The influence of the SNP rs174575 (C/G) within the fatty acid desaturase 2 gene on the levels of long-chain PUFA was determined through statistical meta-analysis. Six databases were searched to retrieve the relevant literature. Original data were analysed using Stata 17·0, encompassing summary statistics, tests for heterogeneity, assessment of publication bias, subgroup analysis and sensitivity analysis. A total of ten studies were identified and grouped into twelve trials. Our results showed that individuals who carried the minor G allele of rs174575 had significantly higher dihomo-γ-linolenic acid levels (P = 0·005) and lower arachidonic acid levels (P = 0·033) than individuals who were homozygous for the major allele. The subgroup analysis revealed that the G-allele carriers of rs174575 were significantly positively correlated with linoleic acid (P = 0·002) and dihomo-γ-linolenic acid (P < 0·001) and negatively correlated with arachidonic acid (P = 0·004) in the European populations group. This particular SNP showed a potential association with higher concentrations of dihomo-γ-linolenic acid (P = 0·050) and lower concentrations of arachidonic acid (P = 0·030) within the breast milk group. This meta-analysis has been registered in the PROSPERO database (ID: CRD42023470562).

An 8-week feeding trial was conducted to evaluate the effects of dietary n-3 LC-PUFA levels on growth performance, tissue fatty acid profiles and relative expression of genes involved in the lipid metabolism of mud crab (Scylla paramamosain). Ten isonitrogenous diets were formulated to contain five n-3 LC-PUFA levels at 7 and 12 % dietary lipid levels. The highest weight gain and specific growth rate were observed in crabs fed the diets with 19·8 and 13·2 mg/g n-3 LC-PUFA at 7 and 12 % lipid, respectively. Moisture and lipid contents in hepatopancreas and muscle were significantly influenced by dietary n-3 LC-PUFA at the two lipid levels. The DHA, EPA, n-3 LC-PUFA contents and n-3:n-6 PUFA ratio in hepatopancreas and muscle significantly increased as dietary n-3 LC-PUFA levels increased at both lipid levels. The expression levels of -6 fatty acyl desaturase and acyl-CoA oxidase in hepatopancreas increased significantly, and expression levels of fatty acid synthase, carnitine palmitoyltransferase I and hormone-sensitive TAG lipase were down-regulated, with increased dietary n-3 LC-PUFA regardless of lipid level. Based on weight gain, n-3 LC-PUFA requirements of S. paramamosain were estimated to be 20·1 and 12·7 mg/g of diet at 7 and 12 % dietary lipid, respectively. Overall, dietary lipid level influenced lipid metabolism, and purified, high-lipid diets rich in palmitic acid reduced the n-3 LC-PUFA requirement of juvenile mud crab.

Fatty acids are important modulators of inflammatory responses, in particular, n-3 and n-6 essential fatty acids and CLA have received particular attention for their ability to modulate inflammation. The objectives of this study were to compare the effects of CLA and essential fatty acids on the expression of pro and anti- inflammatory cytokines and their protective efficacy against inflammatory status in mammary gland by an in vitro model based on bovine mammary epithelial cells (BME-UV1). Bovine mammary epithelial cells were treated with complete medium containing either 50 µM of cis-9, trans-11 CLA (c9,t11 CLA) or trans-10, cis-12 CLA (t10,c12 CLA) or (α)-linolenic acid (aLnA) or (γ)-linolenic acid (gLnA) or linoleic acid (LA). After 48 h by fatty acids administration the cells were treated for 3 h with 20 µM of lipopolysaccharide (LPS) to induce inflammatory stimulus. Reactive oxygen species (ROS) production after treatments was assessed to verify and to compare the potential protection of different fatty acids against LPS-induced oxidative stress. The messenger RNA abundance of bovine pro and anti-inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and interleukine-10 (IL-10)) and peroxisome proliferator receptor-α/γ (PPARγ/α) were determined in BME-UV1 by real-time PCR. The results showed that cells treated with fatty acids and LPS increased ROS production compared with control cells. Among treatments, cells treated with c9,t11 CLA and t10,c12 CLA isomers revealed significant lower levels of ROS production compared with other fatty acids. All fatty acids reduced the gene expression of pro- and anti-inflammatory cytokines. Among fatty acids, t10,c12 CLA, LA and gLnA showed an homogeneous reduction of the three pro-inflammatory cytokines and this may correspond to more balanced and efficient physiological activity and may trigger a better protective effect. The PPARγ gene expression was significantly greater in cells treated with t10,c12 CLA, aLnA and LA, whereas the PPARα gene expression levels were significantly lower in cells treated with all different fatty acids, compared with the control. These results suggest that fatty acids inhibited the transcription of pro-inflammatory cytokines by the upregulation of PPARγ expression.

