Fat content and fatty acid compositions of 34 marine water fish species from the Mediterranean Sea

Fish is the best source of polyunsaturated fatty acids (PUFA), specifically n-3 fatty acids, especially eicosapentaenoic acid and docosahexaenoic acid. The objective of the present study was to determine the fat content and fatty acid compositions of 34 marine water fish species from the Mediterranean Sea. The fatty acid compositions of fish consisted of 30.10–46.88% saturated fatty acids, 11.83–38.17% monounsaturated fatty acids and 20.49–49.31% PUFA. In most species, the following fatty acids were identified: mystiric acid (C14:0, 0.72–8.09%), pentadecanoic acid (15:0, 0.05–2.35%), palmitic acid (C16:0, 15.97–31.04%), palmitoleic acid (C16:1, 1.48–19.61%), heptadecanoic acid (C17:0, 0.31–1.84%), cis-10-heptadecenoic acid (C17:1, 0.17–2.01%), stearic acid (C18:0, 2.79–11.20%), oleic acid (C18:1n9, 2.44–28.97%), linoleic acid (C18:2n-6, 0.06–3.48%), arachidonic acid (C20:4n-6, 0.12–10.72%), cis-5,8,11,14,17-eicosapentaenoic acid (C20:5n-3, 1.94–10%) and cis-4,7,10,13,16,19-docosahexaenoic acid (C22:6n-3, 3.31–31.03%). The proportions of n-3 PUFA ranged from 12.66% for annular seabream to 36.54% for European hake, whereas the proportions of PUFA n-6 were between 1.24% for oceanic puffer and 12.76% for flathead mullet. The results of this study show that these fish species were rich in n-3 PUFA, especially, eicosapentaenoic acid and docosahexaenoic acid.     

Dietary n-3 and n-6 fatty acids alter avian metabolism: molecular-species composition of breast-muscle phospholipids

The effects of diets high in n-3 polyunsaturated fatty acids (PUFA; provided by fish oil), n-6 PUFA (sunflower oil) or in more-saturated fatty acids (tallow) on the distribution of subclasses of choline phospholipids (PC) and ethanolamine phospholipids (PE) from the breast muscle of broiler chickens were examined. Supplementation with the different fatty acids had no effect on the distribution of phospholipid subclasses. Feeding sunflower oil or tallow gave a molecular-species profile similar in both fatty acid subtype and proportion. In the diacyl PC phospholipids, 16 : 0-18 : 1n-9 and 16 : 0-18 : 2n-6 accounted for approximately 60 % of the total molecular species, whereas for the alkylenyl PC the predominant species were 16 : 0-18 : 1n-9 and 16 : 0-20 : 4n-6. Of the diacyl PE the dominant species was 18 : 0-20 : 4n-6 which accounted for 50 % of the molecular species, and of the alkylenyl PE the dominant species were 16 : 0-18 : 1n-9, 16 : 0-20 : 4n-6 and 18 : 0-20 : 4n-6. Supplementation with fish oil significantly increased levels of both eicosapentaenoic acid (20 : 5n-3) and docosahexaenoic acid (22 : 6n-3) in PC and PE when compared with either sunflower oil or tallow supplementation. The increase in the n-3 PUFA incorporation was associated with a corresponding decrease in the proportion of arachidonic acid (20 : 4n-6) in both PC and PE. Different dietary fats induce different patterns of fatty acid incorporation and substitution in the sn-2 position of the diacyl and alkylenyl PC and PE of avian breast muscle, and this finding is indicative of selective acyl remodelling in these two phospholipids.     

Replacement of fish oil with rapeseed oil in diets of Atlantic salmon (Salmo salar) affects tissue lipid compositions and hepatocyte fatty acid metabolism

