The effects of fish or fish oil on the omega‐3 index

Aim: To compare the impact of recommended intakes of fish and fish oil supplements on the omega‐3 index and selected risk factors in patients with coronary heart disease. Methods: A 12‐week crossover intervention comparing the impact of 1 g/day of long‐chain omega‐3 polyunsaturated fatty acids from fresh salmon or fish oil capsules on the omega‐3 index and cardiovascular risk factors. Eleven patients with coronary heart disease, recruited from St. Vincent's Hospital, Melbourne, participated in the study. Results: A decrease in blood pressure (>5 mmHg; P < 0.05) was observed after the fish but not the fish oil. The change in waist to hip ratio also favoured the fish intervention. Resting heart rate fell by a similar amount on both interventions, and the omega‐3 index increased significantly on both; from 6% to 7–8% (P < 0.01). Blood lipids did not improve on either arm. Conclusions: In Australians with coronary heart disease, 1 g/day of long‐chain omega‐3 polyunsaturated fatty acid from fish or supplements over 12 weeks was effective in increasing the omega‐3 index. Fish intake may have additional cardiovascular benefits beyond the omega‐3 effect as evidenced by the substantial blood pressure reduction following the fish arm warranting examination in a larger study.     

Rapid Enrichment of Cell Phospholipids in Long‐Chain Polyunsaturated ω‐3 Fatty Acids After a Bolus Intravenous Injection of a Medium‐Chain Triacylglycerol

The present review aims at highlighting the use of a recently developed medium‐chain triacylglycerol:fish oil (MCT:FO) emulsion for the rapid and sustained enrichment of long‐chain polyunsaturated ω‐3 fatty acids in cell phospholipids. Preclinical in vitro, in vivo, and ex vivo experiments are briefly considered with emphasis on the changes in the fatty acid pattern of cell phospholipids in several organs, the partial correction of liver steatosis, and the cardiovascular modification of cationic and functional variables observed in ω‐3‐depleted rats examined 60–120 minutes after a bolus intravenous (IV) injection (1.0 mL) of the MCT:FO emulsion. The clinical findings collected in healthy male volunteers before or after the bolus IV injection (50.0 mL) of either the MCT:FO emulsion or a control medium‐chain triacylglycerol:long‐chain triacylglycerol emulsion are also reviewed, with emphasis on the rapid (within 60 minutes) and sustained (up to 2–3 days) enrichment of platelet and white blood cell phospholipids in long‐chain polyunsaturated ω‐3 fatty acids and hemostatic safety of the present procedure proposed as a tool for the rapid prevention or correction of metabolic and functional disturbances in humans with a relative deficiency in such ω‐3 fatty acids.     

Incorporating omega‐3 in the food chain – why,where and how?

Summary It has been recognised for decades that high fat intakes are not conducive to good health and, more recently, that the fatty acid profile of the diet (sometimes referred to as fat quality) is also important. Fat intake as a proportion of total food energy has declined over recent years in line with recommendations. Although there have been changes in the types of fats consumed and a fall in the total intake of saturates towards the recommended level, there is still room for improvement. The proportion of energy derived from saturates is still too high in most EU countries. The recommended level is 10% or less of total energy (<11% total food energy) but data show that only two Member States consume 12% or less of total energy as saturates. As the main factor determining serum cholesterol is the amount of saturates in the diet, there are heart health benefits to be gained from achieving a reduction. Meanwhile, research investigating the promise of health benefits linked to increased consumption of n‐6 polyunsaturated fatty acids, monounsaturates and long‐chain n‐3 (omega‐3) polyunsaturates has expanded our knowledge of the health effects of these fatty acids in our diets. Attempts to modify dietary fatty acid profile started with meat and dairy products but developments throughout the food chain have now taken place, such as production of lower fat meats, meat products and spreads; low‐fat milks and dairy products, and a variety of manufactured foods with a reduced fat content and enhanced fatty acid profile. Together these initiatives have led to a fall in saturates intake and improvements in the overall fatty acid profile of our diets, although targets have generally not been met as yet. More recently there have been recommendations to increase our intake of fish, the primary dietary source of long‐chain n‐3 fatty acids. However, the latter has been accompanied by environmental concerns about the safety and sustainability of fish and fish oil supplies. Dietary sources of these long chain n‐3 fatty acids are very limited, oily fish being the only major source. Meanwhile, across Europe, associated with the increased prevalence of obesity and related morbidities, health care costs have soared, exacerbated by the fact that people are living longer although these extra years are often spent in poor health. This has provoked a renewed and reinvigorated search for dietary approaches to health promotion that can potentially be applied to the food supply at the population level. Exploring ways of enhancing the food supply with respect to long‐chain n‐3 fatty acids has been the focus of researchers associated with the EU‐funded Lipgene project. Possible routes include enrichment of meat and meat products through standard animal husbandry techniques, enrichment of milk (either via the cows’ diet or during processing), and more controversially the development of transgenic plants capable of producing long‐chain n‐3 fatty acids, which could be used as a vehicle to introduce these important fatty acids into the food chain.     

