The content of favorable and unfavorable polyunsaturated fatty acids found in commonly eaten fish

Changes in diet during the past century have caused a marked increase in consumption of saturated fatty acids and n-6 polyunsaturated fatty acids (PUFAs) with a concomitant decrease in the intake of n-3 PUFAs. Increased fish consumption has been shown to be the only realistic way to increase dietary quantities of beneficial long-chain n-3 PUFAs such as eicosapentaenoic acid and docosahexaenoic acid and re-establish more balanced n-6:n-3 ratios in the diets of human beings. Our objective in this research was to characterize some of the relevant fatty acid chemistry of commonly consumed fish, with a particular focus on the four most commonly consumed farmed fish. To do this, 30 commonly consumed farmed and wild fish were collected from supermarkets and wholesalers throughout the United States. Fatty acid composition of samples from these fish was determined using gas chromatography. The 30 samples studied contained n-3 PUFAs ranging from fish having almost undetectable levels to fish having nearly 4.0 g n-3 PUFA per 100 g fish. The four most commonly farmed fish, Atlantic salmon, trout, tilapia, and catfish, were more closely examined. This analysis revealed that trout and Atlantic salmon contained relatively high concentrations of n-3 PUFA, low n-6:n-3 ratios, and favorable saturated fatty acid plus monounsaturated fatty acid to PUFA ratios. In contrast, tilapia (the fastest growing and most widely farmed fish) and catfish have much lower concentrations of n-3 PUFA, very high ratios of long chain n-6 to long chain n-3 PUFAs, and high saturated fatty acid plus monounsaturated fatty acid to PUFA ratios. Taken together, these data reveal that marked changes in the fishing industry during the past decade have produced widely eaten fish that have fatty acid characteristics that are generally accepted to be inflammatory by the health care community.     

Long-term intake of trans (n-3) polyunsaturated fatty acids reduces the b-wave amplitude of electroretinograms in rats

Weanling rats were fed three diets differing in their concentrations of the cis- and trans-isomers of alpha-linolenic acid [18:3(n-3)] for 12 mo to study the long-term effects of these fatty acids on the electroretinogram (ERG). The diets contained 18:3(n-3) in its natural form at 2.0 g/100 g total fatty acids (C group), partially isomerized 18:3(n-3) [1.3 g/100 g cis 18:3(n-3) + 0.7 g/100 g trans 18:3(n-3); cT group] and the control level of cis 18:3(n-3) with trans 18:3(n-3) [2.0 g/100 g cis 18:3(n-3) + 0.7 g/100 g trans 18:3(n-3); CT group]. The ERG and the levels of trans-isomers of the polyunsaturated fatty acids (PUFA) of retinal and hepatic phospholipids were determined after 3, 6, 9 and 12 mo of feeding the experimental diets. Dietary trans alpha-linolenic acid altered the fatty acid composition of retinal and hepatic phospholipids by significantly increasing the Delta19trans-isomer of docosahexaenoic acid. Moreover, dietary trans-isomers of alpha-linolenic acid significantly decreased the b-wave amplitude of the ERG by 9 mo of feeding. We conclude that long-term intake of small amounts of trans-isomers of alpha-linolenic acid could disturb visual function. However, further studies are required to determine the mechanisms responsible for this phenomenon.     

Effects of including a ruminally protected lipid supplement in the diet on the fatty acid composition of beef muscle