Duplicate groups of Atlantic salmon post-smolts were fed five practical-type diets in which the added lipid was 100% fish oil [FO; 0% rapeseed oil (0% RO)], 90% FO + 10% RO (10% RO), 75% FO + 25% RO (25% RO), 50% FO + 50% RO (50% RO) or 100% RO, for a period of 17 wk. There were no effects of diet on growth rate or feed conversion nor were any histopathological lesions found in liver, heart, muscle or kidney. The greatest accumulation of muscle lipid was in fish fed 0% RO, which corresponded to significantly lower muscle protein in this group. The highest lipid levels in liver were found in fish fed 100% RO. Fatty acid compositions of muscle lipid correlated with RO inclusion in that the proportions of 18:1(n-9), 18:2(n-6) and 18:3(n-3) all increased with increasing dietary RO (r = 0.98-1.00, P < 0.013). The concentrations of eicosapentaenoic acid [20:5(n-3)] and docosahexaenoic acid [22:6(n-3)] in muscle lipid were significantly reduced (P < 0.05), along with total saturated fatty acids, with increasing dietary RO. Diet-induced changes in liver fatty acid compositions were broadly similar to those in muscle. Hepatic fatty acid desaturation and elongation activities, measured using [1-(14)C] 18:3(n-3), were increased with increasing dietary RO. Limited supplies of marine fish oils require that substitutes be found if growth in aquaculture is to be maintained such that fish health and product quality are not compromised. Thus, RO can be used successfully as a substitute for fish oil in the culture of Atlantic salmon in sea water although at levels of RO >50% of dietary lipid, substantial reductions occur in muscle 20:5(n-3), 22:6(n-3) and the (n-3)/(n-6) polyunsaturated fatty acid (PUFA) ratio, which will result in reduced availability of the (n-3) highly unsaturated fatty acids that are beneficial for human health.     

Nutritional Importance of Selected Fresh Fishes,Shrimps and Mollusks to Meet Compliance with Nutritional Guidelines of n-3 LC-PUFA Intake in Spain

Fishery products are the main source of dietary n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA). Following the European Commission’s request to address the risks and benefits of seafood consumption, and taking into account the great variability of nutrient and contaminant levels in fishery products, the present work aims to estimate the n-3 LC-PUFA provided per serving of selected fishes, shrimps and mollusks that are commonly consumed in Spain. This would enable the establishment of a risk–benefit analysis of fish consumption and provide recommendations for fish intake to comply with nutritional guidelines of n-3 LC-PUFA intake. We confirmed high variation in the pattern and contents of fatty acids for different species. n-6 PUFA were minor fatty acids, whereas palmitic (C16:0), oleic (C18:1 n-9), and mainly eicosapentaenoic (C20:5 n-3) and docosahexaenoic (C22:6 n-3) acids were the major fatty acids in the sample. Therefore, consumption of 2–3 servings per week of a variety of fishery products may contribute to compliance with the recommended daily n-3 LC-PUFA intake while maintaining an adequate balance to avoid contaminant-derived potential risks (metals and others). Taking the fatty acid content of fishery products described in this study into consideration, it is advisable to include one serving of fatty fish per week in order to meet recommended n-3 LC-PUFA levels.     

Fatty acid, cholesterol and fat-soluble vitamin composition of wild and captive freshwater crayfish (Astacus leptodactylus)

The proximate analysis (dry matter, protein, fat and ash), cholesterol, fatty acid and fat-soluble vitamin compositions of the tail muscle of wild caught and captive crayfish (Astacus leptodactylus) were investigated. Captive crayfish contained higher moisture and fat content than wild crayfish. In contrast, wild crayfish contained a higher level of crude protein, ash and n-3 polyunsaturated fatty acids (PUFA), particularly eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) than captive crayfish. Arachidonic acid (C20:4 n-6) was the major n-6 PUFA in wild A. leptodactylus, and linoleic acid (C18:2 n-6) was the major n-6 PUFA in captive A. leptodactylus. The percentages of total saturated fatty acids (SFA), PUFA, and n-3/n-6 ratio were higher in wild crayfish and total monounsaturated fatty acids (MUFA) were lower. Although differences existed between wild and captive crayfish in vitamins A (p??0.05). The differences may be originated from the diet provided to captive crayfish. Since wild A. leptodactylus contained higher n-3/n-6 ratio than captive A. leptodactylus, crayfish farms can potentially produce a better quality of crayfish meat by increasing the PUFA n-3 (especially DHA and EPA) in the diets of A. leptodactylus.     