The health effects of dietary unsaturated fatty acids

• 2.1 The chemistry of fatty acids
• 2.2 Digestion, absorption and metabolism
• 2.3 Functions of unsaturated fatty acids

3 Unsaturated fatty acids in the UK diet

• 3.1 Sources of fat in the diet
• 3.2 Dietary recommendations for fat
• 3.3 Intakes of unsaturated fatty acids
• 3.4 Major contributors to unsaturated fatty acid intake
• 3.5 Trends in intake

4 Unsaturated fatty acids in health and disease

• 4.1 Unsaturated fatty acids and cardiovascular disease
• 4.2 Unsaturated fatty acids and diabetes
• 4.3 Unsaturated fatty acids and cancer
• 4.4 Unsaturated fatty acids and inflammatory conditions
• 4.5 Unsaturated fatty acids in fetal and infant development
• 4.6 Unsaturated fatty acids and cognitive function and behaviour
• 4.7 Emerging aspects of unsaturated fatty acids and health

5 Unsaturated fatty acids and public health

• 5.1 Labelling of unsaturated fatty acids
• 5.2 Are current UK recommendations adequate?
• 5.3 Opportunities to increase intake of long chain n‐3 PUFAs
• 5.4 Implications of optimising intakes of unsaturated fatty acids

6 Conclusions

Acknowledgements

References

Appendix 1

Summary Fat provides energy; indeed it is the most energy dense of all the macronutrients, with 1 g providing 37 kJ (9 kcal). However, the constituent parts of fat, fatty acids, are required by the body for many other functions than simply as an energy source, and there is an increasing awareness of the potential health benefits of specific types of fatty acids. Fatty acids are long hydrocarbon chains, with a methyl group at one end (the omega or n‐end) and an acid group at the other. Unsaturated fatty acids are hydrocarbon chains containing at least one carbon–carbon double bond; monounsaturated fatty acids contain one double bond, and polyunsaturated fatty acids (PUFAs) contain many double bonds. The position of the double bond relative to the omega end determines whether a PUFA is an n‐3 (omega 3) or an n‐6 (omega 6) fatty acid. Most fatty acids can be synthesised in the body, but humans lack the enzymes required to produce two fatty acids. These are called the essential fatty acids and must be acquired from the diet. In humans, the essential fatty acids are the n‐3 PUFA α‐linolenic acid and the n‐6 PUFA linoleic acid. Although humans can elongate dietary α‐linolenic acid to the long chain n‐3 PUFAs eicosapentaenoic acid and docosahexaenoic acid, the rate of synthesis may not be sufficient to meet requirements, and it is, therefore, recommended that good sources of these fatty acids, namely, oil‐rich fish, are also included in the diet. Fat is found in most food groups, and foods containing fat generally provide a range of different fatty acids, both saturated and unsaturated. In the UK, the major dietary sources of unsaturated fatty acids include meat & meat products, cereals & cereal products and potatoes & savoury snacks; primarily as a result of the vegetable oil used in processing. Recommended intakes of both total fat and the different types of fatty acids have been set for the UK population, and it is possible to monitor fat intake from the data collected in nationwide dietary surveys. As a population, we are not currently meeting these recommendations, so there is still scope for dietary change. In Western diets, n‐6 fatty acids are the predominant PUFAs, and this is in line with current dietary advice to consume a minimum of 1% energy as n‐6 PUFAs and 0.2% energy as n‐3 PUFAs. The balance of n‐3 and n‐6 PUFAs in Western diets has changed substantially over the last 100 years or so, and as the two families of PUFAs share a common metabolic pathway, concerns have been raised that this might be detrimental to health; what is becoming increasingly clear is that both n‐3 and n‐6 PUFAs have independent health effects in the body, and as intakes of the n‐6 PUFAs are within the guidelines for a healthy diet, concerns about the n‐6 to n‐3 ratio are driven by low intakes of n‐3 rather than high intakes of n‐6. Currently in adults n‐6 PUFAs contribute to 5.3% energy. Detecting associations between components of the diet and risk of various diseases is notoriously complex and in many cases, the evidence is still accumulating. Cardiovascular disease, characterised by hardening and narrowing of blood vessels and/or the development of blood clots, is one of the leading causes of mortality and morbidity worldwide. The type and total amount of dietary fat has a clear part to play in affecting an individual’s disease risk, yet the precise mechanisms by which unsaturated fatty acids reduce cardiovascular disease risk are still unclear. A number of mechanisms whereby dietary fatty acids could influence the progression of cardiovascular disease and its risk factors have been identified. These include effects on blood lipid concentrations, blood pressure, inflammatory response, arrhythmia and endothelial function, along with many other effects, both known and as yet undefined. A well‐established risk factor for cardiovascular disease is an elevated plasma low density