Fish oil replacement in current aquaculture feed : is cholesterol a hidden treasure for fish nutrition?

Teleost fish, as with all vertebrates, are capable of synthesizing cholesterol and as such have no dietary requirement for it. Thus, limited research has addressed the potential effects of dietary cholesterol in fish, even if fish meal and fish oil are increasingly replaced by vegetable alternatives in modern aquafeeds, resulting in progressively reduced dietary cholesterol content. The objective of this study was to determine if dietary cholesterol fortification in a vegetable oil-based diet can manifest any effects on growth and feed utilization performance in the salmonid fish, the rainbow trout. In addition, given a series of studies in mammals have shown that dietary cholesterol can directly affect the fatty acid metabolism, the apparent in vivo fatty acid metabolism of fish fed the experimental diets was assessed. Triplicate groups of juvenile fish were fed one of two identical vegetable oil-based diets, with additional cholesterol fortification (high cholesterol, H-Chol) or without (low cholesterol, L-Chol), for 12 weeks. No effects were observed on growth and feed efficiency, however, in fish fed H-Col no biosynthesis of cholesterol, and a remarkably decreased apparent in vivo fatty acid b-oxidation were recorded, whilst in LChol fed fish, cholesterol was abundantly biosynthesised and an increased apparent in vivo fatty acid b-oxidation was observed. Only minor effects were observed on the activity of stearyl-CoA desaturase, but a significant increase was observed for both the transcription rate in liver and the apparent in vivo activity of the fatty acid D-6 desaturase and elongase, with increasing dietary cholesterol. This study showed that the possible effects of reduced dietary cholesterol in current aquafeeds can be significant and warrant future investigations.

Fish oil diet associated with acute reperfusion related hemorrhage, and with reduced stroke-related sickness behaviors and motor impairment

Ischemic stroke is associated with motor impairment and increased incidence of affective disorders such as anxiety/clinical depression. In non-stroke populations, successful management of such disorders and symptoms has been reported following diet supplementation with long chain omega-3-polyunsaturated-fatty-acids (PUFAs). However, the potential protective effects of PUFA supplementation on affective behaviors after experimentally induced stroke and sham surgery have not been examined previously. This study investigated the behavioral effects of PUFA supplementation over a 6-week period following either middle cerebral artery occlusion or sham surgery in the hooded-Wistar rat. The PUFA diet supplied during the acclimation period prior to surgery was found to be associated with an increased risk of acute hemorrhage following the reperfusion component of the surgery. In surviving animals, PUFA supplementation did not influence infarct size as determined 6 weeks after surgery, but did decrease omega-6-fatty-acid levels, moderate sickness behaviors, acute motor impairment, and longer-term locomotor hyperactivity and depression/anxiety-like behavior.

Youth depression alleviation: the Fish Oil Youth Depression Study (YoDA-F): A randomized, double-blind, placebo-controlled treatment trial.

US authorities have recommended 'black-box' warnings for antidepressants because of the increased risk of suicidality for individuals up to age 25. There is thus a clinical and ethical imperative to provide effective treatment for youth depression with an acceptable risk-benefit balance. Long-chain omega-3 polyunsaturated fatty acids (PUFAs) play an important role in a range of physiological processes in living organisms. Supplementation with omega-3 PUFAs has been shown to have a range of beneficial effects on both physical and mental health, and results of previous trials suggest that omega-3 PUFAs may be a safe and effective treatment for depression. However, conclusions from these trials have been limited by their relatively small sample sizes.

Randomized controlled trial examining the effects of fish oil and multivitamin supplementation on the incorporation of n-3 and n-6 fatty acids into red blood cells

The present randomized, placebo-controlled, double-blind, parallel-groups clinical trial examined the effects of fish oil and multivitamin supplementation on the incorporation of n-3 and n-6 fatty acids into red blood cells. Healthy adult humans (n = 160) were randomized to receive 6 g of fish oil, 6 g of fish oil plus a multivitamin, 3 g of fish oil plus a multivitamin or a placebo daily for 16 weeks. Treatment with 6 g of fish oil, with or without a daily multivitamin, led to higher eicosapentaenoic acid (EPA) composition at endpoint. Docosahexaenoic acid (DHA) composition was unchanged following treatment. The long chain LC n-3 PUFA index was only higher, compared to placebo, in the group receiving the combination of 6 g of fish oil and the multivitamin. Analysis by gender revealed that all treatments increased EPA incorporation in females while, in males, EPA was only significantly increased by the 6 g fish oil multivitamin combination. There was considerable individual variability in the red blood cell incorporation of EPA and DHA at endpoint. Gender contributed to a large proportion of this variability with females generally showing higher LC n-3 PUFA composition at endpoint. In conclusion, the incorporation of LC n-3 PUFA into red blood cells was influenced by dosage, the concurrent intake of vitamin/minerals and gender.

