Journal of nutritional science and vitaminology最新文献

Skeletal muscle mass is maintained by a balance between the synthesis and degradation of muscle proteins, the collapse of which causes muscle wasting. The prevention of muscle wasting improves the quality of life and extends a healthy life. The methyl xanthine theophylline showed strong preventive activity against dexamethasone-induced muscle atrophy, as determined using the expression level of myosin heavy chain in C2C12 myotubes. Mechanistically, theophylline inhibited the expression of ubiquitin ligases MuRF1 and Cbl-b, but not that of atrogin-1. Furthermore, theophylline inhibits glucocorticoid receptor translocation to the nucleus. A pull-down assay using a theophylline probe revealed that theophylline and dexamethasone competitively interacted with the glucocorticoid receptor, suggesting an antagonistic activity of theophylline on glucocorticoid receptors. Additionally, theophylline inhibited the dexamethasone-induced phosphorylation of p38 and FoxO3a in C2C12 myotubes. These findings suggest that theophylline is an effective food ingredient in the prevention of glucocorticoid-induced skeletal muscle atrophy.

Concerns about the negative intergenerational effects of excessive fructose intake are being raised, with evidence suggesting that prenatal fructose intake increases susceptibility to metabolic and cognitive dysfunction later in life. In the present study, we hypothesized that prenatal and postnatal fructose intake acts synergistically to impact on hippocampus of adult offspring. Female Sprague-Dawley rats received distilled water or 20% high-fructose corn syrup (HFCS) solution in addition to standard chow throughout gestation and lactation. Male offspring were weaned at postnatal day 21 (PD21) and were randomized to receive distilled water or 20% HFCS solution until PD60. The following experimental groups were: CC: distilled water dams and post-weaning distilled water, CH: distilled water dams and post-weaning HFCS solution, HC: HFCS solution dams and post-weaning distilled water and HH: HFCS solution dams and post-weaning HFCS solution. The synergistic effect of maternal and post-weaning HFCS intake on the hippocampus was investigated by studying the expression of pro-inflammatory cytokine genes (Tnfa, Il1b, and Il6). At weaning, expression levels of pro-inflammatory cytokines between the offspring of the distilled water and HFCS solution fed dams were not significantly different. At PD60, Tnfa expression was significantly higher in the HH group than in the CC, HC and CH groups, whereas no significant differences were found between the CC, HC, and CH groups. These results suggest that postnatal fructose intake negatively impacts the hippocampus by acting synergistically with prenatal fructose intake.

Perilla oil is a valuable food source of α-linolenic acids. However, its high reactivity with oxygen shortens its shelf-life after opening. This study investigated the antioxidative profiles of 15 plant materials, including herbs, and examined methods to suppress the oxidation of perilla oil using these plant materials. These plant materials had wide ranges of phenolic, carotenoid, and chlorophyll contents. They exhibit radical scavenging activities and suppress lipid peroxidation, which show highly positive correlations with the phenolic contents. Dipping most of the plant materials examined in perilla oil suppressed its oxidation, and the peroxide values of the oil mixtures indicated a negative correlation with the carotenoid and chlorophyll contents of the plant materials. The leaves of Angelica, Astragalus, and Thyme herbs exhibited the same effect as that of ascorbyl palmitate, which was used as a positive control after 8 wk of incubation in the dark. The suppression of lipid peroxidation was found to be related to the herbal contents of carotenoids and chlorophylls, rather than phenols. Hence, herbal leaves can suppress the oxidation of perilla oil in the dark. The oxidation of n-3 polyunsaturated fatty acids could be suppressed effectively by utilizing plant materials with abundant carotenoids and chlorophylls.

