Trans fatty acids. 2. Fatty acid composition of the brain and other organs in the mature female pig

Female pigs were fed from three wk of age and up to two years a diet containing partially hydrogenated fish oil (PHFO, 28%trans monoenoic fatty acids), partially hydrogenated soybean oils (PHSBO, 36%trans fatty acids) or lard. No consistent differences were found between PHFO and PHSBO with regard to incorporation oftrans fatty acids in organ lipids, buttrans incorporations were highly organ-specific. Notrans fatty acids were detected in brain phosphatidylethanolamine (PE). The incorporation of monoenoictrans isomers, as a percentage of totalcis + trans, in other organs was highest in subcutaneous adipose tissue and liver mitochondria PE, followed by blood lipids with the lowest level in heart PE. The percentage oftrans isomers compared with that of dietary lipids was consistently lower for 20∶1, compared with 18∶1 in organs from PHFO-fed pigs. The only effect of dietarytrans fatty acids on the fatty acid pattern of brain PE was an increased level of 22∶5n−6. Heart PE and total serum lipids of pigs fed the hydrogenated fats contained higher levels of 18∶2n−6, and these lipids of the PHFO-fed group also contained slightly elevated amounts of 20∶3n−6, 18∶3n−3 and 20∶5n−3. Liver mitochondria PE of the PHFO group also contained higher levels of 20∶3n−6 and 22∶5n−6. Dietarytrans fatty acids caused a consistent decrease of saturated fatty acids compensated by increased levels of monoenes. Thus, it may be concluded that dietary long-chaintrans fatty acids in PHFO behaved similarly metabolically to 18∶1-trans in PHSBO in pigs, without noticeable influence on brain PE composition and with moderate to slight effects on the fatty acid profile of the other organs.     

Trans fatty acids. 3. Fatty acid composition of the brain and other organs in the newborn piglet

The effects of dietarytrans fatty acids on tissue fatty acid composition were studied in newborn piglets delivered from sows fed partially hydrogenated fish oil (PHFO) (28%trans) or partially hydrogenated soybean oil (PHSBO) (36%trans) in comparison with lard (0%trans) from 3 wk of age and through gestation in Experiment 1, or fed PHFO or “fully” hydrogenated fish oil (HFO) (19%trans) in comparison with coconut oil (CF) (0%trans) with two levels, 1 and 2.7%, of dietary linoleic acid from conception through gestation in Experiment 2. The piglets were sampled immediately after delivery, without having access to mothers' milk. Incorporation oftrans fatty acids into brain PE (phosphatidylethanolamine) were non-detectable or very low (less than 0.1%). The incorporation of 18∶1trans into heart-PE, liver mitochondria-PE, total plasma lipids and adipose tissue was low, and 20∶1trans was not detected. Dietarytrans fatty acids had no consistent effects on the overall fatty acid composition of the different tissue lipids. It is conclude thattrans fatty acids from PHFO, HFO and PHSBO have no significant effects on the fatty acid accretion in the fetal piglet.     

trans fatty acids, 5. Fatty acid composition of lipids of the brain and other organs in suckling piglets

