Nutrition and metabolism最新文献

A blood pressure-lowering effect of increased prostaglandin synthesis via polyunsaturated fatty acids has been demonstrated in animal experiments. To our knowledge, for the first time an attempt was made to lower elevated blood pressures in adolescents (age 15-18 years) through a diet enriched in polyunsaturated fatty acids. This community-based dietary trial involved 30 students in the diet group and 20 students in the control group without any dietary intervention. Within 6 weeks the systolic blood pressure decreased by almost 11 mm Hg in the diet group and by 6 mm Hg in the control group. Diastolic blood pressure fell by 2 and 1 mm Hg, respectively. The effect on blood pressure was markedly different in normal weight adolescents. Systolic blood pressure in the diet group decreased by 14 mm Hg but only by 5 mm Hg in the control group. Diastolic blood pressure levels fell by 4 mm Hg in the diet group and increased by 4 mm Hg in the control group. Unfortunately, the numbers in these two comparison groups were rather small. The majority (70%) of adolescents with high blood pressure was overweight (greater than or equal to 20% above normal weight). However, for the small group of normal weight adolescents, the diet enriched with polyunsaturated fatty acids may be suitable to reduce elevated blood pressure levels.

Monitoring secular trends in mortality as well as morbidity from coronary heart disease (CHD) is important in order to relate favourable or unfavourable habits of daily living to the risk of disease, with a view toward effective preventive measures. A marked decline in CHD mortality has been observed in the United States during the past decade. Similar, but smaller, reductions have been recorded in a few other countries but the overall international tendency is toward unchanged or increasing mortality. There is a suggestion for countries with initially higher rates to register declines while the reverse tends to occur for low-mortality countries. The favourable trends in the United States can be linked to improvements in the style of life but parallel information in other countries is largely lacking. International, collaborative efforts to monitor CHD disease rates, living habits and risk factor distributions by country, region and social groups is a major need in the search for effective prevention programmes in the community.

Healthy individuals were given different carbohydrate-rich test meals (each with an energy content of 300 kcal) after a standardization period. Plasma glucose and insulin were measured during the tests. When compared with an ordinary oral glucose load, potato had a post-prandial plasma glucose and insulin response not statistically different from the glucose load, the bread group had a weaker and slower response than the potato group, and rice had a response between the two other groups. Gastric emptying, the availability of the starch for digestion and differences in the carbohydrate content are discussed as possible explanations for these differences.

Premature infants have a lower selenium concentration in serum than full-term infants and children. The selenium concentration goes down quickly in infants treated for respiratory distress syndrome without supplementation. One premature infant with bronchopulmonary dysplasia had persistently low concentrations of selenium. Vitamin E supplements did not affect the serum selenium concentration in healthy premature infants. Supplementation with 3 microgram/kg of selenium in parenteral fluids prevented the fall in the concentration seen in other infants not supplemented. Premature infants and especially those treated with oxygen may warrant selenium supplementation to the parenteral nutrition solution. Vitamin E supplements alone are apparently not sufficient to prevent selenium deficiency and potential oxygen toxicity.

10 men and 9 women consumed diets that were identical, except for the 30% of the calories derived from either starch or sucrose, for 6 weeks in a crossover design. Of the total calories, 10% were given at breakfast and 90% at dinner. A sucrose load of 2 g/kg body weight was administered 1 week before and during the last week of both dietary periods. Blood was drawn before (fasting) and 0.5, 1, 2 and 3 h after the sucrose load. Serum uric acid was significantly higher (p < 0.01) and blood fructose significantly lower (p < 0.05) before and at all times after the sucrose load when subjects consumed the sucrose versus the starch diet. Levels of serum inorganic phosphorus and blood lactic acid were not affected by kind of carbohydrate in the diet.

Within the framework of a project of primary prevention of coronary heart disease the erythrocyte fatty acid composition was determined in 140 Italian middle-aged men on free diet. The linoleic/oleic ratio ranged from 0.27 to 0.96 pointing out remarkable differences in dietary fat intake. A negative correlation was observed between erythrocyte linoleic/oleic ratio and plasma cholesterol levels. This gives indirect support to the validity of this ratio as an index of adherence to cholesterol-lowering diets in long-term studies.

