In this study, we examined the intestinal uptake of thiamin (vitamin B1), riboflavin (vitamin B2) and pyridoxine (vitamin B6) administered at high concentration using intestinal epithelial Caco-2 cells as an in vitro model of drugs and food absorption. The effect of vitamin concentration, culture age, transport direction and incubation temperature on vitamin transport was determined. The vitamin transport was expressed as an apparent permeability coefficient and changes in cumulative fraction transported across epithelial membrane in time. It was found that transepithelial transport of these vitamins is dependent on the experimental factors. At low concentrations an active transport mechanism was observed, whereas at high vitamin concentration a passive transport dominated. At high vitamin concentration the transepithelial flux of vitamins in both directions was similar, which proves the mechanism of passive transport.
Background: Despite long-standing iodine supplementation in Iran, the prevalence of goiter remains high in some areas. This suggests other nutritional deficiencies may be considered as responsible factors for goiter persistence. In the present study we investigated the possible role of vitamin A deficiency (VAD) and low vitamin A status in the etiology of endemic goiter in Semirom, Iran. Materials and Methods: In this cross-sectional study, 1,828 students from 108 primary schools of urban and rural areas of Semirom were selected by multistage random cluster sampling. Thyroid size was estimated in each child by inspection and palpation. Urinary iodine concentration (UIC) and serum retinol (SR) were measured. Results: Overall, 36.7% of schoolchildren had goiter. The median UIC was 18.5 μg/dL. The mean±SD of SR in goitrous and nongoitrous children was 38.84± 10.98 and 39.17±10.85 μg/dL respectively (p=0.82). There were two children with VAD (SR less than 20 μg/dL); one in the goitrous and one in the nongoitrous group. The prevalence of subjects with low vitamin A status (SR less than 30 μg/dL) in the goitrous and nongoitrous groups was 26.2 and 21.5% respectively (p=0.42). Conclusion: Goiter is still a public health problem in this region. Iodine deficiency, VAD or low vitamin A status is not among the contributors of goiter persistence in schoolchildren of Semirom. The role of other micronutrient deficiencies or goitrogens should be investigated.
The present study investigated the effect of dietary soy protein isolate (SPI) on tumor necrosis factor-α (TNF) productivity in peritoneal macrophages from nephritic and hepatoma-bearing rats. Dietary SPI significantly inhibited the elevated production of TNF by lipopolysaccharide-stimulated macrophages in nephritic and hepatoma-bearing rats compared with dietary casein, while it exerted no influence on the TNF productivity in normal rats. Removal of the minor components contained in SPI by ethanol extraction could significantly or partially restore the reduced TNF production caused by SPI in nephritic and hepatoma-bearing rats, respectively. These results suggest that dietary SPI could suppress the enhanced productivity of TNF associated with the progression of nephritis and hepatoma, and some factors existing in the ethanol extract of SPI are suggested to be involved in suppressing TNF productivity by macrophages.
Preschool children in developing countries are likely to have multiple, concurrent micronutrient deficiencies. This study was designed to evaluate the effectiveness of different combinations of nutritional fortified diet to improve the blood levels of iron, vitamin A and other essential micronutrients in the preschool population of Banan District of Chongqing, China. From December 2005 to June 2006, a total of 226 2-6 y old preschool children were recruited from three nurseries in the area, and they were randomly assigned to three different fortified diet groups for 6 mo. Group I was fortified with vitamin A; groups II and III were fortified with vitamin A plus iron and vitamin A plus iron, thiamine, riboflavin, folic acid, niacinamide, zinc and calcium, respectively. Subjects' weight and height were measured for assessing the children's growth and development. Blood samples were taken at the beginning and the end of the 6-mo study period for measuring serum levels of micronutrients. Group III with the multiple micronutrient fortified diet was the most effective to improve the serum level of retinol from [media (P25, P75): 1.06 (0.89, 1.32)] μmol/L to 1.29 (1.04, 1.39) μmol/L (p<0.05) and retinol binding protein from 17.0 (12.6, 25.6) mg/L to 31.6 (24.4, 44.0) mg/L (p<0.05) and to mobilize the stored iron in the liver (p<0.05). In addition, the three groups' hemoglobin levels were elevated from 117.0 (109.0, 124.1) g/L, 114.0 (109.2, 119.7) g/L and 115.0 (109.5, 122.7) g/L to 125.7 (119.2, 133.1) g/L, 126.5 (122.2, 135.9) g/L and 125.1 (119.8, 131.6) g/L over the 6 mo of intervention period, but there were no difference among the three groups (p>0.05). Nevertheless, unexpected results were obtained when comparing the effects on growth status among the different supplement groups. Our study has demonstrated that a multiple micronutrient fortified diet for 6 mo is more effective to improve the levels of hemoglobin, serum retinol, and RBP as well as to facilitate the mobilization of iron storage in preschool children.
