Altered levels of n-6/n-3 fatty acids in rat heart and storage fat following variable dietary intake of linoleic acid

Fat-supplemented dies enriched with linoleic acid by the addition of 12% w/w sunflower seed oil or proportionally reduced in linoleic acid by addition of 12% mutton fat were fed to rats for 18 months before the fatty acid composition of perirenal storage fat and myocardial membranes (phospholipids) was determined. Although the fatty acid composition of perirenal fat generally reflected that of the diet, there was an inverse relationship between the consumption of n-6 and the deposition of n-9 fatty acids. In addition, enhanced deposition of oleic acid (18:1, n-9) appears to be related to the dietary intake of stearic acid (18:0). In contrast, in myocardial membranes the n-3 polyunsaturated fatty acids are found to be increased when the intake of n-6 polyunsaturated fatty acids is reduced. This is particularly evident for docosahexaenoic acid (22:6, n-3) which is significantly increased in phosphatidylcholine, phosphatidylethanolamine, and diphosphatidylglycerol fractions of myocardial membranes, when the mutton fat diet was fed. After feeding the sunflower seed oil diet, the increased consumption of linoleic acid produced only small changes in the 18:2, n-6 content of cardiac phosphatidylcholine and phosphatidylethanolamine. These major classes of membrane phospholipids also showed only small increases in 20:4, n-6. In diphosphatidylglycerol, increased 18:2, n-6 also followed increased dietary intake, but this was not accompanied by increased 20:4, n-6. These changes in myocardial phospholipid fatty acid composition are similar to those observed after short-term feeding reported previously and confirm that changes in dietary n-6/n-3 fatty acid intake affect the fatty acid composition of both myocardial membranes and storage fat. These changes persist for the duration of the feeding period.     

Ratio of Omega-6 to Omega-3 Fatty Acids and Childhood Asthma

Asthma is a leading cause of morbidity for children and is a major public health problem in Australia. Ecological and temporal data suggest that dietary factors may have a role in recent increases in the prevalence of asthma. Aim: The aim of conducting this study was to investigate whether childhood asthma was associated with the ratio of omega 6 (n-6) to omega 3 (n-3) fatty acids in the diet (n-6:n-3). Method: The Western Australian Pregnancy Cohort Study is a prospective birth cohort of 2602 children. Using a nested case-control cross-sectional study design within this cohort, a group of children were identified as cases with current asthma at 6 or at 8 years of age or as controls with no asthma at 6 or at 8 years. Dietary details including n-6 and n-3 fatty acid intake data were collected by parent response to a questionnaire when the children were 8 years old. Logistical regression was used to compare quartiles of n-6:n-3 intake in cases and controls. Adjustment was made for covariates: gender, gestational age, breastfeeding, older siblings, maternal smoking during pregnancy, maternal age, maternal asthma, child's current age in months, body mass index, total energy intake, and antioxidant intake (vitamins A, C, E, and zinc). Results: A response rate of 83% was achieved by providing complete data from 335 children [49% cases with current asthma (n = 166), 51% controls (n = 169)]. Following adjustment for covariates the association between the ratio of n-6:n-3 fatty acids and risk for current asthma was statistically significant (p = 0.022). Conclusion: We found evidence for a modulatory effect of the dietary n-6:n-3 fatty acid ratio on the presence of asthma in children. Our results provide evidence that promotion of a diet with increased n-3 fatty acids and reduced n-6 fatty acids to protect children against symptoms of asthma is warranted.     

Ratio of omega-6 to omega-3 fatty acids and childhood asthma.

