Growth, hormonal status and protein turnover in rats fed on a diet containing peas (Pisum sativum L.) as the source of protein.

The inclusion of peas (Pisum sativum L.) as the source of protein in the diet of growing rats brings about a reduction in growth rate as well as the impairment in the liver, muscle and spleen weights as compared with casein fed controls. Also, a fall in plasma glucose, triglycerides and protein was observed in the legume fed animals, while no changes in cholesterol levels were found. Furthermore, the rats fed on the diet containing peas showed lower levels of plasma insulin, corticosterone, IGF-I and T4 as compared with casein controls. Liver and muscle total protein (mg) and total DNA (mg) were markedly decreased in the legume fed animals, but DNA/g, protein/DNA and RNA/protein ratios were similar in both dietary groups. Likewise, liver and muscle fractional synthesis rates were similar in the casein and legume groups, while the whole body protein synthesis is assumed to be lower in the legume fed animals due to differences in body weights. It is concluded that animals fed on a diet containing peas (Pisum sativum L.) as the only source of protein showed less adverse effects than those found with other legumes such as Vicia faba L. or Phaseolus vulgaris L., in which protein quality, antinutritional factors and nutrient availability could be involved.

Skeletal growth after oral administration of demineralized bone matrix.

Oral administration of bone extracts obtained from bovine demineralized bone matrix to rats has a direct effect on bone metabolism, affecting bone proportions and some markers of bone formation such as bone malate dehydrogenase, serum alkaline phosphatase and serum osteocalcin. Furthermore collagen deposition, bone protein synthesis and nucleic acids content were significantly increased by the treatment.

Nutritional outcome and immunocompetence in mice fed on a diet containing raw field beans (Vicia faba, var. minor) as the source of protein.

Feeding growth mice on diets containing raw field beans (Vicia faba var. minor) as the only source of protein brought about an impairment in growth, muscle mass and liver weight. No changes in food consumption were observed, but the food intake:weight gain ratio was increased in those animals. Plasma protein, triacylglycerols and cholesterol values were not affected by the dietary treatment although serum glucose and zinc levels fell after legume intake as well as the number of circulating erythrocytes. The relative enlargement of thymus and spleen in the legume-fed mice was apparently accompanied by a reduction in the cell number and an increase in cell size, while the protein synthesis capacity followed differentiated patterns in both tissues when assessed through protein, DNA and RNA determinations. The haemagglutination titres and the number of rosette-forming cells were lower in those animals fed on the field bean diet as well as the splenic lymphocyte responses to phytohaemagglutinin, Concanavalin A or lipopolysaccharide mitogens used to evaluate the functional status of T and B lymphocytes. The present study describes, apparently for the first time in mice, the involvement of field bean intake in some immunological disturbances affecting both humoral- and cell-mediated aspects of the immune response.

Intestinal absorption of D-galactose in the presence of extracts from Phaseolus vulgaris hulls.

The relatively low nutritional value of protein from legume seeds has been attributed to the occurrence of some antinutritional factors and the poor content in sulphur aminoacids, which leads to undesirable physiological and biochemical alterations. However, the intimate nature of these processes remains unclear. In order to evaluate the influence of naturally occurring substances of legume constituents on nutrient utilization, the intestinal absorption of D-galactose in the presence of aqueous or alcoholic extracts, obtained from Phaseolus vulgaris hulls, has been measured by use of the in vivo successive absorption technique. Aqueous extracts inhibited significantly (p less than 0.01) the uptake of D-galactose at different times of exposure, while no changes in sugar transport were observed with the alcoholic solutions. Polyamide treatment (a polyphenolic complexing agent) of the aqueous extracts decreased its ability to inhibit sugar uptake. Kinetic studies showed that the aqueous fractions modify Vmax values for D-galactose absorption and also KT data. This inhibition appeared to be reversible after short periods of exposure, affecting mainly the active component of transport. Therefore, it can be suggested that some substances, contained in aqueous extracts of Phaseolus vulgaris reduce sugar absorption. Furthermore, our studies seem to indicate that polyphenols are, at least partly, involved in this phenomenon.

A reappraisal of the nutritional utilization of legumes.

A survey of the physiological, biochemical and immunological changes found in growing mice, rats and chickens fed on raw legumes as the main source of protein from our experimental research is reported. Evidence is summarized about the fact that the inclusion of these vegetable proteins on animal diets brings about a number of undesirable effects such as stunting of growth, reduced protein deposition, altered digestibility and absorption of nutrients and impairment of the immune response, which have been attributed to the occurrence of various antinutritional factors and to a poor sulphur amino acid content. The possible role of tannins and phytates on some of those alterations is reviewed.