The cholesterol-lowering action of soybean protein was studied with rats from the aspect of sulfur-containing amino acids using casein as a counterpart. Weanling rats were fed for 3 wk on a soybean protein isolate (SPI) or casein diet. Serum cholesterol levels did not differ between the two diet groups, but were lowered by supplementing methionine to a 10% SPI diet or cystine to an amino acid mixture diet, equivalent to a 10% SPI or to a 20% SPI diet. By adding methionine or cystine to a 10% SPI diet, cholesterol 7α-hydroxylase activity was elevated concomitantly with elevated hepatic glutathione (GSH) level, while hydroxyl methyl-glutalyl coenzyme A reductase activity was reduced by methionine, regardless of GSH levels. Excretion of fecal steroid was not significantly changed by addition of either amino acid, as expressed per body weight. These results indicate that the relative amount of methionine and cystine in a diet affected cholesterol metabolizing enzyme activity in a way not parallel to GSH concentration.
A cross-sectional study of 292 primary school children was conducted in rural Vietnam to investigate the relationship among micronutrient deficiencies, and other risk factors for anemia. Serum levels of iron, copper, zinc, selenium and magnesium were determined by inductively coupled plasma mass spectrometry and that of retinol by high performance liquid chromatography. Hemoglobin concentration in whole blood was measured by the cyanmethemoglobin method. The incidence of low serum zinc, selenium, magnesium, and copper in the children was 91.4, 75.6, 59.5, and 8.6%, respectively. Forty-five percent of the children were anemic and 11.3% suffered from vitamin A deficiency. A parameter significant associated with anemia was low serum selenium and vice versa (OR 1.85, 95% CI 1.06-3.24, p<0.05). Other factors associated with anemia were serum retinol <1.05 μmol/L (OR 2.05, 95% CI 1.25-3.36, p<0.01), and age in years (OR 1.59, 95% CI 1.16-2.18, p<0.01). The study showed that low selenium is associated with anemia among school children in Vietnam. Interventions are required to gain insight into the potential role of selenium on prevention and control of anemia.
We examined the effects of lipopolysaccharide (LPS) injection on body temperature and plasma free amino acid concentrations in rats. A catheter was placed in the jugular vein of the rats in order to draw blood from and to inject LPS into awake animals. On the day of the experiment, body temperature was recorded during the experiment (330 min) and blood was drawn before and at several time points after injection of LPS (10 μg/kg body weight). Body temperature in LPS-treated rats began to rise ∼30 min after injection with a peak at 120 min, and afterward remained ∼1oC higher than that in control rats through the end of the experiment. Concentrations of many plasma free amino acids were decreased by LPS treatment, with a nadir at ∼120 min, and then were increased to the level of or over the control. It appears that thermoregulatory responses induced by LPS treatment may be related to alterations in plasma free amino acid concentrations. Effects of LPS treatment on the dynamics of plasma free branched-chain amino acid (BCAA) concentrations in rats with peroral or intravenous administration of BCAAs were also examined. The results showed that the rise in plasma BCAA concentrations after peroral BCAA administration was significantly suppressed by LPS treatment, but the dynamics of plasma BCAAs after intravenous administration was not affected by LPS, suggesting that LPS treatment inhibited the intestinal absorption of BCAAs into the circulation. These results suggest that the availability of administered BCAAs to the body tissues during sepsis is higher following parenteral than peroral administration.
