To study the adequate intake (AI) for vitamin D in the elderly, we have performed an intervention study with 800 IU/d of vitamin D3 in the institutionalized elderly. Sixty-two institutionalized elderly were randomly assigned to two groups; receiving either supplements of 200 mg calcium plus 800 IU vitamin D3/d (Ca+VD group), or supplements of 200 mg calcium/d (Ca group) for 30 d in October. Serum concentrations of 25-hydroxyvitamin D (25OH-D), parathyroid hormone (PTH), and bone turnover markers were measured before and after intervention. Average dietary vitamin D intake during the intervention period was approximately 300 IU/d in both groups, exceeding the AI in Dietary Reference Intakes for Japanese 2005 of 200 IU/d. In both groups, mean serum 25OH-D level at baseline fell into the hypovitaminosis D range (9.7 ng/mL), despite apparently adequate vitamin D intake. Serum PTH level at baseline was within the reference range. Mean serum 25OH-D concentration significantly increased to 19.3 ng/mL in the Ca+VD group and to 11.1 ng/mL in the Ca group. Post intervention serum 25OH-D level was significantly higher in the Ca+VD group than in the Ca group (p<0.001). In 53 subjects (85.5%) who took more than 80% of their supplements for 30 d, serum PTH level in the Ca+VD group was significantly lower than in the Ca groups (p=0.05). Bone turnover markers were not significantly changed after intervention in either group. Daily supplementation of 800 IU vitamin D3 was considered effective in the institutionalized elderly with minimal chance of sun exposure, but further studies with longer duration are necessary.
We have previously reported the levels of water-soluble vitamins in the blood and urine of Japanese young adults. In the present paper, to assess the variations in these water-soluble vitamin markers during the above experiment, we comprehensively determined the intra- and inter-individual variations of blood and urinary water-soluble vitamins to exactly the same amount of water-soluble vitamin intakes in the same experiment. The blood samples before breakfast and the 24-h urine samples were periodically collected from Japanese college male (n=10) and female (n=10) students consuming a semi-purified diet with water-soluble vitamins based on Japanese Dietary Reference Intakes for 7 d, and the intra- and inter-individual variations of blood and urinary water-soluble vitamins or their metabolites in blood and urine samples after adaptation were calculated. Although urinary excretion of vitamin B12 and vitamin C showed high intra-individual variations in both males and females, other urinary vitamins and all blood vitamins showed less than 20% of within-subject coefficients of variance in either male or female. Those showing more than 20% of between-subject coefficients of variances in both male and female were blood vitamin B6, vitamin B12 and folate levels, and urinary vitamin B1, vitamin B2, vitamin B12, nicotinamide metabolites, pantothenic acid, biotin and vitamin C. These results showed that oral administration of constant of water-soluble vitamins generally decreased intra-individual variation, while individual differences in urinary vitamin excretion were observed.
The Nagano Purple grape (Vitis (V.) vinifera×V. labrusca) is a hybrid created by a cross between Kyoho (V. vinifera×V. labrusca) and Rosario Bianco (V. vinifera) grapes. The grape, including its skin, can be eaten and contains no seeds because of gibberellin treatment. The skins of various fruits have been shown to contain antioxidant activity. However, it is unclear whether the Nagano Purple grape contains antioxidant activity. We prepared the skins and dried fruits (including the skins) of the Nagano Purple grape, so as to assay for the presence of an antioxidant activity. We examined the concentration of polyphenols in the grape and further assayed whether components in the grape inhibited the oxidation of low-density lipoprotein (LDL). We detected the presence of cyanidin-3-glucoside (Cy-3-glc), five anthocyanidins and resveratrol in the skins. A trace of resveratrol was detected in the pulp. LDL collected from human subjects 1 h following the consumption of the skins or dried fruits revealed significant inhibition of LDL oxidation compared to that observed in fasting venous blood samples. We further observed the antioxidant activity of Cy-3-glc. Our results suggest that the consumption of the Nagano Purple grape can give rise to resistance to LDL oxidation.
