In order to establish the human requirements of niacin, it is first important to know how much tryptophan is converted to niacin in the human body. In a general, 60mg of tryptophan is equivalent to 1mg of niacin, whereas the conversion ratio of tryptophan to niacin is yet to be confirmed. The aim of this study was to know the conversion ratio of tryptophan to niacin in Japanese females fed a purified diet, which followed the Japanese Dietary Reference Intakes. Ten young Japanese females were housed in the same facility and given the same daily living activity schedule for 7d. The composition of their purified diet was conformed to the Dietary Reference Intakes in Japan. The diet was niacin free. In order to investigate the conversion ratio, daily urinary outputs were collected. Tryptophan-niacin metabolites in the urine were measured and the conversion ratio of tryptophan to niacin calculated. The conversion ratio was calculated by comparing the dietary intake of tryptophan and the sum of the niacin catabolites such as N1-methylnicotinamide, N1-methyl-2-pyridone-5-carboxamide, and N1-methyl-4-pyridone-3-carboxamide, which were derived only from the dietary intake of tryptophan. The ratio was calculated as 1.5±0.1(mean±SE for 10 women; in molar basis) on the last day of the experiment. It was calculated that if the excretory percentage of niacin metabolites in the urine were 60% of the tryptophan ingested, the conversion factor would be a value of 67, meaning that is 67mg of tryptophan is equal to 1mg of niacin.
NAD is biosynthesized from tryptophan. Therefore, experimental studies including tryptophan metabolism studies could provide insight into niacin nutrition in pregnancy. Our aim was to determine the change in niacin metabolism during pregnancy by a systemic investigation of how pregnancy alters the tryptophan-niacin metabolism in Japanese women and rats. For the human study, spot urine samples were collected from a total of 434 pregnant Japanese women who were at 5-40 wk of gestation, 50 women at 4-6 wk postpartum, and 10 nonpregnant women as the controls. For the animal study, pregnant rats were fed with a niacin-free diet, and daily urine samples were collected from day 6 of gestation to day 6 postpartum. The intermediates and metabolites of the tryptophan-niacin pathway in the urine samples were measured. The urinary excretions of niacin metabolites in humans and rats increased from mid pregnancy in a time-dependent manner, reached a peak of 2-3-fold during late pregnancy, and declined to control levels after childbirth.
Probiotic bacteria improve fermentation in the large intestine through interaction with indigenous bacteria. The microflora in the large intestine differ from one individual to another. The objective of this study was to determine whether the different cecal microflora induce different probiotic effects on cecal fermentation in three pigs (pig A, B and C). Pigs were administered fermented milk prepared with the Lactobacillus casei strain Shirota (LCS) as a probiotic for 2 wk. The average number of LCS was higher than 5.0 (log cfu/ g cecal digesta) in all pigs. The hierarchical clustering of the temperature-gradient gel elec-trophoresis (TGGE) profile of cecal bacteria showed that the cecal microflora was slightly altered by the LCS dose in all pigs. However, the molar ratios of cecal butyrate in pigs A and C were significantly increased by LCS. Inversely, the molar ratio of propionate in pigs A and C was significantly decreased by LCS. However, the molar ratio of individual short-chain fatty acid in pig B was not significantly affected by LCS. The hierarchical clustering of the TGGE profiles indicated that the cecal microflora of pig A resembled that of pig C and that of pig B was dissimilar to those of pigs A and C. These results indicated that the effect of LCS on fermentation in the large intestine was possibly dependent on the composition of indigenous microflora.
To evaluate the molybdenum (Mo) status in the Japanese population, the Mo content in various foods and human milk was determined using inductively coupled plasma mass spectrometry (ICP-MS) and the average Mo intake was estimated. The difference in Mo content among food groups was marked; Mo levels in several plant foods such as cereals were more than 0.5μg/g while those in most animal foods were less than 0.1μg/g. In particular, Mo contents in several samples of seeds and pulses were more than 1μg/g. The variation in Mo contents in each type of cereal was also conspicuous, Based on the present quantification of Mo in foods and the recent National Nutrition Survey in Japan, the average Mo intake of the Japanese population was estimated as 225μg/d/capita. The principal Mo source in the Japanese diet was rice followed by soybean products, and approximately 90% of the Mo intake was derived from plant foods. Seventeen human milk samples were collected from 3 healthy mothers once or twice a month from 96 to 327d after delivery. The median and range of Mo in human milk samples were 4.5ng/mL and 2.0 to 8.8ng/mL, respectively. Mo levels in Japanese formula milk were 2 to 3ng/L. Based on the Mo levels in human milk and formula milk, the Mo intake of Japanese infants was estimated to be 2 to 4μg/d/capita.