Substituting fish oil with crude palm oil in the diet of Atlantic salmon (Salmo salar) affects muscle fatty acid composition and hepatic fatty acid metabolism

Supplies of marine fish oils (FO) are limited and continued growth in aquaculture production dictates that substitutes must be found that do not compromise fish health and product quality. In this study the suitability of crude palm oil (PO) as a replacement for FO in diets of Atlantic salmon was investigated. Duplicate groups of Atlantic salmon post-smolts were fed four practical-type diets in which the added lipid was either 100% FO and 0% crude PO (0% PO); 75% FO and 25% PO (25% PO); 50% FO and 50% PO (50% PO); and 100% PO, for 30 wk. There were no effects of diet on growth rate or feed conversion ratio nor were any histopathological lesions found in liver, heart or muscle. Lipid deposition was greatest in fish fed 0% PO and was significantly greater than in fish fed 50% and 100% PO. Fatty acid compositions of muscle total lipid were correlated with dietary PO inclusion such that the concentrations of 16:0, 18:1(n-9), 18:2(n-6), total saturated fatty acids and total monoenoic fatty acids increased linearly with increasing dietary PO. The concentration of eicosapentaenoic acid [20:5(n-3)] was reduced significantly with increasing levels of dietary PO but the concentration of docosahexaenoic acid [22:6(n-3)] was significantly reduced only in fish fed 100% PO, compared with the other three treatments. Similar diet-induced changes were seen in liver total lipid fatty acid compositions. Hepatic fatty acid desaturation and elongation activities were approximately 10-fold greater in fish fed 100% PO than in those fed 0% PO. This study suggests that PO can be used successfully as a substitute for FO in the culture of Atlantic salmon in sea water. However, at levels of PO inclusion above 50% of dietary lipid, significant reductions in muscle 20:5(n-3), 22:6(n-3) and the (n-3):(n-6) PUFA ratio occur, resulting in reduced availability of these essential (n-3) highly unsaturated fatty acids to the consumer.     

Comparison of n-3 polyunsaturated fatty acid contents of wild and cultured Australian abalone

The fatty acid contents of wild and cultured Australian adult blacklip abalone, Haliotis rubra, were analysed by gas liquid chromatography. Wild abalone contained significantly higher levels of total n-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (20:5n-3), docosapentaenoic acid (22:5n-3) and alpha-linolenic acid (18:3n-3) than cultured abalone (P<0.05). The predominant n-3 PUFA was docosapentaenoic acid in wild abalone, while in cultured abalone a high level of eicosapentaenoic acid was found. The concentration of docosahexaenoic acid (22:6n-3) was low in both wild and cultured abalone, and cultured abalone had a significantly higher percentage composition of this fatty acid than wild abalone (P<0.01). Significantly higher levels of arachidonic acid (20:4n-6), 22:2n-6, 22:4n-6 and total n-6 PUFA were also found in wild abalone than in cultured animals (P<0.05). The ratio of n-3 PUFA to n-6 PUFA was the same in wild and cultured abalone. Manipulation of nutrient sources of cultured abalone may influence their lipid composition. Consumption of either wild or cultured abalone will contribute to dietary n-3 PUFA intake, with benefits to human health.     

A practical approach to increasing intakes of n-3 polyunsaturated fatty acids: use of novel foods enriched with n-3 fats

OBJECTIVES: To assess the effects of providing a wide range of foodstuffs containing n-3 polyunsaturated fatty acids (PUFA), occurring naturally or from fortification, on intake and blood and tissue proportions of n-3 PUFA. DESIGN: Before/after dietary intervention study. SETTING: Adelaide, Australia. SUBJECTS: 16 healthy males recruited from the community. INTERVENTIONS: Subjects were provided with a range of foodstuffs naturally containing n-3 PUFA (fresh fish, canned fish, flaxseed meal, canola oil) and items fortified with fish oil (margarine spread, milk, sausages, luncheon meat, french onion dip). Food choices were left to the discretion of each subject. Intake was estimated by diet diary. Blood was collected at-2, 0, 2, and 4 weeks for fatty acid analysis. MAIN OUTCOME MEASURES: Dietary intakes; plasma, platelet, and mononuclear cell phospholipid fatty acids. RESULTS: Consumption of n-3 PUFA increased significantly: alpha-linolenic acid (ALA) from 1.4 to 4.1 g/day (P<0.001), eicosapentaenoic acid (EPA) from 0.03 to 0.51 g/day (P<0.001), and docosahexaenoic acid (DHA) from 0.09 to 1.01 g/day (P<0.001). Linoleic acid (LA) intake decreased from 13.1 to 9.2 g/day (P<0.001). The proportions of EPA and DHA increased significantly in all phospholipid pools examined; plasma EPA from 1.13% of total fatty acids to 3.38% (P<0.001) and DHA from 3.76 to 7.23% (P<0.001); mononuclear cell EPA from 0.40 to 1.25% (P<0.001) and DHA from 2.33 to 4.08% (P<0.001); platelet EPA from 0.41 to 1.2% (P<0.001) and DHA from 1.64 to 3.07% (P<0.001). CONCLUSION: Incorporating fish oil into a range of novel commercial foods provides the opportunity for wider public consumption of n-3 PUFA with their associated health benefits. SPONSORSHIP: Dawes Scholarship, Royal Adelaide Hospital.     

