Essential trace elements play pivotal roles in numerous structural and catalytic functions of proteins. Adequate intake of essential trace elements from the daily diet is indispensable to the maintenance of health, and their deficiency leads to a variety of conditions. However, excessive amounts of these trace elements may be highly toxic, and in some cases, may cause damage by the production of harmful reactive oxygen species. Homeostatic dysregulation of their metabolism increases the risk of developing diseases. Specific transport proteins that facilitate influx or efflux of trace elements play key roles in maintaining the homeostasis. Recent elucidation of their crucial functions significantly facilitated our understanding of the molecular mechanisms of iron (Fe), copper (Cu), and zinc (Zn) absorption in the small intestine. This paper summarizes their absorption mechanisms, with a focus on indispensable functions of the molecules involved in it, and briefly discusses the mechanisms of homeostatic control of each element at the cellular and systemic levels.
β-Glucans are a class of polysaccharides consisting of D-glucose units that are polymerized primarily via the β-1,3 glycosidic bonds, in addition to the β-1,4 and/or β-1,6 bonds. They are present in various food products such as cereals, mushrooms, and seaweeds and are known for their numerous effects on the human body, depending on their structures, which are diverse. The major physicochemical properties of β-glucans include their antioxidant property, which is responsible for the scavenging of reactive oxygen species, and their role as dietary fiber for preventing the absorption of cholesterol, for promoting egestion, and for producing short-chain fatty acids in the intestine. Dietary β-glucans also exert immunostimulatory and antitumor effects by activation of cells of the mucosal immune system via β-glucan receptors, such as dectin-1. In this review, we elaborate upon the diversity of the structures and functions of β-glucans present in food, along with discussing their proposed mechanisms of action. In addition to the traditional β-glucan-containing foods, recent progress in the commercial mass cultivation and supply of an algal species, Euglena gracilis, as a food material is briefly described. Mass production has enabled consumption of paramylon, a Euglena-specific novel β-glucan source. The biological effects of paramylon are discussed and compared with those of other β-glucans.
Increased parathyroid hormone (PTH) was associated with cardiovascular mortality and morbidity in CKD patients. Our aim was to investigate the associations among estimated glomerular filtration rate (eGFR), albumin/creatinine ratio (ACR) and PTH independent of 25-hydroxyvitamin D (25(OH)D). This study included 9,162 individuals who completed the baseline survey of the Dong-gu Study, which was conducted in Korea from 2007 to 2010. The eGFR, ACR, PTH and 25(OH)D were measured in participants who met the detailed inclusion criteria. After being adjusting for covariates (sex, age, waist circumference, smoking, alcohol intake, physical activity, hypertension medications, diabetes medication, total cholesterol, triglyceride, HDL cholesterol) and log-ACR, the PTH value stratified by 25(OH)D level significantly decreased with increasing eGFR levels in each 25(OH)D stratum. Moreover, after adjustment for the same covariates and log-eGFR, the PTH value stratified by 25(OH)D level significantly increased with increasing ACR levels in each 25(OH)D stratum. In conclusion, the PTH values significantly decreased with increasing eGFR levels and increased with increasing ACR levels independently of 25(OH)D in an adult Korean population ≥50 y of age.
The aim of this study was to investigate the effects of folic acid on impaired wound healing in diabetic mice. Male mice were divided into three groups: group 1, the non-diabetic mice (control); group 2, the streptozotocin (STZ)-induced type 1 diabetic mice; and group 3, the diabetic mice that received a daily dose of 3 mg/kg folic acid via oral gavage. Full-thickness excision wounds were created with 8-mm skin biopsy punches. Each wound closure was continuously evaluated until the wound healed up. Wound healing was delayed in diabetic mice compared with the non-diabetic mice. There were significantly reduced levels of hydroxyproline content (indicator of collagen deposition) and glutathione in diabetic wounds, whereas levels of lipid peroxidation and protein nitrotyrosination were increased. Daily supplementation with folic acid restored diabetes-induced healing delay. Histopathology showed that folic acid supplementation accelerated granulation tissue formation, proliferation of fibroblasts, and tissue regeneration in diabetic mice. Interestingly, folic acid alleviated diabetes-induced impaired collagen deposition in wounds. Moreover, folic acid significantly decreased levels of lipid peroxidation, protein nitrotyrosination and glutathione depletion in diabetic wounds. In conclusion, our results indicate that folic acid supplementation may improve impaired wound healing via suppressing oxidative stress in diabetic mice.