Enhancing the polyunsaturated fatty acid (PUFA) and decreasing the saturated fatty acid content of beef is an important target in terms of improving the nutritional value of this food for the consumer. The present study examined the effects of feeding a ruminally protected lipid supplement (PLS) rich in PUFA on the fatty acid composition of longissimus thoracis muscle and associated subcutaneous adipose tissue. Animals were fed ad libitum on grass silage plus one of three concentrate treatments in which the lipid source was either Megalac (rich in palmitic acid; 16 : 0) or PLS (soybean, linseed and sunflower-seed oils resulting in an 18 : 2n-6:18 : 3n-3 value of 2.4:1). Treatment 1 contained 100 g Megalac/kg (Mega, control); treatment 2 (PLS1) contained 54 g Megalac/kg with 500 g PLS/d fed separately; treatment 3 (PLS2) contained no Megalac and 1000 g PLS/d fed separately. The PLS was considered as part of the overall concentrate allocation per d in maintaining an overall forage:concentrate value of 60:40 on a DM basis. Total dietary fat was formulated to be 0.07 of DM of which 0.04 was the test oil. Total intramuscular fatty acids (mg/100 g muscle) were decreased by 0.31 when feeding PLS2 compared with Mega (P<0.05). In neutral lipid, the PLS increased the proportion of 18 : 2n-6 and 18 : 3n-3 by 2.7 and 4.1 on diets PLS1 and PLS2 v. Mega, respectively. Similar responses were noted for these fatty acids in phospholipid. The amounts or proportions of 20 : 4n-6, 20 : 5n-3 or 22 : 6n-3 were not influenced by diet whereas the amounts and proportions of 22 : 4n-6 and 22 : 5n-3 in phospholipid were decreased with inclusion of the PLS. The amounts of the saturated fatty acids, 14 : 0, 16 : 0 and 18 : 0, in neutral lipid were on average 0.37 lower on treatment PLS2 compared with Mega. Feeding the PLS also decreased the proportion of 16 : 0 in neutral lipid. The amount of 18 : 1n-9 (P=0.1) and the amount and proportion of 18 : 1 trans (P<0.01) were lower on treatments PLS1 and PLS2 in neutral lipid and phospholipid. Conjugated linoleic acid (cis-9, trans-11) was not influenced by diet in the major storage fraction for this fatty acid, neutral lipid. The PUFA:saturated fatty acids value was increased markedly (x2.5) with inclusion of the PLS (P<0.001) while the Sigman-6 : n-3 value increased slightly (x1.2; P=0.015). The results suggest that the protected lipid used, which was rich in PUFA, had a high degree of protection from the hydrogenating action of rumen micro-organisms. The PLS resulted in meat with a lower content of total fat, decreased saturated fatty acids and much higher 18 : 2n-6 and 18 : 3n-3. The net result was a large shift in polyunsaturated: saturated fatty acids, 0.28 v. 0.08, on feeding PLS2 compared with Mega, respectively.     

Alpha-linolenic acid content of commonly available nuts in Hangzhou

The total lipid content of eight species of nuts available in Hangzhou ranged from 49.5 g/100 g weight in Cannabis sativa to 75.4 g/100 g in walnut. The predominant content of lipid is triacylglycerol, ranging from 91.1% in Cannabis sativa to 98.4% in macadamia. There were two polyunsaturated fatty acids (PUFA) in all nuts analyzed; 18:2n-6 and 18:3n-3. The content of 18:3n-3 ranging from 0.2% in almond to 15.2% in Cannabis sativa, 18:2n-6 ranged from 2.5% in macadamia to 61.6% in pine nut. The proportion of total PUFA in analyzed eight nut species ranging from 2.8% in macadamia to 71.7% in walnut (p < 0.001). Monounsaturated fatty acid composition ranged from 18.0% in Cannabis sativa to 82.6% in macadamia (p < 0.001). The proportion of saturated fatty acid ranged from 7.4% in filbert to 14.7% of total fatty acids in macadamia (p < 0.001). No C20 fatty acids were detected in any of the samples in the present study. The lipids content and fatty acid compositions in analyzed samples were varied between nut species. Cannabis sativa and walnut contained relatively high 18:3n-3, consumption of several these nuts each day can contribute to n-3 PUFA intake, especially for the vegetarian population.     