lipoprotein (LDL) cholesterol concentration. Replacing saturated fatty acids with either monounsaturated fatty acids or n‐6 PUFAs reduces LDL (the ‘bad’) cholesterol, and so reduces the risk of developing the disease. Unsaturated fatty acids, such as linoleic acid or monounsaturated fatty acids, also slightly raise high density lipoprotein (HDL) (the ‘good’) cholesterol, which assists in the removal of triacylglycerols from the bloodstream. Interest in the health effects of the long chain n‐3 PUFAs found in fish oils is also increasing. There is strong supportive, but not yet conclusive, evidence that these fatty acids protect against fatal heart disease. On the basis of this conclusion, in 2004 the Scientific Advisory Committee on Nutrition advised the UK government to adopt the population‐wide dietary recommendation to eat at least two portions of fish per week, of which one should be oil‐rich, equivalent to 0.45 g of the long chain n‐3 PUFAs per day. In recent years, the potential health benefits of α‐linolenic acid has attracted attention, and evidence is mounting on the role that this n‐3 fatty acid may play in preventing the progression of cardiovascular disease, although it is currently unclear what, if any, association exists. Brain cells are especially rich in certain long chain PUFAs. This has led to the suggestion that dietary status of these long chain fatty acids might influence cognitive function and behaviour. Research in this field is still in its early stages, but there is a small amount of evidence to suggest improvements in cognitive function following fatty acid supplementation. In contrast, it is well established that pregnant women must have an adequate supply of the long chain n‐3 PUFAs before and throughout pregnancy and lactation to support normal growth, neurological development and cognitive function of the baby. As n‐6 PUFAs are more abundant in the diet, achieving an adequate intake is less problematic. However, this is not the case for the n‐3 PUFAs; increasing fish consumption beyond two servings of oil‐rich fish per week or relying on fish oil supplementation is not appropriate during pregnancy due to the potential problems associated with heavy metal contamination of fish, or the high vitamin A level in some fish oil supplements. Unsaturated fatty acids have also been associated with a number of other diseases and although the evidence is by no means conclusive, it is an area that is attracting a huge amount of interest. Dietary fat affects a number of different metabolic pathways, including those involved with glycaemic control, so the types and amounts of dietary fat may have a role to play in the management of type 2 diabetes. Unsaturated fatty acids may also be associated with a reduced risk of developing certain cancers, including cancers of the colon, breast and prostate, although currently the level of evidence is not deemed sufficient by authoritative bodies, such as the World Cancer Research Fund, World Health Organization and the Department of Health, to make any specific dietary recommendations. There are a number of inflammatory conditions, such as asthma, Crohn’s disease and arthritis, which could potentially be alleviated by dietary modification. The fatty acid composition of cell membranes can be altered by consumption of both n‐3 and n‐6 PUFAs, and this can result in reduced inflammatory activity. However, whether this effect brings about a significant reduction in clinical symptoms is still unclear. It is also important to note that there are concerns that the beneficial effects on certain disease outcomes are only observed with very high intakes of unsaturated fatty acids, which could realistically only be achievable by supplementation. Few nutritionists would be comfortable recommending supplement use as the only alternative to fish, as this can be expensive and goes against the idea that all the nutrients that our bodies require can be obtained from the food that we eat if the right choices are made. Unsaturated fatty acids are now a nutritional hot topic, and their presence in foods has attracted both public and industrial interest. There is currently no specific legislation to control the use of health claims relating to the fatty acid content of foods. However, a European Union (EU) Directive is expected imminently which will formally set down the criteria that a product will have to meet in order to make any nutrition or health claim. With regards to the current recommendations, those for the UK are in line with those around the world. However, as a population, we need to increase our consumption of long chain n‐3 PUFAs and decrease intake of saturated fatty acids. To facilitate this, food technologists are looking at ways in which the fatty acid profile of a food can be modified in order to bring dietary improvements without requiring a major change in dietary habits. However, public health messages surrounding the optimum intakes of fatty acids must be clear and consistent to ensure that a favourable change in the fatty acid profile of the UK diet occurs.     