Asthma is a leading cause of morbidity for children and is a major public health problem in Australia. Ecological and temporal data suggest that dietary factors may have a role in recent increases in the prevalence of asthma. AIM: The aim of conducting this study was to investigate whether childhood asthma was associated with the ratio of omega 6 (n-6) to omega 3 (n-3) fatty acids in the diet (n-6:n-3). METHOD: The Western Australian Pregnancy Cohort Study is a prospective birth cohort of 2602 children. Using a nested case-control cross-sectional study design within this cohort, a group of children were identified as cases with current asthma at 6 or at 8 years of age or as controls with no asthma at 6 or at 8 years. Dietary details including n-6 and n-3 fatty acid intake data were collected by parent response to a questionnaire when the children were 8 years old. Logistical regression was used to compare quartiles of n-6:n-3 intake in cases and controls. Adjustment was made for covariates: gender, gestational age, breastfeeding, older siblings, maternal smoking during pregnancy, maternal age, maternal asthma, child's current age in months, body mass index, total energy intake, and antioxidant intake (vitamins A, C, E, and zinc). RESULTS: A response rate of 83% was achieved by providing complete data from 335 children [49% cases with current asthma (n = 166), 51% controls (n = 169)]. Following adjustment for covariates the association between the ratio of n-6:n-3 fatty acids and risk for current asthma was statistically significant (p = 0.022). CONCLUSION: We found evidence for a modulatory effect of the dietary n-6:n-3 fatty acid ratio on the presence of asthma in children. Our results provide evidence that promotion of a diet with increased n-3 fatty acids and reduced n-6 fatty acids to protect children against symptoms of asthma is warranted.     

Plasma fatty acid composition in patients with ileal dysfunction

Chemical signs of essential fatty acid deficiency (EFD) were studied in 31 patients who has undergone an ileal resection on an average 7 years earlier by determining fatty acid composition in serum lipids. The subjects were divided into two groups in accordance with the presence (greater than 7 g/day) or absence (less than 7 g/day) of fat malabsorption. The two groups were matched for age, nutritional status, and essential fatty acid intake, but the patients with steatorrhea had higher levels of fecal bile acids and serum triglycerides and lower levels of serum cholesterol than those without steatorrhea. The contents of linoleic acid (LA; 18:2,n-6), the sum of n-6 polyunsaturated fatty acids, and eicosapentaenoic acid levels were lower, whereas those of the C 14-18 saturated and monoenoic fatty acids and eicosatrienoic fatty acid (ETA; 20:3,n-9), a characteristic fatty acid of EFD, were higher in the serum lipids of the patients with fat malabsorption. The LA of cholesterol esters, the ETA of phospholipids, and the ETA to arachidonic acid ratio of phospholipids were closely correlated with the amount of fecal fat, less significantly with the composition of dietary fat or the length of excluded intestine, and not at all with relative body weight or the amount of fecal bile acids. Changes in fatty acid patterns, considered characteristic of EFD, were found for almost a third of the patients with fat malabsorption; yet no clinical evidence of EFD was documented. Thus, the results demonstrate that chemical signs of EFD are common in patients with fat malabsorption after gut resections despite the good nutritional status. The findings suggest that, for preventive purposes, patients with gut resections should increase their dietary intake of polyunsaturated fatty acids in proportion to the amount of fecal fat.     

Hepatic metabolism of dietary alpha-linolenic acid in suckling rats, and its possible importance in polyunsaturated fatty acid uptake by the brain

The presence of large amounts of long chain-polyunsaturated fatty acids (PUFA) in the brain implies an exogenous intake of unsaturated fatty acids, either as essential fatty acids, or in the form of higher homologues resulting from hepatic metabolism. To determine the influence of the diet upon the potential availability of polyunsaturated fatty acids to the brain, four different diets were used with comparable amounts of 18:2 n-6, but variable amounts of 18:3 n-3 (0.2, 1, 2 and 9%). These diets were administered to female rats from the day of mating and during the periods of gestation and lactation. Fifteen days after birth suckling animals were killed and the fatty acid distribution was studied in the serum in two lipoprotein classes (VLDL-LDL and HDL). On the whole, an increase in dietary 18:3 n-3 resulted in an increase of polyunsaturated fatty acids of the n-3 series and a decrease in fatty acids of the n-6 series. The modification chiefly concerned the terminal fatty acids in each series (22:5 n-6 and 22:6 n-3). It is noteworthy that the influence of exogenous 18:3 n-3 upon the 20:4 n-6 content of lipoproteins was not significant below 2% of 18:3 n-3 intake, a level that we have previously shown to be both necessary and sufficient to satisfy the requirements of the brain for fatty acids of the n-3 series. In the liver, the intermediary metabolism ensures an important release of long-chain polyunsaturated fatty acids, which may help to satisfy the lipid requirements of the brain.     