Beta-cryptoxanthin (β-CRX) is a carotenoid pigment found especially in Satsuma mandarin (Citrus unshiu Marc.) fruit, which is mainly produced in Japan. Previously, we found that serum β-CRX concentrations rose to extreme levels as the frequency of consumption of Satsuma mandarin increases. Using 94 non-smoking female volunteers, the present study evaluated the relationship between serum concentration of β-CRX and serum lipid levels in September, when the Satsuma mandarin is not in season, and in January of the next year, when it is in season. The mean of increment in serum β-CRX concentrations from September to January was 95.9±84.0g/dl (mean±SD). Although the changes in serum lipid levels did not correlate with the changes in serum β-CRX, the serum HDL-cholesterol and apo-lipoprotein Al levels in the highest quartile of the increment in serum β-CRX from September to January were significantly higher than those in the lowest quartile in both September and January. In cross-sectional analyses, serum β-CRX concentrations were correlated positively with those of LDL-cholesterol and apo-lipoprotein B levels in September, but these correlations were not observed in January. In contrast, serum β-CRX concentrations were correlated positively with those of HDL-cholesterol and apo-lipoprotein Al levels in January. These results suggest that habitual eating of Satsuma mandarin while it is in season may influence lipid metabolism throughout the year.
Dietary supplementation of conjugated linoleic acids (CLA) is known to have some beneficial effects such as anti-carcinogenic and anti-obesity effects in several animal species, while it also induces insulin resistance and fatty liver, especially in mice. To explore the possible factors responsible for the CLA-induced insulin resistance, we examined the plasma and mRNA expression levels of several adipocytokines, which are likely involved in the regulation of insulin sensitivity, in normal C57BL, mildly obese/diabetic KK and morbidly obese/diabetic KKAy mice. Feeding a diet supplemented with 05% CLA oil consisting of 30.5% c9, t11-CLA and 28.9% t10, c12-CLA for 4 wk resulted in a decrease in white adipose tissue (WAT), an increase in liver weight with excess accumulation of triglyceride, and insulin resistance associated with hyperglycemia and hyperinsulinemia. The plasma and WAT mRNA levels of leptin were higher in KK and KKAy mice than C57BL mice, whereas those of adiponectin were higher in C57BL mice. CLA-feeding decreased the levels of leptin, adiponectin and resistin, especially in KK and KKAy mice. In contrast, tumor necrosis factor-α (TNFα) mRNA levels were higher in KK and KKAy mice than C57BL mice, and were increased by CLA feeding. The present results thus indicate that CLA feeding promotes insulin resistance in obese/diabetic mice by at least inverse regulation of leptin and adiponectin, and TNFα, adipocytokines known to either ameliorate or deteriorate insulin sensitivity, respectively.
We examined the effects of a fermented vegetable product (FVP), fermented by yeast as well as lactic acid bacteria, on body weight and fat deposition after ovariectomy in 10-wk-old Sprague-Dawley rats. The rats were divided into the following 5 groups; l) ovariectomized rats fed as usual (OVX); 2) ones receiving FVP at a daily dose of 100mg/leg (LOW); 3) ones receiving FVP at a daily dose of 1, 000mg/leg (HIGH); 4) ones receiving a calcium-free diet (Ca-FREE); 5) sham-operated rats (SHAM), A slight increase in body weight was observed in the LOW group compared with the OVA group. The rate of increase in total fat content was lowest in the LOW group, but both bone weight and strength were similar to those in the other ovariectomized groups. In conclusion, the low dose of FVP turned out to reduce fat content without affecting bone weight and strength.
The author has previously reported on the higher antioxidative activity in vivo of defatted soybean oncom (D-oncom), fermented defatted soybeans with Neurospora intermedia, in comparison with that of defatted soybeans (DSB). In this paper, the hydrophilic antimutagenicity of D-oncom against N-nitrosodimethylamine (NDMA) was investigated. Water-extract of D-oncom had a stronger antimutagenicity than that of DSB. The main antimutagenic fraction of D-oncom was anionic, and stable against heating at 37°C. Its antimutagenicity was about one sixth of that of ascorbic acid. Actually the fraction scavenged superoxide anions. Therefore, the antimutagenicity of D-oncom against NDMA might be involved in the reduction of oxidative stress by scavenging superoxide anions. Nonetheless the main antimutagenic fraction was not polyphenol, peptide nor nucleotide, its molecular weight being distributed about 5, 000-12, 500.