Changes in chemical composition of frozen coated fish products during deep-frying

This work evaluates the influence of deep-frying coated fish products on total fat, fatty acid (FA) and amino acid profile, and on the formation of volatile compounds, with special attention on furan and its derivatives due to their potential harmful characteristics. As expected, deep-frying in sunflower oil increased linoleic acid content, but total fat amount increased only by 2% on a dry basis. Eicosapentanoic and docosahexanoic acids were preserved while γ- and α-linoleic acids were oxidised. Deep-frying also induces proteolysis, releasing free AA, and the formation of volatile compounds, particularly aldehydes and ketones arising from polyunsaturated FA. In addition, high quantities of furanic compounds, particularly furan and furfuryl alcohol, are generated during deep-frying coated fish. The breaded crust formed could contribute simultaneously for the low uptake of fat, preservation of long chain n?3 FA, and for the high amounts of furanic compounds formed during the deep-frying process.     

The role of fat in the diet – quantity,quality and sustainability

Dietary fat should supply at least 15% of food energy including 2.5% energy and 0.5% energy as linoleic acid and alpha‐linolenic acid respectively: docosahexaenoic acid may also need to be supplied in infants. The proportion of energy from fat is not linked to risk of obesity, cardiovascular disease and cancer. The total cholesterol/HDL cholesterol, which is the most robust lipid indicator of risk of coronary heart disease (CHD), is lowered by unsaturated fatty acids, increased by trans fatty acids and not affected by saturated fatty acids compared with carbohydrates. Using clinical outcomes as endpoints, trans fatty acids increase, polyunsaturated fatty acids decrease and monounsaturated and saturated fatty acids have no effect on CHD risk. Recent recommendations for the prevention of CHD suggest partial replacement of saturated with polyunsaturated fatty acids to give energy intakes in the range of 6–11% energy and a daily intake of 0.25 g long‐chain n‐3 polyunsaturated fatty acids. The recommendation to increase the intake of long‐chain n‐3 fatty acids needs to be considered against the backdrop of falling fish stocks; it is likely that a novel source will be needed in the future. The projected growth in world population will require more fat, mainly for food energy. The oil palm requires only one tenth of the land required by oil seeds to produce the same amount of oil. The impact of increased use of vegetable oils as biodiesel needs to be urgently reconsidered owing to the adverse environmental and economic consequences to people living in South East Asia.     

Risks and benefits of consumption of Great Lakes fish

Background: Beneficial effects of fish consumption on early cognitive development and cardiovascular health have been attributed to the omega-3 fatty acids in fish and fish oils, but toxic chemicals in fish may adversely affect these health outcomes. Risk–benefit assessments of fish consumption have frequently focused on methylmercury and omega-3 fatty acids, not persistent pollutants such as polychlorinated biphenyls, and none have evaluated Great Lakes fish consumption.Objectives: The risks and benefits of fish consumption have been established primarily for marine fish. Here, we examine whether sufficient data are available to evaluate the risks and benefits of eating freshwater fish from the Great Lakes.Methods: We used a scoping review to integrate information from multiple state, provincial, and federal agency sources regarding the contaminants and omega-3 fatty acids in Great Lakes fish and fish consumers, consumption rates and fish consumption advisories, and health effects of contaminants and omega-3 fatty acids.Data synthesis: Great Lakes fish contain persistent contaminants—many of which have documented adverse health effects —that accumulate in humans consuming them. In contrast, data are sparse on omega-3 fatty acids in the fish and their consumers. Moreover, few studies have documented the social and cultural benefits of Great Lakes fish consumption, particularly for subsistence fishers and native communities. At this time, federal and state/provincial governments provide fish consumption advisories based solely on risk.Conclusions: Our knowledge of Great Lakes fish has critical gaps, particularly regarding the benefits of consumption. A risk–benefit analysis requires more information than is currently available on the concentration of omega-3 fatty acids in Great Lakes fish and their absorption by fish eaters in addition to more information on the social, cultural, and health consequences of changes in the amount of fish consumed.     