The Effect of Cod Liver Oil in Two Populations with Low and High Intake of Dietary Fish

ABSTRACT Two subgroups of healthy males from an inland and a coastal community in Norway with a traditionally low and high consumption of dietary fish were given a dietary supplement of 20 ml cod liver oil rich in n-3 polyunsaturated fatty acids for 3 weeks. Cod liver oil induced an increase in serum high density lipoprotein (HDL) cholesterol in men from the inland. Both groups showed a prolonged primary bleeding time, whereas platelet aggregation and thromboxane A₂ production induced by collagen were mainly unaffected. Platelet phospholipid fatty acids showed similar changes in both groups with a decrease in n-6 and an increase in n-3 polyunsaturated fatty acids. No changes were observed in total cholesterol or platelet phospholipid content. This study shows that dietary supplement with cod liver oil induces changes in serum lipids and platelets that may reduce the tendency to thrombosis both in subjects with a low and in those with a high intake of dietary fish. The effects were more pronounced in the subjects with a traditionally low fish consumption.     

Erythrocyte n-3 Polyunsaturated Fatty Acid and Seafood Intake Decrease the Risk of Depression: Case-Control Study in Korea

Background/Aims: Low intake or tissue levels of n-3 polyunsaturated fatty acids (PUFA) have been associated with an increased risk of depression, but some studies do not support the association. The purpose of the present study was to evaluate the hypothesis that erythrocyte levels of n-3 PUFA and intake of seafood are negatively associated with the risk of depression in Koreans. Methods: We investigated 80 patients diagnosed with a score ≥25 on the Center for Epidemiological Studies Depression Scale, Korean version, and confirmed by a psychiatrist. Eighty-eight controls without a chronic disease were matched to the cases for age and sex. Results: Multivariate-adjusted regression analysis showed that the risk of depression was significantly and negatively associated with erythrocyte levels of 20:5 n-3, 22:6 n-3, 16:0 and 18:0, but positively associated with erythrocyte levels of 18:2t and 16:1 after adjusting for confounding factors. In addition, the risk of depression was negatively associated with the intake of energy, carbohydrate, seafood and grains, but positively with the intake of fat and meat after adjustment for confounding factors. Conclusions: The risk of depression could be decreased with increased erythrocyte levels of n-3 PUFA and saturated fatty acids, as well as seafood intake, but decreased erythrocyte levels of trans fatty acids in Koreans.     

Dietary fat and meat intake and idiopathic pulmonary fibrosis: a case-control study in Japan.

SETTING: There is sparse epidemiologic information regarding the role of dietary factors in the development of idiopathic pulmonary fibrosis (IPF). OBJECTIVE: To examine the relationship between specific types of fatty acids and selected foods high in fat and IPF in Japan. DESIGN: Included were 104 cases aged > or = 40 years who had been diagnosed in the last 2 years in accordance with the most recent criteria. Controls aged > or = 40 years consisted of 56 hospitalised patients diagnosed as having acute bacterial pneumonia and four out-patients with common cold. RESULTS: Intake of saturated fatty acids, mono-unsaturated fatty acids, n-6 polyunsaturated fatty acids and meat was independently associated with an increased risk of IPF. Specifically, the multivariate OR for comparison of the highest with the lowest quartile of intake of saturated fatty acids was 6.26 (95%CI 1.79-24.96, P for trend = 0.01) and for meat it was 7.19 (95%CI 2.15-27.07, P for trend = 0.02). Intake of cholesterol, n-3 polyunsaturated fatty acids, fish, eggs and dairy products was not related to the risk. CONCLUSION: These findings suggest that consumption of saturated fatty acids and meat may increase the risk of IPF.     

Dietary Omega-3 Polyunsaturated Fatty Acid Supplementation and Airway Hyperresponsiveness in Asthma

