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PubMed1991

Fatty acid composition of subcutaneous adipose tissue and diet in postmenopausal US women.

The distributions of fatty acids in subcutaneous-adipose-tissue aspirates and their relation to intake as assessed by a semiquantitative food-frequency questionnaire were investigated in 115 postmenopausal US women free from cancer. Percentages of fatty acids in adipose tissue were significantly correlated with the percentage of total fat intake for polyunsaturated fatty acids (Spearman correlation = 0.37), n-3 fatty acids of marine origin (Spearman correlation = 0.48), and trans fatty acids (Spearman correlation = 0.51) but not for saturated and monounsaturated fatty acids. Correlations were somewhat stronger in 78 women with stable weight over the 6 mo before fat aspiration. These data suggest that intakes of polyunsaturated fatty acids, including n-3 fatty acids, and trans fatty acids are reflected in the adipose tissue but that intakes of saturated and monounsaturated fatty acids are not. The data also provide further support for the validity of the food-frequency questionnaire in the assessment of fat intake.

Adipose Tissue↗
PubMed1993

Trans monounsaturated fatty acids in nutrition and their impact on serum lipoprotein levels in man.

Trans-C18:1 in the diet originate predominantly from partially hydrogenated oils, with beef, mutton and dairy products being an additional source. These fatty acids are absorbed and incorporated into lipids. Their estimated consumption is about 5-7% of total fatty acids, although reliable data are lacking. In addition, large variations between individuals exist. There is no evidence that trans fatty acids accumulate in human tissues. Elaidic acid and its positional isomers do, however, raise LDL cholesterol and apoprotein B and Lp(a) and probably depress HDL cholesterol and apoprotein A-I, compared with the cis isomer, oleic acid. In view of these adverse effects, patients at high risk for atherosclerosis, in addition to reducing their intake of saturated fatty acids and of cholesterol might also do well to avoid excessive intakes of trans fatty acids. Still, trans fatty acids form only a minor component of the diets of most patients and therefore even marked relative reductions in intake will probably have less of an impact on LDL cholesterol than a sizeable reduction in saturated fatty acids and cholesterol will produce.

Diet↗
PubMed1996

Dietary trans-monounsaturated fatty acids negatively impact plasma lipids in humans: critical review of the evidence.

Trans fatty acids (t-FA) are geometrical isomers of unsaturated fatty acids that assume a saturated fatty acid-like configuration. Human diets contain t-FA derived from animal sources (e.g., dairy products and ruminant meats), but most are supplied by products containing industrially hydrogenated vegetable oils (e.g., margarines, shortenings and baked goods). Typical intake of t-FA in American diets has been estimated to be between 8-15 g/day, although wide variation exists between individuals. Human clinical studies since 1990 have revealed that relative to cis-monounsaturated fatty acids (i.e., oleic acid), t-FA increase total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C), and tend to decrease high density lipoprotein cholesterol (HDL-C) concentrations. Additionally, t-FA tend to increase the atherogenic lipoprotein (a). Thus, t-FA induce an adverse plasma lipid profile (increased ratios of TC/LDL-C and LDL-C/HDL-C), which represents increased risk for coronary heart disease. The effects of t-FA on LDL-C and HDL-C appear to be directly related to intake and clinically measurable above 3%en as t-FA. The cholesterol-raising ability of t-FA is analogous to that of the 12-16 carbon saturated fatty acids, possibly reflecting increased LDL production or delayed LDL clearance. By contrast, t-FA are unlike the saturated fatty acids in their depression of HDL-C. Preliminary evidence suggests that at least part of their impact on lipoproteins reflects increased serum cholesteryl ester transfer protein activity, i.e., increased transfer of cholesteryl esters from HDL to LDL. Since the adverse effects of t-FA on human plasma lipids may be confined to specific isomers, future studies delineating their effects are warranted.

Animals↗
PubMed1990

A trans-unsaturated fatty acid in a psychrophilic bacterium, Vibrio sp. strain ABE-1.

