Since dietary lipids provide more energy than dietary carbohydrates and proteins, there has been a stereotypic image that lipid intake leads to the development of various diseases. However, the contribution of dietary lipids to the development and prevention of metabolic syndrome (MetS) and nonalcoholic fatty liver disease (NAFLD) is dependent on their quantity as well as quality, and their resulting effect on lipid metabolism. Growing evidence indicates that dietary phospholipids (PLs) , especially phosphatidylcholine (PC) , phosphatidylethanolamine (PE) , phosphatidylinositol (PI) , phosphatidylserine and sphingomyelin, have beneficial effects in comparison with dietary triacylglycerol. We have investigated the physiological functions and molecular actions of dietary PLs such as n-3 PUFA rich-PC and PI in the development and progression of MetS and NAFLD in animal models. These bioactive PLs prevented and/or alleviated the development and progression of these diseases through regulation of hepatic lipid metabolism and an increase in the levels of circulating adiponectin. In addition, we quantified the contents of PL molecular classes in samples of meals served in the dormitory and cafeteria of a Japanese company and then conducted stepwise multiple regression analysis to identify predictors (food groups) of each PL class intake. Our results clarified the daily intake of PL molecular classes among Japanese individuals and the food sources of PC and PE, suggesting that multiple regression analysis is useful for prediction of food sources of bioactive components.

This study investigated how galactooligosaccharide (GOS) administration influences the efficacy of oral immunotherapy (OIT). Mouse models of egg allergy were prepared using alum as an adjuvant. The mice were divided into three groups: Non-OIT, OIT, GOS-administered, and OIT＋GOS-administered. Non-sensitized mice were also prepared. During a four-week treatment period, the OIT groups (OIT and OIT＋GOS) were fed a diet containing 1％ egg white, and the GOS groups (GOS and OIT＋GOS) were force-fed 30 mg of GOS daily. Allergy severity was evaluated following egg white oral and abdominal food challenge. Regulatory T cells (Tregs) were also examined as the ratio of CD4⁺ Foxp3⁺ cells among splenic lymphocytes. In the oral food challenge experiment after OIT, the decrease in the rectal temperature of the mice in the OIT group was suppressed relative to the decrease in the Non-OIT group; however, no such suppression was observed in the OIT＋GOS group. The CD4⁺ Foxp3⁺ (Treg) cell ratio was highest in the OIT group, followed in order by the OIT＋GOS group and the Non-OIT group. Therefore, the relationship between Tregs and OIT was also investigated. Interestingly, after 2 weeks of OIT in the model mice with reduced Tregs after administration of anti-mouse CD25 antibody, no suppression of the decrease in rectal temperature was observed following oral food challenge. We observed that combining GOS with OIT diminished the efficacy of OIT, potentially due to a reduction of Tregs.

Seaweed is a popular and traditional Japanese food rich in various minerals and vitamins, as well as dietary fibre. However, its effects on human lipid metabolism are poorly understood. We aimed to evaluate the effect of wakame, the Japanese name for the brown seaweed Undaria pinnatifida, on postprandial serum lipid responses to consumption of a high-fat diet in humans. In a randomized crossover trial, 10 women with normolipidemia or mild hypertriglyceridemia were administered a high-fat diet containing approximately 40.6 g of lipid with or without 4 g of dried wakame. Serum lipid levels were measured in the fasting state and 2, 3, 4, 6 hours after consuming the high-fat diet. With reference to the control group, intake of wakame suppressed the elevation of serum remnant like particle-cholesterol (RemL-C) (at 6 hours), and lipoprotein (Origin) (at 4 hours) levels. In conclusion, this trial demonstrated that wakame consumption attenuates the postprandial increase in serum TG, RemL-C, and CM levels following a fat load, suggesting its potential role in reducing the risk of arteriosclerotic diseases.