Serum concentrations of carotenoids, alpha-tocopherol, fatty acids, and lipid peroxides among Japanese in Japan, and Japanese and Caucasians in the US

Serum concentrations of carotenoids, alpha-tocopherol, fatty acids, and thiobarbituric acid-reactive substances (TBARS) were measured in 217 Japanese residents of Japan, and in 99 Japanese and 100 Caucasian residents of the US, aged from 50 y to 74 y. In females, serum values of carotenoids such as beta-carotene (BC) and zeaxanthin & lutein (ZL) were highest among Japanese in Japan, followed by Japanese in the US and Caucasians in the US. In males, these values, except for serum BC values, were also highest among Japanese in Japan. Moreover, serum values of n-3 polyunsaturated fatty acids (n-3PUFAs) such as eicosapentaenoic acid and docosahexaenoic acid were significantly higher among Japanese in Japan than among Japanese and Caucasians in the US in both sexes. In contrast, serum values of n-6 polyunsaturated fatty acids such as linoleic acid and arachidonic acid were lowest among Japanese in Japan. For women, serum levels of n-9 unsaturated fatty acids were lowest among Japanese living in Japan. Serum TBARS values were highest among Japanese in Japan, followed by Japanese in the US and Caucasians in the US. A significant positive correlation was observed between serum values of TBARS and n-3 PUFAs among Japanese both in Japan and in the US. Serum TBARS values showed a significant inverse relationship with the serum values of BC and ZL among Japanese in Japan and with those of BC among Japanese in the US. These relationships were not always observed among Caucasians in the US. The results of this study suggest that the high TBARS values among Japanese in Japan may depend in part on lipid peroxidation induced in vitro by n-3PUFAs, while high reduction of lipid peroxidation could be expected among Japanese in Japan with high antioxidants such as BC and ZL. In conclusion, serum levels of nonprovitamin A carotenoids such as ZL may be a useful intake marker of vegetables. Dietary intakes of dark green vegetables and fish rich in n-3PUFAs might be more important in the prevention of some sites of cancer and of ischemic heart disease.     

Levels of Omega 3 fatty acids in Australian seafood

The aim of this study was to determine the quantity of omega 3 (n-3) fatty acids in commonly consumed species of South Australian fish. Omega 3 fatty acids ranged from 17.7% to 53.7% of total fat with docosahexaenoic acid (DHA, 22:6n-3) as the major omega 3 fatty acid in all 26 species tested (range 9.5 % to 47.1% of total fat). The levels of total omega 6 (n-6) fatty acids ranged from 2.3% to 20.2% of total lipids, chiefly as arachidonic acid (AA, 20:4n-6). Fatty fish such as Gemfish, Atlantic Salmon and Swordfish were found to be good sources of omega-3 fatty acid (1360, 2252 and 2571 mg/100g fish respectively), while low fat fish such as Ling, Deep Sea Bream (Blue Warhou) and Blue Grenadier (0.5, 0.7 and 0.7% fat) had low levels of omega 3 fatty acid (222, 257 and 247 mg/100g). Because most white table fish consumed by Australians are so low in fat they are actually a limited source of omega 3 fats. The amount of fish required to be consumed to provide 1 g of omega 3 fatty acid per day ranged from 40 to 450 g.     

Microparticulate protein in foods.

omega-3 fatty acids, alpha-tocopherol, ascorbic acid, beta-carotene and glutathione determined in leaves of purslane (Portulaca oleracea), grown in both a controlled growth chamber and in the wild, were compared in composition to spinach. Leaves from both samples of purslane contained higher amounts of alpha-linolenic acid (18:3w3) than did leaves of spinach. Chamber-grown purslane contained the highest amount of 18:3w3. Samples from the two kinds of purslane contained higher leaves of alpha-tocopherol, ascorbic acid and glutathione than did spinach. Chamber-grown purslane was richer in all three and the amount of alpha-tocopherol was seven times higher than that found in spinach, whereas spinach was slightly higher in beta-carotene. One hundred grams of fresh purslane leaves (one serving) contain about 300-400 mg of 18:3w3; 12.2 mg of alpha-tocopherol; 26.6 mg of ascorbic acid; 1.9 mg of beta-carotene; and 14.8 mg of glutathione. We confirm that purslane is a nutritious food rich in omega-3 fatty acids and antioxidants.     

