A comparison between an in vitro method to determine carbohydrate digestion rate and the glycemic response in young men.

OBJECTIVE: This study examines the relationship between the results of in vitro determinations of carbohydrate digestion rates and the glycemic index. SUBJECTS: Ten healthy non smoking men, aged between 21 and 24-y-old, were selected to participate in the study. METHODS: Six different meals with similar levels of carbohydrates were assayed at breakfast in ten subjects and blood samples were obtained at 0, 15, 30, 60 and 120 min to determine glucose levels. The Englyst's enzymatic method was used in the in vitro study. The six meals were based in cereals (rice or spaghetti); legumes (lentil soup and beans with spaghetti); and potato (potato stew with meat and vegetables). RESULTS: The meals showed different glycemic indices: rice and spaghetti based meals had lower values (mean value 31.4 and 42, respectively); the intermediate values corresponded to lentil soup and the bean dish (49.3, and 76.8 respectively) and the higher glycemic index was shown by the potato based meal (82). CONCLUSIONS: A significant correlation was observed when the ratio of rapid carbohydrate digestion rate and the lente carbohydrate digestion rate was correlated with the glycemic index of the meals, but not when only the rapid carbohydrate digestion rate was considered. These results demonstrate a useful, simple and inexpensive method to estimate the biological response of high carbohydrate meals.

[Effect of dietary polyunsaturated fatty acids on the content and metabolism of glutathione in rat kidney]. / Contenido de glutation en riñon de ratas: effecto del aumento de los acidos grasos poliinsaturados dieteticos.

The effect of dietary polyunsaturated fatty acids (PIFA) upon the content of reduced glutathione (GSH) of the kidney was studied in 32 male Wistar rats. Two equal size groups were fed diets supplemented with either 10% or 18% corn oil. Sixteen hours before death, half of each experimental group was submitted to fasting. The content of GSH and the activity of gamma glutamyl transpeptidase (GGTP) and gamma glutamyl cysteine synthetase was determined in kidney tissue. Fasting led to a reduction of GSH from 3.21 +/- 0.54 to 1.25 +/- 0.20 mumol per gm in the group fed 10%. PIFA. Equivalent figures for the group fed 18% PIFA were 3.49 +/- 0.54 and 0.49 +/- 0.08, respectively. GGTP activity increased significantly after fasting but no differences were observed according to level of PIFA intake. The exaggerated reduction of GSH during fasting after a high PIFA intake may expose the animals to risk of cell damage induced by peroxides or other oxidating agents.

[Effect of increase of dietary polyunsaturated fatty acids (omega 6) on the hepatic glutathione content and gamma-glutamil transpeptidase activity in the kidney of rats]. / Efecto del aumento de los ácidos grasos poliinsaturados (omega 6) dietéticos en el contenido de glutatión hepático y actividad de gama glutamil transpeptidasa en riñón de ratas.

The effect of feeding 24 to 52-days-old male rats of the Wistar strain, with beans diet deficient in sulfur-containing amino acids or supplemented with 0.3% DL-methionine and two corn oil concentrations, 2% and 20% (g/kg/diet), on the glutathione content (GSH) in liver, and on the renal gamma glutamyl transpeptidase (GGTP) (E.C.2.3.2.2) activity was studied. Results indicated that rats fed the bean diet with 2% corn oil decreased significantly the liver GSH content and GGTP renal activity. Supplementation with 0.3% methionine and/or the 20% increment of the diet corn oil, significantly stimulated the liver GSH content and the transpeptidase activity in the kidney. It is postulated that the increase of polyunsaturated fatty acids, stimulated the GGTP activity as a way of increasing substrate bioavailability for synthesis de novo of liver GSH, necessary for the protection of the hydroperoxides formation, attributed to the increment of polyunsaturated acids at cellular level.

[Soluble and insoluble dietary fiber in cereals and legumes cultivated in Chile]. / Fibra dietética soluble e insoluble en cereales y leguminosas cultivadas en Chile.