The effects of dietarytrans fatty acids on the fatty acid composition of the brain in comparison with other organs were studied in 3-wk-old suckling piglets. In Experiment (Expt.) 1 the piglets were delivered from sows fed partially hydrogenated fish oil (PHFO) (28%trans), partially hydrogenated soybean oil (PHSBO) (36%trans) or lard (0%trans). In Expt. 2 the piglets were delivered from sows fed PHFO, hydrogenated fish oil (HFO) (19%trans) or coconut fat (CF) (0%trans) with two levels of dietary linoleic acid (1 and 2.7%) according to factorial design. In both experiments the mother's milk was the piglets' only food. The level of incorporation oftrans fatty acids in the organs was dependent on the levels in the diets and independent of fat source (i.e., PHSBO, PHFO or HFO). Incorporation oftrans fatty acids into brain PE (phosphatidylethanolamine) was non-detectable in Expt. 1. In Expt. 2, small amounts (less than 0.5%) of 18∶1trans isomers were found in the brain, the level being slightly more on the lower level of dietary linoleic acid compared to the higher. In the other organs the percentage of 18∶1trans increased in the following order: heart PE, liver mitochondria PE, plasma lipids and subcutaneous adipose tissue. Small amounts of 20∶1trans were found in adipose tissue and plasma lipids. Other very long-chain fatty acids from PHFO or HFO (i.e., 20∶1cis and 22∶1cis+trans) were found in all organ lipids except for brain PE. Dietarytrans fatty acids increased the percentage of 22∶5n−6 in brain PE. Except for the brain and the heart, dietarytrans fatty acids reduced the percentage of saturated fatty acids and increased the percentage of monoenoic acids (includingtrans). The overall conclusion was that dietarytrans fatty acids had no noticeable effect on the brain PE composition but slight to moderate effects on the fatty acid profile of other organs of suckling piglets.     

Trans fatty acids. 1. Growth,fertility, organ weights and nerve histology and conduction velocity in sows and offspring

Effects of dietarytrans fatty acids on the pre- and postnatal growth and development in pigs were studied with special emphasis on nervous tissue. In experiment 1, female pigs were fed partially hydrogenated fish oil (PHFO) (28%trans) or soybean oil (PHSBO) (36%trans), in comparison with lard (0%trans) from weaning (3 wk) through the first reproduction cycle (up to 2 yr). In experiment 2, female pigs were fed two fish oils (33 and 19%trans) in comparison with coconut oil (0%trans) in diets with low and high levels of linoleic acid (18∶2n−6cis,cis) from gestation until their offspring were three wk old. Compared with thetrans-free fats, thetrans-containing fats had no effect on growth and development, feed consumption and utilization or on the weight of the brain, heart, kidneys, liver, lungs or spleen in the adult sows and their offspring. No effects from the experimental fats were found on histology and conduction velocity of the peroneal nerve. An increased number of the sows fed PHFO had fertility problems compared with those fed lard and PHSBO in Expt. 1, but no similar effects were seen in Expt. 2. It is concluded that consumption oftrans fatty acids with 18–22 carbon atoms from PHFO and with 18 carbon atoms from PHSBO at levels that were 5 to 12 times higher than those normally consumed by humans had no detrimental effects on female pigs or their offspring during pregnancy and lactation.     

Influence of dietary linoleic acid andtrans fatty acids on the fatty acid profile of cardiolipins in rats

Cardiolipins (CL) have unique fatty acid profiles with generally high levels of polyunsaturated fatty acids, primarily 18∶2n−6, and low levels of saturated fatty acids. In order to study the effect of dietary fatty acid isomers on the fatty acid composition of cardiolipins, rats were fed partially hydrogenated marine oils (HMO), rich in 16∶1, 18∶1, 20∶1, and 22∶1 isomeric fatty acids, supplemented with linoleic acid at levels ranging from 1.9% to 14.5% of total fat. Although the dietary fats contained 33%trans fatty acids, the levels oftrans fatty acids in CL were below 2.5% in all organs. The fatty acid profiles of cardiolipins of liver, heart, kidney and testes showed different responses to dietary linoleic acid level. In liver, the contents of 18∶2 reflected the dietary levels. In heart and kidney, the levels of 18∶2 also parallelled increasing dietary levels, but in all groups fed HMO, levels of 18∶2 were considerably higher than in the reference group fed palm oil. In testes, the 18∶2 levels were unaffected by the dietary level of 18∶2 and HMO.     

