[New concepts in nutrition: considerations on the connection diet-health]. / Novos conceitos em nutrição. Reflexões a respeito do elo dieta e saúde.

The physiological effects of several foods are discussed as possible factors reducing the risk of degenerative diseases as cardiovascular and some cancers. The new emmerging concept of functional foods is presented with examples as the phytoestrogens of soya beans. The importance of consuming olive oil is emphatic, but with criticism to the lost of physiological bioactive material during the normal extractions of the olive oil and the refinement. So, much attention is needed. The way to obtain much of these bioactive protectors foods is summarized.

Enhancement of sodium intestinal secretion in relation to absorption in malnourished rats. Hyperosmolar challenge.

Two experimental models were tried in young malnourished rats in order to study effect of an hyperosmolar challenge in the small intestine on the bi-directional fluxes of sodium. Weanling rats were fed with energy restricted diets. In model I 1 mL of NaCl 900 mOsm/kg was introduced in the small intestine of the rats and left from 5 up to 70 min, in order to determine the moment of higher net Na+ secretion, which occurred at 10 min. In model II, the bi-directional fluxes of Na+ and Cl- were studied using NaCl or mannitol 900 mOsm/kg under the effect of mecholil, atropine or 2-4 dinitrophenol, for 10 min. Mecholil decreased the Na+ absorption enhancing the net secretion. Control rats were used as reference. In the restricted diets animals occurred an increase of the net secretion stimulated by NaCl 900 mOsm/kg, and this effect was enhanced by mecholil. It is suggested that in malnutrition there is an impairment in Na- intestinal absorption.

Differential effects of protein restriction on gamma-glutamyltranspeptidase [EC 2.3.2.2] activity in young and mature rats.

Gamma-glutamyltranspeptidase (GGT, EC 2.3.2.2) activity was determined in the plasma and liver of 40 young (50 days old) and 40 mature (300 days old) male Wistar rats, after a protein restriction period of 28 days. Casein protein levels used were: 1%, 3%, 5%, 7% and 28% (control). Weanling rats submitted to protein-free diet and adult rats submitted to that and other low-protein diets (1%, 3% or 5% casein) presented weight reductions (-0.38 +/- 0.07 g/day and -0.98 +/- 0.19 g/day, respectively). Only in young animals did these weight reductions parallel those of food consumption (37 +/- 12% of control), plasma protein (52 +/- 11% of control), plasma albumin (70 +/- 12% of control), hepatic RNA (68 +/- 7% of control) and protein (71 +/- 8% of control). A marked effect of the protein restriction, increasing the GGT activity, was also observed only in young rats. A significant (P < 0.05) rise was promoted by the protein-free diet in the plasma GGT (2.83 +/- 1.39 vs 0.69 +/- 0.50 mU/ml for control) and by both the protein-free and 3% casein diets, in the liver GGT (respectively, 16.00 +/- 6.72 and 7.75 +/- 3.49 vs 0.94 +/- 0.57 U/g protein for control). The different results obtained for young in relation to mature animals could be explained by the reduction of both protein and sulfur-containing amino acid requirements with aging.

Dietary nitrite and scavenger antioxidants trace elements.

Rats initially weighing 138 +/- 14 g were fed the following diets for 150 days: control (Co), control plus nitrite-bacon-proline 24 mg/kg, 100 g/kg and 10 mg/kg, respectively (NB), NB plus 0.04 micrograms/g selenium (NBSe) and NB plus 0.020 g/kg ascorbic acid (NBC). The NB diet provoked body weight and feeding efficiency enhancement with a reduction in body density increasing serum lactic acid, uric acid and cholesterol levels. The serum selenium decreased by the presence of NB in the diet. The addition of selenium and ascorbic acid to the NB diet prevented the reduction in body density and also affected uric acid and cholesterol levels. It is suggested that the NB diet has adverse effects and that some of the alterations it causes are prevented by the reducing elements selenium and ascorbic acid.

Effects of dietary fat and nitrite on plasma and corporal density.

Two groups of nine weanling male rats each were fed different diets for 60 days. Group A (control) was fed a full casein diet containing 17% protein. The group B received the same diet plus nitrite, fried bacon and proline. Diet B induced increased body weight gain and increased plasma l-lactic acid and cholesterol levels, as well as a decrease in plasma selenium. We suggest that the adverse effects of diet B are related to peroxidation, with an increased nutritional need for selenium.

