Extraction of omega‐6 fatty acids from speciality seeds

‘Omega‐6 vegetable oils’ are a small but important group of vegetable oils used widely in the food, neutraceutical, cosmetic and pharmaceutical industries for their linoleic acid (18:2 n‐6) and more importantly gamma linolenic acid (18:3 n‐6) content. These omega‐6 fatty acids have numerous health benefits recognized worldwide. With linoleic acid being readily available from many dietary sources, one wonders why there is a need to extract the oil from speciality oilseeds, however those that suffer with many of the conditions that omega‐6 fatty acids are said to be beneficial for are frequently advised to take extra supplements of these fatty acids. Due to their wide use as a nutraceutical, omega‐6 fatty acids are in high demand, causing a niche market for extraction of these oils from speciality seeds.     

Changes in fatty acids and volatile components in mackerel by broiling

Mackerel is known to be a rich source of omega‐3 family PUFAs. The acid value and conjugated dienoic acid value of mackerel, known as indices of oxidation, were determined. Fatty acids in both raw and broiled mackerels were analyzed by GC. PUFAs and saturated fatty acids were observed at a low level in broiled mackerel, possibly as a result of thermal degradation of the lipids. In addition, volatile components in mackerel extracted by solvent‐assisted flavor evaporation were analyzed by GC‐MS. In total, 38 volatile components were detected in raw mackerel, whereas 53 volatiles were found in broiled mackerel. Hydrocarbons and methyl‐ and/or ethyl‐substituted benzenes were quantitatively dominant. Levels of aldehydes and alcohols were significantly enhanced in broiled mackerel, as was the level of benzothiazole, which possibly forms as a result of the condensation of thermal degradation products from amino acids and/or proteins, and lipids.     

Abnormalities in Plasma Phospholipid Fatty Acid Profiles of Patients with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer‐related death worldwide. In the present study, we aimed to profile the possible changes in plasma phospholipid fatty acid composition of HCC patients, and to identify the fatty acid biomarkers that could distinguish HCC patients from healthy controls. A total of 37 plasma samples from healthy controls and HCC patients were collected and their phospholipid fatty acid profiles were characterized by gas chromatography–mass spectrometry followed by multivariate statistical analysis. Twenty‐five fatty acids were identified and quantified, their proportions varied greatly between two groups, suggesting each group has its own fatty acid pattern. Orthogonal partial least squares discriminant analysis in terms of fatty acid profiles showed that HCC patients could be clearly distinguished from healthy controls. More importantly, linoleic acid (18:2n‐6), oleic acid (18:1n‐9), arachidonic acid (20:4n‐6) and palmitic acid (16:0) were identified as the potential fatty acid biomarkers of HCC patients. Additionally, to further identify the major cause of the abnormality of plasma fatty acid profile, fatty acid distributions of cancerous tissue and its surrounding tissue from 42 HCC patients were also examined. Due to have similar variation trend of major fatty acid biomarkers, linoleic acid (18:2n‐6), oleic acid (18:1n‐9), abnormalities in plasma phospholipid fatty acid profiles of HCC patients may be mainly attributed to the alternation of intrinsic fatty acid metabolism caused by cancer per se, but not to the differences in dietary factors.     

Omega‐3 and children's brains: New insights from the DHA Oxford Learning and Behaviour (DOLAB) study

Blood concentrations of long‐chain omega‐3 fatty acids in UK children are low, and associated with poor cognitive performance and behaviour, according to a recent study conducted at the University of Oxford. In a randomised controlled trial, dietary supplementation with the long‐chain omega‐3 DHA (docosahexaenoic acid) significantly improved reading performance and behaviour in healthy but underperforming children aged 7–9 years. (And no – it's not another ‘fishy tale': the DHA in this case were from algae).     