Common purslane: a source of omega-3 fatty acids and antioxidants.

omega-3 fatty acids, alpha-tocopherol, ascorbic acid, beta-carotene and glutathione determined in leaves of purslane (Portulaca oleracea), grown in both a controlled growth chamber and in the wild, were compared in composition to spinach. Leaves from both samples of purslane contained higher amounts of alpha-linolenic acid (18:3w3) than did leaves of spinach. Chamber-grown purslane contained the highest amount of 18:3w3. Samples from the two kinds of purslane contained higher leaves of alpha-tocopherol, ascorbic acid and glutathione than did spinach. Chamber-grown purslane was richer in all three and the amount of alpha-tocopherol was seven times higher than that found in spinach, whereas spinach was slightly higher in beta-carotene. One hundred grams of fresh purslane leaves (one serving) contain about 300-400 mg of 18:3w3; 12.2 mg of alpha-tocopherol; 26.6 mg of ascorbic acid; 1.9 mg of beta-carotene; and 14.8 mg of glutathione. We confirm that purslane is a nutritious food rich in omega-3 fatty acids and antioxidants.     

Comparison between omega-3 and omega-6 polyunsaturated fatty acid intakes as assessed by a food frequency questionnaire and erythrocyte membrane fatty acid composition in young children

OBJECTIVE: We conducted a dietary validation study in youth aged 1-11 years by comparing dietary intake of omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) as assessed by a parent-completed semiquantitative food frequency questionnaire (FFQ) over time to erythrocyte membrane composition of the same fatty acids. DESIGN: The study population included youth aged 1-11 years who were participants in the Diabetes Autoimmunity Study in the Young (DAISY), a longitudinal study in Denver, Colorado that is following a cohort of youth at risk for developing type I diabetes. Four hundred and four children who had erythrocyte membrane fatty acid data matched to an FFQ corresponding to the same time frame for a total of 917 visits (matches) were included. PUFA intake was expressed both as g/day (adjusted for total energy) and as percent of total fat intake. We used mixed models to test the association and calculate the correlation between the erythrocyte membrane estimates and PUFA intake using all records of data for each youth. RESULTS: Intakes of total omega-3 fatty acids (beta=0.52, P<0.0001, rho=0.23) and marine PUFAs (beta=1.62, P<0.0001, rho=0.42), as a percent of total fat in the diet, were associated with percent of omega-3 and marine PUFAs in the erythrocyte membrane. Intakes of omega-6 PUFAs (beta=0.04, P=0.418, rho=0.05) and arachidonic acid (beta=0.31, P=0.774, rho=0.01) were not associated. CONCLUSIONS: In these young children, an FFQ using parental report provided estimates of average long-term intakes of marine PUFAs that correlated well with their erythrocyte cell membrane fatty acid status.     

Relation between the fatty acid composition of peripheral blood mononuclear cells and measures of immune cell function in healthy,free-living subjects aged 25-72 y

BACKGROUND: There is little information about the relation between the fatty acid composition of human immune cells and the function of those cells over the habitual range of fatty acid intakes. OBJECTIVE: The objective of the study was to determine the relation between the fatty acid composition of human peripheral blood mononuclear cell (PBMC) phospholipids and the functions of human immune cells. DESIGN: One hundred fifty healthy adult subjects provided a fasting blood sample. The phagocytic and oxidative burst activities of monocytes and neutrophils were measured in whole blood. PBMCs were isolated and used to measure lymphocyte proliferation in response to the T cell mitogen concanavalin A and the production of cytokines in response to concanavalin A or bacterial lipopolysaccharide. The fatty acid composition of plasma and PBMC phospholipids was determined. RESULTS: Wide variations in fatty acid composition of PBMC phospholipids and immune cell functions were identified among the subjects. The proportions of total polyunsaturated fatty acids (PUFAs), of total n-6 and n-3 PUFAs, and of several individual PUFAs in PBMC phospholipids were positively correlated with phagocytosis by neutrophils and monocytes, neutrophil oxidative burst, lymphocyte proliferation, and interferon gamma production. The ratios of saturated fatty acids to PUFAs and of n-6 to n-3 PUFAs were negatively correlated with these same immune functions. The relation of PBMC fatty acid composition to monocyte oxidative burst was the reverse of its relation to monocyte phagocytosis and neutrophil oxidative burst. CONCLUSION: Variations in the fatty acid composition of PBMC phospholipids account for some of the variability in immune cell functions among healthy adults.     