Nonalcoholic steatohepatitis (NASH) can progress to hepatic fibrosis, and is associated with cardiovascular and liver-related mortality. To understand the pathogenesis of NASH, reliable animal models of the disease are useful. In animal studies, the animals are usually fasted overnight before biospecimens are taken, but little is known about the effects of fasting. Here, we investigated the impact of overnight fasting for approximately 9 to 17 h on glucose and lipid metabolism in a Sprague-Dawley (SD) rat model of diet-induced moderate and advanced NASH in comparison to normal SD rats. Our results revealed that in the moderate NASH model rats, the fasting duration did not affect glucose and lipid metabolism, the histopathological findings, or the hepatic mRNA expression levels of genes related to lipid metabolism, cholesterol metabolism, inflammation, fibrosis, and oxidative stress. In contrast, in the normal rats, significant fasting time-dependent reductions were observed in the epididymal fat pad weight and the hepatic mRNA expression levels of adipose differentiation-related protein and heme oxygenase-1. Moreover, in the advanced NASH model rats, a significant fasting time-dependent reduction and increase were observed in the serum insulin level and mRNA expression level of alpha-smooth muscle actin, respectively. Our present results suggest that the influence of the overnight fasting duration differs among the healthy condition, moderate NASH, and advanced NASH statuses. Further studies are needed in humans to determine the appropriate overnight fasting duration for the accurate evaluation of glucose and lipid metabolism in NASH patients.

Recent studies have described that vitamin D deficiency/insufficiency is associated with hypertension, insulin resistance, and dyslipidemia, which are major components of metabolic syndrome causing atherosclerosis. Therefore, we investigated the relationship between serum 25-hydroxyvitamin D [25(OH)D] concentration and atherosclerotic disease risk factors in healthy Japanese adults. In the present cross-sectional study, 1,177 subjects (348 males and 829 females) aged 20-72 y living in Japan (34.7-35.0ºN) were evaluated for vitamin D status by measuring serum 25(OH)D concentration. Atherosclerotic disease risk factors were defined as the presence of two or more of the following three risk factors: high blood pressure, dyslipidemia, and hyperglycemia. The percentages of vitamin D deficient and insufficient subjects were 33% and 46% in males and 59% and 32% in females, respectively. Subjects with atherosclerotic disease risk factors were significantly older and had higher BMI than those without it in both sexes. Male subjects with atherosclerotic disease risk factors had significantly lower physical activity and serum 25(OH)D concentration than those without it. In a logistic regression analysis adjusted for confounding factors, serum 25(OH)D concentration showed a significant inverse association with risk factors of atherosclerotic disease in males (OR=0.951, 95%CI: 0.906-0.998), but not in females. A covariance structure analysis also suggested that serum 25(OH)D level has a direct association with risk factors of atherosclerotic disease. In conclusion, we have demonstrated that low serum 25(OH)D level is a significant factor for increased atherosclerotic disease risk factors in males.

We investigated the associations of plasma 25-hydroxy vitamin D (25(OH)D) concentration and the dietary intake of vitamin D with insulin resistance in Japanese women. Study participants were 406 Japanese women attended a health examination. They were not taking hormones or medications for diabetes and had no history of cancer, ischemic heart disease, or stroke. Information regarding medical history and lifestyle factors was obtained by a self-administered questionnaire, while hours of sun exposure were determined through interviews. Dietary intake of vitamin D was evaluated using a validated food frequency questionnaire. Fasting plasma glucose and insulin concentrations were measured, and insulin resistance (HOMA-IR) scores were calculated based on homeostasis model assessment. Women with vitamin D deficiency (25(OH)D<20 ng/mL) had significantly higher fasting plasma insulin concentration and HOMA-IR than did the other women. Plasma 25(OH)D concentration was significantly and inversely associated with fasting plasma insulin level and HOMA-IR after controlling for age, season, menopausal status, BMI, smoking status, alcohol intake, physical exercise, and intakes of fat and calcium. Dietary vitamin D intake was not associated with HOMA-IR concentration after adjusting for these covariates and hours of sun exposure. Although significant inverse association between plasma 25(OH)D concentration and HOMA-IR was observed in women with a low BMI, low fat intake, or a high calcium intake, the interaction terms were not statistically significant. Data suggest that plasma vitamin D, but not dietary vitamin D, is inversely associated with fasting plasma insulin concentration and HOMA-IR in non-diabetic Japanese women.