The effect of cupric and calcium ions on zinc absorption was examined in Sprague-Dawley rats. In in vivo studies test solutions containing 7.5 mM 65ZnCl2 alone or in combination with 500 mM of either CuSO4 or CaCl2 were administered intraduodenally to three groups of rats. 2 h later the animals were sacrificed and their organ 65Zn content was determined. The results of these studies revealed that excess cupric ions had no effect on the 65Zn content of rat internal organs, whereas excess calcium ions decreased organs 65Zn content to 40%. Similar results were obtained in in vitro studies using three sets of rat jejunal sacs each filled with one of the above test solutions and incubated in oxygenated Eagle's medium. To investigate the reason(s) for the observed decreased rate of zinc absorption in the presence of excess luminal calcium, we examined zinc transport in 6 sets of jejunal sacs using six test solutions, each containing 7.5 mM 65ZnCl2 with 0, 12.5, 25, 37.5, 50, or 62.5 mM CaCl2. These experiments showed that 65Zn transport from mucosa to serosa was decreased by 40% in the presence of 25.0 mM CaCl2 but lower calcium concentrations had no effect on zinc transport. Increasing the luminal calcium concentration from 25 to 62.5 mM did not cause a further significant decrease in the rate of zinc transport. These results strongly suggest that zinc absorption in the rat is mediated by a transcellular transport process different from that which mediates copper and calcium absorption. The fact that calcium has been shown to reduce passive cation movements via shunt pathways in the gallbladder mucosa suggests the possibility that calcium in high luminal concentration may depress zinc absorption by reducing the passive component of jejunal zinc absorption.

Rats were physically trained by treadmill running and fed normal, high fat, or identical diets supplemented with 1.0% D,L-carnitine. Fatty acid oxidation, stimulated by exercise and/or by a high fat diet was studied to determine if it might be further augmented by supplemental dietary carnitine. Fatty acid oxidation in vitro or in vivo was unaffected by carnitine feeding. Carnitine feeding was associated with an increase in heart and muscle palmitylcarnitine acyltransferase activity and reduced serum cholesterol in trained rats fed the high fat diet. Under the conditions of this study, supplemental dietary carnitine did not greatly alter glyceride synthesis, lipolysis, or fatty acid oxidation, which indirectly indicates that the increased demands for fatty acid oxidation resulting from exercise or from fat feeding are adequately supported by endogenous levels of carnitine.

In former experiments we found that the extent of experimentally induced hypercholesterolemia in male Sprague-Dawley rats was significantly reduced by incorporation of 20% Scenedesmus powder in the diet. This paper reports on the localization of the activity in Scenedesmus powder following extraction of hydrophilic and lipophilic fractions. The fractions obtained by hot water treatment and chloroform-methanol extraction and the remaining extracted algae were incorporated in the standard diet in amounts corresponding to 20% Scenedesmus powder. In animals fed on the standard diet + 3% cholesterol for 6 weeks, the average concentration of blood plasma cholesterol increased from 2.0 to 3.5 mmol/l. The average cholesterol level in animals receiving the different algae extracts + 3% cholesterol amounted to between 2.1 and 2.9 mmol/l. The hot water extracted algae material held the plasma cholesterol levels in cholesterol-stressed animals at normal values. The content of plasma triglyceride in animals receiving the different fractions was lowered by 35-55% in nearly all groups. In cholesterol-stressed animals the excessive deposition of cholesterol in the liver was reduced by untreated algal powder as well as algal material extracted with water or chloroform/methanol. The decrease in liver cholesterol amounted to 50%.

Albino rats were malnourished from neonatal to weanling stage by increasing the litter size. The in vivo incorporation of (1-(14)C)-acetate, (1-(14)C)-palmitate into the lipid classes was examined in the animals. A stimulated incorporation of the label was observed in total lipids, phospholipids, cholesterol, cerebrosides and sulfatides of the brain of malnourished animals compared to controls.