Fatty foods are very palatable. Most mammals, including humans, prefer high-fat food to low-fat food. Neuropeptides and neurotransmitters, which are related to the hedonic or aversive response in the brain, are released after a basic tastant (i.e., sweet, sour, salty, bitter or umami) is accepted by the taste receptors in the taste bud cells. In addition, recent evidence suggests that dietary fat, especially free fatty acids, may be perceived chemically in taste bud cells as well as the basic tastant. Recently, it was suggested that long-chain fatty acids accepted into CD36/FAT, a long-chain fatty acid transporter, in circumvallate papillae of the tongue play an extremely important role in the palatability of dietary fat. In this review, we describe the studies on the reception of fatty acids in the oral cavity, and on the signal transmission from the oral cavity to the brain. We hypothesize that long-chain fatty acids are recognized on the tongue, and then neuropeptides and neurotransmitters such as β-endorphin and dopamine are released in the brain. We suggest that this knowledge is one of the mechanisms of the palatability of dietary fat.
To evaluate the effect of lactulose on calcium (Ca) and magnesium (Mg) absorption, we performed a clinical trial with a double-blind, randomized, crossover design in 24 healthy adult male volunteers. The absorptions of Ca and Mg were evaluated by a single-labeling method using stable isotopes. The test foods, containing lactulose at a dose of 0 g (placebo), 2 g (low-dose), or 4 g (high-dose) together with 300 mg of Ca containing 20 mg of 44Ca, and 150 mg of Mg containing 28 mg of 25Mg, were administered orally. Urine samples were collected for 8 h after the ingestion of the test food. The ratios of stable isotopes in urine (44Ca/40Ca and 25Mg/24Mg) were measured by ICP-MS (inductively coupled plasma-mass spectrometry). The urinary stable-isotopes ratios (44Ca/40Ca and 25Mg/24Mg) increased with lactulose dosage. Significant differences were observed in the Ca ratio between placebo and high-dose lactulose (p<0.01), and in the Mg ratio between placebo and low-dose lactulose and between placebo and high-dose lactulose (p<0.01). Lactulose ingestion did not change the levels of bone-resorption markers (type I collagen cross-linked N-telopeptide and deoxypyridinoline) in urine. The test foods did not cause any side effects. This study demonstrates that lactulose enhances the absorptions of Ca and Mg in adult men.
The ingestion of a sufficiently large amount of non-digestible and/or non-absorbable sugar substitutes causes overt diarrhea. The objective is to estimate the non-effective dosage that does not cause transitory diarrhea for xylitol, lactitol, and erythritol in healthy subjects. Twenty-seven males and 28 females gave informed and written consent to participate, were selected, and participated in the study. The oral dose levels of xylitol were 10, 20, 30, 40 and 50 g, while those of lactitol were 10, 20, 30, and 40 g. Those of erythritol were 20, 30, 40 and 50 g. The test substance was ingested in 150 mL of water 2-3 h after a meal. The ingestion order progressed from the smallest to larger amounts, and stopped at the dose that caused diarrhea, or at the largest dose level to be set up. The non-effective dose level of xylitol was 0.37 g/kg B.W. for males and 0.42 g/kg B.W. for females. That of lactitol was 0.25 g/kg B.W. for males and 0.34 g/kg B.W. for females, and that of erythritol was 0.46 g/kg B.W. for males and 0.68 g/kg B.W. for females. These results appear reasonable, because xylitol is poorly absorbed from the small intestine, and the absorption rate is less than that of erythritol, while lactitol is not hydrolyzed. Non-digestible and/or non-absorbable sugar alcohols and oligosaccharides with beneficial health effects inevitably cause overt diarrhea. The estimation of the non-effective dose level of these sugar substitutes is essential and important to produce processed foods that the consumer can use safely and with confidence.
This study was designed to investigate the effects of dietary onion flesh or onion peel on lipid peroxides and DNA damage in aged rats. Sprague Dawley male rats (n=40, 16 mo old) were blocked into five groups and raised for 3 mo with either an onion-free control diet or onion diets (Allium cepa L., intermediate-day variety) containing either 5% (w/w) powdered dried onion flesh, 5% (w/w) powdered dried onion peel or ethanol extracts of the two powdered forms of onion. Total antioxidant status (TAS) and levels of total polyphenols and quercetin were greatest in onion peel ethanol extract, followed by onion peel powder, onion flesh ethanol extract, and onion flesh powder. Plasma quercetin and isorhamnetin levels were markedly increased by onion peel powder and onion peel ethanol extract. Rats fed onion flesh powder or onion peel powder had a higher plasma TAS than rats fed the control diet. Onion peel powder reduced liver thiobarbituric reactive substances relative to those of the control diet in aged rats (p<0.05). Brain 8-isoprostane levels were markedly decreased by all four onion diets and the decrease was significant for the onion flesh powder and onion peel powder diets (p<0.05). There was no significant decrease in cellular DNA damage in the kidney or brain tissue among rats fed the four onion diets. Onion flesh or onion peel enhanced antioxidant status in aged rats and may be beneficial for the elderly as a means of lowering lipid peroxide levels.