A high level of a trans-unsaturated fatty acid was found in the phospholipids of a psychrophilic bacterium, Vibrio sp. strain ABE-1. This fatty acid was identified as 9-trans-hexadecenoic acid (C16:19t) by gas-liquid chromatography and infrared absorption spectrometry. C16:1(9)t accounted for less than 1% of the total fatty acids in cells grown at 5 degrees C and reached 12% of the total at 20 degrees C. We suggest that the increase in the level of the trans-unsaturated fatty acid is related to the high growth rate of this bacterium at elevated temperatures. Possible biological roles of the trans-unsaturated fatty acid in the adaptation of the microorganism to the ambient temperature are discussed.

Chromatography, Gas↗
PubMed1984

Phospholipid metabolism in V79-R membranes composed of phospholipid molecular species containing trans-monoenoic fatty acids.

The interrelationship between the inhibition of cell growth and changes in phospholipid molecular species was studied in the presence of elaidic, trans-11-eicosenoic, or brassidic acids in Chinese hamster V79-R cells. The addition of trans-monoenoic fatty acids to the medium inhibited cell growth and caused an increase in the total cellular content of phospholipids. However, there was no difference in the polar head group composition of these phospholipids among all the cells supplemented with trans-monoenoic fatty acids. Exogenous trans-monoenoic fatty acids were incorporated into cellular phospholipids to form novel phospholipid molecular species. Phospholipid synthesizing enzyme activities bound to the membranes composed of phospholipid molecular species of trans-monoenoic fatty acids were determined. Cholinephosphotransferase [EC 2.7.8.2] and ethanolaminephosphotransferase [EC 2.7.8.1] activities were decreased by trans-11-eicosenoic acid, but not changed by elaidic acid. Glycerophosphate acyltransferase [EC 2.3.1.15] activity was increased by elaidic acid and decreased by trans-11-eicosenoic acid. Cholinephosphate cytidylyltransferase [EC 2.7.7.15] activity was not changed by trans-monoenoic fatty acids.

Animals↗
PubMed2001

Serum cholesterol predictive equations with special emphasis on trans and saturated fatty acids. an analysis from designed controlled studies.

The effects of dietary trans fatty acids on serum total and low density lipoprotein (LDL) cholesterol have been evaluated by incorporating trans fatty acids into predictive equations and comparing their effects with the effects of the individual saturated fatty acids 12:0, 14:0, and 16:0. Trans fatty acids from partially hydrogenated soybean oil (TRANS V) and fish oil (TRANS F) were included in previously published equations by constrained regression analysis, allowing slight adjustments of existing coefficients. Prior knowledge about the signs and ordering of the regression coefficients was explicitly incorporated into the regression modeling by adding lower and upper bounds to the coefficients. The amounts of oleic acid (18:1) and polyunsaturated fatty acids (18:2, 18:3) were not sufficiently varied in the studies, and the respective regression coefficients were therefore set equal to those found by Yu et al. [Yu, S., Derr, J., Etherton, T.D., and Kris-Etherton, P.M. (1995) Plasma Cholesterol-Predictive Equations Demonstrate That Stearic Acid Is Neutral and Monounsaturated Fatty Acids Are Hypocholesterolemic, Am. J. Clin. Nutr. 61, 1129-1139]. Stearic acid (18:0), considered to be neutral, was not included in the equations. The regression analyses were based on results from four controlled dietary studies with a total of 95 participants and including 10 diets differing in fatty acid composition and with 30-38% of energy (E%) as fat. The analyses resulted in the following equations, where the change in cholesterol is expressed in mmol/L and the change in intake of fatty acids is expressed in E%: delta Total cholesterol = 0.01 delta(12:0) + 0.12 delta(14:0) + 0.057 delta(16:0) + 0.039 delta(TRANS F) + 0.031 delta(TRANS V) - 0.0044 delta(18:1) - 0.017 delta(18:2, 18:3) and deltaLDL cholesterol = 0.01 delta(12:0) + 0.071 delta(14:0) + 0.047 delta(16:0) + 0.043 delta(TRANS F) + 0.025 delta(TRANS V) - 0.0044 delta(18:1) - 0.017 delta(18:2, 18:3). The regression analyses confirm previous findings that 14:0 is the most hypercholesterolemic fatty acid and indicate that trans fatty acids are less hypercholesterolemic than the saturated fatty acids 14:0 and 16:0. TRANS F may be slightly more hypercholesterolemic than TRANS V or there may be other hypercholesterolemic fatty acids in partially hydrogenated fish oil than those included in the equations. The test set used for validation consisted of 22 data points from seven recently published dietary studies. The equation for total cholesterol showed good prediction ability with a correlation coefficient of 0.981 between observed and predicted values. The equation has been used by the Norwegian food industry in reformulating margarines into more healthful products with reduced content of cholesterol-raising fatty acids.

