We have clarified that the amounts of water-soluble vitamins excreted into urine closely reflect the surplus amount of water-soluble vitamins in the body, based on data from experiments involving rats and humans. We have also tried to calculate the cut-off values for preventing water-soluble vitamin deficiency and its resulting toxicity. Nutritional assessment using biomarkers is a persuasive approach, and facilitates easy adjustment of habitual dietary intake.

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We examined changes in physical function and also the correlation between physical function or mastication ability (MA), or comprehensive QOL and nutritional status, in elderly persons who received long-term comprehensive training for preventive care. For physical functions such as knee extension power (KEP), equilibrium function (EF), walking ability (WA), and compound movement (CM), there were significant negative correlations between their initial values and changes resulting from training. These improvements in physical function by long-term training were much more evident when their initial values were lower. There were significant correlations between physical functions such as WA, CM, and MA, and energy intake. Hence, it was suggested that these functions would be improved when energy intake was higher. In addition, there was a significant positive correlation between mental component summary (MCS) and BMI: that is, when elderly persons were better nourished, comprehensive mental health was better. It was suggested that mental QOL became higher when elderly persons were well nourished. Consequently, it is suggested that long-term training would be useful for preventive care in elderly persons, especially those with lower physical function. Furthermore, it was clear that good mastication led to a better state of nourishment, which in turn led to better physical function and QOL.

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Previously, we have demonstrated that administration of 2.5％ trehalose in drinking water for 8 weeks to mice fed a high-fat diet (HFD) suppresses adipocyte hypertrophy and mitigates insulin resistance, in comparison with other saccharides (glucose, maltose, high-fructose corn syrup, or fructose). Therefore, we hypothesized that the hypoinsulinemic effect of trehalose would also be effective for protecting the islets of Langerhans in mice with HFD-induced obesity. Sections of the pancreas from these mice were double-stained with antibodies against insulin and glucagon, and the mean area of islets of Langerhans, the insulin-stained area of β-cells, and glucagon-stained area of α-cells were analyzed on digital images using Scion Image software. In islets, trehalose significantly suppressed HFD-induced hypertrophy in comparison with those from mice fed water, maltose or fructose. Interestingly, trehalose significantly suppressed hypertrophy in the α-cell area in comparison with other saccharide/HFD groups and the DW/HFD group. It is known that α-cells increase in number along with aggravation of type 2 diabetes, and secrete glucagon, which raises the level of blood glucose. Moreover, intake of trehalose for 15 weeks with a HFD suppressed the increase in the circulating level of glucagon at 30 min after glucose administration in an oral glucose tolerance test (OGTT), compared with maltose/HFD. Our findings suggest that trehalose suppresses the compensatory hypertrophy of islets of Langerhans and elevation of the glucagon level in HFD-induced obese mice by suppressing the proliferation of α-cells. Therefore, trehalose would be an excellent food for protection of pancreatic islets in patients with metabolic syndrome.

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This study examined the effect of deficient zinc intake on the palatability of lard and fish-oil diets. Four-week-old male Fischer 344 rats were fed one of four diets: zinc-deficient lard diet （－ZnLD）, zinc-deficient fish-oil diet （－ZnFD）, zinc-adequate lard diet （＋ZnLD）, zinc-adequate fish-oil diet （＋ZnFD）. After 3 weeks, six rats in each group were dissected. The remaining －Zn rats were placed on a two-choice diet program of －ZnLD and －ZnFD, and the ＋Zn rats were placed on a two-choice diet program of ＋ZnLD and ＋ZnFD. After the self-selection period, all rats were dissected. Throughout the experimental period, the －Zn groups showed significantly low plasma zinc concentrations, food intake, and body weight, compared to the ＋Zn groups. The plasma and hepatic lipid levels were also lower in the －Zn groups. While the ＋Zn groups selectively ingested LD and FD at an n-6/n-3 ratio of approximately 3, the n-6/n-3 ratio was 1.9 in the －ZnLD group and 6.6 in the －ZnFD group. These results suggest that the ＋Zn groups were capable of taking in essential fatty acids at a fixed n-6/n-3 ratio, and that deficient Zn intake appeared to reduce this ability.

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The amylopectin in waxy amylose-extender (wx/ae) double mutant rice has a characteristic structure, functioning as a resistant starch, and a rich source of γ-oryzanol. In this study, we investigated the effects of long-term intake of wx/ae brown rice on human lipid metabolism in a single-blind crossover test. We fed 6 healthy men roasted brown rice flour made from either wx/ae or Uruchi, a non-waxy japonica cultivar, for 28 days. Each group ate 10 g of roasted brown rice flour three times a day, in addition to their ordinary meals. Although two groups had the same body weight and body fat, the total cholesterol levels in the wx/ae group were significantly lower than those in the Uruchi group. Triglyceride and LDL-cholesterol levels also declined in the wx/ae group. These results indicate that wx/ae roasted brown rice flour is a useful food material for prevention of hyperlipemia.

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