The replacement of fish oil (FO) with vegetable oil (VO) in feed formulations reduces the availability of n-3 long-chain PUFA (LC-PUFA) to marine fish such as gilthead seabream. The aim of this study was to examine compositional and physiological responses to a dietary gradient of n-3 LC-PUFA. Six iso-energetic and iso-nitrogenous diets (D1–D6) were fed to seabream, with the added oil being a blend of FO and VO to achieve a dietary gradient of n-3 LC-PUFA. Fish were sampled after 4 months feeding, to determine biochemical composition, tissue fatty acid concentrations and lipid metabolic gene expression. The results indicated a disturbance to lipid metabolism, with fat in the liver increased and fat deposits in the viscera reduced. Tissue fatty acid profiles were altered towards the fatty acid compositions of the diets. There was evidence of endogenous modification of dietary PUFA in the liver which correlated with the expression of fatty acid desaturase 2 (fads2). Expression of sterol regulatory element binding protein 1 (srebp1), fads2 and fatty acid synthase increased in the liver, whereas PPARα1 pathways appeared to be supressed by dietary VO in a concentration-dependent manner. The effects in lipogenic genes appear to become measurable in D1–D3, which agrees with the weight gain data suggesting that disturbances to energy metabolism and lipogenesis may be related to performance differences. These findings suggested that suppression of β-oxidation and stimulation of srebp1-mediated lipogenesis may play a role in contributing toward steatosis in fish fed n-3 LC-PUFA deficient diets.

The present study aimed to determine the minimum requirements of the essential n-3 fatty acids EPA and DHA in Atlantic salmon (Salmo salar) that can secure their health under challenging conditions in sea cages. Individually tagged Atlantic salmon were fed 2, 10 and 17 g/kg of EPA + DHA from 400 g until slaughter size (about 3·5 kg). The experimental fish reared in sea cages were subjected to the challenging conditions typically experienced under commercial production. Salmon receiving the lowest EPA + DHA levels showed lower growth rates in the earlier life stages, but no significant difference in final weights at slaughter. The fatty acid composition of various tissues and organs had remarkably changed. The decreased EPA + DHA in the different tissue membrane phospholipids were typically replaced by pro-inflammatory n-6 fatty acids, most markedly in the skin. The EPA + DHA levels were maintained at a higher level in the liver and erythrocytes than in the muscle, intestine and skin. After delousing at high water temperatures, the mortality rates were 63, 52 and 16 % in the salmon fed 2, 10 and 17 g/kg EPA + DHA. Low EPA + DHA levels also increased the liver, intestinal and visceral fat amount, reduced intervertebral space and caused mid-intestinal hyper-vacuolisation. Thus, 10 g/kg EPA + DHA in the Atlantic salmon diet, a level previously regarded as sufficient, was found to be too low to maintain fish health under demanding environmental conditions in sea cages.

Farmed salmon feeds have changed from purely marine-based diets with high levels of EPA and DHA in the 1990s to the current 70 % plant-based diets with low levels of these fatty acids (FA). The aim of this study was to establish the impacts of low dietary EPA and DHA levels on performance and tissue integrity of Atlantic salmon (Salmo salar). Atlantic salmon (50 g) in seawater were fed fourteen experimental diets, containing five levels (0, 0·5, 1·0, 1·5 and 2·0 %) of EPA, DHA or a 1:1 EPA+DHA plus control close to a commercial diet, to a final weight of 400 g. Lack of EPA and DHA did not influence mortality, but the n-3-deficient group exhibited moderately slower growth than those fed levels above 0·5 %. The heart and brain conserved EPA and DHA levels better than skeletal muscle, liver, skin and intestine. Decreased EPA and DHA favoured deposition of pro-inflammatory 20 : 4n-6 and 20 : 3n-6 FA in membrane phospholipids in all tissues. When DHA was excluded from diets, 18 : 3n-3 and EPA were to a large extent converted to DHA. Liver, skeletal and cardiac muscle morphology was normal in all groups, with the exception of cytoplasm packed with large or foamy vacuoles and sometimes swollen enterocytes of intestine in both deficient and EPA groups. DHA supplementation supported normal intestinal structure, and 2·0 % EPA+DHA alleviated deficiency symptoms. Thus, EPA and DHA dietary requirements cannot be based exclusively on growth; tissue integrity and fish health also need to be considered.