Soluble Fiber Inulin Consumption Limits Alterations of the Gut Microbiota and Hepatic Fatty Acid Metabolism Caused by High-Fat Diet

Diet shapes the gut microbiota which impacts hepatic lipid metabolism. Modifications in liver fat content are associated with metabolic disorders. We investigated the extent of dietary fat and fiber-induced alterations in the composition of gut microbiota and hepatic fatty acids (FAs). Mice were fed a purified low-fat diet (LFD) or high-fat diet (HFD) containing non-soluble fiber cellulose or soluble fiber inulin. HFD induced hepatic decreases in the amounts of C14:0, C16:1n-7, C18:1n-7 and increases in the amounts of C17:0, C20:0, C16:1n-9, C22:5n-3, C20:2n-6, C20:3n-6, and C22:4n-6. When incorporated in a LFD, inulin poorly affected the profile of FAs. However, when incorporated in a HFD, it (i) specifically led to an increase in the amounts of hepatic C18:0, C22:0, total polyunsaturated FAs (PUFAs), total n-6 PUFAs, C18:3n-3, and C18:2n-6, (ii) exacerbated the HFD-induced increase in the amount of C17:0, and (iii) prevented the HFD-induced increases in C16:1n-9 and C20:3n-6. Importantly, the expression/activity of some elongases and desaturases, as well as the gut microbiota composition, were impacted by the dietary fat and fiber content. To conclude, inulin modulated gut microbiota and hepatic fatty acid composition, and further investigations will determine whether a causal relationship exists between these two parameters.     

Lipophilic antioxidants and polyunsaturated fatty acids in lipoprotein classes: distribution and interaction

OBJECTIVE: To study the lipoprotein distribution of supplemented coenzyme Q10 (CoQ10), vitamin E, and polyunsaturated fatty acids (PUFA). DESIGN: Balanced three-period crossover study. SETTING: University research unit. SUBJECTS: Eighteen apparently healthy free-living non-smoking volunteers (nine women, nine men), mean age 26 +/- 3 y, recruited among the university students; no dropouts. INTERVENTIONS: Three supplementation periods of 10 days: 100 mg/day CoQ10, 350 mg/day D-alpha-tocopherol, and 2 g/day concentrated fish oil. Fasting venous blood samples were collected twice before the first period and then after each period. Plasma and isolated lipoproteins were analysed for cholesterol, triacylglycerol, alpha- and gamma-tocopherol, CoQ10, and fatty acid composition. RESULTS: Significant (P < 0.05) increase in CoQ10 and alpha-tocopherol occurred in all lipoprotein classes after supplementation. CoQ10 was primarily incorporated into low-density lipoprotein (LDL). alpha-tocopherol and fish oil n-3 PUFAs had similar patterns. They were equally distributed between LDL and high-density lipoprotein (HDL), with a smaller part in VLDL. The total sum of PUFA was unchanged following all supplementations, but fish oil increased the amount of n-3 fatty acids at the expense of n-6 fatty acids. CONCLUSION: Lipoprotein distribution of CoQ10 is markedly different from that of alpha-tocopherol, suggesting that they may be metabolised by distinct routes. alpha-Tocopherol is distributed similarly to n-3 fatty acids, thus providing protection on location for the oxidatively labile PUFAs.     

Acute ingestion of a meal rich in n-3 polyunsaturated fatty acids results in rapid gastric emptying in humans

BACKGROUND: n-3 Polyunsaturated fatty acids (PUFAs) have proven benefits for both the development of atherosclerosis and inflammatory conditions. The effects on atherosclerosis may be partly mediated by the observed reduction in fasting and postprandial triacylglycerol concentrations after both acute and chronic n-3 PUFA ingestion. OBJECTIVE: The aim of this study was to assess gastric emptying and gastrointestinal hormone release after the consumption of mixed meals rich in n-3 PUFAs or other classes of fatty acids. DESIGN: Ten healthy women (aged 50-62 y) completed 4 separate study visits in a single-blind, randomized design. On each occasion, subjects consumed 40 g oil rich in either saturated fatty acids, monounsaturated fatty acids, n-6 PUFAs, or n-3 PUFAs as part of a mixed meal. [1-(13)C]Octanoic acid (100 mg) was added to each oil. Gastric emptying was assessed by a labeled octanoic acid breath test, and concentrations of gastrointestinal hormones and plasma lipids were measured. RESULTS: Recovery of (13)C in breath was enhanced after n-3 PUFA ingestion (P < 0.005). The cholecystokinin response after the n-3 PUFA meal was significantly delayed (P < 0.001), and the glucagon-like peptide 1 response was significantly reduced (P < 0.05). CONCLUSION: The inclusion of n-3 PUFAs in a meal alters the gastric emptying rate, potentially as the result of changes in the pattern of cholecystokinin and glucagon-like peptide 1 release.     

