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The health benefits of fish oil, and its omega-3 long chain polyunsaturated fatty acid content, have attracted much scientific attention in the last four decades. Fish oils that contain higher amounts of eicosapentaenoic acid (EPA; 20:5n-3) than docosahexaenoic acid (DHA; 22:6n-3), in a distinctive ratio of 18/12, are typically the most abundantly available and are commonly studied. Although the two fatty acids have traditionally been considered together, as though they were one entity, different physiological effects of EPA and DHA have recently been reported. New oils containing a higher quantity of DHA compared with EPA, such as fractionated and concentrated fish oil, tuna oil, calamari oil and microalgae oil, are increasingly becoming available on the market, and other oils, including those extracted from genetically modified oilseed crops, soon to come. This systematic review focuses on the effects of high DHA fish oils on various human health conditions, such as the heart and cardiovascular system, the brain and visual function, inflammation and immune function and growth/Body Mass Index. Although inconclusive results were reported in several instances, and inconsistent outcomes observed in others, current data provides substantiated evidence in support of DHA being a beneficial bioactive compound for heart, cardiovascular and brain function, with different, and at times complementary, effects compared with EPA. DHA has also been reported to be effective in slowing the rate of cognitive decline, while its possible effects on depression disorders are still unclear. Interestingly, gender- and age- specific divergent roles for DHA have also been reported. This review provides a comprehensive collection of evidence and a critical summary of the documented physiological effects of high DHA fish oils for human health.

The tropical edible red seaweed (Eucheuma cottonii L.) is rich in nutrients and polyphenolic compounds that may suppress cancer through its antioxidant and antiproliferative properties. The study reports on rat mammary tumor suppression and tissue antioxidant status modulation by E. cottonii ethanol extract (ECE). The effect of orally administered ECE (100 mg/kg body-weight) was compared with that of tamoxifen (10 mg/kg body-weight). Rat was induced to develop mammary tumor with subcutaneous injection of LA-7 cells (6 × 10(6) cells/rat). The ECE was more effective than tamoxifen in suppressing tumor growth (27%), improving tissues (plasma, liver, and kidney) malondialdehyde concentrations, superoxide dismutase activity and erythrocyte glutathione concentrations (P < 0.05). Unlike tamoxifen, the ECE displayed little toxicity to the liver and kidneys. The ECE exhibited strong anticancer effect with enzyme modulating properties, suggesting its potential as a suppressing agent for mammary gland tumor.

Purpose of review Docosapentaenoic acid (DPA) is a minor omega-3 fatty acid (FA) which has been frequently overlooked in lipid research. This review examines the biochemical and physiological outcomes of human trials which have used pure preparations of DPA (n − 3 DPA) and also recent developments in specialized proresolving lipid mediators (SPMs) derived from n − 3 DPA. Recent findings There have been only been two human studies and eleven animal studies with pure n − 3 DPA. The doses of n − 3 DPA used in the human trials have been 1–2 g/day. n − 3 DPA abundance is increased in blood lipid fractions within 3–4 days of supplementation. n − 3 DPA has the potential for unique properties, with a greater similarity in biological functioning with docosahexaenoic acid (DHA), than eicosapentaenoic acid (EPA). Despite the typically low levels of n − 3 DPA in most tissue lipids relative to EPA and DHA, unique SPMs, such as resolvins, maresins and protectins of the n − 3 DPA type, are involved in resolution of inflammation and regulating immune function. Summary We suggest that measurement of blood levels of n − 3 DPA gives no indication of its broad biological roles, but that the true functionality of this enigmatic n − 3 polyunsaturated fatty acid (PUFA) remains obscure until more is known about the properties of the unique DPA-derived SPMs.

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