Essential fatty acids (EFA) are PUFA that are metabolised to long-chain PUFA and are important for brain development and cognitive function. The objective of this study was to determine the association between whole-blood EFA and cognitive function in Tanzanian children. A total of 325 2–6-year-old children attempted the dimensional change card sort (DCCS) tasks to assess executive function. Blood samples were collected for fatty acid (FA) analysis by GC. Associations between executive function and FA levels were assessed by regression. Among the 130 4–6-year-old children who attempted the DCCS tasks, whole-blood levels of linoleic acid were positively associated with executive function, whereas whole-blood levels of α-linolenic acid and nervonic acid were inversely associated with executive function. A full model including all twenty-five FA explained 38 % of the variation in executive function, whereas a reduced model including only the EFA (α-linolenic acid and linoleic acid), DHA and EPA explained 25 % of the variation in executive function. Children who had sufficient whole-blood levels of EFA were 3·8 times more likely to successfully complete all DCCS tasks compared with children with insufficient EFA. These results suggest that whole-blood FA levels are associated with cognitive abilities. Intervention trials that include assessment of whole-blood FA levels are required to determine the relationships between intake, blood levels and executive function in Tanzanian children.

Essential fatty acids (EFA) such as α-linolenic acid (ALA) and linoleic acid (LA) are needed for healthy growth and development of children. Worldwide, reliable intake data of EFA are often lacking. The objective of this study was to investigate dietary intake of EFA in Indonesian children. Dietary intake data of 4–12-year-old children (n 45 821) from a nationally representative Indonesian survey were used to estimate median intake and distribution of population fatty acid intake. Missing data on individual fatty acids in the Indonesian food composition table were complemented through chemical analyses of national representative food samples and imputation of data from the US nutrient database. Nutrient adequacy ratios were calculated as a percentage of FAO/WHO intake recommendations. The medians of total fat intake of the children was 26·7 (10th–90th percentile 11·2–40·0) percentage of total daily energy (%E). Intakes of fatty acids were 4·05 (10th–90th percentile 1·83–7·22) %E for total PUFA, 3·36 (10th–90th percentile 1·14–6·29) %E for LA and 0·20 (10th–90th percentile 0·07–0·66) %E for ALA. Median intake of PUFA was 67 % and that of ALA 40 % of the minimum amounts recommended by FAO/WHO. These data indicate that a majority of Indonesian children has intakes of PUFA and specifically ALA that are lower than recommended intake levels. Total fat and LA intakes may be suboptimal for a smaller yet considerable proportion of children. Public health initiatives should provide practical guidelines to promote consumption of PUFA-rich foods.

Barramundi (Lates calcarifer), a catadromous teleost of significant and growing commercial importance, are reported to have limited fatty acid bioconversion capability and therefore require preformed long-chain PUFA (LC-PUFA) as dietary essential fatty acid (EFA). In this study, the response of juvenile barramundi (47·0 g/fish initial weight) fed isolipidic and isoenergetic diets with 8·2 % added oil was tested. The experimental test diets were either devoid of fish oil (FO), and thus with no n-3 LC-PUFA (FO FREE diet), or with a low inclusion of FO (FO LOW diet). These were compared against a control diet containing only FO (FO CTRL diet) as the added lipid source, over an 8-week period. Interim samples and measurements were taken fortnightly during the trial in order to define the aetiology of the onset and progression of EFA deficiency. After 2 weeks, the fish fed the FO FREE and FO LOW diets had significantly lower live-weights, and after 8 weeks significant differences were detected for all performance parameters. The fish fed the FO FREE diet also had a significantly higher incidence of external abnormalities. The transcription of several genes involved in fatty acid metabolism was affected after 2 weeks of feeding, showing a rapid nutritional regulation. This experiment documents the aetiology of the onset and the progression of EFA deficiency in juvenile barramundi and demonstrates that such deficiencies can be detected within 2 weeks in juvenile fish.

