Clinical, epidemiological and chronobiological studies on the relationship between blood pressure and mineral intake have been on-going for the past thirty years. They can be divided into five groups. 1) Clinical studies on salt sensitivity in patients with idiopathic hypertension. 2) Chronobiological studies of blood pressure (BP) fluctuation and urinary electrolyte excretion in relation to BP regulation. These include the Fukuoka-Minnesota collaborative chronoepidemiological study, studies on the circadian rhythns of urinary electrolyte excretion during total parenteral nutrition, and the reapportionment of salt intake in relation to circadian blood pressure patterns. 3) The estimation of the 24-h urinary sodium and potassium excretion from spot-urine specimens. 4) Comparative epidemiological studies on the genesis of hypertension in Nepal. 5) The effects of high-potassium, high-magnesium or high-fiber intake on blood pressure and the metabolism of lipids and carbo-hydrates in man. A larger proportion of te population are expected to suffer from either mild or borderline hypertension in the future. Non-pharmacological treatment of this condition by regulating the dietary intake of minerals such as sodium, potassium, magnesium and calcium, is now considered to be of increasing importance for the treatment of this condition.

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Regulatory mechanisms of hepatic protein metabolism and gene expression mediated by amino acids and vitamin B₆ were investigated. 1) Rats were nourished by total parenteral nutrition, and the effects of variations in the amino acid supply on the rates of hepatic protein synthesis and degradation were investigated. Amino acids decreased the rate of degradation whilst the rate of synthesis was relatively unaffected. Protein degradation, therefore, predominates the regulation of liver protein mass. 2) Studies on cystathionase and aspartate aminotransferase (AspAT) in the liver of vitamin B₆-deficient rats showed that their rates of synthesis and degradation were both increased. The enhanced degradation was caused by different susceptibilities of apo- and holo-enzymes to lysosomal proteolysis. 3) Pyridoxal phosphate (PLP) was found to modulate AspAT gene expression by preventing the glucocorticoid receptor from binding to glucocorticoid-responsive elements. PLP also modulated albumin gene expression by inactivat ng the DNA-binding activity of tissue-specific transcriptional factors such as HNF-1 and C/EBP. 4) Amino acid vinfusion increased the albumin mRNA level and decreased the PLP concentration. The decrease in PLP concentration would prevent the inactivation of tissue-specific transcription factors and enhance albumin gene expression. The present study sheds new light on the physiological role of PLP as a mediator of gene regulation in protein/amino acid nutrition.

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The effect of vinegar, made from soybean oligosaccharides, on lipid metabolism was investigated in rats fed a cholesterol-free 25% casein basal diet. The saccharides in this vinegar were mainly composed of manninotriose. The experimental diet was prepared by the addition of 15% (w/w) powdered vinegar (SOV, soybean oligosaccharide vinegar), to the basal diet. This SOV diet contained approximately 3.3% oligosaccharides and 1.9% acetic acid. Serum cholesterol (VLDL+LDL) and triacylglycerol levels were significantly lower in the SOV diet group than in the control group. These differences were found for 2-5 weeks or at 4th week, respectively, for serum cholesterol and triacylglycerol. The liver cholesterol content was also significantly lower in rats fed the SOY diet, but there was no change in total bile acid excretion into the feces. In all groups, a strong positive correlation was observed between the liver cholesterol content and the serum VLDL+LDL cholesterol level at a 5 week period. No relationship was fou d between the cecal short-chain fatty acids (SCFA) and liver cholesterol content, and there was no correlation between the cecal SCFA content and the serum VLDL + LDL cholesterol level. These results suggest that SOY exerts some beneficial effect on lipid metabolism.

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The effect of vitamin E on the antioxidative defense mechanism was investigated in streptozotocin (STZ) -induced diabetic rats. Sprague-Dawley male rats were randomly assigned either to one of three STZ-diabetic groups, classified as STZ-0 E (basal diet), STZ-40 E (40mg vitamin E/kg of diet) and STZ-400 E (400mg vitamin E/kg of diet), or to the control group. After 26 days on the experimental diets, STZ (55mg/kg body weight) was administred intravenously to the diabetic groups. The blood glucose levels of the diabetic rats were three times higher than those of the controls. In groups STZ-0 E and STZ-40E, the serum glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and liver xanthine oxidase activities were all higher than those of the controls. However, the activities of these enzymes in the STZ-400E group did not differ from those of the controls. Compared to the controls, liver superoxide dismutase (SOD) activity was significantly increased in group STZ-0E and STZ-40E, while the ac ivities of liver glutathione peroxidase (GSH-Px) and glutathione S-transferase (GST) were significantly reduced. The liver vitamin E contents in groups STZ-0 E and STZ-40 E significantly lower than those of the controls. In addition, the activity of reduced glutathione (GSH) was decreased in the livers of all diabetic rats by 59%, 51%, and 19% for groups STZ-0 E, STZ-40 E and STZ-400 E respectively, relative to the controls. Dietary supplementation with large amounts of vitamin E resulted in an increase of GSH/GSSG activity. In the livers of rats in groups STZ-0 E and STZ-40E, the lipid peroxide levels were 5.6 and 2.5 times higher than those of the controls. These results suggest that STZ-induced diabetic rats are more sensitive to oxidative stress and have higher rates of lipid peroxidation. Dietary vitamin E may reduce this peroxidative tissue damage by promoting antioxidative mechanism.