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.     

Reduction in n-3 PUFA levels and EPA/AA ratio in serum after desert travels in China

OBJECTIVES: The effects of 3 months of desert travel in China on serum fatty acids and tocopherol were studied. METHODS: In project staff members (6 males, 3 females, aged 19-27 years), serum levels of fatty acids and alpha-tocopherol were analyzed before and after travel by gas liquid chromatography and high-performance liquid chromatography, respectively. RESULTS: Comparison of the levels before and after the trip showed no differences in serum total cholesterol, triglycerides, total protein or alpha-tocopherol. There were no changes in the levels of total fatty acids, while the percentage of polyunsaturated fatty acids increased (p < 0.05). Levels of n-3 PUFA lowered from 166 micrograms/ml to 103 micrograms/ml, and those of n-6 PUFA had increased from 988 micrograms/ml to 1140 micrograms/ml after the trip (p < 0.01 and p < 0.001, respectively). No change was observed in the serum levels of alpha-linolenic acid (C18:3n-3), but lowering of the levels of eicosapentaenoic acid (EPA, C20:5n-3) from 41.4 micrograms/ml to 16.3 micrograms/ml and docosahexaenoic acid (DHA, C22:6n-3) from 107.8 micrograms/ml to 71.7 micrograms/ml was found after the trip (p < 0.05 and p < 0.01, respectively). Serum levels of linoleic acid (LA, C18:2n-6) increased from 832 micrograms/ml to 598 micrograms/ml (p < 0.001), and arachidonic acid (AA, C20:4n-6) tended to increase. The ratios of n-3/n-6 PUFA and EPA/AA decreased from 0.171 to 0.091 and from 0.258 to 0.096 after the trip, respectively (p < 0.01 for both). CONCLUSIONS: Our findings indicated that 3 months of desert travel increased the serum levels of n-6 PUFA and LA and reduced the serum levels of n-3 PUFA and EPA and the ratios of n-3/n-6 PUFA and EPA/AA, possibly due to a relative essential fatty acid deficiency.     

Effects of Different Dietary Fatty Acids on the Fatty Acid Compositions and the Expression of Lipid Metabolic-Related Genes in Mammary Tumor Tissues of Rats

In this study, the effects of dietary fatty acids on the fatty acid compositions and lipid metabolic-related genes expression in N-methyl-N-nitrosourea (MNU)-induced rat mammary carcinogenesis were evaluated. The 50-day-old female Sprague-Dawley rats were intervened by different dietary fats (15% wt/wt), including saturated fatty acid (SFA), monounsaturated fatty acid (MUFA), n-6 polyunsaturated fatty acid (PUFA), n-3 PUFA, 1:1 n-6/n-3, 5:1 n-6/n-3, 10:1 n-6/n-3, and 1:2:1 S/M/P (1:1 n-6/n-3), alone or in combination with MNU. There was no mammary tumor occurrence in the control and MNU-treated n-3 PUFA groups after 18 wk. n-3 PUFA diet retarded the weight growth of rats. 1:1 n-6/n-3 diet significantly reduced the MNU-induced tumor incidence and tumor multiplicity compared with SFA, MUFA, n-6 PUFA, 5:1 n-6/n-3, 10:1 n-6/n-3 and 1:2:1 S/M/P diets (42.86% vs. 83.33%–92.31%, 0.79 vs. 2.62–2.85, P < 0.01). Additionally, 1:1 n-6/n-3 diet substantially increased cis-5,8,11,14,17-eicosapentaenoic acid and cis-4,7,10,13,16,19-docosahexaenoic acid levels, whereas it decreased C20:4 level and the mRNA expressions of fatty acid synthase, Cyclooxygenase-2 (COX-2), and 5-lipoxygenase (5-LOX) in mammary tissues (P < 0.05). These results suggest that 1:1 n-6/n-3 in the diet is effective in the prevention of mammary tumor development by increasing the n-3 PUFA content and reducing the expression of lipid metabolic-related genes.     