Muscle and liver protein synthesis and degradation in growing rats fed a raw field bean (Vicia faba L.) diet.

Body weight gain, food intake, gastrocnemius muscle and liver weight, protein and RNA content, as well as the fractional rates of muscle and liver protein synthesis (ks, according to the method of constant infusion of L-[14C]tyrosine), growth (kg) and degradation (kd), along with RNA activity (g of protein synthesized per day/g RNA) of both organs, were determined in growing male rats fed ad libitum over a period of 10 days on 18.7% protein diets containing either casein (5% of methionine added) (control) or the raw legume field bean (Vicia faba L.) as the sole sources of protein. It has been found that as compared to control rats, those fed the raw legume diet exhibited a significant reduction in the rate of growth, muscle RNA, ks, kg, kd and RNA activity, and a significant increase in liver ks, kd and RNA activity. All differences were statistically significant at least at the 5% level. The possible nature of these findings is discussed.

Liver and muscle proteolytic activity in field bean (Vicia faba L.) fed birds. Effect of vitamin E.

Liver and muscle proteolytic activities (cathepsin A and D) were measured in growing male chickens fed ad libitum over periods of 30 and 60 days on 20% protein diets containing either heated soybean (HSB, control) or raw field bean (RFB, Vicia faba L.) as the main sources of protein. Vitamin E (250 mg/100 g diet) was added or not to the RFB diet. It has been found that in comparison to control HSB-fed animals, RFB-fed birds showed a significant reduction in the rate of growth, together with a significant increase in the activities of both cathepsins A and D in liver and muscle. The addition of vitamin E to the RFB diet had no significant effect on either weight gain or liver and muscle proteolytic activities. The possible nature of these effects is discussed.

[Role of polyphenols in the low nutritive value of Vicia faba]. / Papel de los polifenoles en el bajo valor nutritivo de la Vicia faba.

The inclusion of field bean (Vicia faba) in diets for growing experimental animals, reduced their growth performance in a similar way as compared with controls fed a casein diet, with 0.2% tannic acid. Hydroalcoholic extracts or isolated tannins obtained from Vicia faba seeds, decreased the intestinal transport of D-glucose. The addition of 0.05, 0.1 or 0.2% of tannic acid to the perfusion solutions containing D-glucose proportionally diminished the intestinal uptake of sugar according to its poliphenolic content. It has been postulated that polyphenols reduce, at least partially, the nutritive value of legumes, by altering monosaccharide absorption. Other constituents, however, could also be involved.

Papel de los polifenoles en el bajo valor nutritivo de la Vicia faba / Role of polyphenols in the low nutritive value of Vicia faba

La inclusión de harina de habas (Vicia faba) en la dieta de animales de experimentación produce un retardo en el crecimiento, semejante al inducido por la adición de 0.2% de ácido tánico en dietas control de caseína. Tanto los extractos hidroalcohólicos obtenidos a partir de semillas de havas. Asimismo, la presencia de ácido tánico al 0.05, 0.1 y 0.2% en las soluciones de glucosa, disminuye proporcionalmente la absorción de ésta por el intestino. Los resultados en cuestión parecen sugerir que los polifenoles afectan, al menos parcialmente, el valor nutritivo d ela leguminosa (Vivia faba), si bien otros componentes d elas mismas también podrían estar involucrados

Liver and muscle proteolytic activity in male growing rats fed a field bean (Vicia faba L.) diet.

Total liver cathepsin A and D and gastrocnemius acid proteolytic activities have been evaluated in male growing rats fed ad libitum over periods of 15 and 30 days on 20%-protein diets containing either casein or raw field bean (Vicia faba L.) as protein sources. It has been found that, compared to the control casein-fed rats, those fed the legume diet exhibited a marked reduction (p less than 0.05) in the rate of growth and protein efficiency rate; liver proteolytic activity increased with ageing in the two dietary treatments and was found to be significantly higher (p less than 0.05) in the legume-fed rats. However, muscle proteolytic activity decreased with ageing and proved significantly increased (p less than 0.05) in the legume-fed rats.

Response of muscle, liver and whole-body protein turnover to two different sources of protein in growing rats.