Headspace Volatile Oxylipins of Eastern Himalayan Moss Cyathophorella adiantum Extracted by Sample Enrichment Probe

Cyathophorella adiantum (Griff.) M. Fleisch. (Division-Bryophyta, Family-Daltoniaceae), an Eastern Himalayan moss was studied for the first time to identify the volatiles derived from cellular and membrane bound fatty acids. A high capacity sample enrichment probe (SEP) was used for extraction of headspace volatile (HSV) molecules followed by GC–MS analysis. Different short-chain oxylipins like alkenes, alkanes, saturated and unsaturated alcohols, saturated and unsaturated aldehydes, ketones were identified along with free and esterified fatty acids, cyclo compounds and some by-products of secondary metabolites. Fatty acid analysis of neutral lipids (NL) and phospholipids (PL) of this plant exhibits the predominance of C16 and C18 fatty acids. It also reveals some interesting information that might indicate the possible fatty acid precursors for volatile generation and their sources in this plant.     

Analytical implications of routine clinical testing for omega‐3 fatty acid biomarkers

Blood biomarkers of omega‐3 (ω3) fatty acids can be used as markers of optimal health and disease risk. Rapid, high‐throughput and cost efficient fatty acid analyses would enable routine clinical screening for ω3 fatty acid status by health professionals. Clinical monitoring of ω3 fatty acid status of individuals would enable prevention strategies for cardiovascular disease and prenatal nutrition.     

Dietary Crude Lecithin Increases Systemic Availability of Dietary Docosahexaenoic Acid with Combined Intake in Rats

Crude lecithin, a mixture of mainly phospholipids, potentially helps to increase the systemic availability of dietary omega‐3 polyunsaturated fatty acids (n‐3 PUFA), such as docosahexaenoic acid (DHA). Nevertheless, no clear data exist on the effects of prolonged combined dietary supplementation of DHA and lecithin on RBC and plasma PUFA levels. In the current experiments, levels of DHA and choline, two dietary ingredients that enhance neuronal membrane formation and function, were determined in plasma and red blood cells (RBC) from rats after dietary supplementation of DHA‐containing oils with and without concomitant dietary supplementation of crude lecithin for 2–3 weeks. The aim was to provide experimental evidence for the hypothesized additive effects of dietary lecithin (not containing any DHA) on top of dietary DHA on PUFA levels in plasma and RBC. Dietary supplementation of DHA‐containing oils, either as vegetable algae oil or as fish oil, increased DHA, eicosapentaenoic acid (EPA), and total n‐3 PUFA, and decreased total omega‐6 PUFA levels in plasma and RBC, while dietary lecithin supplementation alone did not affect these levels. However, combined dietary supplementation of DHA and lecithin increased the changes induced by DHA supplementation alone. Animals receiving a lecithin‐containing diet also had a higher plasma free choline concentration as compared to controls. In conclusion, dietary DHA‐containing oils and crude lecithin have synergistic effects on increasing plasma and RBC n‐3 PUFA levels, including DHA and EPA. By increasing the systemic availability of dietary DHA, dietary lecithin may increase the efficacy of DHA supplementation when their intake is combined.     

Emission of Volatile Aldehydes from DAG-Rich and TAG-Rich Oils with Different Degrees of Unsaturation During Deep-Frying

The purpose of the present study was to compare the emission of volatile aldehydes from diacylglycerol-rich oils (DAG-OILs) and triacylglycerol-rich oils (TAG-OILs) with different degrees of unsaturation of fatty acid moieties during the deep-frying of sliced potatoes. To examine the effect of fatty acid composition, four kinds of oils with different fatty acid compositions were selected: rape seed (RS); sunflower oil as a high oleic (HO); safflower oil as high linoleic (HL); and, perilla oil as high linolenic (HLn) oils. The emissions of volatile aldehydes were determined during the deep-frying of sliced potatoes by using the above fresh test oils or deteriorated RS oils. The statistical analysis showed no significant difference in volatile aldehyde emission and profile between the DAG-OIL and TAG-OIL with the fatty acid composition of RS, HL, and HLn. Although a statistically significant difference was noted in the volatile aldehyde emission between the DAG-OIL and TAG-OIL with HO, this difference was extremely small when compared to the variations found in the oils with four types of fatty acid composition. Finally, no difference was found in the volatile aldehyde emissions between the deteriorated DAG-OIL and TAG-OIL, although volatile aldehyde emissions increased with frying time. In addition, the acrylamide contents in potato chips prepared with RS–DAG or RS–TAG were at comparable levels.     

