Protein and amino acid requirements and the composition of complementary foods

In this paper, factorial models of the dietary requirements for protein, nitrogen and individual indispensable amino acids are developed from published information on the relationship between age and protein deposition and between protein (amino acid) intake and nitrogen balance. The results are used to develop recommendations on the protein-energy ratio and the amino acid pattern of the diet. As part of the development of the models, factors affecting dietary protein digestibility, bioavailability and efficiency of utilization are discussed. Over the age range of 6-24 mo the models predict a fall in the weight-specific protein and amino acid requirement that results almost entirely from the changes in the growth rate of the children. It is also concluded that the requirement for the maintenance of body protein equilibrium (so-called maintenance) changes little with age. This contrasts markedly with the relationship between age and energy requirements. The amino acid modeling implies that the optimum pattern of individual essential amino acids also changes only marginally across the age range considered in the report. The calculations of the dietary requirement for whole protein imply that achieving a minimum protein-energy ratio of 6.3% is desirable. The amount of protein needed from complementary foods for breast-fed children is discussed.     

Proximate composition,phytic acid,polyphenols and digestibility (in vitro) of four brown cowpea varieties

Four cultivars of brown cowpea (Vigna unguiculata. L. Walp) were analysed for their proximate composition, phytic acid, polyphenols and protein and starch digestibility (in vitro). Crude protein values ranged from 20.07 to 24.60%. Ether extract and crude fiber contents varied from 1.77 to 1.96% and 4.27 to 4.95%, respectively. All the four cowpea varieties differed significantly for their starch content which ranged from 46.84 to 53.63%. Antinutrients, phytic acid and polyphenols, showed significant variations among the varieties. In vitro digestibility of protein and starch of grains had a narrow variation. The variety CS-46 containing minimum amount of antinutritional factors had the highest protein digestibility.     

Carotenoids,chlorophylls, vitamin E and amino acid profile in fruits of nineteen Chaenomeles cultivars

This study aimed to identify and quantify carotenoids, chlorophylls, tocopherols, tocotrienols and the free amino acid profile of 19 fruit cultivars of Chaenomeles × superba, Chaenomeles japonica, and Chaenomeles speciosa. For this purpose ultra-performance liquid chromatography (UPLC) with a photodiode array (PDA) and fluorescence (FL) detector coupled with quadrupole time-of-flight electrospray ionization mass spectrometry (QToF–ESI–MS) was used. Most of the Chaenomeles species and cultivars analyzed in this study have not been examined in this respect until now. Fruits contained 32.44–314.94 mg of carotenoids, 19.27–227.19 mg of chlorophylls, 5.51–37.58 mg of tocopherols, and 2.06–42.30 mg of tocotrienols per kg of dry weight (dw). Analysis of the amino acid profile revealed the presence of 10 amino acids, three of them essential (l-threonine, l-valine and l-isoleucine). The highest content of total amino acids was shown by C. × superba ˈJet Trailˈ (2326.33 mg/100 g dw). Among tested species, C. speciosa was characterized by the highest content of all analyzed compounds, except for chlorophylls, present in the highest concentration in C. × superba fruits. These results indicate that Chaenomeles fruits could be regarded as a promising source of bioactive functional food containing vitamins A and E and indispensable amino acids.     

Proximate composition, phytic acid, polyphenols and digestibility (in vitro) of four brown cowpea varieties

Four cultivars of brown cowpea (Vigna unguiculata. L. Walp) were analysed for their proximate composition, phytic acid, polyphenols and protein and starch digestibility (in vitro). Crude protein values ranged from 20.07 to 24.60%. Ether extract and crude fiber contents varied from 1.77 to 1.96% and 4.27 to 4.95%, respectively. All the four cowpea varieties differed significantly for their starch content which ranged from 46.84 to 53.63%. Antinutrients, phytic acid and polyphenols, showed significant variations among the varieties. In vitro digestibility of protein and starch of grains had a narrow variation. The variety CS-46 containing minimum amount of antinutritional factors had the highest protein digestibility.     