Seven isoproteic and isolipidic semi-purified diets were formulated to assess specific nutrient deficiencies in sulphur amino acids (SAA), n-3 long-chain PUFA (n-3 LC-PUFA), phospholipids (PL), P, minerals (Min) and vitamins (Vit). The control diet (CTRL) contained these essential nutrients in adequate amounts. Each diet was allocated to triplicate groups of juvenile gilthead sea bream fed to satiety over an 11-week feeding trial period. Weight gain of n-3 LC-PUFA, P–Vit and PL–Min–SAA groups was 50, 60–75 and 80–85 % of the CTRL group, respectively. Fat retention was decreased by all nutrient deficiencies except by the Min diet. Strong effects on N retention were found in n-3 LC-PUFA and P fish. Combined anaemia and increased blood respiratory burst were observed in n-3 LC-PUFA fish. Hypoproteinaemia was found in SAA, n-3 LC-PUFA, PL and Vit fish. Derangements of lipid metabolism were also a common disorder, but the lipodystrophic phenotype of P fish was different from that of other groups. Changes in plasma levels of electrolytes (Ca, phosphate), metabolites (creatinine, choline) and enzyme activities (alkaline phosphatase) were related to specific nutrient deficiencies in PL, P, Min or Vit fish, whereas changes in circulating levels of growth hormone and insulin-like growth factor I primarily reflected the intensity of the nutritional stressor. Histopathological scoring of the liver and intestine segments showed specific nutrient-mediated changes in lipid cell vacuolisation, inflammation of intestinal submucosa, as well as the distribution and number of intestinal goblet and rodlet cells. These results contribute to define the normal range of variation for selected biometric, biochemical, haematological and histochemical markers.

Many African diets are low in fat but are currently changing because of nutrition transition. We studied fat and fatty acid (FA) intake and the essential fatty acid (EFA) status of adolescent girls (aged 14–19 years, n 262) in Zambezia Province, central Mozambique. A cross-sectional study was carried out in a city as well as in the towns and rural villages of a coastal and an inland district. Dietary intake and FA sources were studied in a 24 h dietary recall. FA compositions of cholesteryl esters and phospholipids of non-fasting serum samples were analysed by GLC. Fat intake was low (13–18 % of energy) in all areas. Coconut and palm oil were the main sources of fat, and soyabean oil and maize were the main sources of PUFA. Compared to Food and Agriculture Organization/WHO 2010 recommendations, intake of linoleic acid (LA, 18 : 2n-6) was inadequate in the coastal district, and intakes of n-3 PUFA were inadequate in all areas. FA compositions of serum lipids differed between areas. The proportions of LA tended to be highest in the city and lowest in the rural areas. The phospholipid mead (20 : 3n-9):arachidonic acid (20 : 4n-6) ratio did not indicate EFA insufficiency. LA proportions in phospholipids were low, but those of long-chain n-6 and n-3 PUFA were high in comparison with Western adolescents. To conclude, fat sources, FA intake and EFA status differed between adolescent girls living in different types of communities. Fat intake was low, but EFA insufficiency was not indicated.

DHA deficiency has been related to skeletal malformations in fish, but high DHA levels have produced controversial results that could relate to the oxidative status of fish tissues in the different reports. In the present study, gilthead seabream (Sparus aurata) larvae were fed deficient, adequate or high DHA levels, or high DHA levels supplemented with the antioxidant α-tocopherol. Larvae fed deficient DHA levels tended to be smaller, and showed the highest incidence of urinary bladder calculi, lordosis and kyphosis and the lowest number of mineralised vertebrae for any given size class. Elevation of dietary DHA increased larval growth and significantly enhanced the expression of the insulin-like growth factor 1 (IGF-1) gene. However, a DHA level increase up to 5 % raised the degree of lipid oxidation in larval tissues and deformities in cranial endochondral bones and in axial skeletal haemal and neural arches. The increase in dietary α-tocopherol supplementation in high-DHA feeds reduced again the occurrence of skeletal deformities. Moreover, the expression of genes coding for specific antioxidants such as catalase, superoxide dismutase or glutathione peroxidase, which neutralised reactive oxygen substances formed by increased dietary DHA, was significantly decreased in larvae fed high α-tocopherol levels. These results denoted the importance of DHA for early bone formation and mineralisation. Low dietary DHA levels delay early mineralisation and increase the risk of cranial and axial skeletal deformities. Excessive DHA levels, without an adequate balance of antioxidant nutrients, increase the production of free radicals damaging cartilaginous structures before bone formation.