Use of microencapsulated fish oil as a means of increasing n-3 polyunsaturated fatty acid intake

Background: The successful incorporation of fish oil into foods may provide a means of increasing intakes of n-3 polyunsaturated fatty acids (n-3 PUFA). The aim of the present study was to evaluate the bioavailability of n-3 PUFA in microencapsulatd fish oil compared with a fish oil capsule. Methods: Twenty-eight healthy volunteers were recruited to take part in this randomized controlled trial. Volunteers were supplemented with 0.9 g n-3 PUFA daily for 4 weeks, delivered either as microencapsulated fish oil in a milkshake or as a fish oil capsule. Plasma fatty acid composition and plasma total cholesterol levels were measured at baseline and after supplementation. In addition, volunteers completed a questionnaire on fish consumption, use of supplements and exercise. Results: Responses to the questionnaire indicated that the males who took part in this study took more physical exercise, consumed less fish and were less likely than the females to take supplements. Plasma n-3 PUFA concentrations were raised significantly and by a similar level by both fish oil supplements. Furthermore, no significant difference was observed in plasma n-3 PUFA concentrations following supplementation with either form of fish oil. Plasma total cholesterol levels were not significantly altered by n-3 PUFA supplementation in either group. The results of this study indicated that there was no difference in the bioavailability of n-3 PUFA given as microencapsulated fish oil compared with n-3 PUFA delivered as a fish oil capsule. Fortification of foodstuffs with microencapsulated fish oil therefore offers the potential to increase intakes of n-3 PUFA in line with current recommendations.     

The benefits of fish consumption

In 2004, The UK government advice stated that consumers should increase fish consumption to two portions a week, one of which should be oil‐rich fish. However, survey data show that this advice has not been acted upon by most members of the public. In addition, limited data on consumer attitudes highlight barriers to increased fish consumption, such as concerns about buying and cooking fish, perceptions that fish is expensive, and worries that fish meals may not be eaten by all family members. The ‘two‐a‐week’ message is underpinned by strong scientific evidence for heart health, while weaker emerging evidence associates certain nutrients found in fish with a lower risk of immune dysfunction, normal brain development in infants, insulin sensitivity and maintenance of cognitive function in later life. Clearly, further refinement of the two‐a‐week message is needed to ensure that greater numbers of people respond. Ideas include determining appropriate portion sizes for babies and children, increasing awareness of the broad range of fish and shellfish species, highlighting sustainable sources of fish, and reassuring consumers that frozen and prepared fish products count towards the two‐a‐week target. Further work is also needed to address barriers to consumption, particularly among teenagers and younger adults, who have the lowest intakes.     

Genetically modified plants are an alternative to oily fish for providing n‐3 polyunsaturated fatty acids in the human diet: A summary of the findings of a Biotechnology and Biological Sciences Research Council funded project

The n‐3 polyunsaturated fatty acids (PUFA) present primarily in oily fish, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are important components of cell membranes and that are needed for normal development and cell function. Humans have very limited capacity for EPA and DHA synthesis from α‐linolenic acid and so they must be obtained pre‐formed from the diet. However, perceived unpalatability of oily fish and fish oil concerns about contamination with environmental pollutants, dietary choices that exclude fish and animal products, and price limit the effectiveness of recommendations for EPA and DHA intakes. Moreover, marine sources of EPA and DHA are diminishing in the face of increasing demands. Therefore, an alternative source of EPA and DHA is needed that is broadly acceptable, can be upscaled and is sustainable. This review discusses these challenges and, using findings from recent nutritional trials, explains how they may be overcome by seed oils from transgenic plants engineered to produce EPA and DHA. Trials in healthy men and women assessed the acute uptake and appearance in blood over 8 hours of EPA and DHA from transgenic Camelina sativa compared to fish oil, and the incorporation of these PUFA into blood lipids after dietary supplementation. The findings showed that postprandial EPA and DHA incorporation into blood lipids and accumulation in plasma lipids after dietary supplementation was as good as that achieved with fish oil. The oil derived from this transgenic plant was well tolerated. This review also discusses the implications for human nutrition, marine ecology and agriculture.     