Insoluble, soluble and total dietary fiber (DF) were determined in 35 varieties of certified whole seeds (without processing) of cereals (rice, oat, rye, and wheat) and legumes (pea, cowpea, beans, chikpea, lentil and lupine). The enzymatic method of Asp, Johansson and Siljestrom was used, with modifications in relation to time of incubation with alpha amylase, filtration system and volumes of the filtrates. Results were expressed as g/100 g dry weight. Total DF for cereals showed a range from 10.1 (wheat var. Chasqui) to 22.2 (rice var Quella). Rye, var. Tetra Baer and oats var. Pony Baer presented the highest soluble fiber content (3.3 and 3.9, respectively). In legumes, total DF fluctuated between 12.7 (pea, var. yellow) and 36.6 (lupine, var. Multolupa). Bean, var. Pinto INIA and lupine var. Multolupa presented the highest soluble fiber values (5.8 for both). Based on the results of this research work, it might be concluded that great variation exists in regard to the amount of total soluble and insoluble DF in cereals and legumes, a fact which impedes generalization as to its content in each food item.

[Legume consumption among pre-school children: effect of energy density and type of preparation]. / Consumo de leguminosas en preescolares: efecto de la densidad energética y tipo de preparación.

The objective of this study was to evaluate the effect of the energy density (E.D.), children's age and type of meals on the consumption of dishes based on legumes and its combination with cereals by preschool children, for the purpose of defining if they were adequate for preschool children's feeding. Thirty children aged 2 to 5 years old who lived in a foster home, were assigned to three experimental groups. Each group was formed by 10 children. Twenty-nine meals were offered to all groups, differing in their energy density: 0.85, 0.94 and 1.03 kcal/g in dishes of legumes and cereals, and 0.47, 0.62 and 0.80 kcal/g in soups. The study was conducted during 29 non-consecutive days throughout a period of 80 days. Food consumption of each child was determined by differential weighing. Food and energy consumption of the legume-cereal dishes was significantly higher than those observed in the case of soups (312 vs 223 g and 288 vs 138 kcal, respectively). The effect of age was verified only when the volume and energy intake was expressed by kg of body weight, being the group with the highest age which showed the lowest food and energy intake, either in dishes or in soups. The relationship between meal consumption and E.D. was significantly inverse. Dishes based on legume-cereal were consumed by pre-school children in sufficient amounts to satisfy their energy requirements in one meal, when these meals have an E.D. of 1.03 kcal/g (3% of added oil). The low E.D. of soups conditioned the fact that these meals were inadequate for the feeding of this age group.

[Index of nutritional quality per volume: a new indicator to evaluate the nutritional quality of food preparations and diets]. / Indice de calidad nutricional por volumen (ICNV): un nuevo indicador para evaluar la calidad nutricional de preparaciones y dietas.

The purpose of this study was to propose a new dietary index to evaluate the nutritional quality of common dishes and diets: the index of nutritional quality per volume (INQV). In its expression, this index takes into account the nutrient density (amount of nutrient/1,000 g of diet) and the nutrient density per reference volume. The last one is the ratio between the recommended allowances of the nutrient and the volume that it is possible to consume during the day, when the diet is offered freely. Zinc was used as example in the analysis. A total of 14 dishes of habitual consumption in Chile were studied in relation to its consumption by 30 preschool children. The volume that children were able to consume was determined by differential weighing between the amount offered and the amount left on the dish, during a period of 180 days. The percentage of water and energy value were established by means of chemical analysis performed according to the AOAC, and the zinc concentration by atomic absorption spectrophotometry. The results of the INQV were then compared with those of the index of nutritional quality (INQ), which considers zinc density/1,000 kcal, and zinc and energy requirements. This comparison demonstrated that the INQV values were lower than those of the INQ in dishes with energy densities lower than 1.0 kcal/g. The opposite tendency was observed in the case of those dishes with energy densities higher than 1.0 kcal/g. The analysis herein presented demonstrates the usefulness of the INQV in diets which are voluminous and with low energy densities, commonly consumed by the low socioeconomic strata of developing countries.

[Extruded beans: potential use in infant nutrition]. / Frijol extruido: potencialidad de su utilización en la alimentación infantil.