Asthma prevalence continues to increase despite the progress that has been made in the treatment options for asthma. Alternative treatment therapies that reduce the dose requirements of pharmacological interventions would be beneficial, and could potentially reduce the public health burden of this disease. There is accumulating evidence that dietary modification has potential to influence the severity of asthma and reduce the prevalence and incidence of this condition. A possible contributing factor to the increased incidence of asthma in Western societies may the consumption of a pro-inflammatory diet. In the typical Western diet, 20-25-fold more omega (n)-6 polyunsaturated fatty acids (PUFA) than n-3 PUFA are consumed, which results in the release of pro-inflammatory arachidonic acid metabolites. Eicosapentaenoic acid and docosahexaenoic acid are n-3 PUFA derived from fish oil that competitively inhibit n-6 PUFA arachidonic acid (AA) metabolism and this reduce the generation of pro-inflammatory 4-series leukotrienes (LTs) and 2-series prostaglandins (PGs) and production of cytokines from inflammatory cells. These data are consistent with the proposed pathway by which dietary intake of n-3 PUFA modulates lung disease. This article will review the existing information concerning the relationship between n-3 PUFA supplementation and airway hyperresponsiveness in asthma. It includes studies assessing the efficacy of n-3 PUFA supplementation in exercise-induced bronchoconstriction. This review will also address the question as to whether supplementing the diet with n-3 PUFA represents a viable alternative treatment regimen for asthma.     

Dietary Omega-3 Polyunsaturated Fatty Acid Supplementation and Airway Hyperresponsiveness in Asthma

Asthma prevalence continues to increase despite the progress that has been made in the treatment options for asthma. Alternative treatment therapies that reduce the dose requirements of pharmacological interventions would be beneficial, and could potentially reduce the public health burden of this disease. There is accumulating evidence that dietary modification has potential to influence the severity of asthma and reduce the prevalence and incidence of this condition. A possible contributing factor to the increased incidence of asthma in Western societies may the consumption of a pro-inflammatory diet. In the typical Western diet, 20–25-fold more omega (n)-6 polyunsaturated fatty acids (PUFA) than n-3 PUFA are consumed, which results in the release of pro-inflammatory arachidonic acid metabolites. Eicosapentaenoic acid and docosahexaenoic acid are n-3 PUFA derived from fish oil that competitively inhibit n-6 PUFA arachidonic acid (AA) metabolism and this reduce the generation of pro-inflammatory 4-series leukotrienes (LTs) and 2-series prostaglandins (PGs) and production of cytokines from inflammatory cells. These data are consistent with the proposed pathway by which dietary intake of n-3 PUFA modulates lung disease. This article will review the existing information concerning the relationship between n-3 PUFA supplementation and airway hyperresponsiveness in asthma. It includes studies assessing the efficacy of n-3 PUFA supplementation in exercise-induced bronchoconstriction. This review will also address the question as to whether supplementing the diet with n-3 PUFA represents a viable alternative treatment regimen for asthma.     

Dietary fat and heart failure: moving from lipotoxicity to lipoprotection

There is growing evidence suggesting that dietary fat intake affects the development and progression of heart failure. Studies in rodents show that in the absence of obesity, replacing refined carbohydrate with fat can attenuate or prevent ventricular expansion and contractile dysfunction in response to hypertension, infarction, or genetic cardiomyopathy. Relatively low intake of n-3 polyunsaturated fatty acids from marine sources alters cardiac membrane phospholipid fatty acid composition, decreases the onset of new heart failure, and slows the progression of established heart failure. This effect is associated with decreased inflammation and improved resistance to mitochondrial permeability transition. High intake of saturated, monounsaturated, or n-6 polyunsaturated fatty acids has also shown beneficial effects in rodent studies. The underlying mechanisms are complex, and a more thorough understanding is needed of the effects on cardiac phospholipids, lipid metabolites, and metabolic flux in the normal and failing heart. In summary, manipulation of dietary fat intake shows promise in the prevention and treatment of heart failure. Clinical studies generally support high intake of n-3 polyunsaturated fatty acids from marine sources to prevent and treat heart failure. Additional clinical and animals studies are needed to determine the optimal diet in terms of saturated, monounsaturated, and n-6 polyunsaturated fatty acids intake for this vulnerable patient population.     