A significant impairment in growth rate, food efficiency and weight of the gastrocnemius muscle was observed in rats fed a raw legume as the source of protein compared to casein-fed animals. No appreciable differences in chemical composition of the carcass were found. The source of dietary protein did not influence the ratio protein/DNA, DNA concentration or protein-synthesizing capacity (RNA/protein). The slower weight gain of animals fed the legume diet was attributed to a lower muscle protein synthesis, mediated by a depression of muscle RNA activity (grams protein synthesized/gram RNA) rather than changes in myofibrillar protein breakdown. In contrast liver protein synthesis appeared to be slightly increased in the legume-fed animals.

Induced biochemical and physiological changes in young and adult growing rats fed on a vegetable or animal protein diet.

The influence of diets containing faba bean or casein as sources of protein were studied in rats at two stages of development. A significant impairment of growth rate, carcass, liver and skeletal muscle were found in young and adult rats fed for a period of 10 days on raw legume. Urinary urea output and the activities of three amino acid degrading enzymes: arginase, alanine aminotransferase and arginine succinate synthetase were all affected by the dietary protein and the stage of development. Urinary creatinine excretion was higher in the adult rats, while serum cholesterol was slightly increased in the young ones. Changes in plasma zinc may be attributed to a reduced zinc bioavailability to rats from the faba bean diet. Other biochemical parameters measured (glucose, triglycerides and plasma proteins) remained unchanged in all the experimental groups. Liver DNA and RNA content (mg/g tissue) decreased with age in both dietary groups, which were accompanied by an increase in tissue size. Furthermore, liver RNA concentration (primarily a measure of protein synthesis capacity) was enhanced in the adult legume fed rats. In this context, it is suggested that other organs (particularly muscle, with lower amino acid requirements for protein synthesis as a consequence of the stunting of growth) could contribute to increase the amino acid supply to liver in the animals fed on the faba bean diet.

Developmental changes on protein turnover in growing rats fed on diets containing field beans (Vicia faba L.) as source of protein.

The effects of nutrition with Vicia Faba L. administered at two different levels (12 and 18% protein) on the developmental changes of protein turnover were investigated in the rat. The myofibrillar gain and synthesis values were lower in the animals fed on legume protein as compared with casein-fed controls, while no differences were found in myofibrillar degradation during the three periods of time evaluated (0-14, 14-28 and 28-45 days). The fractional myofibrillar gain, breakdown and synthesis calculated as the sum of both, decreased with age in all the dietary groups. The antinutritional effects of the inclusion of Vicia faba L. in diets were more evident in the first 28 days, and attributed to a decreased muscle protein synthesis.

Muscle protein turnover in rats fed on diets containing different levels of Vicia faba L. and casein as source of protein.

The effects of intake of Vicia faba L. and casein as the sources of protein on protein synthesis and breakdown were investigated. The results showed that the protein deposition as a percentage of body weight as well as the muscle and myofibrillar nitrogen content are not altered by the experimental diets. The values of myofibrillar gain (mg N2/day) were higher in the animals fed on casein diets than those fed on legume protein at both levels (12 and 18%) while no differences were found in the myofibrillar protein breakdown assessed by the urinary excretion of 3-methylhistidine. Therefore, it is suggested that the stunting of growth is not due to an increased protein degradation, but an impaired protein synthesis.

Influence of diets containing different levels of Vicia faba L. as source of protein on body protein composition and nitrogen balance of growing rats.

Rats fed on Vicia faba as source of protein grew less than those fed a casein control diet. However, no differences were found on protein content of whole body, liver, muscle, and myofibrillar fraction. Nitrogen balance values were significantly higher in animals fed the casein diet than in those nourished with V. faba as source of protein. Minor differences due to the protein level of the diets were found. Retained nitrogen values were similar in all dietary groups. The inclusion of V. faba in the diet did not affect specifically muscle mass and protein distribution. It is suggested that differences reported in nitrogen balance are a consequence, at least in part, of the impairment of growth, although some other factors must be involved in this phenomenon.

Liver proteolytic activity in growing male chickens fed a raw field bean (Vicia faba L.) diet.

As compared to well-nourished chickens, a significant reduction (p less than 0.05) in the rate of growth, along with a significant increase (p less than 0.05) in liver activities of both cathepsin A and D has been found in growing male chickens fed ad libitum over a period of 60 days on a diet containing raw field bean (Vicia faba L.) as the main source of protein. Moreover, addition of methionine (250 mg/100 g diet) to the legume diet had no significant effect in restoring either rate of growth or liver proteolytic activity. The possible nature of these findings are briefly discussed.