Although we previously observed significant associations between intakes of several foods and constipation, definition of constipation was completely based on subjective perception assessed by a quite simple and single question: do you often have constipation? In this study, we examined the associations between food intake and functional constipation as defined according to symptom-based criteria (Rome I criteria: straining, hard stools, incomplete evacuation, and infrequency of bowel movement). Subjects were 3,835 female Japanese dietetic students aged 18-20 y from 53 institutions in Japan. Dietary intake was estimated with a validated, self-administered diet history questionnaire. The prevalence of functional constipation was 26.2%. Dietary intakes of several foods were significantly associated with functional constipation. A multivariate adjusted odds ratio (95% confidence interval; p for trend) for women in the highest quintile of dietary intake compared with those in the lowest was 0.59 (0.46-0.75; <0.0001) for rice, 0.77 (0.61-0.97; 0.003) for pulses, 1.64 (1.30-2.08; <0.0001) for confectioneries, and 1.41 (1.11-1.78; 0.01) for bread. In conclusion, intake of rice and pulse was negatively and that of confectioneries and bread was positively associated with functional constipation among a population of young Japanese women, which was generally consistent with our previous study where constipation was assessed by a quite simple question.
While lower serum albumin concentration is often found in the elderly, a relation between serum albumin and age has not been fully elucidated. We conducted population-based cross-sectional and 5-y longitudinal study to examine the relation. A total of 22,705 male and 40,149 female, aged 65 y and older, living in Gifu, participated in the health check service conducted by Gifu City Medical Association. They were self-supported in the activity of daily living and 3,438 of them were followed up every year from 1999 to 2003. Serum albumin levels decreased with age in both men and women. In the cross-sectional study, median value declined from 4.3 g/dL in males aged 65-69 y to 3.9 g/dL in 90≤ y, and 4.3 g/dL to 4.0 g/dL in females. Incidence of hypoalbuminemia (serum albumin≤3.5 g/dL) increased in parallel with age from 1.2% (65-69 y) to 6.6% (85-89) in males, and 0.6% to 4.1% in females. In the longitudinal study, regression analysis showed a significant decline in serum albumin of 0.015 g/dL per year (r=−0.716) in males, and 0.012 g/dL per year (r=−0.794) in females. Relative reduction of serum albumin in 5 y was larger in advanced age; 1.2% in females aged 65-69 y and 3.1% in 85-89 y (p<0.05), but not in males. In conclusion, a fall in serum albumin concentration in community-dwelling, self-supported elderly persons was associated significantly with aging.
Equol, a metabolite of daidzein for some intestinal microflora, is known to retain highly estrogenic activity and is of wide interest in relation to human health. However, not all humans can produce equol. In this study, detection of urinary equol using thin-layer chromatography (TLC) was performed to distinguish between equol producers and non-producers. After 36 h of soy food intake, urine, collected from 7 volunteers, was hydrolyzed, purified by reverse phase silica gel column and applied to normal phase TLC. Consequently, equol was clearly separated from the urine samples and discriminated the equol producers in this system. The detection limit of equol was at least 20 ng.
Oxidative stress is a major cause of cardiovascular tissue fibrosis. We evaluated the effects of daily doses of soy isoflavones, genistein and daidzein on cardiovascular tissue fibrosis in Otsuka Long-Evans Tokushima Fatty (OLETF) diabetic rats and Long-Evans Tokushima Otsuka (LETO) non-diabetic rats as a severe or mild oxidative stress model, respectively. Glucose and lipid metabolisms did not improve with genistein or daidzein treatment. However, genistein decreased hydroxyproline concentrations in the heart. Hydroxyproline reductions as a result of genistein were mildly stronger than those of daidzein. Thus, genistein significantly suppressed the progression of myocardial fibrosis in LETO rats despite the insignificant changes in OLETF rats. Although a daily dosage of isoflavone was not sufficient to prevent tissue fibrosis under marked oxidative stress in the early stage of diabetes, isoflavones might promise significant clinical benefits by reducing oxidative stress in the heart during aging.
