Yoko Sato

National Institute of Health and Nutrition, Edo, Tōkyō, Japan

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Publications (11)14.94 Total impact

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    ABSTRACT: This in vivo study in rats evaluated whether Coleus forskohlii extract (CFE) taken orally interacted with tolbutamide, a hypoglycemic drug metabolized by CYP2C enzymes. Rats were fed 0%, 0.3%, 1% (w/w) CFE diet for 2 weeks, followed by 0% CFE diet for 1 day. They were then given 40 mg/kg tolbutamide by intragastric gavage. Blood glucose level was determined up to 6 h after tolbutamide administration. CFE treatment increased total CYP content and various CYP subtypes in the liver. In particular, increases in activity and protein expression were noted for the CYP2B, CYP2C, and CYP3A subtypes. CFE treatment dose-dependently attenuated both the hypoglycemic action of tolbutamide at 6 h and the plasma concentration of tolbutamide. The activity of (S)-warfarin 7-hydroxylase, a CYP2C enzyme was negatively correlated with plasma tolbutamide level, which also showed a negative correlation with the reduction of blood glucose level. These results indicate that CFE induced hepatic CYPs in rats and attenuated the hypoglycemic action of tolbutamide via a hepatic CYP2C-mediated mechanism.
    Journal of the Food Hygienic Society of Japan (Shokuhin Eiseigaku Zasshi) 01/2014; 55(2):73-8. · 0.33 Impact Factor
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    ABSTRACT: Salt reduction is one of the most important lifestyle modifications for the prevention of hypertension. The health promotion law regulates the labeling of the nutrient content of food in Japan and, the level of sodium, not salt (sodium chloride), has to be printed on the labels of manufactured foods. In order to control their salt intake, consumers need to apply a conversion factor to the sodium levels listed on the labels to obtain the salt equivalent. However, it is not known whether people have the knowledge appropriate for making the conversion. We carried out a questionnaire survey at the 7th National Shokuiku (food education) Conference in 2012, asking subjects to determine the salt equivalent of 1000 mg of sodium on food labels. We also asked about the target values of salt reduction in grams in the Dietary Reference Intakes for Japanese 2010 (DRI2010) and the Guidelines for Management of Hypertension 2009 by the Japanese Society of Hypertension (JSH2009). We analyzed the data from 683 respondents (169 men and 514 women); only 13.3% of respondents gave a correct answer for the salt equivalent of 1000 mg of sodium (2.50-2.60 g), whereas 61.8 and 40.4% of respondents chose the correct target values for salt reduction according to DRI2010 and JSH2009, respectively. In conclusion, few people could convert sodium content to salt, which suggested difficulty in using food labels to control their salt intake. Salt content in grams, not sodium content, should be labeled on food packages for effective salt reduction and prevention of hypertension.Hypertension Research advance online publication, 31 October 2013; doi:10.1038/hr.2013.149.
    Hypertension Research 10/2013; · 2.79 Impact Factor
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    ABSTRACT: Herb-drug interactions are mainly mediated by hepatic cytochrome P450 (CYP) enzymes. Here, we examined the effect of three herbs (valerian, salacia and black cohosh) on CYP activity in vivo in mice and in liver microsomes in vitro. Extracts which showed activity in the preliminary tests were then fed to mice at various doses (0, 0.5, 1.5 and 4.5%). Valerian did not show any effect on hepatic CYPs. Black cohosh increased the liver weight, total CYP content and CYP activities (2B and 3A) in a dose-dependent manner (up to 4.5%). Salacia inhibited CYP1A2 activity in liver microsomes in vitro. Also, salacia at the dietary dose of 4.5% suppressed body weight gain, decreased hepatic total CYP content and increased CYP activities (1A1, 2B and 2C). These findings suggest that black cohosh and salacia at high dose affect the activity of hepatic CYPs, and therefore may interact with drugs that are metabolized by CYP.
    Journal of the Food Hygienic Society of Japan (Shokuhin Eiseigaku Zasshi) 01/2013; 54(1):56-64. · 0.33 Impact Factor
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    ABSTRACT: From studies in mice, we have reported that Coleus forskohlii extract (CFE), a popular herbal weight-loss ingredient, markedly induced hepatic drug metabolizing enzymes, especially cytochrome P450 (CYP), and interacted with co-administered drugs. This study was designed to examine how the induction of drug metabolizing enzymes by CFE was influenced by different levels of macronutrients in the diet. Mice were fed a non-purified diet or semi-purified diet with and without CFE (0.3-0.5%) for 14-18 d, and changes in the ratio of liver weight to body weight, an indicator of hepatic CYP induction, and hepatic drug metabolizing enzymes were analyzed. The ratio of liver weight to body weight, content and activities of CYPs, and activity of glutathione S-transferase were higher in a semi-purified standard diet (AIN93G formula) group than in high sucrose (62.9%) and high fat (29.9%) diet groups. Different levels of protein (7%, 20%, and 33%) in the diets did not influence CFE-induced CYP induction or increase the ratio of liver weight to body weight. The effect of CFE on the ratio of liver weight to body weight was higher with a semi-purified diet than with a non-purified diet, and was similar between dietary administration and intragastric gavage when the CFE dose and the diet were the same. There was a positive correlation between CFE-induced CYP induction and the content of starch in the diets, suggesting that dietary starch potentiates CFE-induced CYP induction in mice. The mechanism of enhanced CYP induction remains unclear.
