellfish than women in Granada. We conclude that the fatty acid composition in plasma phospholipids is different between women from the two European centres. For polyunsaturated fatty acids, differences were observed for (n-3) fatty acids. In relation to these differences, we observed that specific food intakes, particularly meat and fish, varied between the two centres.     

Acides gras trans : nature, origine et impact sur la santé

Trans fatty acids include mono- and poly-unsaturated fatty acids having methylene interrupted double bonds. Trans monounsaturated fatty acids are formed during hydrogenation of oils to produce margarine and shortening but are also present in ruminant meat and milk as a result of biohydrogenation in the rumen. The linoleic and a-linolenic acid trans isomers may also be present in non-hydrogenated fats as the result of exposure of these polyunsaturated fatty acids to heat treatment, such as steam deodorization, or deep fat frying in food.Trans monounsaturated isomers are the major trans isomers consumed by humans. Data on trans fatty acids were obtained from nutritional interventions but also from epidemiological studies. For example, a meta analysis of 60 controlled trials published between 1970 to 1998 which included over 1,600 volunteers showed that replacing carbohydrates isoenergetically (1% of total energy) by 18: 1 trans would increase LDL cholesterol while the effect on HDL would be similar. The calculated impact on the ratio of total cholesterol/HDL would be of +0.022nmoles/L (p=0.015). A recent meta analysis of the four larger epidemiological studies showed that increasing the total energy intake with 2% trans fatty acids would result in a 23% increase in cardiovascular disease risk.However, it is essential now to answer the following question: Are trans fatty acids from natural origin have the same effects as those demonstrated for the “industrial ones”. Some studies which are being carried out should give some new information on this important still pending question despite the number of studies so far carried out.     

Reassessment of trans fatty acid availability in the US diet

This report updates our 1984 estimate of the amount of trans fatty acids available for consumption in the US diet, namely 7.6 g.person-1.d-1, for 1989. Compared with 1984 data, we found essentially no change in 1989 for the per capita availability of trans fatty acids from total food service fats and oils. The 1989 value we obtained for industrial fats and oils is somewhat higher than the value we reported for 1984, in part because more complete data were available for 1989. In contrast, however, since 1984 the per capita availability of trans fatty acids from household salad and cooking oils, household shortenings, and all margarines and spreads (retail, food service, and industrial) has decreased. Overall, our reassessed (1989) value for total trans fatty acid availability is 8.1 g.person-1.d-1, which is similar to our original estimate. This total may increase slightly (approximately 0.3 g.person-1.d-1) as a result of the recent switch by many establishments from the use of tallow to partially hydrogenated vegetable oils for frying.     

Comparative physiological effects of partially hydrogenated herring and rapeseed oils in the rat. 1. Mean-term effects on growth, organ weights and heart histology]

Two partially hydrogenated herring oils, containing 15% or 30% of C 22: 1, supplemented or not with linoleic (maize oil), have been fed for 16 weeks to growing rats (15% by weight in the diet), and their effects have been compared to those of peanut oil (controls), and to those of 2 mixtures of rapeseed oil and peanut oil having similar C 22:1 contents (15% and 30%). On the basis of equal amounts of ingested food, the growth of the rats is lower with herring and rapeseed oil than with peanut oil; this phenomenon is emphasized in the case of the non--C 18:2--supplemented herring oils. Herring and rapeseed oils induce an increase of liver particularly with the one having the highest content of trans fatty acids. Heart lesions have been observed in rats feed herring or rapeseed oils, not in the control group. The frequency of these lesions is greater with rapeseed oil (11/13) than with herring oils (11/24). This result suggests that erucic acid (cis delta 13 docosenoic acid) is more pathogenic than at least some of its isomers present in the hydrogenated herring oils (particularly the trans isomers). In the second part of this paper, we report the effects of the tested dietary fats on organ lipids after very short-term (3-7 days) or mean-term (16 weeks) experiments.     

Comparison between plasma and erythrocyte fatty acid content as biomarkers of fatty acid intake in US women

BACKGROUND: Erythrocyte fatty acids may be superior to plasma fatty acids for reflecting long-term fatty acid intake because of less sensitivity to recent intake and a slower turnover rate. OBJECTIVE: The objective was to compare the fatty acid content of erythrocytes with that of plasma with respect to their abilities to reflect usual fatty acid intake. DESIGN: Fatty acids in plasma and erythrocytes were measured by capillary gas-liquid chromatography in 306 US women aged 43-69 y. Fatty acid intake was assessed with a food-frequency questionnaire, which was validated for measuring intakes of various fatty acids. RESULTS: Docosahexaenoic acid (DHA, 22:6n-3) in erythrocytes and plasma provided the strongest correlations with its intake, but erythrocyte DHA concentrations [Spearman's partial correlation coefficient (r(s))=0.56] were better than plasma DHA concentrations (r(s)=0.48) as a biomarker. Total trans fatty acids (r(s)=0.43) and total 18:1 trans isomers (r(s)=0.42) in erythrocytes were also more strongly correlated with intake than were those in plasma (r(s)=0.30 and r(s)=0.29, respectively). Moderate correlations were observed for linoleic acid (18:2n-6; erythrocytes, r(s)=0.24; plasma, r(s)=0.25), alpha-linolenic acid (18:3n-3; erythrocytes, r(s)=0.18; plasma, r(s)=0.23), and eicosapentaenoic acid (20:5 n-3; erythrocytes, r(s)=0.38; plasma, r(s)=0.21). For polyunsaturated and trans fatty acids, correlations between intakes and biomarkers improved moderately when average intakes over previous years were used. CONCLUSION: Erythrocyte n-3 fatty acids of marine origin and trans fatty acid content are suitable biomarkers for long-term intake.