What is the most effective way of increasing the bioavailability of dietary long chain omega-3 fatty acids-daily vs. weekly administration of fish oil?

The recommendations on the intake of long chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFA) vary from eating oily fish ("once to twice per week") to consuming specified daily amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) ("250-500 mg per day"). It is not known if there is a difference in the uptake/bioavailability between regular daily consumption of supplementsvs. consuming fish once or twice per week. In this study, the bioavailability of a daily dose of n-3 LC-PUFA (Constant treatment), representing supplements, vs. a large weekly dose of n-3 LC-PUFA (Spike treatment), representing consuming once or twice per week, was assessed. Six-week old healthy male Sprague-Dawley rats were fed either a Constant treatment, a Spike treatment or Control treatment (no n-3 LC-PUFA), for six weeks. The whole body, tissues and faeces were analysed for fatty acid content. The results showed that the major metabolic fate of the n-3 LC-PUFA (EPA+docosapentaenoic acid (DPA) + DHA) was towards catabolism (β-oxidation) accounting for over 70% of total dietary intake, whereas deposition accounted less than 25% of total dietary intake. It was found that significantly more n-3 LC-PUFA were β-oxidised when originating from the Constant treatment (84% of dose), compared with the Spike treatment (75% of dose). Conversely, it was found that significantly more n-3 LC-PUFA were deposited when originating from the Spike treatment (23% of dose), than from the Constant treatment (15% of dose). These unexpected findings show that a large dose of n-3 LC-PUFA once per week is more effective in increasing whole body n-3 LC-PUFA content in rats compared with a smaller dose delivered daily.

Metabolic fate (absorption, β-oxidation and deposition) of long-chain n-3 fatty acids is affected by sex and by the oil source (krill oil or fish oil) in the rat

The effects of krill oil as an alternative source of n-3 long-chain PUFA have been investigated recently. There are conflicting results from the few available studies comparing fish oil and krill oil. The aim of this study was to compare the bioavailability and metabolic fate (absorption, β-oxidation and tissue deposition) of n-3 fatty acids originating from krill oil (phospholipid-rich) or fish oil (TAG-rich) in rats of both sexes using the whole-body fatty acid balance method. Sprague-Dawley rats (thirty-six male, thirty-six female) were randomly assigned to be fed either a krill oil diet (EPA+DHA+DPA=1·38 mg/g of diet) or a fish oil diet (EPA+DHA+DPA=1·61 mg/g of diet) to constant ration for 6 weeks. The faeces, whole body and individual tissues were analysed for fatty acid content. Absorption of fatty acids was significantly greater in female rats and was only minimally affected by the oil type. It was estimated that most of EPA (>90 %) and more than half of DHA (>60 %) were β-oxidised in both diet groups. Most of the DPA was β-oxidised (57 and 67 % for female and male rats, respectively) in the fish oil group; however, for the krill oil group, the majority of DPA was deposited (82-83 %). There was a significantly greater deposition of DPA and DHA in rats fed krill oil compared with those fed fish oil, not due to a difference in bioavailability (absorption) but rather due to a difference in metabolic fate (anabolism v. catabolism).

A computational search for lipases that can preferentially hydrolyze long-chain omega-3 fatty acids from fish oil triacylglycerols

Consumption of long-chain omega-3 fatty acids is known to decrease the risk of major cardiovascular events. Lipases, a class of triacylglycerol hydrolases, have been extensively tested to concentrate omega-3 fatty acids from fish oils, under mild enzymatic conditions. However, no lipases with preference for omega-3 fatty acids selectivity have yet been discovered or developed. In this study we performed an exhaustive computational study of substrate-lipase interactions by docking, both covalent and non-covalent, for 38 lipases with a large number of structured triacylglycerols containing omega-3 fatty acids. We identified some lipases that have potential to preferentially hydrolyze omega-3 fatty acids from structured triacylglycerols. However omega-3 fatty acid preferences were found to be modest. Our study provides an explanation for absence of reports of lipases with omega-3 fatty acid hydrolyzing ability and suggests methods for developing these selective lipases.

