Nine clinically healthy young women were given two different kinds of experimental diet; a control (C: containing 5g/day crude fiber) or a high-fiber (F: 15 g/day) diet for 10days each starting from the first day of menstruation. Reduction of systolic and diastolic blood pressure was significantly greater on the F diet than on the C diet. Plasma renin activity was lower on the F diet than on the C diet. Urinary aldosterone and kallikrein excretions were significantly higher on the F diet than on the C diet. Total cholesterol, HDL-cholesterol and triglyceride concentrations in serum were significantly lower on the F diet than on the C diet, and the atherogenic index (total cholesterol-HDL-cholesterol) was also significantly lower on the F diet. Serum insulin and glucose concentrations showed no difference between the two dietary regimens. As a high-fiber diet also contains a high amount of potassium, the reduction of blood pressure may be due to the effect of high potassium intake. A high-fiber diet may be useful for the dietary treatment of hypertensive subjects, especially those with accompanying hyperlipemia.

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Nine clinically healthy young women were given two different kinds of experimental diet; a control (C: containing 10 g/day salt and 2.5g/day potassium) or a high-potassium (K: given 1.9g K as KCl tablets/day with the C diet) diet for 10 days each starting from the first day of menstruation. Systolic blood pressure was decreased significantly after the K diet, whereas it was unchanged after the C diet. Plasma renin activity was lower on the K diet than on the C diet. Both urinary aldosterone and kallikrein excretions were significantly higher on the K diet than, on the C diet. Total cholesterol and triglyceride concentrations and atherogenic indices were significantly lower on the K diet than on the C diet. The serum insulin concentration was significantly higher on the K diet than on the C diet, whereas the serum glucose concentration did not differ between the two dietary regimens. These results suggest that a high-K diet not only decreases blood pressure but also improves lipid metabolism. Further investigation will be necessary in order to confirm the effects of dietary treatment on hypertensive and/or hyperlipidemic subjects.

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The effects of dietary protein levels (10% and 20%) on changes in the activity of serum alkaline phosphatase (APase, E.C. 3.1.3.1) and zinc concentrations in the serum and femur of zinc-deficient rats were determined using a demineralized soybean protein isolate as the source of dietary protein. When rats were fed a diet containing 10ppm zinc, body weight gain and food intake were higher in the 20% protein (HP) group than in the 10% protein (LP) group. However, serum APase activity, and serum and femur zinc concentrations were lower in the HP group than in the LP group. Similar tendencies were observed in rats fed a protein diet containing 4ppm zinc. The rates of reduction of these parameters in zinc-deficient rats during the feeding period were higher in the HP group than in the LP group. Rats fed the LP-zinc-deficient diet survived longer than those fed the HP-zinc-deficient diet. These results suggest that the higher rate of reduction of serum APase activity and serum and femur zinc concentrations in rats fed the HP-zinc-deficient diet might be due to an increased zinc requirement in the body.

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The effects of protein quality on changes in the activity of serum alkaline phosphatase (APase, E.C. 3.1.3.1) and tissue zinc concentrations in zinc-deficient rats were determined using demineralized soy protein (DP) and alkali-treated soy protein (AP) as sources of dietary protein. When rats were fed a zinc-deficient diet, no differences in body weight gain or food intake were observed between the 10% AP and 10% DP groups. Both serum APase activity and femur zinc concentration in zinc-deficient rats were decreased more in the 10% DP group than in the 10% AP group. The rates of reduction of these parameters in zinc-deficient rats during the feeding period were higher in the 10% DP group than in the 10% AP group. Rats fed the 10% AP zinc-deficient diet survived for 49 days, whereas those fed the 10% DP zinc-deficient diet survived for 33 days. These results suggest that the nutritive value as well as the level of dietary protein might affect the zinc requirement of rats.