Administration of an amino acid (AA) mixture stimulates muscle protein synthesis and elevates core body temperature (Tb), as characteristically found under anesthetic conditions. We tested the hypothesis that not only AA given, but also AA produced by degradation of endogenous muscular protein are provided for muscle protein synthesis, which is further reflected in Tb modifications. Rats were intravenously administered an AA mixture or saline in combination with the anesthetic propofol or lipid emulsion. We measured plasma 3-methylhistidine (MeHis) concentrations as an index of myofibrillar protein degradation, rectal temperature and mRNA expression of atrogin-1, MuRF-1 and ubiquitin in gastrocnemius and soleus muscles of rats following 3 h infusion of test solutions. Tb did not differ significantly between conscious groups, but was higher in the AA group than in the saline group among anesthetized rats. Plasma MeHis concentrations were higher in the AA group than in the saline group under both conditions. Plasma MeHis levels correlated positively with Tb of rats under both conditions. AA administration decreased mRNA levels of atrogin-1 and ubiquitin in gastrocnemius muscle and all mRNA levels in soleus muscle. These results suggest that AA administration enhances myofibrillar protein degradation and that the change is a determinant of Tb modification by AA administration. However, the mechanisms underlying AA administration-associated enhancement of myofibrillar proteolysis remains yet to be determined.
This study aimed to measure and evaluate the intakes for the four trace elements of Fe, Zn, Mn, and Cu in 3- to 5-y-old Japanese preschool children. The study group consisted of a total of 90 3- to 5-y-old children living in Yokkaichi, Mie, Japan. Diet samples were collected by the duplicate-portion technique on 3 d at three different seasons between summer in 1999 and winter in 2000. The medians of annual mean daily intakes (25th-75th percentile) of Fe, Zn, Mn, and Cu in the 3- to 5-y-old children were 3.1 mg (2.4 to 3.6), 4.0 mg (3.4 to 4.7), 1.3 mg (1.1 to 1.6), and 0.45 mg (0.35 to 0.56), respectively. The annual mean value of the total daily diet intake had significant correlations with the Fe, Zn, Mn and Cu intakes (Spearman's r=0.55, 0.67, 0.58, and 0.55, respectively; p<0.001 for all). There were significant correlations between each mineral intake. The Zn and Mn intakes had differences among ages (p=0.003 and 0.005, respectively) and the Zn intake significantly differed between boys and girls (p=0.031). The proportion of subjects whose Mn intake was the AI or less was 82%, and the proportions of subjects whose Fe, Zn, and Cu intakes were the estimated average requirements (EARs) or less were 72, 83, and 13%, respectively. Many Japanese children are deficient in Fe and Zn compared with the dietary reference intakes (DRIs). However, data in a balance study examining intakes and excretion of trace minerals are insufficient in children and DRIs for trace elements may change in future.
To clarify the relationship between dietary choline level and plasma homocysteine concentration, the effects of choline deprivation on plasma homocysteine concentration and related variables were investigated in rats fed a standard (25%) casein (25C) diet or standard soybean protein (25S) diet. Using the 25S diet, the time-dependent effect of choline deprivation and the comparative effects of three kinds of lipotropes were also investigated. Feeding rats with the choline-deprived 25S diet for 10 d significantly increased plasma total homocysteine concentration to a level 2.68-times higher than that of the control group, whereas choline deprivation had no effect in rats fed the 25C diet. Increases in hepatic S-adenosylhomocysteine and homocysteine concentrations, decreases in hepatic betaine concentration and the activity of cystathionine β-synthase, but not betaine-homocysteine S-methyltransferase, and fatty liver also occurred in rats fed the choline-deprived 25S diet. Plasma homocysteine concentration increased when rats were fed the choline-deprived 25S diet for only 3 d, and the increase persisted up to 20 d. The hyperhomocysteinemia induced by choline deprivation was effectively suppressed by betaine or methionine supplementation. Choline deprivation caused hyperhomocysteinemia also in rats fed a choline-deprived low (10%) casein diet. The results indicate that choline deprivation can easily induce prominent hyperhomocysteinemia when rats are fed relatively low methionine diets such as a standard soybean protein diet and low casein diet, possibly through the suppression of homocysteine removal by both remethylation and cystathionine formation. This hyperhomocysteinemia might be a useful model for investigating the role of betaine in the regulation of plasma homocysteine concentration.