Bioavailability of long-chain omega-3 polyunsaturated fatty acid enriched luncheon meats

(Nutr Diet 2005;62:130–137) Objective: To determine the acute and chronic effects of low doses of long chain (LC) n‐3 polyunsaturated fatty acids (PUFA) on plasma LC n‐3 PUFA levels. Design: In the acute study, six healthy omnivores, avoiding fish meals on the day prior to the study, provided a fasting blood sample initially and post prandially at four hours. In the chronic study, 12 healthy subjects provided a fasting blood sample at baseline and three weeks after daily consumption of the test food. Main outcome measures: Plasma non‐esterified fatty acid and phospholipid LC n‐3 PUFA composition. Statistical analysis: Differences in plasma non‐esterified fatty acids and phospholipid LC n‐3 PUFA. A pre‐ and post‐consumption of the test food were assessed using paired t‐tests (spss ). Results: The acute study demonstrated that a low dose of LC n‐3 PUFA (25% eicosapentaenoic acid and 75% docosahexaenoic acid) significantly increased eicosapentaenoic acid levels in plasma of human subjects postprandially from 0.30% to 0.42% of total non‐esterified fatty acids, a per cent change of 39% (P < 0.05). The chronic study demonstrated a significant increase in total n‐3 phospholipids from zero weeks (5.48% of total fatty acids) to three weeks (7.92% of total fatty acids), representing a per cent increase of 44% (P = 0.006). The n‐6 to n‐3 ratio of LC PUFA phospholipids demonstrated a significant reduction from 5.1 at zero weeks to 4.07 at three weeks, representing a reduction of 20% (P = 0.006). Conclusions: These findings demonstrate the bioavailability of LC n‐3 PUFA consumed as a low‐fat omega‐3‐enriched luncheon meat.     

Poisson, acides gras oméga 3 et risque cardiovasculaire : données épidémiologiques

Thirty years ago Bang and Dyerberg have found for the first time an inverse relation between the low coronary heart disease rate and the high fish and marine products consumption in Eskimos and to this high long chain omega 3 fatty acids content. Then, almost all the epidemiological studies (ecological studies, case-control studies, prospective studies) have shown that a small intake of fish (one or twice a week), fatty fish mainly, was linked to a low cardiovascular mortality and morbidity, without a greatest benefit of an higher consumption. This effect disappears on some conditions as a simultaneous high mercury intake. Epidemiological studies have also shown a correlation between omega 3 fatty acids and increase of HDL cholesterol and decrease of triglycerides.Interventional studies in secondary prevention have confirmed that there is a causal relationship between the omega 3 fatty acids intake and a short term reduction in cardiovascular mortality mainly on sudden death. This suggests that the involved mechanism is due to an improve in thrombosis risk through prostaglandins and its effects on platelet aggregation and to a decrease of arrhythmia correlated to the omega 3 phospholipid tissue incorporation.     

Docosahexaenoic acid (DHA): an ancient nutrient for the modern human brain

Modern humans have evolved with a staple source of preformed docosahexaenoic acid (DHA) in the diet. An important turning point in human evolution was the discovery of high-quality, easily digested nutrients from coastal seafood and inland freshwater sources. Multi-generational exploitation of seafood by shore-based dwellers coincided with the rapid expansion of grey matter in the cerebral cortex, which characterizes the modern human brain. The DHA molecule has unique structural properties that appear to provide optimal conditions for a wide range of cell membrane functions. This has particular implications for grey matter, which is membrane-rich tissue. An important metabolic role for DHA has recently been identified as the precursor for resolvins and protectins. The rudimentary source of DHA is marine algae; therefore it is found concentrated in fish and marine oils. Unlike the photosynthetic cells in algae and higher plants, mammalian cells lack the specific enzymes required for the de novo synthesis of alpha-linolenic acid (ALA), the precursor for all omega-3 fatty acid syntheses. Endogenous synthesis of DHA from ALA in humans is much lower and more limited than previously assumed. The excessive consumption of omega-6 fatty acids in the modern Western diet further displaces DHA from membrane phospholipids. An emerging body of research is exploring a unique role for DHA in neurodevelopment and the prevention of neuropsychiatric and neurodegenerative disorders. DHA is increasingly being added back into the food supply as fish oil or algal oil supplementation.     