Japanese dietary lifestyle and cardiovascular disease

To demonstrate the reasons for low morbidity and mortality from coronary artery disease (CAD) and reconfirm the effectiveness of the Japanese dietary lifestyle for preventing CAD, we herein review the CAD risk transition, and post-war changes in Japanese food and nutrient intake. Large-scale cohort studies in Japan were selectively reviewed. Low serum total cholesterol contributed to preventing CAD, and decreased blood pressure was the major factor favoring stroke reduction. Japanese consumed more plant and marine origin foods, but fewer animal foods with saturated fatty acids (SFA) during the 1960-70s than in recent decades. Adequate control of total energy with restriction of saturated fatty acids from animal foods, increased intake of n-3 polyunsaturated fatty acids, including fish, soybean products, fruits and vegetables together with low salt intake are responsible for promoting CAD and stroke prevention. A diet with adequate total calories and increased intake of fish and plant foods, but decreased intake of refined carbohydrates and animal fat, a so-called Japan diet, appears to be quite effective for prevention of CAD risk factors and is recommended as dietary therapy for preventing CAD.     

Relation of long chain n-3 polyunsaturated fatty acid intake to serum high density lipoprotein cholesterol among Japanese men in Japan and Japanese-American men in Hawaii: the INTERLIPID study

Epidemiologic evidence shows an inverse relationship between fish consumption and coronary heart disease (CHD) mortality. Associations between dietary intake of long chain n-3 polyunsaturated fatty acids (PUFA) and serum high density lipoprotein (HDL) cholesterol concentration are unknown. In this study, the association between n-3 PUFA (eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA)) intake and serum HDL cholesterol among Japanese men and women in Japan and Hawaii was examined. The study population consisted of Japanese ancestries from five research centers of the International Study of Macronutrients and Blood Pressure (INTERMAP) study, in Japan and Hawaii (672 men and 676 women), surveyed between 1996 and 1998. Four 24-h dietary recalls and one set of serum lipid measurements were performed. For men, n-3 PUFA intake and HDL cholesterol were higher in Japan than in Hawaii (n-3 PUFA: 1.32 g/day versus 0.47 g/day, p<0.001). For women, n-3 PUFA intake was higher in Japan than in Hawaii (p<0.001) but HDL cholesterol was not significantly different (p=0.752). After adjustment for age, body mass index, physical activity, number of cigarettes per day, alcohol intake, and hormone replacement therapy (for women), n-3 PUFA intake was positively associated with serum HDL cholesterol in men (4.6 mg/dl higher HDL cholesterol with 1%kcal higher n-3 PUFA intake, p=0.011). This association was not observed in women. This positive association of dietary n-3 PUFA with serum HDL cholesterol may partially explain the low mortality from CHD among Japanese men.     

Progressing Insights into the Role of Dietary Fats in the Prevention of Cardiovascular Disease

Dietary fats have important effects on the risk of cardiovascular disease (CVD). Abundant evidence shows that partial replacement of saturated fatty acids (SAFA) with unsaturated fatty acids improves the blood lipid and lipoprotein profile and reduces the risk of coronary heart disease (CHD). Low-fat diets high in refined carbohydrates and sugar are not effective. Very long-chain polyunsaturated n-3 or omega-3 fatty acids (n-3 VLCPUFA) present in fish have multiple beneficial metabolic effects, and regular intake of fatty fish is associated with lower risks of fatal CHD and stroke. Food-based guidelines on dietary fats recommend limiting the consumption of animal fats high in SAFA, using vegetable oils high in monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA), and eating fatty fish. These recommendations are part of a healthy eating pattern that also includes ample intake of plant-based foods rich in fiber and limited sugar and salt.     

N-3 polyunsaturated fatty acids in coronary heart disease: a meta-analysis of randomized controlled trials

PURPOSE: Observational studies have shown an inconsistent association between n-3 polyunsaturated fatty acids and the risk of coronary heart disease. We investigated the effects of dietary and non-dietary (supplemental) intake of n-3 polyunsaturated fatty acids on coronary heart disease. SUBJECTS AND METHODS: We searched the literature to identify randomized controlled trials that compared dietary or non-dietary intake of n-3 polyunsaturated fatty acids with a control diet or placebo in patients with coronary heart disease. Studies had to have at least 6 months of follow-up data, and to have reported clinical endpoint data. We identified 11 trials, published between 1966 and 1999, which included 7951 patients in the intervention and 7855 patients in the control groups. RESULTS: The risk ratio of nonfatal myocardial infarction in patients who were on n-3 polyunsaturated fatty acid-enriched diets compared with control diets or placebo was 0.8 (95% confidence interval [CI]: 0.5 to 1.2, P = 0.16; Breslow-Day test for heterogeneity, P = 0.01), and the risk ratio of fatal myocardial infarction was 0.7 (95% CI: 0.6 to 0.8, P <0.001; heterogeneity P >0.20). In 5 trials, sudden death was associated with a risk ratio of 0.7 (95% CI: 0.6 to 0.9, P <0.01; heterogeneity P >0.20), whereas the risk ratio of overall mortality was 0.8 (95% CI: 0.7 to 0.9, P <0.001; heterogeneity P >0.20). There was no difference in summary estimates between dietary and non-dietary interventions of n-3 polyunsaturated fatty acids for all endpoints. CONCLUSION: This meta-analysis suggests that dietary and non-dietary intake of n-3 polyunsaturated fatty acids reduces overall mortality, mortality due to myocardial infarction, and sudden death in patients with coronary heart disease.     

