High dietary fish oil alters the brain polyunsaturated fatty acid composition

Feeding adult rats a 17% corn-oil diet for 8 weeks did not change brain polyunsaturated fatty acids (PUFA) compared to rats fed 2.2% corn oil (with 2.2% lard added). When the corn-oil diet was supplemented with 14.5% cod liver oil or 12.5% salmon oil, the fatty acid composition of brain PUFA was significantly altered, even if alpha-tocopherol was added to the salmon-oil diet. Comparing salmon-oil- and cod-liver-oil-fed animals with corn-oil-fed animals, arachidonic acid 22:4(n-6) and 22:5(n-6) were reduced, and 20:5(n-3), 22:5(n-3) and 22:6(n-3) were increased. Liver fatty acids were also significantly altered. Thus, the brain is not protected against a large excess of very-long-chain n-3 PUFA, which increase n-3/n-6 ratio and could lead to abnormal function, and which might be difficult to reverse.     

The influence of dietary docosahexaenoic acid and arachidonic acid on central nervous system polyunsaturated fatty acid composition

Numerous studies on perinatal long-chain polyunsaturated fatty acid nutrition have clarified the influence of dietary docosahexaenoic acid (DHA) and arachidonic acid (ARA) on central nervous system PUFA concentrations. In humans, omnivorous primates, and piglets, DHA and ARA plasma and red blood cells concentrations rise with dietary preformed DHA and ARA. Brain and retina DHA are responsive to diet while ARA is not. DHA is at highest concentration in cells and tissues associated with high energy consumption, consistent with high DHA levels in mitochondria and synaptosomes. DHA is a substrate for docosanoids, signaling compounds of intense current interest. The high concentration in tissues with high rates of oxidative metabolism may be explained by a critical role related to oxidative metabolism.     

Effects of dietary polyunsaturated fatty acid deficiencies on mortality, growth and gill structure in the turbot, Scophthalmus maximus

The preparation of fish oil concentrates containing only ( n -3) polyunsaturated fatty acids (PUFA) with different ratios of 20:5 ( n -3)/22:6 ( n -3) is described. Three groups of turbot were maintained on different diets containing: 1, 10% of the dry weight of the diet as natural fish oil, equivalent to 2.5% ( n -3) PUFA and 0–23% ( n -6) PUFA; 2, 10% of the dry weight of the diet as palmitic acid, i.e. no PUFA; 3, 8–7% palmitic acid and 1–3% of the dry weight as ( n -3 PUFA and negligible ( n -6) PUFA. Only the fish on the diet containing natural fish oil showed significant growth over a 15-week period. In addition there were high mortalities on the two experimental diets (2 and 3). Changing the ratio of 20:5 ( n -3)/22:6 ( n -3) from 13–8 to 2–2 in the diet containing 1 3% (n-3) PUFA and negligible ( n -6) PUFA markedly decreased the mortalities. Fish fed the two experimental diets (2 and 3) developed gross changes in gill structure involving the disappearance of chloride cells, a 'sloughing off' of the epithelium along the primary and secondary filaments and an accumulation of cellular material in the inter-lamellar spaces. The tissue ultimately disintegrated to leave a skeleton of connective tissue and a mass of cellular material in the inter-lamellar spaces. It is concluded that 22:6 (n-3) is an essential fatty acid for turbot and that the gill epithelium is a sensitive indicator of this deficiency in this species.     

The effect of dietary and plasma fatty acids on platelet aggregation in senior generation of Japanese women

Dietary factors that influence platelet aggregation have not been fully clarified in humans. 63 Japanese women, aged 40-70 years old, completed one-day weighted dietary records, and received physical and laboratory examinations. Platelet aggregation was measured by 1.0 and 3.0 microM ADP induction. The results were analyzed with special reference to fatty acids. The short and medium chain fatty acid intake showed negative correlation with maximum percent of platelet aggregation induced by 1.0 microM ADP. Short and medium chain fatty acids in this study were mostly derived from milk and dairy products. Importance of short and medium chain fatty acid intake on platelet aggregation requires further study for prevention of cardiovascular diseases.     

The effect of dietary polyunsaturated fatty acid on insulin sensitivity and lipid metabolism in Otsuka Long-Evans Tokushima Fatty (OLETF) rats

The effects of insulin sensitivity and lipid metabolism of dietary lard, eicosapentaenoic acid-rich oil (EPA oil) or arachidonic acid oil (AA oil) in Otsuka Long-Evans Tokushima Fatty (OLETF) rats were examined. Blood glucose was not different in each group at 30, 60, 120 min on an oral glucose tolerance test. Fasting blood glucose levels were lower in lard and AA oil groups than in controls. Hepatic triglyceride concentration and liver histochemistry revealed that the fat content was higher in the lard group and the AA oil group than in controls. The EPA oil group showed TG levels as high as the control group. Serum total cholesterol in the EPA oil group was lower, while the level in the AA oil group was higher than in the lard and control groups. HDL cholesterol was 1.5-fold higher in the AA oil group than in controls. Dietary EPA oil or AA oil supplementation showed different effects on lipid metabolism in this model.     

Enhancement of polyunsaturated fatty acid production by cerulenin treatment in polyunsaturated fatty acid-producing bacteria

When docosahexaenoic acid (DHA)-producing Moritella marina strain MP-1 was cultured in the medium containing 0.5 μ g cerulenin ml⁻¹, an inhibitor for fatty acid biosynthesis, the cells grew normally, but the␣content of DHA in the total fatty acids increased from 5.9–19.4%. The DHA yield of M. marina strain MP-1 cells also increased from 4 to 13.7 mg l⁻¹ by cerulenin treatment. The same effect of cerulenin was observed in eicosapentaenoic acid (EPA)-producing Shewanella marinintestina strain IK-1 grown in the medium containing 7.5 μg cerulenin ml⁻¹, and the cerulenin treatment increased the EPA yield from 1.6 to 8 mg l⁻¹. The use of cerulenin is, therefore, advantageous to increase the content of intracellular polyunsaturated fatty acids (PUFA) in particular PUFA-containing phospholipids in bacterial cells.An erratum to this article can be found at .     

