Motoi Tamura

Effect of the long-term feeding of dietary lipids on the learning ability, fatty acid composition of brain stem phospholipids and synaptic membrane fluidity in adult mice: a comparison of sardine oil diet with palm oil diet

The effect of 12 month feeding of 5% palm oil or sardine oil diet on the maze-learning ability, fatty acid composition of brain stem phospholipids and synaptic membrane fluidity in mice was studied. The time required to reach the maze exit and the number of times that a mouse strayed into blind alleys in the maze were measured three times every 4 days. The time and number of mice fed on the sardine oil diet were less than those of animals fed on the palm oil diet in the first and second trials. The results of fatty acid composition analysis of brain stem phosphatidylethanolamine showed that the percentage of docosahexaenoic acid (22:6, n-3; DHA) was higher, but the arachidonic acid (20:4, n-6; AA) and docosatetraenoic acid (22:4, n-6; DTA) were lower in the sardine oil diet fed-mice than in the palm oil diet fed-animals. Moreover, the microviscosity of the synaptic plasma membrane in the sardine oil diet group was lower than that in the palm oil diet group. These results suggest that the adult mice fed on the sardine oil diet for a long period maintain higher levels of docosahe xaenoic acid in brain phospholipids, synaptic membrane fluidity and maze-learning ability than animals fed on the palm oil diet.

Lactobacillus gasseri: effects on mouse intestinal flora enzyme activity and isoflavonoids in the caecum and plasma

The effects of Lactobacillus gasseri JCM 1131(T) on isoflavonoid levels within the caecum and plasma were assessed in adult mice. Male 5-week-old mice were fed an AIN 93M diet for 30 d. Two groups of mice were administered either L. gasseri JCM 1131(T) (the LGI group) or physiological saline solution (the control (CI) group) daily for 5 d before dissection. The plasma daidzein concentration was significantly higher in the LGI group, however, their plasma equol concentration was significantly less than in the CI group. The total amount of equol present as aglycone in the caecum was significantly greater in the CI group, but there was no significant difference in the total daidzein present as caecal aglycone. In an in vitro incubation of daidzein with the faecal flora of mice, the equol concentration was significantly higher in the CI group. The numbers of lactobacilli present were significantly higher in the LGI group. The present data suggest that the administration of L. gasseri is likely to influence the effect of isoflavonoids on the host via changes in the gastrointestinal environment.

Xylitol Affects the Intestinal Microbiota and Metabolism of Daidzein in Adult Male Mice

This study examined the effects of xylitol on mouse intestinal microbiota and urinary isoflavonoids. Xylitol is classified as a sugar alcohol and used as a food additive. The intestinal microbiota seems to play an important role in isoflavone metabolism. Xylitol feeding appears to affect the gut microbiota. We hypothesized that dietary xylitol changes intestinal microbiota and, therefore, the metabolism of isoflavonoids in mice. Male mice were randomly divided into two groups: those fed a 0.05% daidzein with 5% xylitol diet (XD group) and those fed a 0.05% daidzein-containing control diet (CD group) for 28 days. Plasma total cholesterol concentrations were significantly lower in the XD group than in the CD group (p < 0.05). Urinary amounts of equol were significantly higher in the XD group than in the CD group (p < 0.05). The fecal lipid contents (% dry weight) were significantly greater in the XD group than in the CD group (p < 0.01). The cecal microbiota differed between the two dietary groups. The occupation ratios of Bacteroides were significantly greater in the CD than in the XD group (p < 0.05). This study suggests that xylitol has the potential to affect the metabolism of daidzein by altering the metabolic activity of the intestinal microbiota and/or gut environment. Given that equol affects bone health, dietary xylitol plus isoflavonoids may exert a favorable effect on bone health.

Effects of soy protein-isoflavone diet on plasma isoflavone and intestinal microflora in adult mice

Effects of supplementing soy protein or casein diet with isoflavones on intestinal microflora and plasma concentrations of lipids and isoflavone metabolites were studied. Male mice were fed a soy protein or casein diet supplemented with isoflavones for four weeks, and feces and plasma samples were collected. Animals were also fed the soy protein or casein diet and feces were collected to investigate the capacity to produce equol from daidzein in vitro. The number of fusiform-shaped bacteria was significantly lower in the soy-isoflavone diet group than in the casein-isoflavone diet group, whereas the number of lactobacilli was significantly higher. No significant difference was observed in the plasma lipid concentration between the soy-isoflavone diet group and casein-isoflavone diet group. Plasma equol concentration was significantly higher in the soy-isoflavone diet group than in the casein-isoflavone diet group. After incubation of daidzein in vitro with the feces from the mice fed the soy protein and casein diets, the production of equol from daidzein was significantly more in the soy protein diet group. The present study indicates that the soy protein diet supplemented with isoflavone has an impact on the composition and metabolism of intestinal microflora and suggests that soy protein plays some roles in the effect of dietary isoflavones on the host through their effects on the intestinal microflora.

