Omega-3 fatty acids from marine and plant sources provide a wide range of benefits in several human health conditions. In vivo studies indicate that omgega-3 fatty acids influence the course of several human diseases, including those that involve abnormal immune function, mental disorders, and genetic abnormalities in lipid metabolism.†
Omega-3 fatty acids are taken up by virtually all body cells and affect membrane composition, eicosanoid biosynthesis, cell signaling cascades, and gene expression. Among various organs, in the brain omega-3 fatty acids are most extensively studied. In fact, the brain is the organ richest in lipids and it was shown that the differentiation and functioning of cultured brain cells requires not only LA, but also omega-3 and omega-6 LC-PUFA.†
Dietary omega-3 fatty acids are certainly involved in the prevention of some neuropsychiatric disorders, particularly depression, as well as in dementia, notably Alzheimer`s disease.
Beside ALA, DHA is essential for nervous tissue growth and function. Inadequate intakes of omega-3 fatty acids decrease DHA and increase omega-6 fatty acids in the brain. Western diets are low in omega-3 fatty acids, including ALA that is found mainly in plant oils. Fish or fish oil is the main source of EPA and DHA. Food safety and the protection of consumer interests are of increasing concern to the general public and there are some general concerns with respect to nutraceuticals mainly relating to safety issues. Certain types of fish are known to be high in methyl-mercury. Thus, mercury poisoning may be a reasonable danger with regular consumption of certain fish. Other environmental pollutants such as dioxins may be present in fish oil products, suggesting discouragement of frequent consumption. Therefore, caution was recommended with frequent intakes and avoided particularly in young children and pregnant/breastfeeding woman.
The other major n-3 fatty acids, ALA, and its main sources such as PFSO do not possess many of the limitations of fish and fish oil. There are little or no concerns with allergy, dietary restriction (e.g. vegetarianism), environmental pollutants, global supply, and methyl mercury with regard to food sources of ALA. Moreover, nausea and fishy burps may accompany regular use of fish oil supplements, which could be avoided using plant derived n-3 fatty acids. Therefore, ALA may be a viable alternative to fish oil. However, its potency is milder in comparison to EPA/DHA, and its conversion to EPA/DHA is limited in human beings. On the other hand, it was demonstrated that dietary ALA increases DHA levels in the brain.
Recently, we investigated the effects of perilla fructens oil, a rich source of ALA, on the central nervous system. Our data provide new insight into potential mechanisms for protective properties of unsaturated fatty acids within the CNS. PFSO was administered chronically to guinea pigs and neuroprotective properties were assessed ex vivo in dissociated brain cells. Dissociated brain cells isolated from PFSO treated guinea pigs were less vulnerable against nitrosative stress as indicated by decreased levels of reactive oxygen species, by stabilized mitochondrial membrane potential and enhanced levels of adenosine-triphosphate. In the brain, levels of oleic-, linolic-, arachidonic- and docosahexaenoic-acid were significantly enhanced (Pharmacol. Res. 61 (2010) 234-41).†
Meanwhile, we extent our research to fish oils and DHA as well. We applied unilamellar transfer liposomes which provided protection from oxidation and effective incorporation of DHA into cell membranes. In HEK-APP cells, DHA significantly increased membrane fluidity and non-amyloidogenic processing of APP, leading to enhanced secretion of sAPPa. This enhanced secretion of sAPPα was associated with substantial protection against apoptosis induced by ER Ca2+ store depletion. Our data suggest that liposomal DHA is able to restore or maintain physiological membrane properties, which are required for neuroprotective sAPPα secretion and autocrine modulation of neuronal survival.