Changes in the fatty acid composition of phospholipids from turbot (Scophthalmus maximus) in relation to dietary polyunsaturated fatty acid deficiencies

Young turbot (1-20 g) were maintained for not less than 14 weeks on three diets: (1) a control diet containing normal amounts of polyunsaturated fatty acids (PUFA); (2) a diet totally deficient in PUFA; (3) a diet deficient in the (n-6) series of PUFA but containing (n-3) PUFA. At 14 weeks the fatty acid compositions of the phospholipids from liver, gut, gills and muscle were analysed. Large changes in the amounts of PUFA in the phospholipids were found. Fish maintained on the totally PUFA deficient diet 2 had retained arachidonic acid, 20:4(n-6), and docosahexaenoic acid, 22:6(n-3), at the expense of eicosapentaenoic acid, 20:5(n-3). Fish maintained on the (n-6) PUFA-deficient diet (3) contained decreased amounts of 20:4(n-6) and 22:6(n-3) while retaining 20:5(n-3). In all cases phosphatidylinositol had the lowest n-3/n-6 ratios. These results are discussed in terms of PUFA function.     

Inhibition of platelet aggregation by omega-3 polyunsaturated fatty acids is gender specific—Redefining platelet response to fish oils

Existence of gender differences in cardiovascular disease (CVD) following long-chain omega-3 polyunsaturated fatty acid (LCn-3 PUFA) supplementation have suggested that sex hormones play a role in cardio-protection. The objective of this study was to determine gender specific responses in the efficacy of LCn-3 PUFA to inhibit platelet aggregation in vitro. Blood was analyzed for collagen-induced platelet aggregation following pre-incubation with LCn-3 PUFA in healthy adults (n=42). Eicosapentaenoic acid (EPA) was significantly more effective in reducing platelet aggregation compared with docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA). When grouped by gender, this differential pattern was followed in males only. In females, DHA, DPA and EPA were all equally effective. Between group analyses (LCn-3 PUFA vs. gender) showed that both DHA and DPA were significantly less effective in males compared with females. EPA was equally effective in reducing platelet aggregation in both groups. These findings show that significant gender differences exist in platelet aggregation in response to various LCn-3 PUFA treatments.     

Effect of level of dietary n-3 polyunsaturated fatty acid supplementation on systemic and tissue fatty acid concentrations and on selected reproductive variables in cattle

Reproductively normal crossbred beef heifers were individually offered a diet of barley straw and concentrate supplemented with one of four levels of a fish oil (FO) enriched supplement. Following oestrous cycle synchronisation, blood samples were collected at appropriate intervals for the measurement of progesterone (P(4)), oestradiol (E(2)), fatty acids, insulin-like growth factor 1 (IGF-1) and metabolites. On days 15 and 16 of the cycle, oxytocin was administered intravenously and the prostaglandin F(2alpha) (PGF(2alpha)) response was measured as venous concentrations of 13,14-dihydro-15-keto PGF(2alpha) (PGFM). The heifers were slaughtered on days 17 or 18 of the oestrous cycle and endometrial tissue, rumen fluid and follicular fluid were collected for determination of fatty acid concentrations. In general there was no effect (P>0.05) of diet on plasma P(4) or E(2) concentrations. Increasing FO supplementation increased CL diameter on day 7 post-oestrus (P<0.0001) but had no effect on diameter on day of slaughter (P>0.05). On day 15, PGFM concentration was greater on the highest level of FO supplementation compared to controls (P<0.05), however, there were no differences between other diet comparisons (P>0.05). There was no effect of diet on PGFM concentration on day 16 (P>0.05). There was a strong positive relationship between plasma and uterine endometrial concentrations of both EPA (R(2)=0.86; P<0.0001) and total n-3 PUFA (R(2)=0.77; P<0.0001). IGF-1 concentrations increased on all diets and were greatest at the highest level of n-3 PUFA supplementation (P<0.05).     

Comparison of the effects of prostaglandin E1 on platelet aggregation in normal and essential fatty acid deficient rats

The inhibition of the collagen-induced platelet aggregation by PGE₁ is considerably reduced in the plasma of EFA-deficient rats.     

Effects of dietary supplementation with polyunsaturated fatty acids and antioxidants on biochemical characteristics of boar semen

The aim of this study was to investigate the effect of providing a supplement containing polyunsaturated fatty acids and antioxidants (PROSPERM) on the biochemical characteristics of boar semen. Two sexually mature boars were fed a standard diet with PROSPERM (250 g daily) for a 24-week period. Ejaculates collected prior to supplementation were used as the control. Semen quality and biochemical parameters were analyzed. The dietary supplementation enhanced sperm characteristics, including the percentage of spermatozoa with intact plasma membrane and osmotic resistance of the acrosomal membrane. Higher production of malondialdehyde was concurrent with increased activity of superoxide dismutase in the seminal plasma and spermatozoa after 8 weeks of supplementation. These changes were accompanied by a high content of total protein and low-molecular antioxidants of the seminal plasma. It was observed that PROSPERM supplementation enhanced the survivability of boar spermatozoa during storage in a standard semen extender supplemented with lipoprotein fractions, isolated from hen egg yolk or ostrich egg yolk, at 5 degrees C and 16 degrees C. These results indicate that PROSPERM supplementation of boars had a beneficial effect on the biological characteristics of the spermatozoa, which could be useful for semen preservation at different temperatures.