Effects of Guar Gum and Cellulose on Cecal Enzyme Activity and Cecal Short-Chain Fatty Acids in Young and Aged Mice

The effects of cellulose or guar gum on cecal enzyme activity and cecal short-chain fatty acids (SCFAs) in young and aged mice were studied. Male Crj:CD-1 (ICR) mice were fed an MF diet for 4 (young mice) or 23 months (aged mice). The MF diet was then replaced with a semisynthetic diet supplemented with 5% guar gum or 5% cellulose. The mice were fed the guar gum or cellulose diet for 3 weeks. There was no significant difference in cecal content between the two diet groups. There were no significant differences in total short-chain fatty acid production between the young mice fed the cellulose and those fed the guar gum diet, and between the aged mice fed the cellulose and guar gum diet. There were significant differences in cecal enzyme activity between the young mice fed the cellulose and those fed the guar gum diet. β-Glucuronidase activity was significantly higher in the young mice fed the guar gum diet than in those fed the cellulose diet. There were also significant differences in cecal enzyme activity between the aged mice fed the cellulose diet and those fed the guar gum diet. β-Glucuronidase activity was significantly higher in the aged mice fed the guar gum diet than in these fed the cellulose diet. β-Glucosidase activity was significantly lower in the aged mice fed the guar gum diet than in those fed the cellulose diet. The effect of cellulose on the microflora between the young and aged mice might be different from the effect of guar gum. The degree of adaptation to the diet of microflora in young and aged mice fed the cellulose diet might differ from that in those fed the guar gum diet. The higher enzyme activities of microflora in aged animals compared to young animals, might have some relation with the incidence of colon cancer in aged animals.

Dihydrodaidzein-producing Clostridium-like intestinal bacterium, strain TM-40, affects in vitro metabolism of daidzein by fecal microbiota of human male equol producer and non-producers

Much attention has been focused on the biological effects of equol, a metabolite of daidzein produced by intestinal microbiota. However, little is known about the role of isoflavone metabolizing bacteria in the intestinal microbiota. Recently, we isolated a dihydrodaidzein (DHD)-producing Clostridium-like bacterium, strain TM-40, from human feces. We investigated the effects of strain TM-40 on in vitro daidzein metabolism by human fecal microbiota from a male equol producer and two male equol non-producers. In the fecal suspension from the male equol non-producer and DHD producer, DHD was detected in the in vitro fecal incubation of daidzein after addition of TM-40. The DHD concentration increased as the concentration of strain TM-40 increased. In the fecal suspension from the equol producer, the fecal equol production was increased by the addition of strain TM-40. The occupation ratios of Bifidobacterium and Lactobacillales were higher in the equol non-producers than in the equol producer. Adding isoflavone-metabolizing bacteria to the fecal microbiota should facilitate the estimation of the metabolism of isoflavonoids by fecal microbiota. Studies on the interactions among equol-producing microbiota and DHD-producing bacteria might lead to clarification of some of the mechanisms regulating the production of equol by fecal microbiota.

Dietary cholesterol lowers plasma and cecal equol concentrations in mice.

This study examined the effects of cholesterol on mouse intestinal microflora and on isoflavonoids in the cecum and plasma. Dietary cholesterol affects bile acid metabolism and bile acids can influence the intestinal microorganisms. Intestinal microflora appear to play an important role in isoflavone metabolism. We hypothesized that dietary cholesterol changes the metabolism of isoflavonoids and intestinal microorganisms in mice. Male mice were randomly divided into two groups, which were fed a cholesterol-daidzein (CDA) or daidzein (DA) diet (control diet) for 60d. Plasma equol and cecal equol concentrations were significantly higher in the DA group (control group) than in the CDA group. However, plasma cholesterol concentrations were significantly higher in the CDA group compared to the DA group. The composition of cecal microorganisms differed between the two dietary groups. The occupation ratios of Clostridium cluster XI, Clostridium subcluster XIVa, and Lactobacillales were significantly higher in the CDA group. The occupation ratio of Bifidobacterium was significantly lower in the CDA group. This study suggests that dietary cholesterol has the potential to affect the metabolism of equol from daidzein by altering the metabolic activity of the intestinal microorganisms and gut physiological function.

Quercetin metabolism by fecal microbiota from healthy elderly human subjects

Quercetin is a polyphenol found in food that has numerous health benefits. This study investigated the relationship between quercetin metabolism, gut microbiota composition, and dietary intake in elderly Japanese subjects. A food frequency questionnaire was used to assess dietary intake during the week prior to stool sample collection. Fecal suspensions from 56 subjects were anaerobically incubated with quercetin and fecal microbiota composition was analyzed by next-generation sequencing. Inter-individual variations in quercetin concentration and fecal microbiota composition at family level suggested differences in microbial quercetin metabolism. The abundance of Sutterellaceae (r = −0.292) and Oscillospiraceae (r = −0.334) was negatively correlated whereas that of Fusobacteriaceae (r = 0.361) and Enterobacteriaceae (r = 0.321) was positively correlated with quercetin concentration. Niacin (r = −0.313), vitamin B6 (r = −0.297), vitamin B12 (r = −0.266), vitamin D (r = −0.301), and ratio of animal protein to total protein (r = −0.27) were also negatively correlated with quercetin concentration. Bacterial abundance was positively or negatively related to intake of food components. This is the first report describing the relationship between fecal quercetin metabolism, human microbiota, and dietary intake in the elderly.

FENS Program for Nutrition Education in Medical Schools

Kurt Widhalma, Austria Beatriz Miranda-da-Cruza, Austria Jan Pokorny, Czech Republic Inge Tetens, Denmark Suvi M. Virtanen, Finland Daniel Lemonnier, France Helmut Oberritter, Germany Antonia Trichopoulou, Greece Brian McKenna, Ireland Nino Battistini, Italy Sigrid Bergea, Norway A. Gronowska-Senger, Poland M.D. Vaz de Almeida, Portugal Flora Correa, Portugal Bergona Olmedilla, Spain Lars H. Ellegard, Sweden U. Keller, Switzerland P.J.F. Vries, The Netherlands Christine A. Edwards, United Kingdom