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The availability of ethanol as an energy source and the effect of ethanol on nitrogen balance were studied by diet supplemenation with a low ethanol concentration. Four-week-old male Sprague-Dawley rats were fed for 2 weeks on a 1.45% whole-egg protein diet. Each diet was supplemented with a weight (but not energy) equivalent of glucose and graded levels of ethanol (0%, 4%, 8%, 16%, and 24% (w/w)), and gelatinized by addition of agar solution. Weight gain tended to increase in accordance with the ethanol concentration in the diet, although weight gain, food intake and epididymal fat pad weight were significantly lower in the 24% ethanol group than in the other groups. The weight of cecum contents was increased in both the 16% and 24% ethanol groups. Protein concentration and activities of GOT, GPT and LDH in serum did not differ among the groups. Concentrations of serum triglyceride. and β-lipoprotein were higher in the 24% ethanol group than in the other groups. There were no differences in the concentrations of total cholesterol and phospholipids in serum and liver among all the groups, although serum HDL-cholesterol and liver triglyceride concentrations were slightly low in the 24% ethanol group. Nitrogen balance was not significantly different among the groups, but markedly low in the 24% ethanol group. However, nitrogen balance tended to be positively enhanced with increased ethanol supplementation. These results suggest that dietary ethanol supplemented below 16% (26% as energy) appears to be effectively utilized as an energy source, and that nitrogen balance in animals receiving such a dietary content of ethanol may not be adversely affected.

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The effects of guar gum and cholestyramine on cholesterol metabolism were studied in meal-fed male Wistar adult rats maintained on a cholesterol-enriched or cholesterol-free purified diet for 2 weeks. At 3.5h after the last meal, blood was withdrawn by cardiac puncture, and then plasma and plasma lipoprotein-lipids, and liver cholesterol were determined. The results obtained were as follows: 1) In the cholesterol-fed rats, guar gum and cholestyramine suppressed the increase of plasma and liver cholesterol, and the decrease of HDL-cholesterol due to cholesterol intake. 2) In the rats fed the cholesterol-free diet, cholestyramine decreased chylomicron+VLDL-cholesterol, but did not alter the level of plasma cholesterol. 3) Guar gum decreased chylomicron+VLDL-, HDL- and plasma cholesterol in rats fed the cholesterol-free diet. These results demonstrate that the mechanism whereby guar gum lowers the plasma cholesterol level cannot be fully explained by interference with absorption of bile acid and cholesterol, which is the mode of action of cholestyramine.

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The effect of protein quality on the storage of retinol and retinyl palmitate in the liver of rats fed provitamin A in carrots was studied using vitamin A-deficient rats. The amino acid scores of casein, gluten, gluten plus amino acids, zein and zein Plus amino acids as dietary protein sources were 88, 22, 58, 2 and 65, respectively. Body weight gain was greater in the group given the casein diet than in the groups given the gluten and zein diets. The rats ingesting the casein diet had higher amounts of retinol and retinyl palmitate in the liver than rats fed the gluten and zein diets. Amino acid supplementation of the gluten and zein diets resulted in on increase of body weight gain and higher contents of hepatic retinol and retinyl palmitate. Efficiency of carotene utilization was greater in the rats fed the casein diet than in those fed the gluten and zein diets. The present results suggest that the quality of dietary protein significantly influences the storage of hepatic retinol and retinyl palmitate from carrot provitamin A.

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The effects of gallic acid and soya lecithin on the decomposition of tocopherol (Toc) in oils by oxidation products (oxidized fatty acids, OFA: fatty substances insoluble in petroleum ether) present in soybean oil were investigated. Olive and soybean oils containing OFA and/or gallic acid and soya lecithin were heated in a Pyrex glass tube (2.7×20 cm) at 180°C. Residual Toc was determined by HPLC. Decomposition of Toc in the oils and methyl oleate was apparently promoted by the addition of OFA, but gallic acid and soya lecithin suppressed the thermal decomposition of Toc by OFA. After complete decolnposition of Toc in olive oil, hardened rapeseed oil, soybean oil or methyl oleate by heating, gallic acid and soya lecithin were added and heating was again carried out at 180°C. Small amounts of Toc monomer-like material appeared in these oils during reheating. The retention time (HPLC), Rf value (TLC) and absorption maxima of the Toc monomer-like material were the same as those of standard Toc. From the above results, it was concluded that the Toc monomer is regenerated from oxidative products of Toc by gallic acid and soya lecithin.

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