To clarify the effects of different physical forms of oil on postprandial serum lutein/zeaxanthin and β-carotene concentrations, we performed a vegetable meal loading test. Eighteen healthy subjects participated in the test, which consisted of broccoli as a control (CON) meal, broccoli with oil (OIL), and broccoli with mayonnaise (MS), consumed in random order. After collection of fasting blood samples, subjects consumed one of the three test meals. Fasting and postprandial changes in serum carotenoids were assessed 2, 4, and 6 h after ingestion of each test meal. Serum lutein/zeaxanthin and β-carotene concentrations were measured. Although no significant change was noted after the CON meal, the serum lutein/zeaxanthin concentration was higher at 4 h after consumption of the OIL meal, and at 2, 4 and 6 h after consumption of the MS meal, as compared with the fasting state. Serum β-carotene concentrations did not change after ingestion of either the CON or the OIL meal but were elevated 2, 4, and 6 h after MS ingestion as compared with the fasting state. The incremental areas under the curves (IAUCs) of serum lutein/zeaxanthin and β-carotene concentrations were higher after the MS meal than after the CON meal. IAUCs after the OIL meal exhibited no statistically significant differences from the CON and MS meals. We suggest that mayonnaise contributes to increase serum lutein/zeaxanthin and β-carotene concentrations when consumed with vegetables rich in these carotenoids.
It has recently been reported that a 4-wk high-fat diet gradually increases skeletal muscle peroxisome proliferator activated receptor (PPAR) γ coactivator-1α (PGC-1α) protein content, which has been suggested to regulate GLUT-4 gene transcription. However, it has not been reported that a high-fat diet enhances GLUT-4 mRNA expression and protein content in skeletal muscle, suggesting that an increase in PGC-1α protein content is not sufficient to induce muscle GLUT-4 biogenesis in a high-fat fed animal. Therefore, we first evaluated the relationship between PGC-1α and GLUT-4 expression in skeletal muscle of rats fed a high-fat diet for 4 wk. The PGC-1α protein content in rat epitrochlearis muscle significantly increased by twofold after the 4-wk high-fat diet feeding. However, the high-fat diet had no effect on GLUT-4 protein content and induced a 30% decrease in GLUT-4 mRNA expression in rat skeletal muscle (p<0.05). To clarify the mechanism by which a high-fat diet downregulates GLUT-4 mRNA expression, we next examined the effect of PPARδ activation, which is known to occur in response to a high-fat diet, on GLUT-4 mRNA expression in L6 myotubes. Incubation with 500 nM GW501516 (PPARδ activator) for 24 h significantly decreased GLUT-4 mRNA in L6 myotubes. Taken together, these findings suggest that a high-fat diet downregulates GLUT-4 mRNA, possibly through the activation of PPARδ, despite an increase in PGC-1α protein content in rat skeletal muscle, and that a posttranscriptional regulatory mechanism maintains GLUT-4 protein content in skeletal muscle of rats fed a high-fat diet.
Recently the American Heart Association has reported that favorable effects of soy protein on blood lipids were characteristic only for high amounts of soy protein and not observed for an intake less than 30 g/d. However, the period of the studies with the smaller amount was 4-6 wk and we thought a longer study was necessary for the conclusion. The death rate by heart disease is very high in Russia; therefore, we have done this study in Russian subjects with hyperlipidemia. Prior to the study we tried to find a favorable method for subjects to take 30 g protein a day from soybean protein isolate (SPI) or skimmed curd protein (SMP) and decided to use Russian style cookies. Thirty subjects with hyperlipidemia were recruited; however, due to the 5-mo long study 28 of them (19 females and 9 males aged 50±2 y) could complete the trial. They were randomly assigned to two groups and were given either cookie for 2 mo separated by a month-long washout interval in a cross-over design. Fasting blood samples were drawn before and after the dietary treatments. Fasting blood samples at 1 mo were also measured as a health check and to observe the trends of the blood parameters in the middle of the study period. Serum samples were used for the lipid and other biochemical measurements. Every month for 3 non-consecutive days, energy and nutrient intakes were assessed and physical activity was estimated by pedometer. With the consumption of SPI for 2 mo, concentrations of total-cholesterol changed from 280±7 to 263±8 mg/dL (−6.5%, p=0.0099), HDL-cholesterol from 57.4±2.5 to 62.6±2.9 mg/dL (+9%, p=0.0047), non-HDL-cholesterol (total-cholesterol−HDL-cholesterol) from 223±7 to 201±8 mg/dL (−11%, p=0.0023) and triglycerides from 204±23 to 173± 19 mg/dL (−18%, p=0.022). There were no significant changes with SMP (p>0.05). Thus, administration of 30 g SPI a day for 2 mo confirmed its favorable effects on serum lipids in Russians with hyperlipidemia.