Adult↗
PubMed1994

Health implications of fatty acids.

1. Although dietary trans fatty acids can effect the fatty acid composition of tissues, they are not considered to be harmful, provided sufficient essential fatty acids are present in the diet. 2. A reduction in dietary saturated fatty acids (SFA) and dietary increases in mono- and polyunsaturated (PUFA) fatty acids are beneficial in reducing the risk of coronary heart disease. 3. There is only limited evidence of a beneficial effect on hypertension by reducing either total fat or SFA in the diet. 4. There is a little evidence of a role for dietary fat in the initiation of cancer but linoleic acid has been implicated in tumor promotion and chemical carcinogenesis. 5. Dietary PUFA might be beneficial in the treatment of certain autoimmune diseases such a multiple sclerosis.

Diet↗
PubMed1998

Trans unsaturated fatty acids inhibit lecithin: cholesterol acyltransferase and alter its positional specificity.

Although dietary trans unsaturated fatty acids (TUFA) are known to decrease plasma HDL, the underlying mechanisms for this effect are unclear. We tested the hypothesis that the decreased HDL is due to an inhibition of lecithin:cholesterol acyltransferase (LCAT), the enzyme essential for the formation of HDL, by determining the activity of purified LCAT in the presence of synthetic phosphatidylcholine (PC) substrates containing TUFA. Both human and rat LCATs exhibited significantly lower activity (-37% to -50%) with PCs containing 18:1t or 18:2t, when compared with the PCs containing corresponding cis isomers. TUFA-containing PCs also inhibited the enzyme activity competitively, when added to egg PC substrate. The inhibition of LCAT activity was not due to changes in the fluidity of the substrate particle. However, the inhibition depended on the position occupied by TUFA in the PC, as well as on the paired fatty acid. Thus, for human LCAT, 18:1t was more inhibitory when present at sn-2 position of PC, than at sn-1, when paired with 16:0. In contrast, when paired with 20:4, 18:1t was more inhibitory at sn-1 position of PC. Both human and rat LCATs, which are normally specific for the sn-2 acyl group of PC, exhibited an alteration in their positional specificity when 16:0-18:1t PC or 16:1t-20:4 PC was used as substrate, deriving 26-86% of the total acyl groups for cholesterol esterification from the sn-1 position. These results show that the trans fatty acids decrease high density lipoprotein through their inhibition of lecithin: cholesterol acyltransferase (LCAT) activity, and also alter LCAT's positional specificity, inducing the formation of more saturated cholesteryl esters, which are more atherogenic.

Animals↗
PubMed1977

Occurrence of individual trans-isomeric fatty acids in human myocardium, jejunum and aorta in relation to different degrees of atherosclerosis.

With the aid of a highly selective capillary column coated with SP 2340, individual trans-fatty acids were identified in all tissue samples studied, the values being unrelated to the degree of atherosclerosis. The mean values of total trans-acids present in human myocardium, jejunum and aorta amounted to less than 1% of the total fatty acids. The trans-acid content was composed of traces of 9-trans-tetradecenoic acid and nearly equal amounts of 9-trans-hexadecenoate and trans-octadecenoate, the double bond in the latter occurring in the delta6, delta9 and delta11 positions. 9-trans,12-trans-octadecadienoate or the corresponding mixed geometric isomers could not be identified in any sample. Additionally, significant increases of 20:4c(n-6), 22:4c(n-6) and 22:6c(n-3) acids were measured in the myocardium of patients who had died from severe atherosclerosis of the aorta and coronary arteries. The atherosclerosis was not attributable to different dietary habits, as judged from the content of linoleic acid in their adipose tissue.

