There are few reports for the interaction between omega-3 and omega-6 fatty acids, but it has been known usefulness of brain function of omega-3 fatty acids. We investigated the interaction of theses essential fatty acids during the growth and developmental period of delta-6-desaturase knockout mice, using the artificial rearing method. As a result, it was found that the arachidonic acid (ARA) was the most critical polyunsaturated fatty acids for supporting body growth and the docosahexaenoic acid (DHA) exhibited clear essentiality for brain function. These indicate that the combination of DHA and ARA is essential for optimal growth and development in early life. Especially, the direct ingestion of ARA and DHA is indispensable in infants with immature lipid metabolic activity, although linoleic acid, α-linolenic acid and eicosapentaenoic acid are actually metabolized to ARA and DHA in adult.

Fish oil is very easily oxidized, as it is rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Hydroperoxides from the EPA and DHA are relatively not stable to readily decompose to low molecular compounds such as aldehydes, causing undesirable flavors from the very early stage of the oxidation. Therefore, the key point for the anti-oxidation of fish oil is to prevent the formation of low molecular compounds in the early stage of the oxidation. Although many studies have been done on the volatile compounds formed in the fish oil oxidation, little volatiles have been recognized as the major contributors to the flavor deterioration. This review discusses the rapid formation of the fishy and metallic off-flavors, focusing especially on an early stage of fish oil oxidation. This review also notes the effective way to inhibit the formation of the volatile compounds responsible for the flavor deterioration.

The extension of healthy life expectancy is a major issue in the super-aging society of Japan. We conducted a cross-sectional study on physical fitness to clarify the characteristics of motor function decline with aging and showed that coordination ability such as agility deteriorates remarkably with aging, in healthy Japanese with exercise habits. We demonstrated that dietary sphingomyelin, which is a polar lipid in milk, activates the motor unit centered on the neuromuscular junction and improves physical fitness. Clinical trials have revealed that dietary sphingomyelin with regular exercise improves agility and reduces the risks of falling and frailty. These findings suggest that the approach to motor units centered on the neuromuscular junction may be useful for enhancing physical fitness through nutrition and moderate exercise intervention.

Sphingosine-1-phosphate (S1P) exerts pleiotropic biological activities including the development of the vasculature and the nervous system, regulation of vascular barrier integrity and lymphocyte trafficking. Many, if not all, of these S1P actions are mediated by five members of the G proteincoupled S1P receptors (S1P₁~S1P₅) with overlapping but distinct coupling to heterotrimeric G proteins. Another striking feature of the S1P signaling system is the presence of a steep concentration gradient of S1P between the blood and the perivascular surrounding tissues. The major target cells of S1P are vascular cells and immune cells including lymphocytes and macrophages. The S1P signaling system regulates vascular development and barrier integrity, circulation and differentiation of lymphocytes, and migration and activation of macrophages. The synthetic compound FTY720, a sphingosine analogue, reduces circulating lymphocytes very effectively and has been approved as a novel therapeutic agent for multiple sclerosis. Further development of S1P receptor agonists and antagonists with improved receptor subtype-selectivity, inhibitors or modulators of sphingolipid-metabolizing enzymes, and their optimal drug delivery system are expected to provide novel therapeutic tactics.

Health benefits of giant scallop oil obtained from discarded portions consist of hepatopancreas and other internal organs, gonads, gill, and mantle are demonstrated. The obtained oil is characterized by the abundant EPA and DHA bound phospholipids including plasmalogens. And the health benefits of the oil can be characterized by high bioavailability, modulating endocannabinoid system, platelet-activating factor and gene expression, as well as the performance in suppressing oxidative stress.