Effects of some leaf-emitted volatile compounds on aphid population increase

A role of some volatile compounds produced by plant tissues may be as defensive molecules against various pests, including arthropods. Volatile six-carbon compounds derived in plant tissue from polyunsaturated fatty acids via lipoxygenase/hydroperoxide lyase reduced tobacco aphid fecundity at certain concentrations when added to headspace vapor to which aphids were exposed. Both C₆ aldehydes and alcohols were effective, with the alcohols having greater activity. (Z)-3-Hexenyl acetate at levels in the headspace similar to those of the alcohols and aldehydes did not reduce aphid fecundity. A 6-hr exposure period to the C₆ aldehydes and alcohols was needed for maximum effect on the aphids feeding on tobacco leaves. Analysis of the direct versus indirect effects of these compounds indicates that the volatile aldehydes had both direct effects on aphid fecundity and indirect effects due to induced changes in the leaves upon which the aphids were feeding, while only indirect effects were observed for the alcohols. Tomato leaves have the capacity to produce volatile compounds at levels that impact aphid population increase, with the volatiles produced from crushed leaves having a much larger effect. The C₆ aldehydes and alcohols may be components of the fecundity reduction seen with tomato volatiles; however, volatile terpenes showed no effect. These results can be of significance for the genetic alteration of plants for improved aphid resistance.The investigation reported in this paper (No. 93-3-1) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with approval of the Director.     

Is the relatively low intake of omega‐3 fatty acids in Western diet contributing to the obesity epidemics?

Alongside the increase of overweight and obesity in the world there is the avoidance of saturated fat and an increased dietary use of vegetable oils rich in omega‐6 fatty acids. These changes result in a marked increase of the omega‐6/omega‐3 ratio and there is increasing evidence that this changed balance is related to lifestyle diseases. There are also indications that this balance between fatty acids may be involved in epigenetics, i. e. that it influences metabolic pathways during intra‐uterine or early life which cause diseases later in life. Such processes would be a possible explanation for the epidemic outburst of obesity during the latest decades.     

Oxidative susceptibility of low density lipoprotein from rabbits fed atherogenic diets containing coconut,palm, or soybean oils

The oxidative susceptibilities of low density lipoproteins (LDL) isolated from rabbits fed high-fat atherogenic diets containing coconut, palm, or soybean oils were investigated. New Zealand white rabbits were fed atherogenic semisynthetic diets containing 0.5% cholesterol and either (i) 13% coconut oil and 2% corn oil (CNO), (ii) 15% refined, bleached, and deodorized palm olein (RBDPO), (iii) 15% crude palm olein (CPO), (iv) 15% soybean oil (SO), or (v) 15% refined, bleached, and deodorized palm olein without cholesterol supplementation [RBDPO(wc)], for a period of twelve weeks. Total fatty acid compositions of the plasma and LDL were found to be modulated (but not too drastically) by the nature of the dietary fats. Cholesterol supplementation significantly increased the plasma level of vitamin E and effectively altered the plasma composition of long-chain fatty acids in favor of increasing oleic acid. Oxidative susceptibilities of LDL samples were determined by Cu²⁺-catalyzed oxidation which provide the lag times and lag-phase slopes. The plasma LDL from all palm oil diets [RBDPO, CPO, and RBDPO(wc)] were shown to be equally resistant to the oxidation, and the LDL from SO-fed rabbits were most susceptible, followed by the LDL from the CNO-fed rabbits. These results reflect a relationship between the oxidative susceptibility of LDL due to a combination of the levels of polyun-saturated fatty acids and vitamin E. Based on a paper presented at the PORIM International Palm Oil Congress (PIPOC) held in Kuala Lumpur, Malaysia, 1993.     