Fatty acid composition of skeletal muscle reflects dietary fat composition in humans

BACKGROUND: It is still unknown whether the fatty acid composition of human skeletal muscle lipids is directly influenced by the fat composition of the diet. OBJECTIVE: We investigated whether the fatty acid composition of the diet is reflected in the fatty acid profile of skeletal muscle phospholipids and triacylglycerols. DESIGN: Thirty-two healthy adults (25 men and 7 women) included in a larger controlled, multicenter dietary study were randomly assigned to diets containing a high proportion of either saturated fatty acids (SFAs) [total fat, 36% of energy; SFAs, 18% of energy; monounsaturated fatty acids (MUFAs), 10% of energy] or MUFAs (total fat, 35% of energy; SFAs, 9% of energy; MUFAs, 19% of energy) for 3 mo. Within each diet group, there was a second random assignment to supplementation with fish oil capsules [containing 3.6 g n-3 fatty acids/d; 2.4 g eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3)] or placebo. A muscle biopsy sample was taken from the vastus lateralis muscle after the diet period. Parallel analyses of diet and supplementation effects were performed. RESULTS: The proportions of myristic (14:0), pentadecanoic (15:0), heptadecanoic (17:0), and palmitoleic (16:1n-7) acids in the skeletal muscle phospholipids were higher and the proportion of oleic acid (18:1n-9) was lower in the SFA group than in the MUFA group. The proportion of total n-3 fatty acids in the muscle phospholipids was approximately 2.5 times higher, with a 5 times higher proportion of eicosapentaenoic acid (20:5n-3), in subjects supplemented with n-3 fatty acids than in those given placebo. Similar differences were observed in the skeletal muscle triacylglycerols. CONCLUSION: The fatty acid composition of skeletal muscle lipids reflects the fatty acid composition of the diet in healthy men and women.     

GC-MS方法检测超重/肥胖男性青年血清游离脂肪酸代谢谱

目的研究超重/肥胖男性血清脂肪酸水平的变化。方法采用气相色谱质谱联用(GC/MS)方法检测30例超重男性和30例体重正常男性血清16种游离脂肪酸水平。结果超重/肥胖组血清高密度脂蛋白胆固醇(HDL-C)水平显著降低(P<0.05)、甘油三酯(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)水平显著升高(P<0.05),血糖(GLU)水平无显著差异(P>0.05);超重/肥胖组血清游离脂肪酸肉豆蔻酸(C14:0)、棕榈酸(C16:0)、软油酸(C16:1)、硬脂酸(C18:0)、油酸(C18:1)、亚油酸(C18:2)、γ-亚麻酸(γ-C18:3)、α-亚麻酸(C18:3)、二十碳二烯酸(C20:2)、二十碳五烯酸EPA(C20:5)、二十二碳六烯酸DHA(C22:6)、二十四碳酸(C24:0)、水平显著高于正常组(P<0.05);总脂肪酸(TFA)、饱和脂肪酸(SFA)、单不胞和脂肪酸(MUFA)、多不饱和脂肪酸(PUFA)、n-3PUFAs、n-6PUFAs水平均高于正常组(P<0.05),PUFA/TFA超重/肥胖组显著低于正常组。多元统计分析结果也显示C14:0、C16:0、C18:0等SFAs以及n-3PUFA C18:3在PCA模型中超重/肥胖组与正常组的分离起到重要作用。结论肥胖发生早期体内即出现血脂和游离脂肪酸等脂类代谢紊乱,C14:0、C16:0、C18:0和C18:3可作为肥胖血清脂肪酸变化的潜在生物标记物。[营养学报,2013,35(2):137-141]     

