Very long-chainn-3 fatty acids and human health: fact, fiction and the future

Abstract

Eicosapentaenoic acid (EPA) and docosahexaenoioc acid (DHA) appear to be the most important omega-3 (n-3) fatty acids, but roles for n-3 docosapentaenoic acid (DPA) are now also emerging. Intakes of EPA and DHA are usually low, typically below those recommended.Increased intakes result in higher concentrations of EPA and DHA in blood lipids, cells and tissues. Increased content of EPA and DHA modifies the structure of cell membranes and the function of membrane proteins. EPA and DHA modulate the production of lipid mediators and through effects on cell signaling can alter the patterns of gene expression. Through these mechanisms, EPA and DHA alter cell and tissue responsiveness in a way that often results in more optimal conditions for growth, development and maintenance of health. DHA has vital roles in brain and eye development and function. EPA and DHA have a wide range of physiological roles which are linked to certain health or clinical benefits, particularly related to cardiovascular disease, cancer, inflammation, and neurocognitive function. The benefits of EPA and DHA are evident throughout the life course. Future research will include better identification of the determinants of variation of responses to increased intake of EPA and DHA; more in-depth dose response studies of the effects of EPA and DHA; clearer identification of the specific roles of EPA, DPA and DHA; testing strategies to enhance delivery of n-3 fatty acids to the bloodstream; and exploration of sustainable alternatives to fish-derived very long chain n-3 fatty acids. Omega-3 (n-3) fatty acids -structure, metabolic interrelationships, dietary sources and intakes Omega-3 (n-3) fatty acids are a family of polyunsaturated fatty acids (PUFAs) (1) . They are defined by the position of the double bond closest to the methyl terminus of the hydrocarbon (acyl) chain. This is on carbon number three when counting the methyl carbon as number one.Eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) appear to be the most important n-3 fatty acids (2,3) , although roles for docosapentaenoic acid (DPA; 22:5n-3) are now also emerging (4,5) . Because of their long hydrocarbon chain, EPA, DPA and DHA are sometimes termed very long chain n-3 fatty acids, in order to differentiate them from the 18-carbon plant-derived n-3 fatty acids like -linolenic acid (ALA; 18:3n-3) and stearidonic acid (SDA; 18:4n-3). In this article, the term "very long chain n-3 fatty acids" will be used to individually and collectively describe EPA, DPA and DHA.EPA, DPA and DHA are metabolically related to one another, and there is a pathway by which EPA can be synthesized from the simpler plant-derived n-3 fatty acids (Figure 1).The conversion of ALA to EPA involves three steps catalyzed, in turn, by delta-6 desaturase, elongase 5 and delta-5 desaturase (Figure 1). Further conversion of EPA to DHA, via DPA, occurs by a complex pathway (Figure 1) involving chain elongation catalyzed by elongase 5, a second chain elongation catalyzed by elongase 2 or 5...

Immunonutrition in Critical Illness: What Is the Role?

“…The potential clinical benefits of supplemental fish oil have been previously summarized as reduced inflammatory response, antithrombotic effects, decreased reactivity to various stimuli (e.g., atrial and ventricular arrhythmias), maintenance of tissue microperfusion, increased tolerance to organ transplantation, improved function of the graft, and prevention of impaired cellular immunity when caused by increased prostaglandin E2 production …”

“…[77][78][79] The potential clinical benefits of supplemental fish oil have been previously summarized as reduced inflammatory response, antithrombotic effects, decreased reactivity to various stimuli (e.g., atrial and ventricular arrhythmias), maintenance of tissue microperfusion, increased tolerance to organ transplantation, improved function of the graft, and prevention of impaired cellular immunity when caused by increased prostaglandin E2 production. 80 Given these physiologic effects, it is not surprising that a series of RCTs in SICU adults have reported that appropriate use of ω-3 PUFA, including EPA and DHA, partially attenuated the metabolic response to surgical and traumatic injury, decreased cardiac arrhythmias, minimized lean body muscle loss, prevented oxidative injury in various tissue beds, and improved overall surgical and ICU outcomes. 76,81 Although study subjects in these RCTs 81 were undergoing major open GI surgery, a similar result on outcomes is supported in the Wong and Aly systematic review and meta-analysis that included 19 RCTs and 2016 patients undergoing elective upper GI surgery found enteral IMN decreased rates of wound infection (RR 0.59, 95% CI 0.40-0.88; P = 0.009) and reduced hospital LOS (mean difference [MD] −2.92 days; 95% CI −3.89-−1.95; p < 0.00001).…”

Enhancing lipid nutritional quality of oysters by hybridization betweenCrassostrea gigasandC. angulata

“…It is now widely accepted that reducing dietary saturated fatty acids (SFA) from meats and dairy products and trans‐fatty acids from hydrogenated vegetable oils can improve cardiovascular health (Siri‐Tarino, Sun, Hu, & Krauss, ). Although human dietary studies often produce conflicting results on the effects of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) on the plasma lipid profile (Lada & Rudel, ), their beneficial effects on human health have been confirmed (Calder, ). On one hand, high MUFA diets reduce cardiovascular risk by lowering plasma cholesterol and triacylglycerol concentrations or improving insulin sensitivity and serum lipids (Bos et al, ; Calder, ; Egert et al, ; Gillingham, Harris‐Janz, & Jones, ).…”

“…Although human dietary studies often produce conflicting results on the effects of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) on the plasma lipid profile (Lada & Rudel, ), their beneficial effects on human health have been confirmed (Calder, ). On one hand, high MUFA diets reduce cardiovascular risk by lowering plasma cholesterol and triacylglycerol concentrations or improving insulin sensitivity and serum lipids (Bos et al, ; Calder, ; Egert et al, ; Gillingham, Harris‐Janz, & Jones, ). On the other hand, foods rich in n‐3 PUFAs, specifically eicosapentaenoic acid (EPA, C20:5 n‐3) and docosahexaenoic acid (DHA, C22:6 n‐3), conferring cardioprotective effects (Calder, ; Calder & Yaqoob, ; Erkkilǎ, Mello, Risérus, & Laaksonen, ; Lavie, Milani, Mehra, & Ventura, ; Riediger, Othman, Suh, & Moghadasian, ).…”

“…On one hand, high MUFA diets reduce cardiovascular risk by lowering plasma cholesterol and triacylglycerol concentrations or improving insulin sensitivity and serum lipids (Bos et al, ; Calder, ; Egert et al, ; Gillingham, Harris‐Janz, & Jones, ). On the other hand, foods rich in n‐3 PUFAs, specifically eicosapentaenoic acid (EPA, C20:5 n‐3) and docosahexaenoic acid (DHA, C22:6 n‐3), conferring cardioprotective effects (Calder, ; Calder & Yaqoob, ; Erkkilǎ, Mello, Risérus, & Laaksonen, ; Lavie, Milani, Mehra, & Ventura, ; Riediger, Othman, Suh, & Moghadasian, ). These n‐3 fatty acids are also required for the normal composition of sperm, retina and brain lipids, and are required for optimal maturity of visual and cortical functions in preterm infants (Calder, ; Lands, ; Yates, Calder, & Ed Rainger, ).…”