Peroxidation reactions in plant membranes: Effects of free fatty acids

Free fatty acids accumulate in plant membranes after exposure of plants to environmental stress, such as freezing and desiccation. Fatty acid accumulation has been linked to various biophysical changes and to the occurrence of lipid peroxidation, but the relationships appear complex and inconsistent. The interactions between oxygen free radicals, free fatty acids and lipid peroxidation in plant membranes were examined further by studying peroxidation reactions in a model membrane system composed of a complex mixture of plant phospholipids, including various free fatty acids. Multilamellar liposomes were treated with oxygen free radicals generated from iron ascorbate. Increased concentrations of free palmitic acid up to 10 mol% (fatty acid/phospholipid) reduced the production of aldehydes detected by the thiobarbituric acid assay, but enhanced the production of fluorescent products. By contrast, increased concentrations of free linolenic acid increased aldehyde production and reduced the formation of fluorescent products. The two free fatty acids both enhanced the susceptibility of phospholipids to degradation as shown by the reduced recovery of esterified polyunsaturated fatty acids (linoleic and linolenic). The free radical reactions with or without free fatty acid additions catalyzed the selective degradation of phospholipids in the order phosphatidylethanolamine > phosphatidylcholine > phosphatidylinositol > phosphatidylglycerol. Selective degradation of phospholipids is often observed after periods of environmental stress or during senescence of plants, and has been cited as evidence for the involvement of phospholipases in these degenerative processes. The results indicate that selectivity is not a criterion for eliminating the involvement of oxygen free radicals in these degenerative processes. Furthermore, the results suggest that modifications of lipid composition during a plant's acclimation to adverse environments may determine the types of free radical reactions that occur due to stress.     

Comparative Fingerprint Changes of Toxic Volatiles in Low PUFA Vegetable Oils Under Deep-Frying

The volatile fraction of three vegetable oils recommended for deep‐frying due to their high MUFA:PUFA ratios, namely extra‐virgin olive oil, peanut oil and canola oil, was compared before and after frying potatoes, with a particular focus on toxic volatiles. For the purpose, a headspace solid‐phase‐micro extraction technique coupled with gas chromatography and mass spectrometry was optimized, with semi‐quantification achieved using two internal standards. Significant qualitative and quantitative differences were observed, both before and after frying. From a total of 51 compounds, aldehydes were the main group formed after deep‐frying, their nature and abundance being highly associated with the initial fatty acid composition, particularly linoleic acid (r² = ?0.999, p ≤ 0.001). Globally, extra‐virgin olive oil revealed fewer formations of unsaturated aldehydes, including toxic ones, and correlated with lower amounts of degradation indicators, as polar compounds (r² = 0.998, p ≤ 0.001) and p‐anisidine value (r² = 0.991, p ≤ 0.001). Despite the similarities in total unsaturation degree between canola and peanut oils, the former presented lower amount of volatiles, including E,E‐2,4‐decadienal and acrolein, the more toxic ones. These results highlight for the pertinence of volatile analyses to evaluate and compare oil degradation under thermal and oxidative stress, while complementing other degradation indicators. Additionally, the optimized methodology allows a direct comparison of different oil matrices, supporting further developments into more general methods for volatiles quantification, enabling more efficient comparison of results between research teams.     

The impact of dietary mono‐ and poly‐unsaturated fatty acids on risk factors for atherosclerosis in humans