Plasma fatty acid composition and depression are associated in the elderly: the Rotterdam Study

BACKGROUND: It has been hypothesized that n-3 polyunsaturated fatty acids (PUFAs) are involved in mood regulation, but epidemiologic evidence for such a link in the general population is lacking. OBJECTIVE: This study examined whether community-dwelling elderly persons with depression have a fatty acid composition that is different from that of nondepressed persons. DESIGN: We screened 3884 adults aged > or = 60 y for depressive symptoms as part of the Rotterdam Study. Subjects who screened positive had a psychiatric interview to diagnose depressive disorders. All eligible subjects had their blood drawn for measurement of plasma phospholipid concentrations. We compared percentages of n-3 and n-6 PUFAs and their ratios between 264 subjects with depressive symptoms, including 106 subjects with depressive disorders, and 461 randomly selected reference subjects. We also investigated whether atherosclerosis or the inflammatory response as measured by C-reactive protein underlies the relation between fatty acid composition and depression. RESULTS: Subjects with depressive disorders had a higher ratio of n-6 to n-3 PUFAs, but differences in individual PUFAs were mostly small. However, depressed subjects with normal CRP concentrations (< 1.5 mg/L) had a substantially altered fatty acid composition; percentages of n-3 PUFAs and ratios of n-6 to n-3 PUFAs were significantly lower and higher, respectively, in subjects with depressive disorders than in control subjects [5.2% compared with 5.9% (P = 0.02) and 7.2 compared with 6.6 (P = 0.01), respectively]. This relation was not due to atherosclerosis. CONCLUSIONS: In community-dwelling persons, fatty acid composition is related to depression. Because this relation was not secondary to inflammation, atherosclerosis, or possible confounders, it suggests a direct effect of fatty acid composition on mood.     

Serum fatty acids and breast cancer incidence

Fatty acid composition of the diet may be essential to the development of breast cancer. We studied the ability of several fatty acids of serum total lipids to predict breast cancer incidence in a case-control study nested within a longitudinal population study. The proportions of fatty acids in serum total lipids were determined from stored serum samples collected at baseline for 127 incident breast cancer cases and 242 matched controls. Women with a higher proportion of total polyunsaturated fatty acids (PUFAs) in serum had a reduced risk of breast cancer. The odds ratio (OR) between the highest and lowest tertiles of serum PUFA was 0.31 (95% confidence interval, CI = 0.12-0.77). This association was mainly due to n-6 PUFAs and especially to linoleic acid. The ORs were 0.35 (CI = 0.14-0.84) and 0.29 (CI = 0.12-0.73), respectively. Of the monounsaturated fatty acids (MUFAs), higher trans-11-18:1 levels were related to an increased breast cancer risk (OR = 3.69, CI = 1.35-10.06). The association was stronger in postmenopausal than in premenopausal women. The present study suggests that higher serum proportions of the n-6 PUFA linoleic acid and lower proportions of the MUFA trans-11-18:1 fatty acid predict a reduced incidence of breast cancer.     

Effects of dietary fat source and breed on the carcass composition,n-3 polyunsaturated fatty acid and conjugated linoleic acid content of sheep meat and adipose tissue