To investigate the causes why pups of dams fed a low-fat high-carbohydrate diet (LFD) showed strong preference for fat, two groups of pregnant rats were fed either the LFD or the control-diet (CTD) during pregnancy and lactation. After weaning, pups in both groups were divided into two groups. Two groups were offered a self-selection regimen of either a carbohydrate-protein diet (CPD) or a fat-protein diet (FPD) (the LFD-CF and the CTD-CF groups) and the remaining groups were fed the same diet as their dams (the LFD and the CTD groups) for 5 wk. Although the body weight of pups fed the LFD was lower than that of pups fed the CTD, the body weight of the LFD-CF group caught up with that of the CTD group. The ratio of FPD intake [FPD intake (g)/total intake (g)] by the LFD-CF group was higher than that of the CTD-CF group. In both dams and their pups, although no significant difference in the plasma glucose concentration was observed between the LFD and the CTD groups, the plasma insulin and triacylglycerol (TG) concentrations of the LFD group were higher than those of the CTD group. However, the self-selection diet appeared to prevent an increase in the plasma insulin and TG concentrations. Therefore, it was supposed that although pups of dams fed the LFD showed strong preference for fat in order to achieve optimal growth, the dietary selection pattern after weaning was associated with the depletion in plasma insulin.
This study examined the effects of maintaining euhydration by ingesting fluids with or without carbohydrate on subjective responses of untrained men during prolonged exercise in a hot environment. Six healthy untrained subjects completed 90 min of cycling exercises at 55% maximal oxygen consumption (VO2max) in a hot environment (temperature: 28oC, humidity: 50%) under three different experimental conditions. During the first trial, subjects did not ingest fluids during exercise (dehydration (DH) trial). In the second and third trials, subjects received mineral water (MW) and hypotonic fluid containing carbohydrate (HF), respectively, in amounts equaling their weight loss in the DH trial. At the end of exercise, the overall rating of perceived exertion (RPE-O) was lower in the MW and HF trials than in the DH trial (14.3±1.0 and 13.7±0.6 vs 17.7±1.0, p<0.05, respectively). RPE-cardiovascular and RPE-legs were lower at the end of exercise in the HF trial compared with the DH trial. VO2, heart rate (HR), and rectal temperature increased during exercise in the three trials. At the end of exercise, the drift in VO2 was lower in the MW and HF trials than in the DH trial (304±41 and 339±40 vs 458±33 mL, p<0.05, respectively). HR at the end of exercise in the HF trial was lower than in the DH trial (158±5 vs 173±7 bpm, p<0.05). These results suggest that maintaining euhydration during prolonged exercise in untrained men could attenuate RPE-O and that hypotonic electrolyte-carbohydrate solution could attenuate RPE-legs during exercise.
Ingestion of a high-protein meal results in body weight loss due to elevated energy expenditure, while also increasing satiety and decreasing subsequent food intake. The present study aimed to clarify the effects of a high-protein, carbohydrate-free diet (HPCFD) on these physiological indicators from a circadian perspective. Rats were given HPCFD or a pair-fed normal protein content diet (20% protein; NPD) for 4 d. The HPCFD group lost more body weight than the NPD group. Oxygen consumption (VO2) in the HPCFD group did not change during the experimental period, and tended to be higher during the light (L) phase than in the NPD group. Carbon dioxide production (VCO2) during the L phase was higher in the HPCFD group than in the NPD group, where VCO2 was gradually decreased during the last dark (D) phase and throughout the L phase. The HPCFD group exhibited higher daily core body temperature (Tb), particularly during the late D phase and throughout the L phase when compared to the NPD group. Locomotor activities during the D phase of the NPD group tended to gradually increase and were thus significantly higher than in the HPCFD group. These results suggest that HPCFD, even if energy intake is insufficient, maintains circadian changes in metabolic rates, resulting in maintenance of elevated daily Tb and body weight reduction without increasing activity.
To clarify the physiological function of pseudovitamin B12 in cyanobacteria, we determined pseudovitamin B12 contents and cobalamin-dependent methionine synthase activity in Synechocystis sp. PCC6803 grown under CoSO4-sufficient and -limited conditions. Pseudovitamin B12 and cobalamin-dependent methionine synthase activity (0.8 nmol/min/mg protein) were found in a homogenate of the Synechocystis cells grown for 10 d in the CoSO4-sufficient medium. The cellular pseudovitamin B12 contents increased significantly at the early logarithmic growth phase and thereafter decreased rapidly at the stationary phase; a similar fluctuation pattern was shown in the cobalamin-dependent methionine synthase activity. Although the CoSO4-limited conditions did not reduce the cell growth, pseudovitamin B12 contents and methionine synthase activity decreased significantly in the limited cells relative to the sufficient cells. These results indicate that the cyanobacterium Synechocystis sp. PCC6803 can synthesize pseudovitamin B12 de novo and utilize it as the cofactor for cobalamin-dependent methionine synthase.