Serum fatty acid composition as a marker of eating habits in normal and diabetic subjects

It is known that the Japanese people have had healthy eating habits, which may explain their low incidence of non-insulin-dependent diabetes mellitus (NIDDM). In the present study, in order to examine dietary habits such as fish consumption, the serum fatty acids from 190 normal people in their 30s and 50s living in Tokyo were surveyed. Furthermore, the fatty acid composition of 44 patients with DM was studied to clarify the difference in eating habits between normal and diabetic patients. The n-3:n-6 ratio of polyunsaturated fatty acids was 0.19 +/- 0.05 for the group in their 30s and 0.27 +/- 0.08 for the group in their 50s (P < 0.01). In patients with DM, the n-3:n-6 ratio was 0.23 +/- 0.05 and glycosylated haemoglobin (HbA1c) was 6.52 +/- 0.55%. After 4 months of dietary education, the n-3:n-6 ratio had increased to 0.27 +/- 0.06 (P < 0.01) and HbA1c had decreased significantly to 6.16 +/- 0.35% (P < 0.01). These findings indicated that people in their 50s tend to eat a traditional diet, which is abundant in fish oil, whereas people in their 30s, as well as patients with NIDDM in their 50s, appear to eat a diet that includes less fish than the traditional diet. Benefits of fish oil have been reported to be limited due to adverse effects in the glycemic controls in patients with NIDDM. Early instruction of newly diagnosed patients to encourage them to change their eating habits to a more traditional diet, which is abundant in fish, proved to be one of the safe methods for interventions in patients with DM.     

Dietary N-3 polyunsaturated fatty acids decrease biliary cholesterol saturation in gallstone disease.

Because fatty acid composition of biliary phospholipids influences cholesterol secretion into bile, we investigated whether replacement of n-1 monounsaturated or n-6 polyunsaturated fatty acids with n-3 polyunsaturated fatty acids in biliary phosphatidylcholines reduces supersaturation with cholesterol and prevents precipitation of cholesterol crystals in bile of gallstone patients. Seven patients with radiolucent gallstones in functioning gallbladders were studied before (control) and after 5 wk of dietary supplementation with marine fish oil (11.3 gm/day = 3.75 gm n-3 polyunsaturated fatty acids/day). Duodenal bile was collected for analysis during intravenous infusion of cholecystokinin. Gallbladder emptying in response to cholecystokinin was comparable before and during intake of n-3 polyunsaturated fatty acids. Intake of n-3 polyunsaturated fatty acids increased (p less than 0.001) the fractions of eicosapentaenoic and docosahexaenoic acids and decreased the fractions of linoleic (p less than 0.001) and arachidonic acids (p less than 0.02) in biliary phospholipids. Concomitantly, the molar ratio of cholesterol to phospholipids decreased (-19%; p less than 0.05). As a consequence, the cholesterol saturation index was reduced by -25% (p = 0.01), from 1.60 +/- 0.44 to 1.24 +/- 0.38. However, in vitro nucleation time of duodenal bile was not prolonged. The decrease in cholesterol saturation was not sufficient to prevent nucleation of cholesterol crystals in bile of gallstone patients. In conclusion, our data suggest that cholesterol saturation can be influenced by the fatty acid composition of the phosphatidylcholines secreted in bile.     