Comparison of n-3 polyunsaturated fatty acid contents of wild and cultured Australian abalone

The fatty acid contents of wild and cultured Australian adult blacklip abalone, Haliotis rubra, were analysed by gas liquid chromatography. Wild abalone contained significantly higher levels of total n-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (20:5n-3), docosapentaenoic acid (22:5n-3) and α-linolenic acid (18:3n-3) than cultured abalone (P<0.05). The predominant n-3 PUFA was docosapentaenoic acid in wild abalone, while in cultured abalone a high level of eicosapentaenoic acid was found. The concentration of docosahexaenoic acid (22:6n-3) was low in both wild and cultured abalone, and cultured abalone had a significantly higher percentage composition of this fatty acid than wild abalone (P<0.01). Significantly higher levels of arachidonic acid (20:4n-6), 22:2n-6, 22:4n-6 and total n-6 PUFA were also found in wild abalone than in cultured animals (P<0.05). The ratio of n-3 PUFA to n-6 PUFA was the same in wild and cultured abalone. Manipulation of nutrient sources of cultured abalone may influence their lipid composition. Consumption of either wild or cultured abalone will contribute to dietary n-3 PUFA intake, with benefits to human health.     

The effect of absence of protozoa on rumen biohydrogenation and the fatty acid composition of lamb muscle

The effects of the absence of protozoa in the rumen of lambs on animal growth, rumen fermentation, microbial diversity and fatty acid profiles in abomasal fluid and intramuscular fat were measured in ten control and ten protozoa-free (PF) lambs. PF lambs were prepared by isolating them from ewes within the first 24 h after birth. The PF and control lambs were kept for 4 months in two different fields and received a daily supplement of 250 g concentrate. The bacterial populations visualised by denaturing gradient gel electrophoresis differed between the two groups of animals and showed a higher bacterial diversity in control lambs than in PF lambs. Abomasal contents from control lambs contained higher concentrations of 22:5n-3 and 22:6n-3 and lower concentrations of vaccenic acid (trans-11-18: 1) and 20:3n-6 than PF lambs. The rest of the fatty acids, including the conjugated linoleic acid (CLA) isomers, were present at the same concentrations in abomasal contents from both experimental groups. Fatty acid composition in intramuscular fat showed differences between the groups. PF lambs had higher proportions of 18:0, 18:3, trans-10, cis-12-CLA and total SFA than control lambs. Control lambs had higher proportions of cis-9-18: 1, cis-9, cis-12-18:2, 20: 3n-6, 22:6n-3 (DHA) and MUFA. In conclusion, rumen defaunation led to higher tissue levels of the trans-10, cis-12-CLA isomer and SFA and lower PUFA:SFA ratio and n-3 PUFA in lamb muscle.     

Marine n-3 polyunsaturated fatty acids affect the blood pressure control in patients with newly diagnosed hypertension – a 1-year follow-up study