Dietary Fish Oil Aggravates Paracetamol‐Induced Liver Injury in Mice

Background: Paracetamol (APAP) hepatotoxicity remains the leading cause of drug‐induced liver failure. Fish oil, which contains ω‐3 fatty acids, has demonstrated therapeutic efficacy in several models of liver disease. Evidence for its use in APAP intoxication, however, is conflicting. The effects of fish oil supplementation on APAP‐induced liver failure were investigated. Methods: Ten C57BL6/J mice were fed a diet based on menhaden fish oil (MEN) or soybean oil (SOY) for 3 weeks followed by APAP intoxication. In a second experiment, the prefeeding period was reduced to 5 days. In a third experiment, 10 mice received the study diets for 3 weeks, after which they received chronic, low‐dose APAP administration for another 4 weeks. Finally, 10 mice received oral parenteral nutrition supplemented with either intravenous (IV) soybean‐based or fish oil–based lipid emulsion for 19 days, followed by APAP intoxication. Results: The extent of hepatocellular necrosis (3.8 ± 0.2 vs 2.8 ± 0.2; P = .021) and serum alanine aminotransferase values (2807 ± 785 vs 554 ± 141 IU/L; P = .048) were significantly elevated in mice fed a MEN diet compared with SOY‐diet fed controls. Long‐term, low‐dose APAP administration did not lead to liver injury irrespective of study diet. Pretreatment with soybean‐ or fish oil–based IV lipid emulsions followed by APAP intoxication demonstrated no significant differences in hepatic injury between groups. Conclusion: Within therapeutic ranges, APAP is harmless to the liver irrespective of dietary fat composition. IV use of fish oil did not increase APAP‐induced hepatotoxicity, but animals fed a fish oil–based diet were more susceptible, rather than resistant, to APAP‐induced hepatotoxicity.     

Update on alpha-linolenic acid

Consumption of omega 3 fatty acids is known to have health benefits. For many years, the importance of the only member of the omega 3 family considered to be essential, alpha-linolenic acid (ALA), has been overlooked. Current research indicates that ALA, along with its longer chain metabolites, may play an important role in many physiological functions. Potential benefits of ALA include cardioprotective effects, modulation of the inflammatory response, and a positive impact on both central nervous system function and behavior. Recommended levels for ALA intake have been set, yet the possible advantages of its consumption are just being revealed.     

Nutritional,Anthropometric and Sociodemographic Factors Affecting Fatty Acids Profile of Pregnant Women’s Serum at Labour—Chemometric Studies

Diet influences the health of pregnant women and their children in prenatal, postnatal and adult periods. GC-FID fatty acids profile analysis in maternal serum and a survey of dietary habits were performed in 161 pregnant patients from the II Faculty and Clinic of Obstetrics and Gynaecology of the Medical University of Warsaw. Their diet did not fulfil all nutritional recommendations regarding dietary fat sources. Olive and rapeseed oil were the most popular edible oils. High usage of sunflower oil as well as high consumption of butter were also observed, whereas fish and fish oil intake by pregnant women was low. A chemometric approach for nutritional data, connected with anthropometric, sociodemographic and biochemical parameters regarding mothers and newborns, was conducted for diet and its impact estimation. It revealed four clusters of patients with differing fatty acids profile, which resulted from differences in their dietary habits. Multiparous women to a lesser extent followed dietary recommendations, which resulted in deterioration of fatty acids profile and higher frequency of complications. Observed high usage of sunflower oil is disquieting due to its lower oxidative stability, whereas high butter consumption is beneficial due to conjugated linoleic acids supply. Pregnant women should also be encouraged to introduce fish and fish oil into their diet, as these products are rich sources of long chain polyunsaturated fatty acids (LC PUFA). Multiparous women should be given special medical care by medical providers (physicians, midwifes and dietitians) and growing attention from the government to diminish the risk of possible adverse effects affecting mother and child.     