Comparative changes in the fatty-acid composition of rat cardiac phospholipids after long-term feeding of sunflower seed oil- or tuna fish oil-supplemented diets

The fatty-acid composition of rat heart phospholipids was examined after long-term, i.e. more than 12 months, feeding of diets supplemented with n-6 fatty acids as sunflower seed oil (SSO), or n-3 fatty acids as tuna fish oil (TFO) which is a particularly rich source of docosahexenoic acid (DHA). Although some small changes occurred in the relative proportions of palmitic and stearic acids and in the ratio of total saturates to total unsaturates, the most important changes were in the relative proportions of 18:2 n-6 and 20:4 n-6 to 20:5 n-3 and 22:6 n-3. In general, the n-6/n-3 ratio of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and diphosphatidyl glycerol (DPG) was altered in favour of the family of fatty acids administered, although the proportions of the individual long-chain polyunsaturated fatty acids which contributed to this ratio varied from one class of phospholipids to another. In cardiac PC and PE, feeding TFO supplements reduced the proportions of arachidonic acid (AA) and significantly elevated (p less than 0.01) the proportions of DHA but produced relatively little change in those of eicosapentenoic acid (EPA). In DPG, feeding TFO led to a significant increase in the proportion of AA as well as an increase in DHA. The level of EPA was relatively low in PC, PE and DPG even after TFO feeding and never reached comparable levels with that of either AA or DHA. Nevertheless the n-6/n-3 ratio in all these classes of major cardiac phospholipids was significantly reduced by feeding TFO compared to the SSO diet or the commercial rat chow (CC) reference group. In contrast to the reports of other workers who have studied the fatty-acid composition of platelet membranes after feeding various fish oil supplements, in the rat heart the major effect of tuna fish oil is an increase in the proportion of DHA rather than EPA in the cardiac phospholipids.     

Steatosis and Collagen Content in Experimental Liver Cirrhosis Are Affected by Dietary Monounsaturated and Polyunsaturated Fatty Acids

Background and Methods: We used thioacetamide administered orally to induce cirrhosis in rats, and after these had recovered for 1 and 2 weeks we examined the effects of dietary supplementation with monounsaturated and n-3 polyunsaturated fatty acids, or with a combination of n-3 and n-6 polyunsaturated fatty acids, on the extent of steatosis and collagen content in the liver. Results: Nodular cirrhosis, increased collagen content, and lipid accumulation were established after 4 months of treatment with thioacetamide. When the animals were fed a diet rich in oleic acid for 2 weeks, the steatosis and fibrosis decreased. Supplementation with n-3 polyunsaturated fatty acids favored reductions in collagen content but did not reduce the fat accumulation. With a diet supplemented with a mixture of n-3 and n-6 fatty acids we found no reduction in either lipid accumulation or collagen content. Conclusions: Fibrosis and steatosis may be influenced by dietary fat, and monounsaturated fat appears to influence favorably the histologic recovery of the damaged liver.     

Comparative effects of feeding different fats on fatty acid composition of major individual phospholipids of rat hearts

Comparative effects of feeding dietary linoleic (corn oil), oleic (olive oil), alpha-linolenic (soybean oil) and polyunsaturated fatty acids (fish oil) on lipid content and fatty acid composition of major individual phospholipids of rat hearts were examined. Feeding different diets did not result in lipid accumulation in the heart. Total triglyceride, nonesterified fatty acid, cholesteryl ester and phospholipid levels of heart tissue were not affected by the type of dietary fatty acid. However, heart free cholesterol levels decreased in both animals fed the olive and the fish oil diets. The percentage of individual phospholipids, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and cardiolipin (CL) did not modify by changes in the dietary fat composition. Heart tissue from animals fed on olive oil were enriched with 18:1 (n-9 + n-7) fatty acid in all phospholipid fractions. Animals fed corn oil contained higher proportions of 18:2 (n-6) for PC, PE and CL, and the ingestion of the soybean oil diet increased 18:2 (n-6) for PC and CL in the same proportion as the ingestion of the corn oil diet. The levels of 22:6 (n-3) were increased in the fish oil-fed group, accompanied by both a decrease in total (n-6) fatty acids and an increase in total (n-3) fatty acids in the three phospholipid fractions. The 20:5 (n-3) was only detected in these animals. These results show that olive oil is as effective as fish oil in reducing heart cholesterol content and support earlier works suggesting the role of fish oil in preventing cardiovascular disease.