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We have previously reported that the fermentation of dietary beet fiber (BF) in the cecum of male Sprague-Dawley rats plays an essential part in the hypocholesterolemic effect of BF. We have now studied the effect of antibiotics on the BF-mediated hypocholesterolemia. Rats were fed a cholesterol-free diet with or without (fiber-free, FF) BF, together with one of the following antibiotics: 0.1% neomycin sulfate (NE), 0.1% streptomycin sulfate (ST) or 0.1% penicillin G potassium (PE). The hypocholesterolemic effect of BF was observed only in rats fed the diet supplemented with NE, but not in rats fed the diets supplemented with ST or PE. Cecal acetate and n-butyrate concentrations together with fecal bile acid excretion, were higher in rats fed the 10% BF diet than in those fed the FF diet. The BF-induced increase in cecal short-chain fatty acids and bile acid excretion were smaller in rats with NE and ST in their diet compared with those with PE in their diet. These results suggest that the fermentation of BF by NE-insensitive bacteria and ST-and PE-sensitive bacteria, may be related to the hypocholesterolemic effect of BF. Cecal infusion of three fractions prepared from cecal contents (water-soluble, ether-chloroform-soluble and residues) of BF-fed rats did not cause any reduction in plasma cholesterol concentration in rats fed the FF diet.

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The aim of this study was to examine the effect of proteins on diarrhea. Soybean protein and the resultant, high molecular weight fraction (HF) obtained after pancreatin digestion, were fed to enterectomized rat as enteral liquid diets. After resecting the small intestine, a catheter was placed into the duodenum for 5 days postoperative enteral feeding. In the first experiment, the rats were divided into three groups and fed on either a soybean protein-based diet (SP), a casein-based diet (CA), or a 1: 2 soybean protein: casein mixture (MX). The incidence of diarrhea in the SP and MX groups was significantly lower than that of the CA group. In the second experiment, the rats fed on CA supplemented with HF were compared with those in groups CA and SP. The incidence of diarrhea in this group was significantly lower than that of the CA group and similar to that of the SP group. These results indicate that soybean protein and HF may reduce diarrhea caused by enteral feeding after surgical operation of the rat dig stive tract.

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The tissue structure of the aleurone layer in different bean seeds, and its content of the glycine-rich protein (GRP) were investigated. The aleurone layers of soybean (Glycine max, cv. Enrei), black soybean (Glycine max, cv. Tanbaguro), and wild soybean (Glycine soja) were thicker compared to those of red kidney bean (Phaseolus vulgaris, cv. Taishokintoki) and marbled kidney bean (Phaseolus vulgaris, cv. Toramame). The soybean GRP, which is a characteristic of the cell walls in the aleurone layer, was found mainly in the pectin fraction. The GRP content, found in the hot-water-soluble fraction of the aleurone layer, in the three kinds of soybean was greater than that found in the two kinds of kidney bean. The estimated molecular size (about 30 kDa) of the GRPs extracted from both the wild and black soybeans was the same as that from Glycine max, cv Enrei. The GRP, found in the aleurone layer of plantS belonging to the soybean genus, probably has some role in strengthening the cell walls in this tissue.

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A clinical study was carried out in 23 patients with borderline hypertension. In order to verify the clinical effects of Chlorella on hypertension, thirteen patients were given 1.5g of Chlorella daily for 6 months (Chlorella group) and the other 10 patients were given health advice only (control group). The Chlorella used for the study, was cultured under heterotrophic conditions with glucose as the carbon source. A significant reduction in both systolic and diastolic blood pressure was observed after 3 months in the Chlorella group, while no significant fluctuations in the blood pressure of the control group were observed during the study period. After 6 months, systolic and diastolic blood pressure in the Chlorella group were reduced by 14.1±1.9 and 6.3±1.8 mmHg, respectively. The results of a questionnaire answered by the Chlorella group also indicated a reduction of hypertension-related symptoms, and improvements in general physical condition. A variety of clinical data showed that Chlorella ingestion had no harmful effects on the subjects. These results suggest that daily ingestion of Chlorella is effective in reducing hypertension.

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We measured the selenium content of Japanese enteral formulas using a fluorimetric procedure. The amount of selenium present in these formulas varied widely, the highest amounts (2.77-5.74μg/100kcal) were found in egg albumin-based diets. Casein-based formulas contained intermediate amounts (0.45-1.88μg/100kcal) whilst the chemically defined formulas contained the lowest amounts (0.04-0.58μg/100kcal). Based on an average caloric ingestion in adult women of 2, 000 kcal/day, or 2, 550 kcal/day, in adult men, we calculated that women would receive 3.2-114.8μg/day of selenium, and men 4.1-146.4μg/day, depending on the formula prescribed. Sixteen of the 22 formulas analyzed contained levels of selenium, which would fall below the USA recommended dietary allowances (RDA). Selenium supplementation should therefore be considered for these formulas.

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The inosinic acid, IMP (inosine monophosphate) and glutamic acid concentrations were measured in bread fermented with baker's yeast (Saccharomyces cerevisiae). In general, the inosinic acid content of bread increased>2x, after fermentation. Dough made from hard wheat flour contained considerably higher levels of inosinic and glutamic acid than dough made from medium or soft flour. Conversely, the glutamate content reduced to less than half of that found in nonfermented dough. The formation of inosinic acid in fermented bread can be explained by the high AMP deaminase activity and the low activity of 5′-nucleotidase in yeast an enzyme that hydrolyzes IMP. Our data shows that inosinic acid plays a principal role, as the taste compound in fermented bread, whilst glutamate has only minor significance.

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