Aged↗
PubMed1970

Lipid metabolism in the perfused chicken liver. The uptake and metabolism of oleic acid, elaidic acid, cis-vaccenic acid, trans-vaccenic acid and stearic acid.

Comparative studies were made of the uptake and metabolism of cis- and trans-octadecenoic acids by the perfused chicken liver. No differences were observed in the rates of uptake of the isomers. There was considerable incorporation of radioactivity into triglycerides and phospholipids, and some release of labelled lipid into the perfusate was observed. The cis-fatty acids were more readily incorporated into triglycerides than phospholipids, the reverse being true of the trans-fatty acids. Examination of the intramolecular distribution of fatty acids in triglycerides showed that the trans-fatty acid and stearate mainly occupied the 1- and 3-positions, and cis-fatty acids the 2-position. In the phospholipids phosphatidylcholine and phosphatidylethanolamine the trans-fatty acids again behaved like stearic acid and favoured the 1-position. No evidence was obtained of atypical patterns of uptake or metabolism of the trans-fatty acids.

Animals↗
PubMed1999

Fatty acids including trans content of commercial bakery products manufactured in Spain.

Fifteen samples of the most common industrial bakery products sold in Spain were analyzed for their fatty acid composition. Saturated fatty acids occurred in the largest proportions in all samples (mean = 52.8%), followed by monounsaturated (mean = 23.5%) and polyunsaturated fatty acids (mean = 17.2%). A small percentage of trans fatty acids, which were found in all samples, showed a mean value of 5.7%. According to their fatty acid composition, that is, their saturated, monounsaturated, and polyunsaturated fatty acid contents, the statistical analysis (discriminant analysis) showed three groups of samples, suggesting that the fat incorporated in these samples was obtained from different sources.

Chromatography, Gas↗
PubMed1996

Trans unsaturated fatty acids in plasma phospholipids and coronary heart disease: a case-control study.

A high intake of trans fatty acids (TFAs) has been shown to have an undesirable effect on serum lipid profiles and lipoprotein(a) (Lpa)) levels and may thereby increase the risk for coronary heart disease (CHD). We performed a study in CHD patients, and measured the TFA concentration of the plasma phospholipid fraction. Comparison was made between a case group with angiographically documented severe CHD (> 80% stenosis in one coronary vessel, n = 83) and a control group of patients who had just minor stenosis on the coronary angiography (< 50% stenosis in all three major vessels, n = 78): All subjects were under 68 years of age and were prestratified on age, gender and smoking habits. The two groups were comparable according to the prestratification criteria, body mass index, blood pressure, number of cigarettes smoked and total fat intake. Controls had higher plasma HDL levels (P < 0.001) and lower, albeit not significantly lower, (P = 0.07) plasma LDL levels. No significant correlations were found between percentages of TFAs in plasma phospholipids and plasma LDL or HDL cholesterol levels. Of the major fatty acid classes, only the percentage of saturated fatty acids was significantly higher in cases (46.2 +/- 0.92%) than in controls (45.8 +/- 1.07% (means +/- S.D.)). The difference in total TFA content between cases and controls (0.32 +/- 0.02% versus 0.35 +/- 0.02%) was -0.03% (P = 0.2). For the specific TFAs C16:1n-7tr, C18:1n-9tr and C18: 2n-6tr, just minor differences were found. Adjusted odds ratios for tertiles of TFA percentages were 0.56 (0.25-1.23) and 0.76 (0.36-1.61) for the highest middle tertile compared to the lowest. These findings do not support an association between TFA intake and risk for coronary heart disease.

Aged↗
PubMed2004

Calibration of a semi-quantitative food frequency questionnaire in early pregnancy.