Rat testicular lipids and dietary isomeric fatty acids in essential fatty acid deficiency

Weanling rats were fed essential fatty acid-deficient diets, either completely fat-free, or with partially hydrogenated fish oil (PHFO, 28 wt %), or with fractions derived from PHFO containing primarily positional isomers oftrans-eicosenoate (20∶1, 3 wt %) ortrans-docosenoate (22∶1, 3 wt %). Control animals were fed a peanut oil-containing diet (28 wt %). After 5 or 15 weeks on the diet, the content of neutral and phosphorus-containing lipids in the testes was determined. The fatty acid distribution in major lipid classes was analyzed for animals fed the diets for 15 weeks. The testicular stage of maturation or degeneration was assessed by histology. The group fed PHFO exhibited signs of complete testicular degeneration, or lack of maturation, already after 5 weeks, whereas the animals on the diets with the very long chain monoenoic acids suffered severe degenerations only after 15 weeks. In the PHFO-fed rats, a sharp decline in the concentration of testicular triacylglycerols was observed. In all of the essential fatty acid-deficient groups, an increase in testicular sphingomyelin was observed. Cholesterol levels were fairly similar among all dietary groups. The total testicular fatty acids of the PHFO-fed animals contained somewhat more eicosadienoic acid than found in the other groups, and somewhat less (n−9)-acids. In all EFA-deficient groups, (n−6)-acids were lowered, in particular in triacylglycerols and phosphatidyl cholines. The PHFO group did not show a lower (n−6)-concentration than the other deficient groups, in spite of the more severe symptoms of deficiency. There was no evidence of a major accumulation of long chain isomeric fatty acids in the degenerated testes of the PHFO-, 20∶1, and 22∶1-fed groups.     

Incorporation ofcis- andtrans-octadecenoic acids into the membranes of rat liver mitochondria

The incorporation of dietary isomeric fatty acids into the membranes of liver mitochondria was investigated. Three groups of rats were fed diets containing 3% sunflower seed oil plus 15%, 20%, or 25% partially hydrogenated arachis oil. A fourth group was fed 25% partially hydrogenated arachis oil, but no sunflower seed oil. All diets were given for 3, 6, or 10 weeks. After 10 weeks, the content oftrans fatty acids in the lipids of the mitochondrial membranes was 15–19% of the total fatty acids. The composition of thetrans- and thecis-octadecenoic acids in the lipids of the mitochondrial membranes was similar for all groups supplemented with sunflower seed oil (SO), irrespective of time and dietary level of partially hydrogenated arachis oil (HAO). Thecis 18∶1 (n−8), which was a major isomer of the partially hydrogenated arachis oil, was almost excluded from the mitochondrial fatty acids. Likewise, the content oftrans 18∶1 (n−8) was considerably lower in the mitochondrial lipids than in the diet. On the contrary, the content oftrans 18∶1 (n−6) was higher in the mitochondrial lipids than in the diet. In the group fed without sunflower seed oil, isomers of linoleic acid and arachidonic acid were observed in the lipids of mitochondrial membranes. Presented in part at the ISF Congress, Marseille, September 1976.     

Dietary linoleic acid and the fatty acid profiles in rats fed partially hydrogenated marine oils

The influence of the linoleic acid levels of diets containing partially hydrogenated marine, oils (HMO) rich in isomeric 16∶1, 18∶1, 20∶1 and 22∶1 fatty acids on the fatty acid profiles of lipids from rat liver, heart and adipose tissue was examined. Five groups of rats were fed diets containing 20 wt% fat−16% HMO+4% vegetable oils. In these diets, the linoleic acid contents varied between 1.9% and 14.5% of the dietary fatty acids, whereas the contents oftrans fatty acids were 33% in all groups. A sixth group was fed a partially hydrogenated soybean oil (HSOY) diet containing 8% linoleic acid plus 32%trans fatty acids, mainly 18∶1, and a seventh group, 20% palm oil (PALM), with 10% linoleic acid and notrans fatty acids. As the level of linoleic acid in the HMO diets increased from 1.9% to 8.2%, the contents of (n−6) polyunsaturated fatty acids (PUFA) in the phospholipids increased correspondingly. At this dietary level of linoleic acid, a plateau in (n−6) PUFA was reached that was not affected by further increase in dietary 18∶2(n−6) up to 14.5%. Compared with the HSOY- or PALM-fed rats, the plateau value of 20∶4(n−6) were considerably lower and the contents of 18∶2(n−6) higher in liver phosphatidylcholines (PC) and heart PC. Heart phosphatidylethanolamines (PE) on the contrary, had elevated contents of 20∶4(n−6), but decreased 22∶5(n−6) compared with the PALM group. All groups fed HMO had similar contents oftrans fatty acids, mainly 16∶1 and 18∶1, in their phospholipids, irrespective of the dietary 18∶2 levels, and these contents were lower than in the HSOY group. High levels of linoleic acid consistently found in triglycerides of liver, heart and adipose tissue of rats fed HMO indicated that feeding HMO resulted in a reduction of the conversion of linoleic acid into long chain PUFA that could not be overcome by increasing the dietary level of linoleic acid.     