Nutrition-physiology link. Need to increase basic research.

Some complex mechanisms of intestinal absorption are commented in relation to their link with interactions among nutrients, or to the alimentary system itself. The nutrient bioavailability is also considered in relation to the individual nutritional status in order to emphasize the need of depth knowledge in physiology for the best understanding of nutrition and reciprocally.

A kinetic study of some factors which influence the intestinal absorption of calcium in rats.

Rats weighing 100 +/- 8 g were used in an in vivo kinetic study of the intestinal absorption of calcium (CaA) from three systems: 1) CaCl2, 2) whole cow's milk (M), and 3) a staple Brazilian diet (SBD). Food substrates were treated with HCl, neutralized and diluted with 0.15 mM NaCl to different concentrations. Each dilution was assayed by introducing 2 ml into the small intestine and the final amount of Ca2+ in the small intestine was determined 30 min later. The values for velocity (v = Vmax (Ca2+)/(Ca2+) + Km) and affinity (1/Km) for the food substrates were 1.35, 15.51 and 2.31 micrograms Ca2+/min and 0.29, 0.016 and 0.266 micrograms Ca2+/ml, respectively. We conclude that the higher affinities observed for CaCl2 and SBD were not correlated with velocity. Factors modifying CaA appear to be protein (stimulator) and phytate and fiber (inhibitors).

Bio-utilization of protein, calcium and zinc from diets based on rice and beans, in human beings.

Nine male healthy adults volunteers of average body weight 69.51 +/- 11.59 kg were submitted to 3 experimental diets: I complete diet, containing rice and beans (RB): II--low protein, low calcium: III--vegetable diet containing RB. The diets were consumed "ad libitum". The total energy intake in each dietary period were: 46.04 +/- 9.18; 37.57 +/- 9.04; 55.27 +/- 7.18 respectively. The average free choice for the proportion of rice/beans was 1.22 and 1.35 in the periods I and III. The protein balance was positive only for the diet I and the balance of calcium was positive in diets I and II. Zinc didn't attained positive balance neither in diet I. It is suggested that the presence of beans in diets I and III plays an important role in decreasing the bio-utilization of the studied nutrients.

Rice and beans--effect of milk, mineral, and vitamin A, on weight gain, food intake, and body protein retention.

Weanling rats were fed on diets of rice/beans (RB) with or without mineral (M) supplement; vitamin A (A); M + A (MA); or milk (L), containing from 3 to 14% protein. As determined by various measures, the best results were observed in the group fed the RB diet, supplemented with L. This group was followed by those receiving the MA and M diets. Protein utilization in the RB diet, as well as minimum protein requirement for maintaining body weight, depend on the supplementary nutrients. The mechanism of this effect may be related to the appetite of the animals and to the voluntary intake, which is influenced and regulated by the diet composition.

[Effect of lactose ingestion on body development. Study in rats]. / Efeito da ingestão de lactose no desenvolvimento corporal. Estudo em ratos.

Dams (rats) and their offsprings were fed on diets containing casein (Cas) or rice and beans (RB) as protein source. The presence of lactose improved the whole animal as well as the intestinal development in Cas diet but not from RB ones. It is suggested that lactose must be maintained permanently in diet but in low concentration. In this investigation it was also observed that the small intestinal development occurs initially by enhancement of length and weight, while after weaning only weight continues to increase independently of the presence or not of lactose in diet.

Effects of protein deficiency and rehabilitation on growth and tissue composition in growing rats.

The objective of the present work was to study the influence of protein quantity and quality on some biochemical parameters in the liver, brain and plasma of rats at 51 days of age. This profile was sketched through the weight of the liver and brain and their content of DNA, RNA and protein and through the total amount of protein, the ratio NE/E and the activity of transaminase GOT and GPT in the plasma. During gestation and lactation, diets of 20% casein, 8% casein and 8% corn were used. At weaning, five experimental groups, with and without nutritional recuperation, were established. As a result, it was observed that the groups fed on a hypoprotein diet (8% casein or 8% corn) were the most seriously compromised in body weight and biochemical parameters with the group fed on corn being the most seriously affected. The animal which were recuperated nutritionally presented a net improvement in all of the parameters. However, the values describing the development of the body and organs in these groups remained inferior to those obtained in the control group. The success of reversibility will depend on the phase of development during which malnutrition occurred and the duration and intensity of the original deficit and the subsequent rehabilitation treatment. Organs in a phase of accelerated development will be especially sensitive to the irreversible effects of malnutrition.