Marine long-chained n-3 polyunsaturated fatty acids (PUFA) are recognized for their cardio-protective effects, including potential lowering of blood pressure. We hypothesized that higher habitual fish intake and n-3 PUFA plasma levels were associated with lower blood pressure and being less likely to receive antihypertensive medication after one-year follow-up. In this prospective study of 115 patients, we assessed 24 h ambulatory and central blood pressure, plasma phospholipid fatty acid composition using gas chromatography and participants completed a food frequency questionnaire, including fish-eating habits. All measurements were repeated at one-year follow-up. At baseline, patients consuming fish ≥2 times per month for dinner had significantly higher plasma levels of total marine n-3 PUFA, docosahexaenoic acid and eicosapentaenoic acid as well as significantly lower central blood pressure and a trend towards lower peripheral blood pressure. At follow-up, 21 patients (18%) without antihypertensive medication had significantly higher plasma levels of n-3 PUFA, docosahexaenoic acid and eicosapentaenoic acid as well as a higher, but still acceptable 24 h ambulatory blood pressure (137/85 mmHg) compared to subjects receiving antihypertensive medication. The untreated group was more prone to take fish oil capsules and increased their plasma levels of n-3 PUFA compared to baseline. In patients with newly diagnosed, untreated hypertension, regular fish consumption was accompanied by lower blood pressure. After one year, patients without antihypertensive medication were characterized by a significant increase and higher plasma levels of n-3 PUFA. This supports a blood pressure-lowering effect and suggests an increase in marine n-3 PUFA intake as part of non-pharmacological treatment of hypertension.     

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.     

The alpha-linolenic acid content of green vegetables commonly available in Australia

Green vegetable consumption has long been considered to have health benefits mainly due to the vitamins, minerals and phytonutrients (such as vitamin C, folate, antioxidants etc) contained in a vegetable-rich diet. Additionally, green vegetables are known to contain a relatively high proportion of omega-3 polyunsaturated fatty acids (PUFAs), primarily in the form of alpha-linolenic acid (18:3n-3). However, there are no data available on the fatty acid composition and concentration of green vegetables commonly consumed in Australia. The present study determined the fatty acid content of 11 green vegetables that are commonly available in Australia. The total fatty acid concentrations of the vegetables under study ranged from 44 mg/100 g wet weight in Chinese cabbage to 372 mg/100 g in watercress. There were three PUFAs in all vegetables analyzed; these were 16:3n-3, 18:2n-6, and 18:3n-3 fatty acids. Sample vegetables contained significant quantities of 16:3n-3 and 18:3n-3, ranging from 23 to 225 mg/100 g. Watercress and mint contained the highest amounts of 16:3n-3 and 18:3n-3, and parsley had the highest amount of 18:2n-6 in both percentage composition and concentration. Mint had the highest concentration of 18:3n-3 with a value of 195 mg/100 g, while watercress contained the highest concentration of 16:3n-3 at 45 mg/100 g. All 11 green vegetables contained a high proportion of PUFAs, ranging from 59 to 72% of total fatty acids. The omega-3 PUFA composition ranged from 40 to 62% of total fatty acids. Monounsaturated fatty acid composition was less than 6% of total fatty acids. The proportion of saturated fatty acids ranged from 21% in watercress and mint to 32% of total fatty acids in Brussels sprouts. No eicosapentaenoic and docosahexaenoic acids were detected in any of the samples. Consumption of green vegetables could contribute to 18:3n-3 PUFA intake, especially for vegetarian populations.     

Persistent changes in the fatty acid composition of erythrocyte membranes after moderate intake of n-3 polyunsaturated fatty acids: study design implications.

To examine the incorporation of n-3 polyunsaturated fatty acids (PUFAs) into erythrocyte membranes during and after moderate n-3 PUFA intake, 12 healthy men were fed three diets for 6-wk periods in a 3 x 3 crossover design, supplying different amounts of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3): a control diet, a fish diet (0.15 g EPA/d, 0.41 g DHA/d), and a fish + oil diet (5 g fish oil/d; 0.99 g EPA/d and 0.99 g DHA/d). A 6-wk washout period was allowed between diets. Between 6 and 12 wk after the fish + oil diet, erythrocyte EPA and DHA were still declining and it was only after 18 wk that erythrocyte EPA had returned to baseline whereas DHA had not. Investigators examining variables that are influenced by altered membrane fatty acid composition should be aware of these prolonged effects when designing studies. Protracted washout periods (greater than 18 wk) make the classic crossover design prohibitive and a parallel design becomes essential.     

