The omega-3 fatty acid nutritional landscape: health benefits and sources

The Role of Essential Fatty Acids in Human Health

Fatty acid research began about 90 years ago but intensified in recent years. Essential fatty acids (linoleic and α-linolenic) must come from diet. Other fatty acids may come from diet or may be synthesized. Fatty acids are major components of cell membrane structure, modulate gene transcription, function as cytokine precursors, and serve as energy sources in complex, interconnected systems. It is increasingly apparent that dietary fatty acids influence these vital functions and affect human health. While the strongest evidence for influence is found in cardiovascular disease and mental health, many additional conditions are affected. Problematic changes in the fatty acid composition of human diet have also taken place over the last century. This review summarizes current understanding of the pervasive roles of essential fatty acids and their metabolites in human health.

Issues of fish consumption for cardiovascular disease risk reduction

Increasing fish consumption is recommended for intake of omega-3 (n-3) fatty acids and to confer benefits for the risk reduction of cardiovascular disease (CVD). Most Americans are not achieving intake levels that comply with current recommendations. It is the goal of this review to provide an overview of the issues affecting this shortfall of intake. Herein we describe the relationship between fish intake and CVD risk reduction as well as the other nutritional contributions of fish to the diet. Currently recommended intake levels are described and estimates of fish consumption at a food disappearance and individual level are reported. Risk and benefit factors influencing the choice to consume fish are outlined. The multiple factors influencing fish availability from global capture and aquaculture are described as are other pertinent issues of fish nutrition, production, sustainability, and consumption patterns. This review highlights some of the work that needs to be carried out to meet the demand for fish and to positively affect intake levels to meet fish intake recommendations for CVD risk reduction.

Toxoplasmosis and Polygenic Disease Susceptibility Genes: Extensive Toxoplasma gondii Host/Pathogen Interactome Enrichment in Nine Psychiatric or Neurological Disorders

Toxoplasma gondii is not only implicated in schizophrenia and related disorders, but also in Alzheimer's or Parkinson's disease, cancer, cardiac myopathies, and autoimmune disorders. During its life cycle, the pathogen interacts with ~3000 host genes or proteins. Susceptibility genes for multiple sclerosis, Alzheimer's disease, schizophrenia, bipolar disorder, depression, childhood obesity, Parkinson's disease, attention deficit hyperactivity disorder (P  from  8.01E - 05  (ADHD)  to  1.22E - 71) (multiple sclerosis), and autism (P = 0.013), but not anorexia or chronic fatigue are highly enriched in the human arm of this interactome and 18 (ADHD) to 33% (MS) of the susceptibility genes relate to it. The signalling pathways involved in the susceptibility gene/interactome overlaps are relatively specific and relevant to each disease suggesting a means whereby susceptibility genes could orient the attentions of a single pathogen towards disruption of the specific pathways that together contribute (positively or negatively) to the endophenotypes of different diseases. Conditional protein knockdown, orchestrated by T. gondii proteins or antibodies binding to those of the host (pathogen derived autoimmunity) and metabolite exchange, may contribute to this disruption. Susceptibility genes may thus be related to the causes and influencers of disease, rather than (and as well as) to the disease itself.

Effect of linseed oil dietary supplementation on fatty acid composition and gene expression in adipose tissue of growing goats

This study was conducted to determine the effects of feeding oil palm frond silage based diets with added linseed oil (LO) containing high α-linolenic acid (C18:3n-3), namely, high LO (HLO), low LO (LLO), and without LO as the control group (CON) on the fatty acid (FA) composition of subcutaneous adipose tissue and the gene expression of peroxisome proliferator-activated receptor (PPAR)α, PPAR-γ, and stearoyl-CoA desaturase (SCD) in Boer goats. The proportion of C18:3n-3 in subcutaneous adipose tissue was increased (P < 0.01) by increasing the LO in the diet, suggesting that the FA from HLO might have escaped ruminal biohydrogenation. Animals fed HLO diets had lower proportions of C18:1 trans-11, C18:2n-6, CLA cis-9 trans-11, and C20:4n-6 and higher proportions of C18:3n-3, C22:5n-3, and C22:6n-3 in the subcutaneous adipose tissue than animals fed the CON diets, resulting in a decreased n-6:n-3 fatty acid ratio (FAR) in the tissue. In addition, feeding the HLO diet upregulated the expression of PPAR-γ (P < 0.05) but downregulated the expression of SCD (P < 0.05) in the adipose tissue. The results of the present study show that LO can be safely incorporated in the diets of goats to enrich goat meat with potential health beneficial FA (i.e., n-3 FA).