In fulminant hepatic failure, various toxins causing multi-organ failure increase in plasma. As a novel toxin, levels of ceramide, a well-studied lipid mediator of apoptosis, were determined by LC-MS/MS in the liver and plasma of carbon tetrachloride (CCl4)-intoxicated rats. After 6 h of oral administration of CCl4 (4 mL/kg body weight as a 1 : 1 mixture of CCl4 and mineral oil) to rats, extensive hepatic failure occurred as evidenced by a severe elevation in plasma AST and ALT. The liver concentration of major ceramide components (C16:0, C24:0, C24:1, C18:0, C22:0, and C24:2 in decreasing order), and the sum of these ceramides increased significantly 2 h after CCl4 intoxication compared to that in the control group given mineral oil. The total ceramide concentration in the plasma was also increased to 4.1 times that in the control 24 h after administration of CCl4. In conclusion, the early increase in liver ceramides may contribute to hepatic cell death and the increase in plasma ceramides during fulminant hepatic failure may cause damage in other organs including the brain and kidney.
A double-blind, placebo-controlled trial was conducted to clinically evaluate the effect of soy isoflavone aglycone on the aged skin of middle-aged women. Twenty-six women volunteers in their late 30s and early 40s were randomly assigned to receive either a test food (13 women, the test food group) or a placebo food (13 women, the control group). These groups were given the test food (40 mg of soy isoflavone aglycone per day) and placebo, respectively, for 12 wk. The extent of linear and fine wrinkles at the lateral angle of the eyes was selected as the major evaluation criterion to assess the effects of foods, and the wrinkles' area ratio was used as the evaluation parameter. The extent of skin microrelief at the lateral angle of eyes and that of malar skin elasticity were used as secondary evaluation criteria, and the skin microrelief's area ratio and recovery of skin elasticity were used as the respective evaluation parameters. These parameters were assessed 4, 8, and 12 wk after the start of the test food or placebo intake. The test food group showed a statistically significant improvement of fine wrinkles at week 12 (p<0.05) and of malar skin elasticity at week 8 (p<0.05), compared with the control group. Although there was no significant difference between the test food group and the control group regarding effects on skin microrelief at lateral angle of the eyes, a significant intragroup improvement was observed at week 8 in the test food group (p<0.05). As for the test food safety, none of the subjects presented adverse symptoms during the study period or discontinued the intake of the test food. These data indicate that the oral intake of 40 mg soy isoflavone aglycones per day improves the aged skin of middle-aged women.
Anti-obesity effects of a fermentation product of phytosterols including campestenone in ICR mice were investigated. Five-week-old male ICR mice were fed by the pair-feeding method for 8 wk. Experimental feed was prepared by adding TO-001, a phytostenone mixture produced by fermentation of phytosterols using Nocardioides simplex, at 0.25, 0.5, 1.0, or 2.0% or no additive to a high fat diet (fat 20%). Mice fed a stock feed (fat 5.6%) ad libitum were used as the standard growth group. In animals fed the high fat diet, control (no added TO-001) mice showed a weight gain that was about 10% higher than for the standard growth group. TO-001 reduced body weight dose-dependently. Final body weights of 0.5% and 1.0% TO-001-fed mice were lowered by about 9% and those of 2.0% TO-001-fed mice by about 12% compared with the control mice. Visceral and subcutaneous fat weight in mice fed TO-001 was significantly lower than that in mice fed the control diet. The concentrations of serum triglyceride (TG) and total cholesterol (TC) were significantly lower in the 1.0% and/or 2.0% TO-001-fed mice. Furthermore, levels of liver TG and TC were decreased in the TO-001-fed group. Increase of total lipid excretion in the feces was dose dependent. No obvious abnormalities due to consumption of TO-001 were detected by a blood biochemical examination, clinical observations or necropsy. The results suggested that TO-001, a fermentation product of phytosterols, may be a promising component of dietetic functional foods.
Enzymatically modified isoquercitrin (EMIQ) is a water-soluble glycoside of quercetin produced from rutin by enzymatic treatment. We investigated the anti-hypertensive effect of orally administered EMIQ in spontaneously hypertensive rats (SHR). The systolic blood pressure (SBP) in SHR administered EMIQ at a dose of 3 and 26 mg/kg/d was significantly lower than that in the control group on d 22, 36 and 50 of administration. The effect of EMIQ (26 mg/kg/d) was higher than equimolar administration of quercetin. Diltiazem administered as a positive control also suppressed the increase in SBP, and the effect was stronger than that of EMIQ. In the control group, the mean values of mean blood pressure (MBP) and diastolic blood pressure (DBP) were increased after the start of administration. Although diltiazem suppressed the increase in MBP, no significant changes were observed in the EMIQ groups. Compared with the control group, EMIQ groups showed the incidental changes of MBP and heart rate on day 22 of administration only. These results indicate that EMIQ suppressed the increase in SBP in SHR dose-dependently, and was more effective than the aglycone quercetin. It was also speculated that EMIQ showed higher antihypertensive effect than quercetin due to the high bioavailability, and the mechanism of SBP suppression is possibly through the improvement of endothelial NO production. In conclusion, our results suggest that EMIQ shows possibility as a naturally-derived safe food material which has an antihypertensive effect.