Niveaux d’apport et sources alimentaires des principaux acides gras polyinsaturés n-6 et n-3 dans la population adulte en France*

The intake of individual n-6 and n-3 polyunsaturated fatty acids (PUFA) have been estimated in 4,884 adult subjects of both sexes, volunteers from the French SUVIMAX intervention trial. On an energy basis, both men and women consumed 4.2% energy as linoleic acid, 0.38% as α-linolenic acid, 0.08% as arachidonic acid, 0.06% as eicosapentaenoic acid (EPA), 0.03% as docosapentaenoic acid (DPA) and 0.11% as docosahexaenoic acid (DHA), with a mean linoleic/α-linolenic acid ratio of 11.3. The intake of α-linolenic acid was well below the current recommendations (0.8% of energy) for almost all subjects, as a consequence of the low consumption of α-linolenic acid-rich oils and fats. The mean intake levels of long-chain n-3 PUFA were higher than the recommended levels, but showed great interindividual variations, due to very large differences in the consumption of fish, especially of fatty fish.     

Biochemical effects of a diet containing foods enriched with n-3 fatty acids

BACKGROUND: Results of many studies indicate that consumption of n-3 fatty acids can benefit persons with cardiovascular disease and rheumatoid arthritis. However, encapsulated fish oil is unlikely to be suited to lifetime daily use and recommendations to increase fish intake have not been effective. OBJECTIVE: The objective was to examine the effectiveness of a diet that incorporates foods rich in n-3 fatty acids in elevating tissue concentrations of eicosapentaenoic acid and in suppressing the production of inflammatory mediators. DESIGN: Healthy male volunteers were provided with foods that were enriched in alpha-linolenic acid (cooking oil, margarine, salad dressing, and mayonnaise) and eicosapentaenoic and docosahexaenoic acids (sausages and savory dip) and with foods naturally rich in n-3 fatty acids, such as flaxseed meal and fish. Subjects incorporated these products into their food at home for 4 wk. Fatty acid intakes, cellular and plasma fatty acid concentrations, and monocyte-derived eicosanoid and cytokine production were measured. RESULTS: Analyses of dietary records indicated that intake of eicosapentaenoic acid plus docosahexaenoic acid averaged 1.8 g/d and intake of alpha-linolenic acid averaged 9. 0 g/d. These intakes led to an average 3-fold increase in eicosapentaenoic acid in plasma, platelet, and mononuclear cell phospholipids. Thromboxane B(2), prostaglandin E(2), and interleukin 1beta synthesis decreased by 36%, 26%, and 20% (P < 0.05), respectively. CONCLUSIONS: Foods that are strategically or naturally enriched in n-3 fatty acids can be used to achieve desired biochemical effects without the ingestion of supplements or a change in dietary habits. A wide range of n-3-enriched foods could be developed to support large-scale programs on the basis of the therapeutic and disease-preventive effects of n-3 fatty acids.     

Long-chain n-3-to-n-6 polyunsaturated fatty acid ratios in breast adipose tissue from women with and without breast cancer

Animal studies suggest that dietary polyunsaturated fatty acids (PUFAs) of the n-6 class, found in corn and safflower oils, may be precursors of intermediates involved in the development of mammary tumors, whereas long-chain (LC) n-3 PUFAs, found in fish oil, can inhibit these effects. This case-control study was designed to examine the relationship between the PUFA composition of breast adipose tissue and the risk of breast cancer. Using fatty acid levels in breast adipose tissue as a biomarker of past qualitative dietary intake of fatty acids, we examined the hypothesis that breast cancer risk is negatively associated with specific LC n-3 PUFAs (eicosapentaenoic acid and docosahexaenoic acid) and positively associated with n-6 PUFAs (linoleic acid and arachidonic acid). Breast adipose tissue was collected from 73 breast cancer patients and 74 controls with macromastia. The fatty acid levels were determined by gas-liquid chromatography. A logistic regression model was used to obtain odds ratio estimates while adjusting for age. The age-adjusted n-6 PUFA (linoleic acid and arachidonic acid) content was significantly higher in cases than in controls (P = 0.02). There was a trend in the age-adjusted data suggesting that, at a given level of n-6 PUFA, LC n-3 PUFAs (eicosapentaenoic acid and docosahexaenoic acid) may have a protective effect (P = 0.06). A similar inverse relationship was observed with LC n-3-to-n-6 ratio when the data were adjusted for age (P = 0.09). We conclude that total n-6 PUFAs may be contributing to the high risk of breast cancer in the United States and that LC n-3 PUFAs, derived from fish oils, may have a protective effect.