The fatty acid composition of the diet has various effects on atherosclerosis risk factors. Dietary saturated fatty acids (SFA) and trans‐unsaturated fatty acids increase the low‐density lipoprotein (LDL)‐/high‐density lipoprotein (HDL)‐cholesterol ratio in serum, while these fats do not have a significant bearing on serum triglyceride levels. By contrast, dietary monounsaturated fatty acids (MUFA), n‐6 polyunsaturated fatty acids (PUFA), and α‐linolenic acid (C18:3n‐3) similarly reduce LDL cholesterol concentrations, while their influence on serum HDL cholesterol and triglycerides is not appreciable. Dietary long‐chain n‐3 PUFA slightly increase serum LDL cholesterol concentrations, but are nevertheless considered salubrious with regard to serum lipids due to the distinct triglyceride‐lowering effects. MUFA‐rich compared to n‐6 PUFA‐rich diets strongly reduce the in vitro oxidizability of LDL. The available studies on this subject also suggest that n‐3 PUFA in the small amounts usually present in the diet are not unduly harmful. These findings are consistent with reports from observational studies: the amount of SFA is positively and the amount of MUFA and n‐6 PUFA in the diet is inversely associated with the risk of cardiovascular disease in most epidemiological studies. The available studies have had an impact on current dietary guidelines, which unanimously recommend that most of the dietary fat should be in the form of MUFA, while the amount of SFA and trans fatty acids in the diet should be as low as possible.     

Novel interactions between iron and n‐3 fatty acids in cognition and immune function

Many children, particularly from low‐ and middle‐income countries, may suffer from both iron deficiency and inadequate omega‐3 fatty acid intake due to poor quality diets. Both, iron and omega‐3 fatty acids are important for the development and functioning of the brain and immune system. Using a translational research approach, we therefore investigated potential interactive effects of iron and omega‐3 fatty acid deficiencies and supplementation on cognition and immune‐related outcomes. Our results indicate that in children with iron deficiency and poor omega‐3 fatty acid intake, it may be crucial to administer iron in combination with omega‐3 long‐chain polyunsaturated fatty acids to ensure optimal cognition and immune function.     

Biomarkers of long‐chain PUFA omega‐3 fatty acids and the human nutritional status

The association of dietary fats with disease risk or outcome can be determined from epidemiological studies and/or from food frequency questionnaires; a better assessment of the dietary intake of the long‐chain polyunsaturated fatty acids omega‐3 is obtained by the fatty acid composition of the platelets or of erythrocyte membranes yet these procedures are lengthy. Other investigators have used adipose tissue obtained by percutaneous biopsy, but it must be pointed out that this procedure is not only invasive but time‐consuming as well. Also, it has to be noted that the turnover time for fatty acids has been estimated to be 1–3 years.     

Elongation and desaturation of dietary fatty acids in turbotScophthalmus maximus L., and rainbow trout,Salmo gairdnerii rich

Turbot and rainbow trout, which had previously recieved diets free of fat, were fed [1-14C] fatty acids. The distribution of radioactivity in the tissue fatty acids was examined 6 days later. In rainbow trout fed [1-14C] 18:3omega3, 70% of the radioactivity was present in 22:6omega3 fatty acid. In contrast, turbot fed [1-14C] 18:1omega9, 18:2omega6, or 18:3omega3 converted only small amounts of labeled fatty acids (3-15%) into fatty acids of longer chain length. The major product of the limited modification found in turbot was the dietary acid elongated by 2 carbon atoms.     

Serum n-3 Tetracosapentaenoic Acid and Tetracosahexaenoic Acid Increase Following Higher Dietary α-Linolenic Acid but not Docosahexaenoic Acid

n‐3 Tetracosapentaenoic acid (24:5n‐3, TPAn‐3) and tetracosahexaenoic acid (24:6n‐3, THA) are believed to be important intermediates to docosahexaenoic acid (DHA, 22:6n‐3) synthesis. The purpose of this study is to report for the first time serum concentrations of TPAn‐3 and THA and their response to changing dietary α‐linolenic acid (18:3n‐3, ALA) and DHA. The responses will then be used in an attempt to predict the location of these fatty acids in relation to DHA in the biosynthetic pathway. Male Long Evans rats (n = 6 per group) were fed either a low (0.1% of total fatty acids), medium (3%) or high (10%) ALA diet with no added DHA, or a low (0%), medium (0.2%) or high (2%) DHA diet with a background of 2% ALA for 8 weeks post‐weaning. Serum n‐3 and n‐6 polyunsaturated fatty acid (PUFA) concentrations (nmol/mL ± SEM) were determined by gas chromatography–mass spectrometry. Serum THA increases from low (0.3 ± 0.1) to medium (5.8 ± 0.7) but not from medium to high (4.6 ± 0.9) dietary ALA, while serum TPAn‐3 increases with increasing dietary ALA from 0.09 ± 0.04 to 0.70 ± 0.09 to 1.23 ± 0.14 nmol/mL. Following DHA feeding, neither TPAn‐3 or THA change across all dietary DHA intake levels. Serum TPAn‐3 demonstrates a similar response to dietary DHA. In conclusion, this is the first study to demonstrate that increases in dietary ALA but not DHA increase serum TPAn‐3 and THA in rats, suggesting that both fatty acids are precursors to DHA in the biosynthetic pathway.     