In Japan, parenteral nutrition (PN) solutions are frequently administered to patients in the postoperative short-term period. In these cases, amino acid-containing peripheral parenteral nutrition (PPN) solutions, amino acid-free maintenance solutions or combinations of the two are used. However, consensus regarding the most beneficial solution for these patients is lacking. Here, we examined the nutritional status and wound healing outcomes in protein-malnourished rats receiving postoperative administrations of PPN solution, maintenance solution or combinations of the two solutions. Protein malnutrition was induced in Sprague-Dawley rats by feeding an AIN-93G-based low-protein diet (5% casein) for 2 wk. After laparotomy, dorsal skin incision, and placement of a jugular vein catheter, the rats were divided into 3 groups. Each group was administered 113 kcal/kg/d, with group A receiving maintenance solutions without amino acid, group B receiving PPN with 1.5% amino acid, and group C receiving PPN with 3% amino acid. After 5 d post-operative administration, we measured the tensile strength of the wound area, skeletal muscle weights, and nutritional parameters. Significantly higher plasma nutritional parameters and gastrocnemius and extensor digitorum longus (EDL) muscle weights were observed in groups B and C than in group A. Group C exhibited significantly elevated tensile strength of the wound area along with up-regulation of type I collagen mRNA expression compared to group A. These findings demonstrate the nutritional status and wound healing benefits of short-term postoperative administration of PPN solutions containing amino acids in protein-malnourished rats.
The biological effects of heat-killed Pediococcus acidilactici R037 (R037) were evaluated when orally administered in mice and rats. Oral R037 administration at a daily dose of 10 and 100 mg/kg for 3 wk dose-dependently reduced fasting and non-fasting serum triglyceride concentrations in KK-Ay/TaJcl mice, a model of type II diabetes, obesity, hypercholesterolemia, and hypertriglyceridemia. Serum levels of free fatty acids in the 100 mg/kg group tended to decrease (not statistically significant), and total cholesterol levels remained unchanged. Treatment with R037 resulted in a significant decrease in blood glucose (at 100 mg/kg) and liver weight (at 10 and 100 mg/kg), and a small body weight gain (at 100 mg/kg) as compared to those in control mice. In addition, oral R037 administration at 100, 200, and 400 mg/kg/d for 1 wk dose-dependently suppressed the increase in serum triglyceride levels in Wistar rats after oral fat loading. Moreover, intraduodenal injection of 120 mg of R037 in Wistar rats suppressed gastric vagal nerve activity (GVNA) indicating suppression of intestinal digestion and absorption of food, and suppression of appetite. The R037 injection potentiated epididymal white adipose tissue sympathetic nerve activity (WAT-SNA) and tended to potentiate pancreatic sympathetic nerve activity (PSNA), suggesting that R037 activated lipolysis. Taken together, these findings indicate that R037 lowers serum triglycerides, possibly through suppressing intestinal absorption and potentiating lipolytic pathways. R037 may be useful for primary prevention of coronary artery diseases in subjects with mild or borderline dyslipidemia in combination with lifestyle changes.
We investigated oral glucose tolerance and tryptophan (Trp) metabolism in non-obese and non-insulin-dependent diabetic Goto–Kakizaki (GK) rats fed high-Trp diets. Five-week-old male Wistar and GK rats were fed a 20% casein diet (control diet) or the same diet supplemented with 1%, 2%, 3%, or 5% Trp for 58 d. Oral glucose tolerance tests were performed on Days 14 and 28 of the experimental period. Urine as well as livers and blood were collected on the last day of the experiment. The glucose concentration and the amount of Trp metabolites were measured. On Day 14 of the experiment, the incremental blood glucose concentrations integrated over a period of 2 h (ΔAUC0-2h) of blood glucose in rats fed the 3% and 5% Trp diets had decreased by 13% and 18%, respectively, compared with that of the control-GK rats. However, no significant differences were found in the rats fed +1% or +2% Trp diets compared with control-GK rats. On Day 28, there were no significant differences found in the ΔAUC0-2h of blood glucose levels in any group including the control-GK group. On the last day, the concentrations of plasma glucose, total cholesterol, and triglyceride did not show differences in any group. There were no specific phenomena observed in the metabolism of Trp in GK rats even when fed an excess of Trp, compared with that of Wistar rats. Oral Trp administration and its continuous use may not improve blood glucose levels in type 2 diabetic rats.