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.     

Essential fatty acid-deficient rats: II. On the fatty acid composition of partially hydrogenated arachis,soybean and herring oils and of normal,refined arachis oil

The fatty acid composition of partially hydrogenated arachis (HAO), partially hydrogenated soybean (HSO) and partially hydrogenated herring (HHO) oils and of a normal, refined arachis oil (AO) was studied in detail by means of direct gas liquid chromatography, ultraviolet and infrared spectrophotometry and by thin layer chromatography fractionation on silver nitrate-silica gel plates followed by gas liquid chromatography. It was shown that the partially hydrogenated oils all contained fatty acids withtrans double bonds. In the plant oils, thetrans acids were present mainly as elaidic acid. The HHO showed an almost equal distribution betweentrans 18∶1 ω9,trans 20∶1 ω>9 andtrans 22∶1 ω>9. Sometrans configuration was also found in the C₂₀-and C₂₂-dienes and trienes of the HHO. In all the oils, conjugated fatty acids were present in minor amounts only (<0.5%). Special attention was given to the ω-acids known to be of specific nutritional value. The HSO contained about 32% linoleic acid, whereas the content ofcis, trans+trans, cis andtrans, trans octadecadienoic isomers was 1.7% and 0.5%, respectively. The amount of linoleic acid in the HSO was even higher than that of AO (29%). The HAO contained only 0.8% 18∶2 ω6 (linoleic acid). Further, two 18∶2 fatty acids with ω>6, acis, cis and atrans, trans isomer, were present in small amounts. The HHO contained 0.5% 18∶2 ω6 (linoleic acid). Isomers of 18∶2 ω>6 were also found in the HHO. They may be hydrogenation products of higher unsaturated C₁₈-acids orginally present. All the C₂₀- and C₂₂-dienes and trienes were shown to have an ω-chain greater than 6. Fatty acids with ω6-structure were not formed during partial hydrogenation of the oils studied.     

Influence of moderate amounts of trans fatty acids on the formation of polyunsaturated fatty acids

The effect of trans fatty acids from partially hydrogenated soybean oil and butterfat on the formation of polyunsaturated fatty acids was investigated. Five groups of rats were fed diets that contained 20 wt% fat. The content of linoleic acid was adjusted to 10 wt% of the dietary fats in all diets, whereas the amount of trans fatty acids from partially hydrogenated soybean oil (PHSBO) was varied from 4.5 to 15 wt% in three of the five diets. The fourth group received trans fatty acids from butterfat (BF), while the control group was fed palm oil without trans fatty acids. Trans fatty acids in the diet were portionally reflected in rat liver and heart phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol, and phosphatidylserine. Incorporation in the sn-1 position was compensated by a decrease in saturated fatty acids. Trans fatty acids were not detected in diphosphatidylglycerol. Compared to the presence in the dietary fats, 8t- and 10t-18:1 were discriminated against in the incorporation in PE and PC from liver and heart, whereas 9t- and 12t-18:1 were preferred. The formation of 20:4n-6 was not influenced by 4.5 wt% trans fatty acids (from PHSBO) but apparently was by 10 wt% in liver. In contrast, even a content of 2.5 wt% trans fatty acids from BF reduced the formation of 20:4n-6. The inhibitory effect of trans isomers on linoleic acid conversion was reflected less in heart than in liver and less for PE than for PC. Groups with trans fatty acids showed increased 22:6n-3 and 22:5n-3 deposition in liver and heart PE and PC.     