The thermolability of ascorbic acid (AA) in aqueous solution at 100°C was assessed in the presence of various seasonings commonly used in Japanese-style cooking. A model system approximated Japanese cooking with regard to the concentrations of AA and seasonings and the heating time. The decrease of AA in the reaction system of this experiment was a first-order reaction with respect to the concentration of AA loss. Although kinetic constants for AA loss decreased with increasing concentrations of AA (25-400μg/ mL), the absolute amounts degraded were almost the same for all AA concentrations, suggesting that dissolved oxygen is one of main factors affecting the stability of AA solutions during heating at 100°C. When each seasoning was added to AA solution, salt stabilized AA and Japanese alcohol-containing admixtures, such as sake and sweet sake (mirin), did not have a significant effect on the stability. Conversely, soy sauce, miso (fermented soybean paste) and broth powder from skipjack accelerated the decrease of AA in a concentrationdependent manner. The kinetic study suggested that oxygen was rapidly consumed and AA loss accelerated by addition of soy sauce or miso to AA solution. Consequently it is likely that a reaction mechanism shifts from aerobic to anaerobic and the forward reactions proceed. Of the constituents of Japanese seasonings, not only iron but also amino acids are involved in the acceleration of AA degradation. The presence of amino acids should be taken into account when considering the levels of AA in soups.
Vitamin B12 contents of green (0046-0263 and 0, 125-0535μg/ 100g dry weight), blue (0.068-0.081 and 0.525-0.528μg/100g dry weight), red (0.061 and 0.663μg/100g dry weight), and black (0.104-0.859 and 0.305-1.20μg/100g dry weight) tea leaves were obtained by intrinsic factor-chemiluminescence and microbiological methods, respectively. Although vitamin Bit was found in all tea leaves tested by both assay methods, the higher values by the microbiological method were not due to occurrence of both deoxyribosides and deoxynucleotides (known as an alkali-resistant factor), but may have been due to that of inactive corrinoid compounds for mammals in the tea leaves.
Previous studies have demonstrated the difference between the basal meta-bolic rate (BMR) and the sleeping metabolic rate (SMR); however, the difference in the Japa-nese population has not yet been explored. This study examined the relationship between the BMR and SMR in ninety-four healthy Japanese subjects (37 males and 57 females, 39±12y of age and 22, 0±7.4% body fat) in a respiratory chamber. The SMR was signifi-cantly lower than the BMR (1, 416±245 vs. 1, 492±256kcal/d); however, there was a highly significant correlation between the two (r=0.867; p<0.001). The ratio of SMR/BMR largely varied among individuals (0.95±0.08, 8.4% of the coefficient of variation). The ratio was significantly lower in males than in females (0.93±0.10 vs. 0.97±0.06, p<0.05). None of the anthropometric measures (age, weight, body mass index, body surface area or percent body fat) correlated with the ratio. These results showed that SMR was 95% of BMR on average in a healthy Japanese group. However, when applied over a longer time period (24h or more), the difference tends to become negligible for most analyses in a group. Although the difference between SMR and BMR will induce a 5% gap of physical activity level defined as the total energy expenditure divided by the BMR or SM, this factor seems to have little practical importance in epidemiological research.
Lymphatic recovery of 1(3)-stearoyl-2, 3 (1)-dilinoleoylglycerol (SLL) and 2-linoleoyl-l, 3-distearoylglycerol (SLS) which had been enzymatically synthesized were compared with those of trilinoleoylglycerol (LLL) and the randomly esterified triacylglycerol which contained stearic acid and linoleic acid at 1:2. Recoveries of linoleic acid in all of the triacylglycerols were more than 94.0%. Lymphatic 24 h-recoveries of stearic acid given as SLL and SLS were significantly lower than that of stearic acid given as the randomly esterified triacylglyceroL Recoveries of stearic acid from SLL, SLS and the randomly esteried triacylglycerol were 88.4%, 68.3% and 101%, respectively.