‘Haiibuki’ is a giant embryo rice cultivar that contains abundant γ-aminobutyric acid (GABA) compared with conventional rice cultivars. Here, we performed a functional evaluation of ‘GABA-enriched brown rice’ (GEBR) prepared by modifying the ‘Haiibuki’ cultivar to contain more GABA. Study 1: Spontaneously hypertensive rats were divided into three groups [control (cornstarch), normal brown rice, and GEBR] and fed an orally administered diet for 4 wk. A significant blood pressure elevation-inhibitory effect was observed in the GEBR group as compared with the other groups. Study 2: Rats were divided into two groups and fed ad libitum for 12 wk. The two groups were control (commercial feed with 5% cornstarch) and GEBR (commercial feed with 5% GEBR). Body weight, blood pressure, food consumption, and water intake were measured during the study period, and blood chemistry was analyzed after the study. Plasma 8-hydroxy-2′-deoxyguanosine (8-OHdG) and urinary isoprostane were measured 12 and 10 wk after the start of the study, respectively. A significant blood pressure elevation-inhibitory effect was observed in the GEBR group. The 8-OHdG and isoprostane levels were significantly lower in the GEBR group than in the control group, demonstrating an oxidative stress-reducing effect. Therefore, GEBR exhibited a blood pressure elevation-inhibitory effect under the conditions of this study. The antioxidative action may occur secondarily to the antihypertensive action of GABA, suggesting that the long-term ad libitum ingestion of GEBR prevents hypertension. A reduction in oxidative stress could reduce the chances of complications in cardiovascular diseases.
The aim of the study was to demonstrate the impairment of trans fatty acids (TFAs) in neurological disorders in mice. Forty-eight male Kunming mice were randomly divided into four groups with twelve in each group, namely a control group (corn oil group), and TFA groups with low, middle and high dosages. The tested chemicals were given by gavage, once a day, for 12 wk in total, with the volume of the intragastric liquid as 0.1 mL/10 g of body weight. The mice in the control group were given corn oil only. The mice in the TFA groups were given TFA solution (doses were 25, 50 and 100 mg/kg of body weight, respectively). The Morris circle water maze was used to test learning and memory of mice. The activity of acetylcholinesterase (AChE), nitric oxide synthase (NOS) and the level of brain amino acid neurotransmitters were tested. In the Morris water maze task, and compared to the control group, TFAs showed no obvious effect on learning or memory. TFA intake led to a significant decrease of AChE in all TFA groups, and the increase in levels of NOS in the high-dose group. Meanwhile, intake of TFAs increased the levels of Asp, Glu, Gly, and Tau in all TFA groups. The results suggest that long-term intake of TFAs probably impairs learning, memory and brain neurotransmitters in mice.
Maintaining skeletal muscle functions by controlling muscle metabolism is of utmost importance. β2-Adrenergic receptor (β2-AR), which is expressed in skeletal muscle, is a member of the G-protein-coupled receptor family that plays a critical role in the maintenance of muscle mass. In the present study, using luciferase reporter assays in β2-AR-expressing HEK293 cells, we discovered several food factors that exhibited agonistic activity at mouse or human β2-AR. Osthole, gramine, and hordenine were identified as both mouse and human β2-AR agonists, whereas berberine was identified as a mouse β2-AR agonist only. Additionally, intramuscular injection of gramine or hordenine in mice facilitated gene expression of several cAMP response element binding protein targets, which is thought to result in increased skeletal muscle protein synthesis. This study provides evidence that several food factors might exert potential health effects on skeletal muscle by enhancing cAMP signaling through the activation of β2-AR.
Piceatannol has been reported to have a wide variety of effects on the skin, including promoting collagen production, inhibiting melanin synthesis, inducing the antioxidant glutathione, and eliminating reactive oxygen species. In this study, a randomized, placebo-controlled, double-blind trial was conducted to clinically evaluate the effects of piceatannol-rich passion fruit seed extract on the skin of healthy Japanese women (age, 35-54 y). Thirty-two women with dry skin received either passion fruit seed extract (5 mg piceatannol) or a placebo (dextrin) for 8 wk. Skin hydration and other parameters on the face were assessed at 0, 4, and 8 wk by using specialized equipment. Furthermore, questionnaire interviews were conducted regarding the physical condition of subjects at 0, 4, and 8 wk. The results showed that consumption of passion fruit seed extract led to significant increases in the moisture content of human skin after 4 and 8 wk compared with that before the trial. The amount of transepidermal water loss decreased over time, although the differences were not significant. Moreover, a stratified analysis of subjects with moisture values of ≤200 μS revealed increased moisture content in the passion fruit seed extract group as compared with the placebo group. Furthermore, the results of questionnaires showed significant reductions in “perspiration” and “fatigue” in the passion fruit seed extract group as compared with the placebo group. These results indicate that oral intake of passion fruit seed extract that is rich in piceatannol could improve the moisture of dry skin and reduce fatigue.