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.     

Hydrolysis of linoleate geometric isomers byGeotrichum candidum lipase

Lipase (EC 3.1.1.3) from the microorganismGeotrichum candidum preferentially hydrolyzescis-9 18∶1 andcis,cis-9,12 18∶2 from triacylglycerols, largely ignoring all other positional isomers ofcis 18∶1 as well astrans-9 18∶1. To obtain additional information about the specificity of the enzyme, two triacylglycerols were prepared and utilized as substrates. The lipase hydrolyzed 85%cis,cis-9,12 18∶2 and 15%trans,trans-9,12 18∶2 from the triacylglycerol, containing ca. 50% of each acid. From the triacylglycerol containing 46.3%cis,trans-9,12 18∶2 and 53.7%trans,cis-9,12 18∶2, 44.8 and 55.2% of the two acids were hydrolyzed. Therefore the enzyme discriminated against thetrans,trans isomer but not between thecis,trans andtrans,cis isomers. Scientific contribution No. 535, Agricultural Experiment Station, University of Connecticut. ARS, USDA.     

Liver subcellular fatty acid profiles of chicks fed diets containing hydrogenated fats and varying linoleate levels

Day-old male broiler chickens were fed semipurified diets containing 5% lipid from one of four different lipid sources: corn oil (CO), partially hydrogenated soybean oil (HSBO), a spent restaurant grease (SRG) and a purified mixture of triolein, tripalmitin and tristearin (OPS). Diets CO and HSBO contained adequate amounts of linoleic acid, but diets SRG and OPS were deficient in linoleate. In addition, SRG and HSBO containedtrans isomers of 16∶1 and 18∶1. The diets were fed for 3 wk to determine the effects of low linoleate levels andtrans isomers on fatty acid profiles in liver microsomes, mitochondria and cytosol. Chicks fed HSBO had the highest body weights, while those fed SRG and OPS had the lowest. The incidence and severity of dermatitis were similar for all treatments. The proportions of linoleate and arachidonate in lipids from liver subcecullar fractions were reduced significantly in chicks fed OPS and SRG; however levels of 20∶3ω9 were not increased. Feeding HSBO, which is high in both linoleate and linolenate, resulted in higher levels of 18∶3ω3 and 20∶5ω3 in liver subcellular fractions and lower levels of 20∶4ω6 than those seen in chicks fed CO. The isomeric forms of 18∶1 present in the partially hydrogenated fats (HSBO and SRG) appeared to be incorporated into the lipids of liver fractions. The results of this study show that dietary lipids influence fatty acid, profiles of chick liver microsomes, mitochondria and cytosol. Decreases in linoleate and arachidonate in these organelles occur before overt essential fatty acid (EFA) deficiency signs in chicks fed EFA-deficient diets. Published as Scientific Paper No. 7512, College of Agriculture and Home Economics Research Center, Project No. 4723, Washington State University, Pullman, WA.     

Influence of partially hydrogenated vegetable and marine oils on lipid metabolism in rat liver and heart

Partially hydrogenated marine oils containing 18∶1-, 20∶1- and 22∶1-isomers and partially hydrogenated peanut oil containing 18∶1-isomers were fed as 24–28 wt % of the diet with or without supplement of linoleic acid. Reference groups were fed peanut, soybean, or rapeseed oils with low or high erucic acid content. Dietary monoene isomers reduced the conversion of linoleic acid into arachidonic acid and the deposition of the latter in liver and heart phosphatidylcholine. This effect was more pronounced for the partially hydrogenated marine oils than for the partially hydrogenated peanut oil. The content oftrans fatty acids in liver phospholipids was similar in groups fed partially hydrogenated fats. The distribution of various phospholipids in heart and liver was unaffected by the dietary fat. The decrease in deposition of arachidonic acid in rats fed partially hydrogenated marine oils was shown in vitro to be a consequence of lower Δ6-desaturase activity rather than an increase in the peroxisomal β-oxidation of arachidonic acid. The lower amounts of arachidonic acid deposited may be a result of competition in the Δ6-desaturation not only from the C22-and C20-monoenoic fatty acids originally present in the partially hydrogenated marine oil, but also from C18- and C16-monoenes produced by peroxisomal β-oxidation of the long-chain fatty acids. Part of this work was presented at the ISF-AOCS Congress, New York City, 1980.     