Marginal efficiencies of long chain-polyunsaturated fatty acid use by barramundi (Lates calcarifer) when fed diets with varying blends of fish oil and poultry fat

An experiment was conducted with barramundi (Lates calcarifer) juveniles to examine the marginal efficiency of utilisation of long chain-polyunsaturated fatty acids (LC-PUFA). A series of five diets with blends of fish (anchovy) oil and poultry fat (F100:P0, F60:P40, F30:P70, F15:P85, F0:P100) were fed to 208. ±. 4.1. g fish over a 12-week period. The replacement of fish oil with poultry fat had no impact on growth performance (average final weight of 548.3. ±. 10.2. g) or feed conversion (mean = 1.14. ±. 0.02). Analysis of the whole body composition showed that the fatty acid profile reflected that of the fed diet. However it was also shown that there was a disproportional retention of some fatty acids relative to others (notably LOA, 18:2n-6 and LNA, 18:3n-3). By examining the body mass independent retention of different fatty acids with differential levels of intake of each, the marginal efficiencies of the use of these nutrients by this species were able to be determined. The differential retention of fatty acids in the meat was also examined allowing the determination of oil blending strategies to optimise meat n-3 LC-PUFA levels.

Decreased oxidative stress in patients with ulcerative colitis supplemented with fish oil omega-3 fatty acids

OBJECTIVE: the potential pathogenicity of free radicals may have a pivotal role in ulcerative colitis. Fish oil omega-3 fatty acids exert anti-inflammatory effects on patients with ulcerative colitis (UC), but the precise mechanism of the action of fish oil on oxidative stress is still controversial. The aim of the present work was to verify the blood oxidative stress in patients with UC and determine whether the association of sulfasalazine to fish oil omega-3 fatty acids is more effective than isolated use of sulfasalazine to reduce the oxidative stress.METHODS:, Nine patients (seven female and two male; me. an age = 40 +/- 11 y) with mild or moderate active UC were studied in a randomized crossover design. In addition to their usual medication (2 g/d of sulfasalazine), they received fish oil omega-3 fatty acids (4.5 g/d) or placebo for 2-mo treatment periods that were separated by 2 mo, when they only received sulfasalazine. Nine healthy individuals served as control subjects to study the oxidative stress status. Disease activity was assessed by laboratory indicators (C-reactive protein, alpha(1)-acid glycoprotein, alpha(1)-antitrypsin, erythrocyte sedimentation rate, albumin, hemoglobin, and platelet count), sigmoidoscopy, and histology scores. Analysis of oxidative stress was assessed by plasma chemiluminescence and erythrocyte lipid peroxidation, both induced by tert butyl hydroperoxide (t-BuOOH) and by plasma malondialdehyde. Antioxidant status was assayed by total plasma antioxidant capacity (TRAP) and microsomal lipid peroxidation inhibition (LPI). Superoxide dismutase (SOD) and catalase erythrocyte enzymatic activities were also determined.RESULTS: No significant changes were observed in any laboratory indicator or in the sigmoidoscopy or histology scores, with the exception of erythrocyte sedimentation rate, which decreased with both treatments. Oxidative stress was demonstrated by significant decreases in TRAP and LPI levels, increased chemiluminescence induced by t-BuOOH, and higher SOD activity in patients with UC. Treatment with fish oil omega-3 fatty acids reverted the chemiluminescence induced by t-BuOOH and LPI to baseline levels but that did not occur when patients received only sulfasalazine. Levels of plasma malondialdehyde, erythrocyte lipid peroxidation, and catalase were not different from those in the control group.CONCLUSIONS: the results indicated that plasma oxidative stress occurs in patients with UC, and there was a significant decrease when the patients used sulfasalazine plus fish oil omega-3 fatty acids. However, there was no improvement in most laboratory indicators, sigmoidoscopy, and histology scores. The results suggested that omega-3 fatty acids may act as free radical scavengers protecting the patients against the overall effect of oxidative stress. (C)Elsevier B.V. 2003.