    Journal of Nutritional Science and Vitaminology 01/2013; 59(1):37-44. · 0.99 Impact Factor
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    ABSTRACT: We investigated the characteristics of dietary supplements and their use by 1,076 Japanese pregnant women, the majority of whom were in mid- to late pregnancy. The subjects completed a self-reported survey on their sociodemographic characteristics, supplement use, and attitudes towards diet. The overall prevalence of supplement use did not change before and after pregnancy (75%); however, daily use increased by approximately twofold with pregnancy (20.2% versus 37.2%). After the onset of pregnancy, supplements containing folic acid were taken for fetal health. Daily users were more likely to be older, have a greater awareness of the risk of neural tube defects (NTD), view supplement use as acceptable, have less diet anxiety, and have more advisers regarding diet. Respondents used supplements containing folic acid alone or with other ingredients. Folic acid intake is recommended to reduce the risk of NTD. However, supplement use began after pregnancy recognition, suggesting a lack of knowledge on the appropriate timing of folic acid use. Information about supplements was obtained mostly from newspapers, magazines, flyers, and stores. These results indicate that more accurate information regarding the optimal timing of folic acid intake and the safety of dietary supplements must be disseminated.
    Asia Pacific Journal of Clinical Nutrition 01/2013; 22(1):83-9. · 1.06 Impact Factor
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    ABSTRACT: Collecting adverse case reports suspected to be due to health foods and evaluation of the causality are important to secure safety, even if the causal relationship between health foods and reported health problem is uncertain. Case reports are mainly collected at three sites: public health centers, practical living information online network system(PIO-NET), and individual companies. The case reports from the three sources are not dealt with consistently. In this study, we investigated and characterized those case reports from the viewpoint of evaluating causality, using the causality association rating methods, namely, the dendritic and pointed methods, which we reported previously. Information in public health centers comprised 20 reports per year; approximately 40% were from health care providers and contained detailed medical data. PIO-NET information comprised 366 reports per year; 80% were self-reports from users, and few medical details were included. Company information covered 1,323 cases from 13 companies; more than 90% were from users and most of them were complaints. Case reports from public health centers and PIO-NET showed that the largerst number of victims were female aged >60, with allergy and gastrointestinal symptoms. When these case reports from the letter two sources were examined using the causality association rating systems, most were rated as "possible" and only a few were rated as "probable". As specific case reports from different information sources were examined in this study, we were able to identify several points that should be improved in our two rating methods. However, to ensure the safety of health foods, it will be necessary to collect a large number of high-quality case reports for evaluation by a suitable causality rating method, and to integrate those evaluated case reports into a single site.
    Journal of the Food Hygienic Society of Japan (Shokuhin Eiseigaku Zasshi) 01/2013; 54(4):282-9. · 0.33 Impact Factor
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    ABSTRACT: Objectives  This study aimed to determine whether Coleus forskohlii extract (CFE) influences the anticoagulant action of warfarin in mice in vivo and its relationship with hepatic cytochrome P450 (CYP). Methods  Mice were fed various doses of CFE standardised with 10% forskolin in a normal diet for one week, or in protein diets containing 7% and 20% casein (low and normal) for four weeks. They were then administered with warfarin by gavage on the last two days of the treatment regimen, and blood coagulation parameters, as well as hepatic CYP, were analysed at 18 h after the last dose. Direct interaction between CFE and forskolin with CYP2C was evaluated in vitro. Key findings  CFE dose dependently increased hepatic total CYP content and S-warfarin 7-hydroxylase activity at a dietary level of ≥0.05%. Warfarin-induced anticoagulation was attenuated by CFE in parallel with CYP induction. The findings were similar in mice fed diets containing CFE and different ratios of protein. CFE directly inhibited CYP2C activity in mouse and human liver microsomes in vitro, whereas forskolin was only slightly inhibitory. Conclusions  CFE attenuates the anticoagulant action of warfarin by inducing hepatic CYP2C; thus, caution is required with the combination of warfarin and dietary supplements containing CFE.
    The Journal of pharmacy and pharmacology. 12/2012; 64(12):1793-801.