Several studies in humans and rodents suggest that postprandial serum triglyceride (TG) levels are decreased by a single oral administration of diacylglycerol (DAG) oil compared with administration of control triacylglycerol (TAG) oil. To gain further insight into the mechanisms underlying the metabolic properties of DAG in a postprandial state, we analyzed the size-based distributions of postprandial lipoproteins in the lymph and serum using gel filtration-based high-performance liquid chromatography. In thoracic duct lymph pooled for 3 h after oral administration of TAG or DAG, the size-based distributions of postprandial lymphatic lipoprotein-TG and -cholesterol levels did not differ significantly, suggesting that DAG did not affect the size of lipoprotein particles secreted from the small intestine. Serum lipoprotein-TG (60%) and -cholesterol levels (90%), however, were significantly different among fractions with a diameter of greater than 80 nm 1 to 2 h after the administration of DAG compared to TAG. In addition, there was a considerable, but nonsignificant, reduction in lipoprotein-TG levels (∼ 40%) in fractions with a diameter of 80 to 30 nm, suggesting that DAG-derived chylomicrons as well as DAG-derived chylomicron remnants were catabolized rapidly. In conclusion, dietary DAG reduced the amount of large-size lipoproteins in the serum, but did not affect the size distribution of lipoproteins produced in the small intestine. Thus, compared with TAG, dietary DAG may reduce the postprandial serum total TG levels.
We investigated the effect of a water-soluble extract from Grifola frondosa, the maitake mushroom, on lipid droplets in brown adipocyte tissue (BAT) cells. This water-soluble extract inhibits the conversion of pre white adipocyte tissue (WAT) cells but does not inhibit that of pre BAT cells. It reduces the amount of accumulated triglycerides (TG) in BAT cells. The glycerol-3-phosphate dehydrogenase (GPDH) activities of BAT cells decreased, but the expression of uncoupling protein 1 (UCP1) levels increased. These results suggest that maitake extract inhibits TG accumulation-related energy metabolism.
The effect of dietary docosahexaenoic acid (DHA, C22:6n-3) with two lipid types on lipid peroxidation of the brain was investigated in streptozotocin (STZ)-induced diabetic mice. Each group of female Balb/c mice was fed a diet containing DHA-connecting phospholipids (DHA-PL) or DHA-connecting triacylglycerols (DHA-TG) for 5 wk. Safflower oil was fed as the control. The lipid peroxide level of the brain was significantly lower in the mice fed the DHA-PL diet when compared to those fed the DHA-TG and safflower oil diets, while the α-tocopherol level was significantly higher in the mice fed the DHA-PL diet than in those fed the DHA-TG and safflower oil diets. The DHA level of phosphatidylethanolamine in the brain was significantly higher in the mice fed the DHA-PL diet than in those fed the safflower oil diet. The dimethylacetal levels were significantly higher in the mice fed the DHA-PL diet than in those fed the safflower oil and DHA-TG diets. These results suggest that the dietary DHA-connecting phospholipids have an antioxidant activity on the brain lipids in mice, and the effect may be related to the brain plasmalogen.
We have reported previously that dietary medium-chain triacylglycerol (MCT) improved serum albumin concentration and protein balance in malnourished rats. To clarify the mechanisms for this effect of MCT, hepatic messenger RNA levels of gluconeogenic enzymes, pyruvate dehydrogenase (PDH) and alanine aminotransferase (ALT) were measured in rats fed low-protein diets containing either MCT or isocaloric long-chain triacylglycerol (LCT) for 2 wk. The serum albumin concentration in rats fed the MCT diet was significantly higher compared with those fed the LCT diet. Serum free fatty acids and ketone body fraction were higher in rats fed MCT compared with those fed the LCT diet. The hepatic mRNA level of PDH was significantly lower in rats fed MCT than those fed LCT. But, there was no significant difference between the two groups in mRNA of gluconeogenic enzymes or ALT. These results suggest that ketone bodies, which are an alternative energy source and might spare blood glucose, increase by MCT feeding, and the reason for the PEM (protein-energy malnutrition)-improving effect of MCT is not caused by suppression of gluconeogenesis.
An examination was conducted to verify D-psicose suppressed the elevation of blood glucose and insulin concentration in a dose-dependent manner under the concurrent administration of maltodextrin and D-psicose to healthy humans. Twenty subjects aged 20-39 y, 11 males and 9 females were recruited. A load test of oral maltodextrin was conducted as a randomized single blind study. The subjects took one of five test beverages (7.5 g D-psicose alone, 75 g maltodextrin alone, 75 g maltodextrin +2.5, 5 or 7.5 g D-psicose). Blood was collected before an intake and at 30, 60, 90 and 120 min after an intake. Intervals of administration were at least 1 wk. The load test with 75 g maltodextrin showed significant suppressions of the elevation of blood glucose and insulin concentration under the doses of 5 g or more D-psicose with dose dependency. An independent administration of 7.5 g D-psicose had no influence on blood glucose or insulin concentration. D-Psicose is considered efficacious in the suppression of the elevation of blood glucose concentration after eating in humans.