Bernard Entressangles

Follow-up of the Δ4 to Δ16 trans-18:1 isomer profile and content in French processed foods containing partially hydrogenated vegetable oils during the period 1995-1999. Analytical and nutritional implications.

A survey of the total content of trans-18∶1 acids and their detailed profile in French food lipids was conducted in 1995–1996, and 1999. For this purpose, 37 food items were chosen from their label indicating the presence of partially hydrogenated vegetable oils (PHVO) in their ingredients. The content as well as the detailed profile of these isomers was established by a combination of argentation thin-layer chromatography and gas-liquid chromatography (GLC) on long polar capillary columns. With regard to the mean trans-18∶1 acid contents of extracted PHVO, a significant decrease was observed between the two periods, i.e., from 26.9 to 11.8% of total fatty acids. However, only minor differences were noted in the mean relative distribution profiles of individual trans-18∶1 isomers with ethylenic bonds between positions Δ4 and Δ16 for the two periods. The predominant isomer was Δ9–18∶1 (elaidic) acid, in the wide range 15.2–46.1% (mean, 27.9±7.2%) of total trans-18∶1 acids, with the Δ10 isomer ranked second, with a mean of 21.3% (range, 11.6 to 27.4%). The content of the unresolved Δ6 to Δ8 isomer group was higher than the Δ11 isomer (vaccenic acid), representing on average 17.5 and 13.3%, respectively. Other isomers Δ4, Δ5, Δ12, Δ13/Δ14, Δ15, and Δ16, were less than 10% each: 1.0, 1.6, 7.4, 7.1, 1.8, and 1.0%, respectively. However, considering individual food items, it was noted that none of the extracted PHVO were identical to one another, indicating a considerable diversity of such fats available to the food industry. A comparison of data for French foods with similar data recently established for Germany indicates that no gross differences occur in PHVO used by food industries in both countries. Estimates for the absolute mean consumption of individual isomers from ruminant fats and PHVO are made for the French population and compared to similarly reconstructed hypothetical profiles for Germany and North America. Differences occur in the total intake of trans-18∶1 acids, but most important, in individual trans-18∶1 isomer intake, with a particular increase of the Δ6–Δ8 to Δ10 isomers with increasing consumption of PHVO. It is inferred from the present and earlier data that direct GLC of fatty acids is a faulty procedure that results (i) in variable underestimates of total trans-18∶1 acids, (ii) in a loss of information as regards the assessment of individual isomeric trans-18∶1 acids, and (iii) in the impossibility of comparing data obtained from human tissues if the relative contribution of dietary PHVO and ruminant fats is not known.

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.

In vitro behavior of marine lipid-based liposomes. Influence of pH, temperature, bile salts, and phospholipase A2.

To deliver polyunsaturated fatty acids (PUFA) by the oral route, liposomes based on a natural mixture of marine lipids were prepared by filtration and characterized in media that mimic gastrointestinal fluids. First the influence of large pH variations from 1.5–2.5 (stomach) to 7.4 (intestine) at the physiological temperature (37°C) was investigated. Acidification of liposome suspensions induced instantaneous vesicle aggregation, which was partially reversible when the external medium was further neutralized. Simultaneously, complex morphological bilayer rearrangements occurred, leading to the formation of small aggregates. These pH- and temperature-dependent structural changes were interpreted in terms of osmotic shock and lipid chemical alterations, i.e., oxidation and hydrolysis, especially in the first hours of storage. Besides, oxidative stability was closely related to the state of liposome aggregation and the supramolecular organization (vesicles or mixed micelles). The effects of bile salts and phospholipase A2 (PLA2) on the liposome structures were also studied. Membrane solubilization by bile salts was favored by preliminary liposome incubation in acid conditions. PLA2 showed a better activity on liposome structures than on the corresponding mixed lipid-bile salt micelles. As a whole, in spite of slight morphological modifications, vesicle structures were preserved after an acid stress and no lipid oxidation products were detected during the first 5 h of incubation. Thus, marine lipids constituted an attractive material for the development of liposomes as potential oral PUFA supplements.

