Nakamichi Watanabe

Antioxidant activities of the water-soluble fraction in tempeh-like fermented soybean (GABA-tempeh)

Tempeh is a traditional fermented soyfood native to Central Java, Indonesia; tempeh is prepared by salt-free aerobic fermentation using Rhizopus. Similar to miso, tempeh is also reported to be antioxygenic. In this study, we used a tempeh-like fermented soybean. First, soybean was incubated aerobically and then successively incubated anaerobically. Because the γ-amino butyric acid (GABA) content was increased remarkably, we named this tempeh GABA-tempeh. The contents of other free amino acids and peptides were significantly higher in GABA-tempeh than in conventional tempeh. In this study, we compared the antioxidant activity of the water-soluble fraction in GABA-tempeh with that of soybean and conventional tempeh. The order of the antioxidant activity was shown as follows: GABA-tempeh > conventional tempeh > soybean. The components responsible for the antioxidant activity of GABA-tempeh were isoflavone aglycones, free amino acids, and peptides, which increased during aerobic and anaerobic fermentations.

Administration of dietary fish oil capsules in healthy middle-aged Japanese men with a high level of fish consumption

The nutritional effects of fish oil, which is rich in the n-3 polyunsaturated fatty acids, have been reported. In this randomized, placebo-controlled, double-blind, crossover study, we evaluated the effects of dietary fish oil capsules on the hematological parameters of healthy middle-aged Japanese men with a high level of fish oil consumption. Over a 4-week period, subjects were administered five fish oil or olive oil (placebo) capsules with every meal (1,260 mg eicosapentaenoic acid and 540 mg docosahexaenoic acid/day). There was a 4-week washout period between the treatment phases. The results did not demonstrate a decrease in plasma triacylglycerol, cholesterol, low-density lipoprotein cholesterol, and whole-blood viscosity. Further, no changes in the fatty acid composition of plasma and erythrocyte phospholipids were noted. These results suggested that the supplementation of fish oil might be effective only for those subjects who have a lower level of fish oil consumption.