Dietary fish oil replacement with lard and soybean oil affects triacylglycerol and phospholipid muscle and liver docosahexaenoic acid content but not in the brain and eyes of surubim juveniles Pseudoplatystoma sp

Triplicate groups of juvenile suribim were fed for 183 days one of four different isonitrogenous (47.6% crude protein) and isolipidic (18.7% lipid) diets formulated using three different lipid sources: 100% fish oil (FO, diet 1); 100% pig lard (L, diet 2); 100% soybean oil (SO, diet 3), and FO/L/SO (1:1:1, w/w/w; diet 4). The tissue levels of fatty acids 18:2n - 6 and 18:3n - 3 decreased relative to corresponding dietary fatty acid values. The 20:5n - 3 and 22:6n - 3 composition of muscle and liver neutral lipids were linearly correlated with corresponding dietary fatty acid composition. In contrast, the 22:6n - 3 composition of the brain and eye were similar among treatments. The 22:6n - 3 level was enriched in all tissues, particularly in the neural tissues. Similar results were observed for tissue polar lipids: fatty acids content reflected dietary composition, with the exception of the 22:6n - 3 level, which showed enrichment and no differences between groups. Given these results, the importance of the biochemical functions (transport and/or metabolism) of 22:6n - 3 in the development of the neural system of surubim warrants further investigation. © Springer Science+Business Media B.V. 2008.

Fish Oil Supplementation Reduces Cachexia and Tumor Growth While Improving Renal Function in Tumor-Bearing Rats

The objective of the present work was to study the renal function of healthy and tumor-bearing rats chronically supplemented with fish oil (FO), a source of n-3 polyunsaturated fatty acids. Weanling male rats were divided in two groups, one control (C) and another orally supplemented for 70 days with FO (1 g/kg body weight). After this time, half the animals of each group were injected in the right flank with a suspension of Walker 256 tumor cells (W and WFO). The W group had less proteinemia reflecting cachectic proteolysis, FO reversed this fact. Tumor weight gain was also reduced in WFO. Glomerular filtration rate (GFR) was not different in FO or W compared to C, but was higher in WFO. Renal plasma flow (RPF) was higher in the FO supplemented groups. The W group had lower plasma osmolality than the C group, but FO supplementation resulted in normalization of this parameter. Fractional sodium excretion (FENa+) of FO rats was similar to C. Proximal Na+ reabsorption, evaluated by lithium clearance, was similar among the groups. Urinary thromboxane B-2 (TXB2) excretion was lower in the supplemented groups. The number of macrophages in renal tissue was higher in W compared to C rats, but was lower in WFO rats compared to W rats. In conclusion, FO supplementation resulted in less tumor growth and cachexia, and appeared to be renoprotective, as suggested by higher RPF and GFR.

Human Leukocyte Death After a Preoperative Infusion of Medium/Long-Chain Triglyceride and Fish Oil Parenteral Emulsions: A Randomized Study in Gastrointestinal Cancer Patients

Background: Parenteral lipid emulsions (LEs) can influence leukocyte functions. The authors investigated the effect of 2 LEs on leukocyte death in surgical patients with gastrointestinal cancer. Material and Methods: Twenty-five patients from a randomized, double-blind clinical trial (ID: NCT01218841) were randomly included to evaluate leukocyte death after 3 days of preoperative infusion (0.2 g fat/kg/d) of an LE composed equally of medium/long-chain triglycerides and soybean oil (MCTs/LCTs) or pure fish oil (FO). Blood samples were collected before (t0) and after LE infusion (t1) and on the third postoperative day (t2). Results: After LE infusion (t1 vs t0), MCTs/LCTs did not influence cell death; FO slightly increased the proportion of necrotic lymphocytes (5%). At the postoperative period (t2 vs t0), MCTs/LCTs tripled the proportion of apoptotic lymphocytes; FO maintained the slightly increased proportion of necrotic lymphocytes (7%) and reduced the percentage of apoptotic lymphocytes by 74%. In the postoperative period, MCT/LCT emulsion increased the proportion of apoptotic neutrophils, and FO emulsion did not change any parameter of apoptosis in the neutrophil population. There were no differences in lymphocyte or neutrophil death when MCT/LCT and FO treatments were compared during either preoperative or postoperative periods. MCT/LCTs altered the expression of 12 of 108 genes related to cell death, with both pro- and antiapoptotic effects; FO modulated the expression of 7 genes, demonstrating an antiapoptotic effect. Conclusion: In patients with gastrointestinal cancer, preoperative MCT/LCT infusion was associated with postoperative lymphocyte and neutrophil apoptosis. FO has a protective effect on postoperative lymphocyte apoptosis. (JPEN J Parenter Enteral Nutr. 2012; 36: 677-684)