PURPOSE: We assessed the validity of a semi-quantitative food frequency questionnaire (FFQ) among pregnant women. METHODS: We enrolled 72 African American and 132 Caucasian pregnant women in a calibration study of an existing FFQ. For eight categories of intake of fatty acids, carotenoids, and gamma- tocopherol estimated by the FFQ (energy-adjusted deciles 1, 2, 3, 4+5, 6+7, 8, 9, 10) we compared measurements of the corresponding nutrient level measured in pooled blood specimens from all participants in each category. RESULTS: For alpha-carotene, plasma levels were 1.9 (p=0.10) and 2.9 (p=0.0007) microg/L higher for every 100 microg increase in dietary intake among African American and Caucasian women, respectively. A high percent increase in plasma levels was apparent between extreme dietary deciles of alpha-carotene (275% for African American and 152% for Caucasian women). Increases across deciles were evident for lycopene, lutein, and gamma-tocopherol, ranging from 12% to 64%. We also observed relationships between dietary intake and their erythrocyte concentrations of long-chain n-3 fatty acids and trans-fatty acids, but not alpha-linolenic acid. CONCLUSION: The observed differences in biomarkers across varying levels of dietary intake suggest that this FFQ is an appropriate epidemiologic tool for assessing intake of at least several important nutrients during early pregnancy in both African American and Caucasian women.

Adult↗
PubMed2005

Polyunsaturated fatty acids inhibit telomerase activity in DLD-1 human colorectal adenocarcinoma cells: a dual mechanism approach.

As high telomerase activity is detected in most cancer cells, telomerase represents a promising cancer therapeutic target. We investigated the inhibitory effect of various fatty acids on telomerase, with particular emphasis on those with antitumor properties, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). To evaluate the direct effect of fatty acids on telomerase, cell lysates of DLD-1 human colorectal adenocarcinoma cells were mixed with sample fatty acids, and the telomerase activity was determined. Saturated fatty acids and trans-fatty acids showed very weak or no inhibition of telomerase. In contrast, cis-unsaturated fatty acids significantly inhibited the enzyme, and the inhibitory potency was elevated with an increase in the number of double bonds. Accordingly, polyunsaturated fatty acids (PUFAs), like EPA and DHA, appeared to be powerful telomerase inhibitors. To assess the transcriptional effect, DLD-1 cells were cultured in the presence of sample fatty acids, and telomerase activity and gene expression were subsequently evaluated. Culturing DLD-1 cells with either EPA or DHA resulted in a remarkable decrease in telomerase activity. EPA and DHA inhibited telomerase by down-regulating human telomerase reverse transcriptase (hTERT) and c-myc expression via protein kinase C inhibition. These results indicate that PUFAs can directly inhibit the enzymatic activity of telomerase as well as modulate the telomerase at the transcriptional level.

Adenocarcinoma↗
PubMed2003

Achievement of dietary fatty acid intakes in long-term controlled intervention studies: approach and methodology.

OBJECTIVE: To describe the calculations and approaches used to design experimental diets of differing saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) compositions for use in a long-term dietary intervention study, and to evaluate the degree to which the dietary targets were met. DESIGN, SETTING AND SUBJECTS: Fifty-one students living in a university hall of residence consumed a reference (SFA) diet for 8 weeks followed by either a moderate MUFA (MM) diet or a high MUFA (HM) diet for 16 weeks. The three diets were designed to differ only in their proportions of SFA and MUFA, while keeping total fat, polyunsaturated fatty acids (PUFA), trans-fatty acids, and the ratio of palmitic to stearic acid, and n-6 to n-3 PUFA, unchanged. RESULTS: Using habitual diet records and a standardised database for food fatty acid compositions, a sequential process of theoretical fat substitutions enabled suitable fat sources for use in the three diets to be identified, and experimental margarines for baking, spreading and the manufacture of snack foods to be designed. The dietary intervention was largely successful in achieving the fatty acid targets of the three diets, although unintended differences between the original target and the analysed fatty acid composition of the experimental margarines resulted in a lower than anticipated MUFA intake on the HM diet, and a lower ratio of palmitic to stearic acid compared with the reference or MM diet. CONCLUSIONS: This study has revealed important theoretical considerations that should be taken into account when designing diets of specific fatty acid composition, as well as practical issues of implementation.