Occurrence of 5c,8c,11c,15t-eicosatetraenoic acid and other unusual polyunsaturated fatty acids in rats fed partially hydrogenated calola oil

Uncommoncis andtrans fatty acids can be desaturated and elongated to produce unusual C₁₈ and C₂₀ polyunsaturated fatty acids in animal tissues. In the present study we examined the formation of such metabolites derived fromcis andtrans isomers of oleic and linoleic acids of partially hydrogenated vegetable oil origin in rats. For two months, aduut male rats were fed a partially hydrogenated canola oil diet containing moderately high levels oftrans fatty acids (9.6 energy%) and an adequate level of linoleic acid (1.46 energy%). Analysis of the phospholipid (PL) fatty acids of liver, heart, serum and brain showed no new C₁₈ polyunsaturated fatty acids, except for those uncommon 18∶2 isomers originating from the diet. However, minor levels (each <0.3% PL fatty acids) of six unusual C₂₀ polyunsaturated fatty acids were detected in the tissues examined, except in brain PL. Identification of their structures indicated that the dietary 9c,13t−18∶2 isomer, which is the majortrans polyunsaturated fatty acid in partially hydrogenated vegetable oils, was desaturated and elongated to 5c,8c,11c,15t−20∶4, possibly by the same pathway that is operative for linoleic acid. Furthermore, dietary 12c−18∶1 was converted to 8c,14c−20∶2 and 5c,8c,14c−20∶3; dietary 9c,12t−18∶2 metabolized to 11c,14t−20∶2 and 5c,8c,11c14t−20∶4, and dietary 9t,12c to 11t,14c−20∶2. These results suggested that of all the possible isomers of oleic and linoleic acids in partially hydrogenated vegetable oils, 12c−18∶1, 9c,13t−18∶2, 9c,12t−18∶2 and 9t,12c−18∶2 are the preferred substrates for desaturation and elongation in rats. However, their conversions to C₂₀ metabolites were not as efficient as that of oleic or linoleic acids.     

Trans fatty acids in adipose tissue of French women in relation to their dietary sources

This study reports the fatty acid composition of subcutaneous adipose tissue in French women with special emphasis on the content of trans fatty acids originating from two main dietary sources, ruminant fats and partially hydrogenated vegetable oils (PHVO). Adipose tissue trans fatty acid levels from 71 women, recruited between 1997 and 1998, were determined using a combination of capillary gas chromatography and silver nitrate thin-layer chromatography. Results indicate that on average cis monounsaturates accounted for 47.9% of total fatty acids, saturates for 32.2%, and linoleic acid for 14.4%. Cis n−3 polyunsaturates represented only 0.7%. Total content of trans fatty acids was 2.32±0.50%, consisting of trans 18∶1 (1.97±0.49%), trans 18∶2 (0.28±0.08%), and trans 16∶1 (0.06±0.03%). Trans 18∶3 isomers were not detectable. The level of trans fatty acids found in adipose tissue of French women was lower than those reported for Canada, the United States, and Northern European countries but higher than that determined in Spain. Therefore, trans fatty acid consumption in France appears to be intermediate between that of the United States or North Europe and that of Spain. Based on the equation of Enig et al., we estimated the mean daily trans 18∶1 acid intake of French women at 1.9 g per person. The major trans 18∶1 isomer in adipose tissue was Δ11trans, as in ruminant fats. Estimates of relative contribution of trans fatty acid intake were 55% from ruminant fats and 45% from PHVO. This pattern contrasts sharply with those established for Canada and the United States where PHVO is reported to be the major dietary source of trans fatty acids.     