Marginal protein deficiency in pregnant rats. Changes in offspring body composition.

The influence of protein on some biochemical parameters in the liver, brain and plasma of rats at weaning was studied. The tissue parameters studied were the amounts of DNA, RNA and protein in the liver and brain. For the plasma, the parameters studied were the total amount of protein and the ratio of non-essential to essential amino acids (ratio NE/E). During the gestation and lactation period, the rats were divided into three groups according to the diet received: group 1, 20% casein; group 2, 8% casein; and group 3, 8% corn. As a result we can assert that groups 2 and 3, fed on hypoprotein diets, were seriously compromised in body weight and in the biochemical parameters and these alteration were enhanced by the corn diet. These results suggest that the alterations depend on the duration and intensity of the malnourishment and that the quality of the protein is an important factor to be considered.

Lactose load diet effect in rats.

Weanling and young adult rats were fed diets containing lactose (L) up to 50 g per 100 g diet for 15 days. The growth rats variation (W), fecal pH, net protein ratio (NPR) and protein efficiency ratio (PER) were determined. In weanling as well as in young adult rats an impairment of L was only detected for higher levels (greater than 20%), and diarrhea occurred only at 50%. The NPR and PER were partially effected by L because of the stimulation of appetite between 1 and 5 g%. The results for 10 and 20 g% of L were not different from controls. It was concluded that rats are not intolerant to levels of L less than or equal to 20%. The evaluation of protein quality in presence of L must be conducted with adapted methodology.

[Quality of maternal diet and biochemical changes in the brain of the offspring. Study in rats]. / Qualidade da dieta materna e alteracões bioquímicas no cérebro dos filhotes. Estudo em ratos.

The present study was undertaken to assess the effect of different levels of nutritional restriction during fetal life, suckling, and after weaning of the brain biochemical composition. At 41 days of age, the rats were killed and the brain was processed for analyses of DNA, RNA and protein. The results showed that the brain weights as well as DNA, RNA and protein brain contents were impaired by hypoprotein diet, and these alterations were enhanced by the corn diet.

[Effect of the intake of imbalanced protein on the liver of growing rats]. / Efeito da ingestão de proteína desbalanceada em fígado de ratos em crescimento.

The goal of the present work was to reproduce in laboratory animals situations frequently observed in low-income population, such as the insufficient energetic ingestion associated with protein sources of inferior quality. Corn was chosen as the protein source of low biological value and casein as the reference protein. The latter was administered in adequate quantity (20%) or equal to that of the corn (10%). Several biochemical parameters and the amounts of DNA, RNA and protein in the liver of rats in a phase of rapid growth were studied. In result, we can attest that the group fed on corn were the most seriously compromised in body weight, liver weight and biochemical parameters with the group fed a restricted diet of corn being the most seriously affected. The results suggest that the alterations caused by ingestion of a balanced diet restricted in quantity were less accentuated that those observed when the diet was of corn "ad libitum".

Corn amino acid imbalance and the role of leucine excess.

A study was conducted using two experimental models with weanling rats of the Wistar strain fed isocaloric diets containing 7% protein, Model I: two genetic varieties of maize were used; common corn (CC) or opaque-2-corn (M); and Model II: casein, 7% protein used without nicotinic acid in the diet in order to enhance the tryptophan limiting conditions like in the CC diet of Model I. PER, nitrogen balance, urinary urea and hepatic fat were determined. The results suggest that the imbalance of CC protein is related to lysine and tryptophan limitation, although the leucine excess content also plays an important role.

[Digestibility and protein efficiency of a mixture of rice and beans]. / Digestibilidade e eficiência da proteína de uma mistura de arroz e feijão.

In spite of considerable work in the area of protein quality, consideration should be given in the monitoring of methodologies. In the present investigation the author studied (in rast) digestibility (D) versus score (s) of the mixture of rice and beans or casein diets, containing different protein levels. The parameter "DS" overestimated the value of protein in relation to other methods. Milk diet at 10% of protein was efficient in all nutritional situations.