Adult↗
PubMed1993

The interaction of dietary cholesterol and specific fatty acids in the regulation of LDL receptor activity and plasma LDL-cholesterol concentrations.

From these brief considerations, it is clear that the steady-state LDL-cholesterol concentration is determined in a powerful way by the interaction of dietary cholesterol and specific fatty acids. There appear to be only a few saturated fatty acids and an even lesser number of unsaturated fatty acids that significantly interact with cholesterol in the liver cell to alter hepatic LDL receptor activity. These effects are uniformly seen in most experimental animals and in humans under circumstances where the experiments are properly designed. Future work is urgently needed to define the metabolic effects of the more unusual fatty acids (e.g., the trans fatty acid) and the more intimate details of how these substances regulate LDL receptor activity in the cell. It is also of considerable importance to extend these studies to the members of the same species that exhibit variable responses to these same dietary lipids. It is now clear that the magnitude of these specific responses to dietary cholesterol and specific fatty acids varies in different individuals with different genetic backgrounds from the same species. Elucidating the reasons for this variability is another area of research of considerable importance to human biology.

Animals↗
PubMed1997

The role of nutritional modifications in the prevention of macrovascular complications of diabetes.

A wide range of dietary changes is likely to reduce the risk of macrovascular complications of diabetes. It is critically important to recommend a balance of macronutrients different from that currently consumed in most Western countries. Saturated fatty acids, especially myristic and palmitic acids, and trans fatty acids must be reduced to lower LDL cholesterol. Intake of polyunsaturated fatty acids should not be excessive (less than 10% total energy). Fiber-rich carbohydrate, derived from cereals, vegetables, and fruit with intact cell walls, and cis monounsaturated fatty acids should provide the bulk of total energy. These changes are likely to be associated with the most favorable lipoprotein profile and increase intake of dietary antioxidants and so reduce the level of oxidative stress. A reduction of sodium to below 6 g per day will help to reduce blood pressure levels. Optimal glycemic control has not yet been proved to reduce the risk of macrovascular complications, though this is a desirable goal for many other reasons. Ensuring appropriate energy balance (so that BMI is within the desirable range), using low glycemic index foods, and appropriately balancing carbohydrate intake with hypoglycemic drug therapy provide the best nutritional means of achieving satisfactory blood glucose levels. Successful implementation of nutritional recommendations requires the availability of dietitians capable of translating appropriate nutrition into appropriate foods acceptable to people with diabetes and their families. Clear food labeling and the availability of appropriate manufactured foods will further help patients with diabetes to achieve the dietary recommendations.

Antioxidants↗
PubMed1984

Trans-unsaturated fatty acids in margarines and human subcutaneous fat in Israel.

Representative Israeli dietary fats were analysed by capillary gas chromatography, with emphasis on the trans-fatty acid (FA) content. The percentages of trans-monoenes were relatively high: 28.5-30.4 in three hard margarines, 13.4 in both of two soft margarines, but 0 in both of two cooking oils and 27.6 for a sample of commercial cookies. The corresponding percentages of trans-dienes were 0.4-0.5, trace-0.9, 0-0.1 and 0 (one oil sample had 0.6 had 0.6 per cent trans-triene). For cis-polyunsaturated FA the percentages were 26.4-28.7, 39.7-41.6, 60.6 and 18.2 respectively. P/S ratios for the hard margarines were 1.69-2.01, higher than those of American margarines, which are about 1.40. When trans-FA were included with the saturated FA, the ratios were almost equal, 0.52-0.60 versus 0.53, respectively. In the subcutaneous fat of 8 Israelis of various ethnic origins and dietary habits, total trans-FA averaged 4.5 per cent (range 1.9-6.6), similar to that in the US and UK. However, the percentages of polyunsaturated FA in the Israelis were very high, 27.2 (20.3-32.3) for linoleic acid and 1.5 (1.0-1.8) for linolenic acid. The average P/S ratio was also very high, 1.19 (0.80-1.60) and P/(S+trans) was 0.98 (0.67-1.37).

Adipose Tissue↗