Association between the levels of polyunsaturated fatty acids and blood lipids in healthy individuals

The levels of polyunsaturated fatty acids (PUFAs) in blood is closely associated with the status of the health of individuals; in particular, the lack of ω-3 fatty acids may lead to the development of numerous diseases. The aim of this study was to investigate the levels of PUFAs, and their correlation with triglycerides and other factors in blood. The levels of PUFAs and blood lipids were detected in 156 healthy individuals; the blood samples were tested by combined thin-layer and gas liquid chromatographic analysis. The level of ω-3 fatty acids was low in the subjects and the ω-3 index was 4.25%, while the ω-6:ω-3 ratio was at a satisfactory level. There was a strong inverse correlation between ω-3 fatty acids and triglycerides, and a strong positive correlation between ω-3 fatty acids and high density lipoprotein (HDL). Eicosapentaenoic acid and docosahexaenoic acid were inversely correlated with triglycerides, and positively correlated with HDL. In conclusion, ω-3 fatty acids are able to adjust the levels of blood lipids, and lower the levels of triglycerides, which may contribute to human health.

Stearidonic acid as a supplemental source of ω-3 polyunsaturated fatty acids to enhance status for improved human health

There is substantial evidence to show that consumption and increased blood levels of the very long-chain (VLC) ω-3 polyunsaturated fatty acids (ω-3 PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are associated with health benefits. The consumption of oily fish is an effective way of increasing EPA and DHA intake and status, but intake in most Western countries remains below the levels recommended for optimal health. The reasons for this include not liking the taste, a concern about sustainability of fish supplies, or potential chemical and heavy metal contamination. Alternative dietary sources of ω-3 fatty acids to enhance EPA and DHA status in the body would therefore be beneficial. There are many non-fish food sources of the essential plant-derived ω-3 fatty acid α-linolenic acid, but conversion from this to longer-chain EPA and especially to DHA is poor. Stearidonic acid (SDA) is an intermediate fatty acid in the biosynthetic pathway from α-linolenic acid to VLC ω-3 PUFAs and the conversion from SDA is more efficient than from α-linolenic acid. However, there are few food sources rich in SDA. Oil crops naturally rich in SDA or enriched through genetic modification may offer an alternative supplemental oil to boost the population status of VLC ω-3 PUFAs. This review discusses the currently available evidence that increased SDA consumption can increase red blood cell EPA content, although this is less than the effect of supplementation directly with EPA. There is now a need for trials specifically designed to assess whether an increased SDA consumption would translate into improved human health outcomes.

Soyfoods and soybean products: from traditional use to modern applications

Soybean products (soyfoods), reported as potential functional foods, are implicated in several health-enhancing properties, such as easing the symptoms of postmenopausal women, reducing the risk of osteoporosis, preventing cardiovascular disease, and antimutagenic effects. Isoflavone, for example, is one of the most important compounds abundantly found in soybean, mainly accounting for the health-enhancing properties as mentioned earlier. However, most biological activities of isoflavones are mainly attributed to their aglycone forms. It has also been demonstrated that isoflavone aglycones are absorbed faster and in greater amount than their glycosides in human intestines. Fortunately, deglycosylation of isoflavones can be achieved during fermentation process by several strains such as lactic acid bacteria, basidiomycetes, filamentous fungus, and Bacillus subtilis with their β-glucosidase activity. This article presents an overview of soybean's chemistry, application, state-of-the-art advances in soybean fermentation processing and products as well as their applications in food and pharmaceutical industries. Different compounds, such as isoflavone, dietary fibers, and proteins which exhibit significant bioactivities, are summarized. The roles of different microorganisms in bioconversion and enhancement of bioactivities of fermented soybean are also discussed.

Suplementação de ácidos graxos poli-insaturados ômega-3 reduz marcadores inflamatórios e melhora a ação da insulina em fígado de camundongos