The nutritional value of extruded bean flour (Phaseolus vulgaris, var. tórtola) obtained from the food industry was assessed in terms of chemical composition, biological value of protein, amino acid supplementation, and hemagglutinin content. The assessment also included several mixtures with extruded bean that could be applicable for infant and preschool feeding. The NPU of the samples ranged from 37.3 to 43.9 and the titer of hemagglutinins, from 0 to 2. A remarkable increase in protein quality was observed when DL-methionine was added. Six mixtures using extruded bean in concentrations ranging from 30 to 80%, plus rice, wheat flour, skimmilk and DL-methionine were formulated. The protein contents varied from 16.4 to 26.8 g/100 g, with a NPU of 58.5 to 69.7. The usefulness of these mixtures to meet the energy and protein allowances according to the WHO/FAO report of 1973, is discussed. It is concluded that extruded bean flour is a promising food for infant and preschool feeding, especially when added to mixtures that will improve their efficiency in meeting nutritional allowances.

[Analysis of the application of methods recommended by FAO/WHO 1973 for determining the protein quality in Chilean food. Effect of the dietary protein concentration]. / Análisis de la aplicación de los métodos recomendados for FAO/OMS 1973 para determinar calidad proteínica en alimentos chilenos. Efecto de la concentración de la proteína dietaria.

The 1973 FAO/WHO Joint Expert Committee on Energy and Protein Requirements has recommended two methods to adjust the safe level of protein intake according to protein quality: chemical score and net protein utilization (NPU). However, the effect of protein concentration on protein utilization is not considered. The results of the present work, as well as those obtained by other investigators, show that there is an inverse relationship between protein concentration and protein utilization. The net protein utilization (NPU) at 10% of protein-calories or the chemical score adjusted by the nitrogen digestibility can be applied when results are to be projected to national average diets, which have values ranging between 9 and 13%. When it is necessary to evaluate the diet of specific relatively homogeneous population groups, the recommended method should use the NPU determined or calculated in each meal considering the level of protein concentration of the diet as eaten (NPU op). This method takes into account the amino acid complementation in each meal. The data on which these conclusions are based have been presented and discussed.

[Effect of various heat treatments in the hemagglutinin content and in the protein quality of beans (Phaseolus vulgaris)]. / Efecto de diversos tratamientos térmicos en el contenido de hemaglutininas y en la calidad protéica del frijol (Phaseolus vulgaris).

The effect of pre-soaking raw seed beans upon detoxification and the biological quality of its protein were evaluated. In whole raw seed beans (Phaseolus vulgaris) var. "tórtola", the net protein utilization (NPU), true digestibility and hemagglutinin titer were determined after 60', 90' and 120' of heat treatment, with and without 14 hours of pre-soaking. It is concluded that soaking prior to cooking is not necessary to eliminate the toxicity of dry beans, but that it does contribute to the softening of seeds and reduction of cooking time. The hemagglutinin levels of six commercial bean flours were evaluated, concluding that almost all of them presented toxic levels. The effect of the cooking methods upon the toxicity of bean flours was studied. Two raw bean flours, var. "tórtola" and "burro" at 10% and 20%, were cooked employing different boiling times (5, 10, 15 and 30'). The two raw samples contained high hemagglutinin levels which were inactivated at 10% with 10' cooking. The presence of toxic levels was detected at 20% after 15' cooking and these were eliminated at 30' of cooking.

[Protein quality and hemagglutin content in tender and dried bean seeds (Phaseolus vulgaris) coscorrón variety]. / Calidad protéica y contenido de hemaglutininas en semillas tiernas y en estado seco de frijoles (Phaseolus vulgaris) var coscorrón.

Protein quality and hemagglutinating content in tender and dry seed beans: The chemical composition, hemagglutinating activity, protein queality (NPU10) and true digestibility of samples at three certified bean seeds (Phaseolus vulgaris) var coscorrón, tender and dry (recollected 90-95 days and 120-125 days after seeding respectively), were determined. The tender and dry seeds were submitted to usual cooking (tender equals 30' boiling and dry equals 90' boiling previously soaked for +/- 14 hours in water). The hemagglutinating activity in raw tender and dry seeds was similar. The hemagglutinating activity was completely destroyed by these treatments. The protein quality and digestibility of cooked tender and dry samples were similar (NPU10) equals 48,4 and 47,5; true digestibility 79,9 and 80,1 respectively). It is concluded that heat treatments used are adquate to eliminate the hemagglutinating activity and toxicity of the seeds. In relation to protein quality there is no nutritional advantage of consuming tender or dry beans.