Excess sodium intake is a risk factor for non-communicable diseases (NCDs), such as cardiovascular diseases and hypertension. Therefore, many countries have set nutrient reference values for sodium, specifically for the prevention of NCDs, and intake is routinely monitored by nutrition surveys. In this review, we aimed to compare the global nutrient reference values and national intakes of sodium, along with the methods of intake assessment used. Data were obtained for Australia, Canada, Ireland, Japan, the UK, the US, and the European Food Safety Authority (EFSA), where information was accessible online in English or Japanese. We collected the following information regarding sodium intake: the term used for reference values to prevent NCDs; year when reference values were established or revised; reference values to prevent NCDs; target NCDs; designation of nutrition survey; method for estimating intake; and average intake. The reference values ranged from 2,000 mg (Australia and EFSA) to 2,953 mg (Japan). Sodium intake ranged from 2,431 mg (Australia) to 3,958 mg (Japan). Out of seven countries/institutions, five used dietary assessment, and two used sodium urinary excretion for estimating dietary sodium intake. Among the dietary assessment methods, the 24-h dietary recall was most frequently used. National sodium intake exceeded the reference values in all countries, and reduction of sodium intake remains a global challenge.

Children with cow's milk allergy (CMA) have lower bone mineral density and shorter height than children without CMA or non-food allergy (FA), and their final height is also affected. Appropriate nutritional guidance for CMA children is therefore needed. The purpose of this study was to conduct a dietary survey of CMA children and to compare their characteristics according to the degree of elimination. A dietary survey of FA children attending the allergy clinic at Shiga Medical Center for Children, Shiga, Japan, was conducted using the brief-type self-administered diet history questionnaire for Japanese children and adolescents (BDHQ15y). To objectively assess the intake of fruit and vegetables, skin carotenoid levels were measured using the Veggie Meter^®. Regarding the degree of CM elimination, of the 147 FA children (89 boys, 58 girls) recruited, 38, 27, and 82 children were allocated to complete-, partial-, and non-elimination groups, respectively. In analyzing the data, boys and girls were combined because there was no difference in sex ratio among the groups. Significantly lower intakes of calcium, animal proteins, and vitamin B2 were observed with increasing degree of CM elimination. Conversely, significantly greater intakes of vegetable proteins, β carotene, α tocopherol, vitamin C, and polyunsaturated fatty acids, as well as significantly higher levels of skin carotenoids, were observed with increasing degree of CM elimination. Intakes of many nutrients with antioxidant and anti-inflammatory effects were higher with increasing degree of CM elimination, presumably reflecting the efforts of caregivers in identifying alternative foods. However, calcium intake was still inadequate, indicating a need for further encouragement of calcium intake in CMA children.

We evaluated the α-glucosidase inhibitory activity of acidic polysaccharides (APs) extracted from seaweeds in vitro and their antidiabetic effects in KK-A^y mice. The α-glucosidase inhibitory activity of APs was differed among various seaweed species. Some APs showed higher inhibitory activity in the high-molecular-weight range, whereas others showed higher inhibitory activity in the low-molecular-weight range. Mice were fed low-molecular-weight APs from hijiki (LMWAPsH), which showed higher α-glucosidase inhibitory activity. Fasting blood glucose and HbA1c levels were significantly lower in the LMWAPsH group than in the control group (p<0.01). The calculated homeostasis model assessment-insulin resistance in the LMWAPsH group was significantly lower than that in the control group (p<0.05). These results suggest that α-glucosidase inhibitory activity differ among APs from different seaweed species, and each have an optimum molecular-weight range, and that LMWAPsH prevents the hyperglycemia in KK-A^y mice.