Egg fat is of considerable importance in the nutrition of the developing chick as a source of energy and essential fatty acids such as linoleic (18:2 n-6) and α-linolenic (18:3 n-3) acids. During incubation, yolk lipids provide fatty acids that are utilized for energy, synthesis of polyunsaturated fatty acids (PUFA)-rich membrane phospholipids, and eicosanoids by the embryo. Eicosanoids derived from n-6 fatty acid are more potent and pro-inflammatory than eicosanoids derived from n-3 fatty acids.

Two models of early life programming as affected by n-3 PUFA are investigated. Egg PUFA enrichment through breeder hen diet (pre-hatch or in ovo) or early post-hatch (within first 5 hours) feeding is investigated. Early access to nutrients (pre- and early post-hatch) is important because in broiler hatchlings that are selected for rapid early growth much of the immune system development occurs early in life. However, the current industry practice of feeding breeding hens diets high in n-6 fatty acids, limits the supply of essential n-3 PUFA in the hatchling. Early access to n-3 PUFA through in ovo or early post-hatch diet led to: (1) increase in the retention of n-3 PUFA in cell membranes, (2) reduction in plasma non-esterified fatty acids, (3) reduced production of pro-inflammatory eicosanoids, (4) suppression of cell-mediated immunity, and (5) alteration in cyclooxygenase-2 protein expression. The effects of an early exposure persisted from 14 to 35 days in different tissues and cells.

Given the fact that broiler birds are raised for 39 to 56 days, and that the effect of pre-hatch and early post-hatch nutrition persists for up to and over 36-47% of post-hatch life, using an early life programming approach will generate new knowledge about the role of maternal and early post-hatch diet in enhancing bird health and welfare.

There is limited information on the specific effects of long-chain PUFA (LCPUFA) on neuron development and functioning. Deficiency of those essential fatty acids impairs escape and avoidance behaviour in fish, where Mauthner cells (M-cells) play a particularly important role in initiating this response. Gilthead seabream larvae fed two different LCPUFA profiles were challenged with a sonorous stimulus. Feeding n-3 LCPUFA increased the content of these fatty acids in fish tissues and caused a higher number of larvae to react to the stimulus with a faster burst swimming speed response. This faster startle response in fish fed n-3 LCPUFA was also associated with an increased immune-positive neural response, particularly in M-cells, denoting a higher production of acetylcholine. The present study shows the first evidence of the effect of n-3 LCPUFA on the functioning of particular neurons in fish, the M-cells and the behaviour response that they modulate to escape from a sound stimulus.

The role of dietary fat in bladder cancer aetiology is currently unclear due to few studies, equivocal findings and a lack of information on important dietary fatty acids. The aim of the present study was to investigate the association between the intake of major dietary fats and fatty acids and the risk of bladder cancer. A case–control study was conducted in New Hampshire, USA. Dietary data were collected from 322 cases and 239 controls, and OR and 95 % CI were calculated using unconditional logistic regression. Adjustment was made for potential confounders: sex, age, smoking status, pack-years smoked, cholesterol and energy intake. Statistically significant reduced odds of bladder cancer were observed for high intakes (highest quartile v. lowest quartile) of α-linolenic acid (ALA) (OR 0·26, 95 % CI 0·10, 0·65; P for trend = 0·01) and vegetable fat (OR 0·39, 95 % CI 0·18, 0·86; P for trend = 0·03). Borderline statistically significant reduced odds were detected for polyunsaturated fat (OR 0·43, 95 % CI 0·19, 0·98; P for trend = 0·07) and linoleic acid (OR 0·43, 95 % CI 0·19, 0·96; P for trend = 0·06). These fats and fatty acids were highly correlated and following adjustment for each other, the only potential inverse association to remain was for ALA. The present findings suggest that ALA may have a protective role against developing bladder cancer; however, further investigation and replication in other epidemiological studies are required. Future research should focus on the type, source and quantities of different dietary fatty acids consumed.