Seventy-two 8-week-old ram lambs from three breeds, Suffolk, Soay and Friesland, were offered one of four diets based on dried grass and formulated to have a similar fatty acid content (60 g/kg DM) and containing: Megalac (high in 16 : 0, control; Volac Ltd, Royston, Herts., UK), whole linseed (18 : 3n-3), fish oil (20 : 5n-3 and 22 : 6n-3) or whole linseed plus fish oil. The lambs were slaughtered at approximately half of their mature live weight (43, 21 and 43 kg for Suffolk, Soay and Friesland lambs, respectively). Fish oil reduced DM intake and lamb live-weight gain (P<0.001), while DM intake, live-weight gain and subcutaneous fat content were highest in Suffolk and lowest in Soay lambs. Linseed feeding doubled the proportion (x100) of 18 : 3n-3 in the longissimus dorsi from 1.4 to 3.1 and in the subcutaneous adipose tissue from 1.2 to 2.6 (P<0.001). Suffolk and particularly Soay lambs contained higher proportions of 18 : 3n-3 than Friesland lambs in the longissimus dorsi, while in the adipose tissue, Suffolk lambs had the highest level. Feeding fish oil increased the muscle proportion (x100) of 20 : 5n-3 from 0.7 to 2.3 and 22 : 6n-3 from 0.3 to 0.8 (P<0.001). By contrast, the proportions of the longer-chain n-3 polyunsaturated fatty acids were similar across all three breeds. All three lipid supplements containing n-3 polyunsaturated fatty acids increased the content of muscle trans-18 : 1 relative to the control values, but conjugated linoleic acid (cis-9,trans-11-18 : 2) only increased in the muscle of lambs fed linseed. Feeding linseed or fish oil lowered the n-6 : n-3 ratio in sheep meat, but neither diet nor breed had much effect on the polyunsaturated fatty acid: saturated fatty acid ratio.     

Shellfish: proximate composition, minerals, fatty acids, and sterols

Proximate composition, minerals, fatty acids, and sterols were determined for eight species of shellfish commonly marketed in the Northwest. Moisture and total lipid content varied with the size of the species, with more variation in mollusca than in crustacea; total lipid content ranged from 0.7% in sea scallops to 3.1% in blue mussels but only from 1.2% in Dungeness crab to 1.3% in pink shrimp. The mineral content was highly variable; the mineral content of Northwest samples tended to be lower than that reported in other studies. Generally, shellfish are good sources of zinc, and Pacific oysters, blue mussels, and Manila clams are also good sources of iron. Five fatty acids (16:0, 16:1, 18:1, 20:5n-3, and 22:6n-3) represented from 60% to 84% of the fatty acid content. Palmitic acid ranged from 13% to 32% of the total fatty acids. Long-chain n-3 polyunsaturated fatty acids were predominant (37.6% to 54.3%), with sea scallops containing more than 50%; n-6 polyunsaturated fatty acids ranged from 1.5% to 6.5%. In crustacea, cholesterol was the primary sterol, and brassicasterol was the only other measurable sterol. In all mollusca except California squid, cholesterol averaged 37 mg/100 gm and ranged from 23% to 39% of the total sterols. In squid, cholesterol, at 231 mg/100 gm, was the only measurable sterol. We conclude that shellfish vary widely in their nutrient content but, in general, are valuable additions to the diet.     

Changes in plasma fatty acid composition after intake of a standardised breakfast in prepubertal obese children

Obese patients typically show a pattern of dyslipidaemia and changes in plasma fatty acid composition reflecting abnormalities in lipoprotein metabolism and dietary habits. Animals and obese adults have been widely studied; however, contradictory results have been published in children. The objective was to assess changes in plasma fatty acid composition in total plasma lipids and plasma lipid fractions in obese prepubertal children compared with those of normal weight and to evaluate changes in postprandial plasma fatty acids during a 3 h period after intake of a standardised breakfast. The study was a case-control study with thirty-four obese and twenty normal-weight prepubertal children (Tanner 1). Anthropometric and metabolic variables and fatty acid concentrations were measured in plasma and its fractions. Liquid chromatography was used to separate lipid fractions and GLC to quantify fatty acids. Plasma total fatty acids (TFA), SFA, MUFA and PUFA concentrations were higher in obese than in control children. Except for 18 : 0, 18 : 3n-3, 20 : 4n-6 and n-3 PUFA, all fatty acids in TAG were also elevated in the obese group. Fatty acids 16 : 1n-7, 18 : 0, 18 : 1n-9, 20 : 2n-6, TFA and MUFA significantly decreased between the 2nd and 3rd hour in normal-weight v. obese children. The concentration of 16 : 1n-7 was positively and the proportion of 20 : 4n-6 inversely associated with a significant increase in risk of obesity. Obese prepubertal children show an altered plasma fatty acid profile and concentrations, mainly related to the TAG fatty acid profile, with a lower clearance of fatty acids v. normal-weight prepubertal children.