Essential fatty acid-deficient rats: I. Growth and testes development

Partially hydrogenated oils as the sole dietary fat enhances the development of essential fatty acid (EFA) deficiency in young rats. Partially hydrogenated herring oil (HHO) caused total impairment of the spermatogenic tissue after five weeks of experiment, while partially hydrogenated arachis oil (HAO) caused severe degeneration of this tissue in 15 weeks. A fat-free diet caused degeneration in 26 weeks. In the dietary fats, the total content oftrans acids, calculated as elaidic acid, was 47% and 23% in HAO and HHO, respectively. Further, varying amounts of different positional isomeric fatty acids were also present in the partially hydrogenated oils. Besides the specific tissue changes, poor growth, poor feed efficiency and skin signs characteristic of EFA deficiency were noticed. On the other hand, partially hydrogenated soybean oil (HSO) as the sole dietary fat kept the animals normal in all respects. this oil still contained 32% linoleic acid; the total content oftrans acids amounted to 11%, calculated as elaidic acid.     

Interrelationship between dietarytrans fatty acids and the 6- and 9-desaturases in the rat

Studies are reported on the effects of dietarytrans fatty acids on the 6- and 9-acyl desaturase activities in the liver microsomes of rats fed essential fatty acid (EFA)-deficient and non-FFA-deficient diets. In experiment I, weanling male rats were fed a semisynthetic diet with either 10% safflower oil (SAF) or 10% hydrogenated coconut oil (HCO). At the age of one year, half of the dietary fat was replaced by a supplement containing elaidate, linolelaidate andcis,trans-trans,cis-18∶2 (TRANS) for 12 weeks. In experiment II, male rats which were kept from weaning on a 10% SAF diet for one year received one of the following fat supplements for a 12-week period: 10% HCO, 9% HCO+1% TRANS, or 5% HCO+5% TRANS. Feeding TRANS depressed the 6-desaturase activity in the liver microsomes, especially in the EFA-deficient rats (HCO+TRANS group of experiment I). Unlike the 6-deaturase activity, the 9-desaturase activity was not inhibited by the dietarytrans fatty acids and was significantly stimulated in the non-EFA-deficient rats (SAF+TRANS group of experiment I and HCO+TRANS groups of experiment II). This was evidenced by incubation reactions and by comparisons of fatty acid consumptions and microsomal fatty acid levels, showing extra biosynthesis of 16∶1 and 18∶1 when TRANS was fed. The biosynthesis of essential (n−6) fatty acids was depressed by the TRANS supplement in EFA-deficient as well as in non-EFA-deficient animals.     

Adenylate cyclase and β-receptors in salivary glands of rats fed diets containingtrans fatty acids

The effects oftrans fatty acids on adenylate cyclase were determined in the submandibular salivary glands (SMSG) of rats fed diets containing 20% corn oil, 20% partially hydrogenated soybean oil (PHSBO) or 18% PHSBO + 2% corn oil. The fluoride-and isoproterenol-stimulated adenylate cyclase activities were higher in the SMSG from rats fed 20% PHSBO than in the control group fed 20% corn oil. The feeding of 2% corn oil with the diet containing 18% PHSBO resulted in a complete restoration of isoproterenol-stimulated and a partial restoration of fluoride-stimulated adenylate cyclase activity. There was no significant difference in the concentration of the β-adrenergic receptor or in the receptor-binding affinity constants among the three dietary groups as measured by [³H]dihydroalprenolol (DHA)-binding. Higher fluorescence polarization of diphenyl hexatriene (DPH) was observed in SMSG membranes of rats fed diet containing 20% PHSBO than in the other two oils, suggesting that membrane fluidity may play a role in adenylate cyclase activity.