Shining a light on the effects of omega‐3 polyunsaturated fatty acids on the brain: The relationship between cerebral blood flow parameters and cognition

Higher dietary intake of omega‐3 polyunsaturated fatty acids (n‐3 PUFAs) is associated with better cognitive function in older adults and reduced incidence of dementia. One potential mechanism underpinning this relationship is via modulation of cerebrovascular parameters and therefore increasingly, neuroimaging techniques such as near‐infrared spectroscopy (NIRS) and fMRI have been applied to investigate the effect of n‐3 PUFAs on cerebral blood flow in humans. These studies have revealed that n‐3 PUFA supplementation has subtle effects on cerebral blood flow which may indeed underpin the positive relationship between their intake and cognition across the lifespan; at present these changes are more apparent in children and younger adults.     

Dietary Supplementation of Tetracarpidium conophorum (African Walnut) Seed Enhances Muscle n‐3 Fatty Acids in Broiler Chickens

The influence of dietary Tetracarpidium conophorum (African Walnut) seed meal (TCSM) on fatty acids, productivity parameters, and physicochemical properties of breast and thigh muscles in broiler chickens are assessed. A total of 180, 28‐d‐old Arbor acre broiler chickens are randomly assigned to dietary treatments containing 0% (control), 2.5%, and 5% w/w TCSM, fed for 28 d, and euthanized. Dietary TCSM reduces (p < 0.05) feed intake, body weight gain (BWG), carcass weight, and abdominal fat. Diet does not affect feed efficiency and hematological parameters. The control birds have higher (p < 0.05) serum total cholesterol and triglycerides than do the supplemented birds. Diet has no effect on pH, water holding capacity, carbonyl and malondialdehyde contents, and organoleptic properties of breast and thigh muscles. The 5% TCSM has higher redness in breast muscle than do other treatments. Dietary TCSM improves (p < 0.05) the concentration of C18:3n‐3 (4.80–8.76% vs 1.56%), C20:5n‐3 (0.54–0.79% vs 0.39%), C22:5n‐3 (0.64–0.89% vs 0.18%), and C22:6n‐3 (0.75–0.97% vs 0.19%), and reduces (p <  0.05) the fat content (2.15–2.45% vs 3.15%) in breast and thigh muscles. Dietary TCSM enhances muscle n‐3 fatty acids without instigating oxidative deterioration, but reduces BWG in broiler chickens. Practical Application: Albeit that broiler meat is rich in polyunsaturated fatty acids (PUFA), its omega 6 (n‐6)/omega 3 (n‐3) is >4. Elevated n‐6/n‐3 could have adverse effect on human physiology thereby promoting the pathogenesis of certain diseases. This heightens the need to enhance the n‐3 PUFA content of broiler meat. Dietary TCSM induced up to a fourfold increase in n‐3 PUFA content of the breast and thigh muscles in broiler chickens. Moreover, dietary TCSM induced up to a tenfold decrease in the n‐6/n‐3 of the breast and thigh muscles in broiler chickens. This finding assumes great significance because the health concerns regarding dietary fat are the foremost factors responsible for the bad image suffered by meat. These results provide insights on the potential of TCSM to improve the nutritional quality without compromising the oxidative shelf life, organoleptic traits, and physicochemical properties of broiler meat.