OBJETIVO: Avaliar os efeitos da suplementação do ácido graxo poliinsaturado ômega-3 (n3) sobre a sinalização da insulina e via próinflamatória no tecido hepático de camundongos. MÉTODOS: Camundongos Swiss foram divididos em seis grupos que receberam, por gavagem esofágica, diferentes doses de óleo de peixe contendo ômega-3 (1mg, 5mg, 10mg e 50mg). O grupo-controle recebeu água. Para determinar os efeitos do ômega-3 dependentes de dose e tempo, a glicemia de jejum foi avaliada nos dias 0 (sem suplementação), 14 e 21 (após suplementação). Como o grupo n-3-21dias (21 dias de suplementação) apresentou menor nível de glicemia, esse intervalo de tempo foi selecionado para as análises moleculares. Após jejum de 8 horas, amostras do tecido hepático foram obtidas do grupo-controle, e n-3-21dias e análises das vias de sinalização da insulina e próinflamatória foram realizadas por western blot. RESULTADOS: Os resultados mostraram que a dose de 10mg induziu maior redução na glicemia no 14° e no 21° dias quando comparada às demais doses. Dessa forma, essa foi a dose utilizada nos experimentos de análises moleculares e foi a que diminuiu de forma significativa a fosforilação da c-Jun n-terminal quinase e quinase e níveis proteicos do fator de transcrição Kappa B. Em paralelo, foi observado aumento na fosforilação do receptor da insulina, substrato do receptor de insulina 1 e proteína quinase B. CONCLUSÃO: O presente estudo sugere que o ômega-3 induza melhora na via de sinalização da insulina no fígado de camundongos, pelo menos em parte, por reduzir inflamação. Esses resultados podem explicar menores níveis de glicose de jejum.

Effects of fatty acids on endothelial cells: inflammation and monocyte adhesion

BACKGROUND

Diet is known to have an important impact on cardiovascular health. n-3 Fatty acids (FAs), found in high quantity in fish oil, have demonstrated beneficial effects in patients with coronary artery disease. The role of n-6 FAs remains more controversial. The objective of this study was to examine the effect of arachidonic acid (AA), an n-6 FA, and eicosapentanoic acid (EPA), an n-3 FA, on the interaction between monocytes and endothelial cells (ECs).

DESIGN

We used a cellular model of ECs (EA.hy.926) and monocytes (human leukemic myelomonocytic U937). Confluent ECs were treated with AA or EPA, in the presence of tumor necrosis factor-alpha (TNF-α) or vehicle alone for either 4 or 24h. Adhesion of monocytes to the endothelial monolayer was performed. For gene expression, reverse transcription, followed by real-time quantitative polymerase chain reaction, was performed.

RESULTS

There was a significant increase in adhesion of monocytes to the endothelial monolayer in the presence of n-6 FAs, both in the presence and in the absence of TNF-α at 4 and 24h. The adhesion of monocytes to the endothelial monolayer was decreased with n-3 FAs at 24h. Intercellular adhesion molecule 1, vascular cell adhesion molecule 1, E-Selectin, Interleukin 6, and TNF-α were significantly increased in ECs treated with n-6 FAs.

CONCLUSIONS

We conclude that AA increases inflammation and enhances the ability of ECs to bind monocytes in vitro. EPA leads to a decrease in the ability of EA.hy.926 to bind monocytes, although the effect appears more modest. Taken together, these data indicate that the n-6 FA AA could potentiate inflammation and early events of atherosclerosis.

Conclusions and recommendations from the symposium, Heart Healthy Omega-3s for Food: Stearidonic Acid (SDA) as a Sustainable Choice

Faculty who had presented at the symposium "Heart Healthy Omega-3s (n-3 fatty acids) for Food: Stearidonic Acid (SDA) as a Sustainable Choice" met and agreed upon conclusions and recommendations that could be made on the basis of evidence provided at the symposium. The participants also submitted manuscripts relating to their topics and these are presented in this supplement. These manuscripts were reviewed and also contributed to the conclusions and recommendations presented herein. The three major objectives of the symposium were to: 1) increase understanding of the current and emerging knowledge regarding the health benefits of (n-3) fatty acids (FA) including a focus on stearidonic acid (SDA) and EPA; 2) evaluate the importance of increasing (n-3) FA consumption in the US and the current challenge of doing so via mainstream foods; and 3) consider the health and food application benefits of SDA as a precursor to EPA and a plant-based sustainable source of highly unsaturated (n-3) FA for mainstream foods. Specific areas for future research were defined and included in the summary and conclusions herein. Overall evidence-based conclusions included: the current evidence provides a strong rationale for increasing (n-3) FA intakes in the US and other populations; current consumption of (n-3) FA in most populations is either insufficient or not efficient at providing adequate tissue levels of the long-chain (n-3) FA EPA and DHA; SDA in soybean oil appears to be a cost-effective and sustainable plant-based source that could contribute to reaching recommended levels of (n-3) FA intake, but more research and surveillance is needed; and adding SDA-enriched soybean oil to foods should be considered as a natural fortification approach to improving (n-3) FA status in the US and other populations. References for these conclusions and recommendations can be found in the articles included in the supplement.