The feasibility of fish oil (FO) replacement by vegetable oils (VO) was investigated in gilthead sea bream (Sparus aurata L.) in a growth trial conducted for the duration of 8 months. Four isolipidic and isoproteic diets rich in plant proteins were supplemented with l-lysine (0·55 %) and soya lecithin (1 %). Added oil was either FO (control) or a blend of VO, replacing 33 % (33VO diet), 66 % (66VO diet) and 100 % (VO diet) of FO. No detrimental effects on growth performance were found with the partial FO replacement, but feed intake and growth rates were reduced by about 10 % in fish fed the VO diet. The replacement strategy did not damage the intestinal epithelium, and massive accumulation of lipid droplets was not found within enterocytes. All fish showed fatty livers, but signs of lipoid liver disease were only found in fish fed the VO diet. Muscle fatty acid profiles of total lipids reflected the diet composition with a selective incorporation of unsaturated fatty acids in polar lipids. The robustness of the phospholipid fatty acid profile when essential fatty acid requirements were theoretically covered by the diet was evidenced by multivariate principal components analysis in fish fed control, 33VO and 66VO diets.

This study describes a methodology with potential application in the estimation of essential fatty acid (EFA) requirements of fish larvae. Senegalese sole (Solea senegalensis) larvae were fed, from 16 days after hatching (DAH), on Artemia enriched with different oils, inducing graded dietary concentrations of DHA: (1) soyabean oil, containing no measurable amounts of DHA (NDHA); (2) fish oil, inducing a medium DHA level (MDHA, 3 g DHA/100 g fatty acids); and (3) a mixture of Easy DHA Selco and Microfeed, resulting in high DHA content (HDHA, 8 g/100 g). At 28 DAH a metabolic trial was conducted where larvae were tube fed [1-14 C]DHA, in order to determine its absorption, retention in the gut and body tissues, as well as its oxidation. At 23 DAH the HDHA treatment induced a significantly higher larval growth, while at 32 DAH significant differences were only found between the NDHA and HDHA treatments. The absorption of tube-fed [1-14 C]DHA was extremely high (94–95 %) and independent of feeding regime. However, in larvae fed NDHA Artemia, a significantly higher amount of label was retained in the gut compartment and a concurrently lower retention was measured in the body. A significantly higher proportion of the absorbed DHA label was oxidized in larvae fed HDHA, compared to NDHA. Based on these results, we suggest that increasing dietary supply of DHA above the larval requirement level results in its increased oxidation for energy purposes and we propose potential applications of the tube feeding methodology using radiolabelled EFA in conjunction with dose–response studies.

In children, but not adults with cystic fibrosis (CF), associations between essential fatty acids (FA) and bone mass have been reported. Low bone mineral density (BMD) is common in these patients. Previously we found a normal annual increase of BMD, suggesting a potential for attaining normal bone mass. The aim of the present study was to investigate phospholipid FA pattern in relation to bone in young adult men with CF compared with healthy controls. Fourteen male patients with CF were compared with forty-two healthy controls, using dual-energy X-ray absorptiometry for total bone, lumbar spine and femur and peripheral quantitative computerised tomography for tibia and radius. A questionnaire concerning physical activity and nutrition was used. FA in serum phospholipids were measured using capillary GLC. CF patients did not differ in physical activity and anthropometry from controls. There were no differences in bone parameters between the two groups, but patients chronically colonised with Pseudomonas aeruginosa had lower BMD than non-colonised patients. The trabecular BMD in the tibia differed between patients and controls, but not after adjustment for age and weight. The endosteal circumference of the radius was significantly associated with serum phospholipid concentration of DHA and inversely with the n-6:n-3 FA ratio in CF patients but not in controls. The present study showed that young physically active adult males with classical CF obtained similar bone mass as controls, although influenced by pseudomonas colonisation. The association between DHA and long bone endosteal circumference suggested a later peak bone mass in those with CF compared with controls.