ω‐3 Fatty Acids Reduce Chemotherapy‐Induced Hematological Toxicity by Bone Marrow Stimulation in Mice

Background: ω‐3 Fatty acids exert several benefits during chemotherapy, such as preventing intestinal mucosal damage and improving response to chemotherapy. However, little is known about the effect of ω‐3 fatty acids on chemotherapy‐induced hematological toxicities. Methods: Mice that had consumed either an ω‐3–rich or an ω–3‐poor diet for 2 weeks were intraperitoneally administered cisplatin. The resultant changes in blood cell count, bone marrow cell count, and cytokine levels in bone marrow supernatant were analyzed. The effect of ω‐3 fatty acids on human peripheral blood mononuclear cells (PBMCs) exposed to cisplatin was also examined. Results: Although peripheral blood cell counts decreased after cisplatin treatment in both groups of mice, the decrease in white blood cell count was significantly lower in mice that consumed the ω‐3–rich diet. The decrease in bone marrow cells after cisplatin treatment was also reduced in mice that consumed the ω‐3–rich diet. Levels of stem cell factor (SCF) and fibroblast growth factor 1 (FGF‐1) were significantly higher in bone marrow supernatants from mice that consumed the ω‐3–rich diet. The rate of apoptosis in PBMCs (after exposure to cisplatin) cultured in medium containing ω‐3 fatty acids was significantly lower than in PBMCs cultured in control medium. Conclusion: ω‐3–Rich diets reduced chemotherapy‐induced leukopenia in mice. This may be the result of increased numbers of bone marrow cells due to higher levels of SCF and FGF‐1 in the bone marrow.     

Lipids in Parenteral Nutrition: Biological Aspects

Lipid emulsions are an integral part of parenteral nutrition, and traditionally have been regarded as an energy-dense source of calories and essential fatty acids. For many years, lipids used in parenteral nutrition have been based on vegetable oils (eg, soybean-oil emulsions). However, soybean-oil emulsions may not have an optimal fatty-acid composition under some circumstances when used as the only lipid source, as soybean oil is particularly abundant in the ω-6 polyunsaturated fatty acid (PUFA), linoleic acid. Hence, a progressive series of more complex lipid emulsions have been introduced, typically combining soybean oil with 1 or more alternative oils, such as medium-chain triglycerides (MCTs) and/or olive oil and/or fish oil. The wide range of lipid emulsions now available for parenteral nutrition offers opportunities to alter the supply of different fatty acids, which potentially modifies functional properties, with effects on inflammatory processes, immune response, and hepatic metabolism. Fish oil has become an important component of modern, composite lipid emulsions, in part owing to a growing evidence base concerning its biological effects in a variety of preclinical models. These biological activities of fish oil are mainly attributed to its ω-3 PUFA content, particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). DHA and EPA have known mechanisms of action, anti-inflammatory, immunomodulatory, and antioxidative properties. Specialized proresolving mediators, such as resolvins, protectins, and maresins, are synthesized directly from DHA and EPA, are key for the resolution of inflammation, and improve outcomes in many cell- and animal-based models and, recently, in some clinical settings.     

Fish Oil–Based Lipid Emulsions Prevent and Reverse Parenteral Nutrition–Associated Liver Disease: The Boston Experience

Parenteral nutrition–associated liver disease (PNALD) is the most prevalent and most severe complication of long‐term parenteral nutrition. Its underlying pathophysiology, however, largely remains to be elucidated. The currently approved parenteral lipid emulsions in the United States contain safflower or soybean oils, both rich in ω‐6 polyunsaturated fatty acids (PUFAs). Mounting evidence indicates that the ω‐6 PUFAs originating from plant oils in these lipid emulsions may play a role in the onset of liver injury. Fish oil–based lipid emulsions, in contrast, are primarily composed of ω‐3 PUFAs, thus providing a promising alternative. The authors review the literature on the role of lipid emulsions in the onset of PNALD and discuss prevention and treatment strategies using a fish oil–based lipid emulsion. They conclude that a fish oil–based emulsion is hepatoprotective in a murine model of PNALD, and it appears to be safe and efficacious for the treatment of this type of liver disease in children. A prospective randomized trial that is currently under way at the authors' institution will objectively determine the place of fish oil monotherapy in the prevention of PNALD.     

Oily fish and fish oil supplements in the prevention of coronary heart disease

Dietary advice for the reduction of coronary heart disease events emphasizes the importance of a low-fat diet and advice on the consumption of oily fish may also be given. This report reviews the evidence linking fish consumption with coronary risk. On the basis of available evidence, a target of two to three portions of oily fish per week (200–400 g, 7–14 oz) is considered reasonable, particularly for secondary prevention. For those who cannot achieve the suggested dietary intake of oily fish, the partial or complete substitution of fish oil supplements may be appropriate. A range of suitable types of fish oil supplements is given, but an awareness of the potential adverse effects of fish oil supplementation is considered important. Further studies are needed to define the role of fish intake in coronary heart disease.