Steady-state fluorescence polarization study of structurally defined phospholipids from liver mitochondria of rats fed elaidic acid

In vivo-modified phospholipids from rat liver mitochondria were used to study the effect of trans-fatty acid incorporation into phospholipids on the steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) embedded in phospholipid liposomes. Pure fractions of mitochondria phospholipids were prepared and analyzed for their fatty acid compositions and fatty acid positional distribution. In rats fed a diet enriched with trielaidin, elaidic acid (trans-9 18:1 acid) was extensively incorporated in position 1 of phosphatidylcholine (PC; 31% of fatty acids esterified to this position), phosphatidylethanolamine (PE; 42.5%) and phosphatidylinositol (PI; 43%). Less than 10% of the incorporated elaidic acid was esterified to position 2 of these phospholipids. More than 90% of elaidic acid esterified to position 1 displaced saturated acids. Consequently, about one-third of PC molecules and two-fifths of PE and PI molecules contained one molecule of elaidic acid instead of one saturated fatty acid molecule in their 1-position. On the other hand, cardiolipin, which is naturally practically devoid of saturated acids, was particularly resistant to elaidic acid incorporation. The fluorescence polarization of DPH incorporated in liposomes made of PC-PI and of PC-PI-PE from liver mitochondria of rats fed or not fed elaidic acid was measured. No significant differences between phospholipids containing or not containing elaidic acid could be detected. Values of DPH fluorescence polarization for all samples were comprized between 0.133 and 0.135 at 25 degrees C. We thus conclude that when elaidic acid replaces saturated fatty acids in phospholipids, even in a high proportion (one-third), the physical state of acyl chains in the hydrophobic core of membranes is not grossly modified. Thus, elaidic acid seems to behave like a saturated fatty acid, not only biochemically for the acylation of phospholipids, but also physically.

Positional distribution of fatty acids in cardiolipin of mitochondria from 21-day-old rats

Pure cardiolipins (1,3-diphosphatidylglycerol) were prepared from mitochondria of heart, liver and kidney from 21-day-old male Wistar rats and submitted toNaja naja venom phospholipase A2 (EC 3.1.1.4) action. Incubation conditions were controlled carefully, and a complete hydrolysis of cardiolipin to lysocardiolipin {di [1 (1″) acylsn-glycero-3-phosphoryl] 1′, 3′-sn-glycerol} and fatty acids from positions 2 (2″) was obtained in less than two hr practically without side reactions. Cardiolipins from the three organs contained low levels of saturated fatty acids; stearic acid accounted for 0.4–0.7% and palmitic acid for 1.4–3.5% of total fatty acids. These percentages apparently depended on the organ. In all three cases, linoleic acid was the major component, but its percentage varied from 62–78% of total fatty acids. Acyl chains linked to positions 1 (1″) of all three cardiolipin preparations exhibited a similar pattern; they were composed of linoleic acid for 85–89%. This fatty acid also was the main component esterified at position 2 (2″), but its percentage was much more variable: from 39.8% in heart to 51.2% in kidney and 67.8% in liver mitochondria. The remaining acids comprised octadecenoic and polyunsaturated fatty acids with more than 18 carbon atoms in different proportions. As opposed to other phospholipids,cis-vaccenic acid, and not oleic acid, was the main octadecenoic acid present in cardiolipins.Octadecenoic acids were nine- to 10-fold more concentrated at positions 2 (2″) than at positions 1 (1″). The percentage ofcis-vaccenic acid was four- to five-fold higher than that of oleic acid at positions 2 (2″), whereas oleic acid dominated at positions 1 (1″). From results presented in this study and selected literature data, it may be concluded that fatty acids are asymmetrically distributed in cardiolipins of different origins, with linoleic acid showing a definite preference for position 1 (1″).

Modification of alkenyl chain profile in plasmalogens of rat heart mitochondria by dietary trielaidin

Effects of dietary trielaidin upon the alkenyl chain profile of plasmalogens were studied using heart mitochondria of rats fed a semi-purified diet containing 10% of fat supplement in which elaidic acid accounted for 69% of total fatty acids. Alkyl substituted dioxane (ASD) derivatives of the alkenyl groups of plasmalogens were prepared and analyzed by silver nitrate TLC and by GLC on different phases (BDS and OV-275). After two months of feeding the experimental diet, 40% of the ASD contained atrans-octadecenyl chain, suggesting that dietary elaidic acid was reduced in vivo to the corresponding alcohol and incorporated into plasmalogens. There was a simultaneous decrease in the percentage of ASD containing saturated chains, but the percentage of ASD substituted withcis-octadecenyl chains was not significantly affected. These observations suggested that elaidic acid may compete with saturated fatty acids, but not withcis-octadecenoic acids during the plasmalogen biosynthesis. Feeding trielaidin did not seem to have any significant influence on the relative proportions of plasmalogens, which accounted for 11–12%, on a phosphorus basis, of total heart mitochondria phospholipids.