The purpose of the present study was to examine the effects of dietary supplementation of arachidonic acid (ARA) on age-related changes in endothelium-dependent vascular responses. Young male Fisher-344 rats (2-mo-old) and aged rats of the same strain (22-mo-old) were randomly separated into a control diet group (young control, YC; old control, OC) and an ARA-containing diet group (young ARA, YA; old ARA, OA). After a 2-mo feeding period, vascular responses were evaluated using both endothelium-intact and -denuded aortic rings. Phenylephrine (α1-adrenoceptor agonist)-induced vasoconstrictor responses in endothelium-intact rings from group OC tended to be augmented compared with those of rings from groups YC and YA, although this augmentation was significantly suppressed by dietary supplementation of ARA. There were no significant differences in vascular responses to phenylephrine in endothelium-denuded rings among groups YC, YA, OC, and OA. Acetylcholine (Ach)-induced, endothelium-dependent vasorelaxation was attenuated in groups OC and OA compared with that in groups YC and YA. ARA supplementation induced slight enhancement of Ach-induced vasorelaxation in aged rats. Ach-induced vasorelaxation correlated very well with aortic ARA concentration in aged rats, but not in young rats. There were no significant differences in endothelium-independent vasodilator responses to sodium nitroprusside in endothelium-denuded rings among groups YC, YA, OC, and OA. These findings suggest that dietary ARA supplementation improves the age-related endothelial dysfunction that leads to various cardiovascular diseases.
The aim of this study was to evaluate the effect of feeding yoghurt, prepared with Lactobacillus delbrueckii subsp. bulgaricus strain 2038, on indigenous lactobacilli in the pig cecum. Three female pigs fistulated at the cecum were fed 250 g of this yoghurt that contained over 1011 colony-forming units of L. delbrueckii subsp. bulgaricus strain 2038 with their daily meal for 2 wk. The relative abundance and the composition of cecal lactobacilli was monitored by analysis of bacterial 16S rDNA with real time PCR and amplified bacterial rDNA restriction analysis using Lactobacillus-group specific primers, respectively, for 2 wk prior to, at the end of 2 wk of and 2 wk after the administration of this yoghurt. The relative abundance of lactobacilli was significantly increased by feeding yoghurt (p<0.01), although the bacterial 16S rDNA matching L. delbrueckii subsp. bulgaricus strain 2038 was not detected by amplified bacterial rDNA restriction analysis during this study. The number of operational taxonomic units (OTUs) detected was increased with feeding of the yoghurt in all pigs. At the same time, the estimated cell number of each OTU was increased with feeding of the yoghurt. It is demonstrated that continuous consumption of the probiotic lactobacilli will stimulate the growth of some indigenous lactobacilli and alter the composition of the lactobacilli.
We previously reported that the increase in blood glucose was more suppressed when palatinose was taken with sucrose or glucose than when either of these sugars was taken alone. In the present study, we examined whether or not palatinose suppresses glucose absorption using everted intestinal sacs from rats. Glucose absorption in the everted rat intestinal sac was measured with 0, 1, 2.5 or 5 mM of palatinose added to 20 mM glucose. The measurement was repeated five times for each palatinose level to calculate a mean value. The result showed glucose absorption to be reduced as the palatinose level increased. It was significantly reduced when 5 mM palatinose was added as compared with no palatinose addition (p<0.05). These results suggest that palatinose suppresses glucose absorption.
Anthocyanins have beneficial effects such as free radical scavenging activity. We investigated the effects of continuous administration of colors from purple corn (PCC), purple sweet potato (PSC) and red radish (RRC) to spontaneously hypertensive rats (SHR). These are rich in anthocyanins. Animals were fed with diets containing PCC, PSC or RRC (1 mass% of diets) for 15 wk. While the body weight and the daily food intake of administered rats were not different from those of the non-administered control rats through the experimental period, the blood pressure and the heart rate of SHR administered each color decreased as compared to the control group from the early stage of administration. These results suggest that plant-derived colors containing anthocyanins have anti-hypertensive effects on hypertensive animals.