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    ABSTRACT: We compared ascorbic acid (AA) levels in the blood and TPA- and fMLP-stimulated superoxide (O(2)(•-)) production in neutrophils of pre-, early, and late hypertensive stroke-prone spontaneously hypertensive rats (SHRSP) with those of age-matched Wistar Kyoto rats (WKY), or two other normotensive strains of rats. Plasma and lymphocyte AA levels were about two-fold higher in SHRSP as early as 4 weeks old compared to WKY, and also higher than those of Wistar and Sprague-Dawley (SD) rats. Levels of AA were high in the liver and adrenal glands of SHRSP, indicating congenitally high AA levels. The production of O(2)(•-) in neutrophils was about two-fold higher in SHRSP than in WKY even at 4 weeks of age, and increased with age in both strains. Among SHRSP, AA levels in lymphocytes decreased at the late hypertensive stages with a decrease in hepatic l-gulono-γ-lactone oxidase (GLO) activities. These data suggest that bi-phasic AA levels in the blood of SHRSP comprise congenitally high levels and a decrease after persistent hypertension due to enhanced O(2)(•-) production and a decrease in de novo AA synthesis through GLO.
    Clinical and Experimental Hypertension 06/2011; 33(6):397-403. · 1.28 Impact Factor
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    ABSTRACT: This study was conducted to examine the characteristics and use of dietary supplements by preschool children in Japan. A survey was conducted among 2,125 parents of preschool children to discover the status of dietary supplement use and their attitudes towards supplement use by their children. Logistic regression models were used to determine which characteristics predict supplement use in this population. For detailed characterization, child supplement users were also categorized as either the users of vitamins and minerals only or the users of other supplement components. For parents of non-user children, the parent's knowledge and attitudes toward supplements for children were investigated. Fifteen percent of children had used dietary supplements. Two parent-related factors were especially important, the frequency with which they referred to nutritional labels and their own supplement use, which had a significant encouraging effect on their children's supplement use. The parents of child supplement users showed limited awareness of the government system concerning diet and food, placed safety over efficacy, selected products with natural ingredients, and did not seek consultations with professionals. These parents, especially those who were aware of the specially designed supplements for children, exhibited positive responses to supplement use by their children. It is likely that parents' knowledge and attitudes toward dietary supplements and nutrition have a striking effect on their children's use of supplements. Unfortunately, their knowledge at present was less than satisfactory. More accurate information on nutrition, dietary intake and dietary supplements must be disseminated.
    Journal of Nutritional Science and Vitaminology 08/2009; 55(4):317-25. · 0.99 Impact Factor
  • Yoko Sato, Yuko Taki
    Journal of the Food Hygienic Society of Japan (Shokuhin Eiseigaku Zasshi) 09/2007; 48(4):J308-11. · 0.33 Impact Factor
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    ABSTRACT: Clinical trials have reported the cholesterol-lowering effects of soy protein intake, but the components responsible are not known. This meta-analysis was primarily conducted to evaluate the precise effects of soy isoflavones on lipid profiles. The effects of soy protein that contains enriched and depleted isoflavones were also examined. PUBMED was searched for English-language reports of randomized controlled trials published from 1990 to 2006 that described the effects of soy protein intake in humans. Eleven studies were selected for the meta-analysis. Soy isoflavones significantly decreased serum total cholesterol by 0.10 mmol/L (3.9 mg/dL or 1.77%; P = 0.02) and LDL cholesterol by 0.13 mmol/L (5.0 mg/dL or 3.58%; P < 0.0001); no significant changes in HDL cholesterol and triacylglycerol were found. Isoflavone-depleted soy protein significantly decreased LDL cholesterol by 0.10 mmol/L (3.9 mg/dL or 2.77%; P = 0.03). Soy protein that contained enriched isoflavones significantly decreased LDL cholesterol by 0.18 mmol/L (7.0 mg/dL or 4.98%; P < 0.0001) and significantly increased HDL cholesterol by 0.04 mmol/L (1.6 mg/dL or 3.00%; P = 0.05). The reductions in LDL cholesterol were larger in the hypercholesterolemic subcategory than in the normocholesterolemic subcategory, but no significant linear correlations were observed between reductions and the starting values. No significant linear correlations were found between reductions in LDL cholesterol and soy protein ingestion or isoflavone intakes. Soy isoflavones significantly reduced serum total and LDL cholesterol but did not change HDL cholesterol and triacylglycerol. Soy protein that contained enriched or depleted isoflavones also significantly improved lipid profiles. Reductions in LDL cholesterol were larger in hypercholesterolemic than in normocholesterolemic subjects.
    American Journal of Clinical Nutrition 04/2007; 85(4):1148-56. · 6.50 Impact Factor