Effects on Cholesterol Balance and LDL Cholesterol in the Rat of a Soft-Ripened Cheese Containing Vegetable Oils

Objective: The purpose of this study was to examine effects of a modified soft-ripened cheese containing vegetable oils on cholesterol status, using the rat as the experimental model and the traditional soft-ripened cheese as the control. Methods: Adult male Wistar rats (≈370 g) were divided into two dietary groups (20 rats/group) and fed either the standard diet (STD, containing traditional cheeses made from whole milk) or the experimental diet (EXP, containing modified cheeses made from the combination of skim milk with the following fat mixture: milk fat/oleic acid-enriched sunflower oil/soybean oil mixture). Lipids of the diets came solely from cheeses (14 g/100 g diet); the EXP diet contained (3-fold) less saturated fat, (2-fold) less cholesterol, and (15-fold) more phytosterols than the STD diet. Results: Although serum triglyceride and total cholesterol concentrations were not affected by the type of diet, the EXP diet resulted in a significant reduction of LDL-cholesterol (31%, p<0.001) and a significant increase of HDL-cholesterol (11%, p<0.05), compared to the STD diet. Thus, a marked reduction (39%) of serum LDL/HDL cholesterol ratio was observed in the EXP group (p<0.001). In addition, the two quantitative balances (excreted/ingested) of cholesterol and total neutral sterols (for which phytosterols were excluded) were significantly higher by 183% and 174%, respectively for the EXP group, compared to the STD group (p<0.05). On another hand, rats fed the EXP diet excreted more cholesterol than they ingested dietary cholesterol (cholesterol balance ≷ 1), indicating that those animals eliminated some endogenous cholesterol in their feces, while the opposite was true for rats fed the STD diet (cholesterol balance < 1). Finally, fecal bile salt concentration was not significantly different between the two dietary groups. Conclusions: The partial substitution of milk fat by vegetable oils in soft-ripened cheese resulted in a decreased blood LDL/HDL cholesterol ratio and an increased fecal excretion of endogenous cholesterol and neutral sterols and, thus, markedly improved its nutritional qualities. Therefore, the consumption of the described modified cheese may meet the demand of subjects who wish to lower their risk for atherosclerosis and cardiovascular disease.

Relationships between Red Blood Cell Vitamin E and Polyunsaturated Fatty Acid in the Premature Infant

Low-birth-weight infants were fed breast milk (BM, n = 25) for 1 of 2 formulas containing 0.5 (PG, n = 32) or 1.7% fatty acids as alpha-linolenic acid (ALA)(ALA-PG, n = 31). Polyunsaturated fatty acids (PUFA) and alpha-tocopherol (alpha T) of RBC membrane phospholipids were measured at days 2 (D2) and 15 (D15) of enteral feeding, and at term. PUFA concentrations did not differ significantly between the 3 groups from D2 to term. The membrane integrity assessed by the alpha T/phospholipids ratio neither changed with time nor differed between formula groups. A metabolic relationship between alpha T and long-chain PUFA in RBC membranes was suggested by multiple regression analysis: alpha T showed a significant positive correlation with docosahexaenoic acid at D15 and term and with arachidonic acid at D15; the correlation with arachidonic acid tended toward significantly (p = 0.06) at term.

Lipolysis and oxidative stability of soft ripened cheeses containing vegetable oils.

In response to nutrition guidelines recommending a reduction in saturated fats in human diets, the dairy industry has developed new products containing unsaturated fats to satisfy the demand of the more health conscious consumer. The fatty acid composition of milk, naturally rich in saturated fatty acids (SFA), can be modified either through genetic selection of dairy cows or by changing feed composition (Palmquist et al . 1993). For example, a number of dairy products including butter (Wood et al . 1975; Badings et al . 1976), Gouda (Badings et al . 1976) and Cheddar (Wong et al . 1973; Lightfield et al . 1993) containing increased amounts of linoleic acid (18[ratio ]2 n –6) have been made from the milk of cows given diets supplemented with unsaturated lipids. However, dairy farmers would prefer to produce milk as cheaply as possible, leaving it to food technologists to modify milk components at the post- production stage (Banks, 1987). Therefore, dairy products made from skim milk combined with a fat mixture could be attractive, but little information is available on this type of modified product. One major problem related to the introduction of unsaturated fats into dairy products is the possible alteration of their properties. Indeed, Badings (1970) reported that butter enriched in polyunsaturated fatty acids (PUFA) has reduced flavour quality and shelf life. It is well known that PUFA are easily oxidized and can form undesirable compounds such as peroxides and aldehydes. Moreover, PUFA are more likely to be oxidized as free fatty acids (FFA) than to be integrated into a triacylglycerol structure. Therefore, when a dairy product is made by recombining skim milk with unsaturated fats, such as the soft ripened cheese in this study, it is important to consider both lipolysis and oxidative stability of the lipid fraction. This was our objective in this study.