Protein and amino acid requirements in the elderly

Estimates of protein and amino acid requirements in this paper are proposed for healthy elderly people. The estimate of protein requirement was based on nitrogen (N) balance, as well as functional indicators such as immune function or muscle strength. Data suggest that the protein requirement for nitrogen equilibrium in the elderly, is greater than 0.8 gm/kg body weight/day. There do not appear to be any adverse consequences with protein intakes that are about 1 gm/kg body weight/day. The tentative recommendation in this paper is higher than the current mean recommended intake of protein (FAO/WHO/UNU, 1985). However, because of methodological difficulties, the data does not allow for a confident prediction of what the exact level of protein intake should be. Further studies are needed to come to a firm conclusion on the exact protein requirement. Indispensable amino acid requirements based on nitrogen balance data, in the elderly, are fragmentary and conflicting. These requirements can alternatively be based on obligatory nitrogen loss, for which data is available in the elderly. The overlap of the obligatory nitrogen loss between the young and the elderly, suggest that the amino acid requirement based on this technique is similar in young and elderly individuals. Tracer based techniques measuring amino acid balance at different amino acid intakes, also support the view that there are no differences in the amino acid requirements between young and elderly people. In general, these amino acid requirement studies have been performed in healthy USA subjects, and data is needed to know if these estimates can be extended to populations from other, less-developed countries.     

Protein and amino acid requirements in human nutrition

The World Health Organization and the Food and Agriculture Organization have worked to quantify the energy and nutrient needs of populations since 1949. This is the latest in a series of reports that aim to provide: updates on protein and amino acid requirements in health and disease for all age groups and pregnant and lactating mothers; recommendations on protein requirements in health and disease, including their implications for developing countries; recommendations on protein quality and labelling for worldwide use. This report provides the tools to address practical questions on the adequacy of food supplies, targets for food and nutrition policy, and labelling of protein quality. It contains specific recommendations for infant, child and adult nutrition. This report is an essential reference for those who need to determine the adequacy of population food intakes; set national food and nutrition guidelines and regulations on the protein and amino acid content of industrially processed foods; determine nutrient needs, and evaluate and ensure the adequacy of rations for vulnerable groups. The tools in this report can also be used to map and monitor global food shortages and under-nutrition through early warning systems.     

Protein intake, brain amino acid and serotonin concentrations and protein self-selection

Analysis of evidence of associations among dietary protein content, brain amino acid and serotonin concentrations, and protein self-selection by rats suggests that 1) protein intake is not regulated precisely, although rats will select between low and high protein diets to obtain an adequate, but not excessive, amount of protein; 2) associations between brain serotonin concentration and protein intake are weak, although consumption of single meals of protein-deficient diets will elevate brain serotonin concentration; 3) the nature of signals that drive rats to avoid diets containing inadequate or excessive amounts of protein remains obscure; (4) whole brain amino acid and serotonin concentrations are quite stable over the usual range of protein intakes, owing to competition among amino acids for uptake across the blood-brain barrier and effective metabolic regulation of blood amino acid concentrations; 5) protein intake and preference are not in themselves regulated, but what appears to be regulation of intake and preference is a reflection of the responses of systems for control of plasma amino acid concentrations; and (6) the relative stability of the average protein intake of groups of self-selecting rats (which gives the appearance of regulation) results from averaging the variable behavioral responses--learned aversions and preferences--of rats to the variety of sensory cues arising from diets that differ in protein content.     

Preparation, consumption, and nutritional composition of west African cowpea dishes

In Africa, nutrient intake deficiencies are widespread. We, therefore, investigated the potential contribution of cowpea dishes to the ingestion of several macro- and micronutrients. Processors and consumers were interviewed and cowpea dishes analyzed. Energy, protein, iron, zinc, and calcium contents ranged from 1647 to 2570 kJ, 10 to 25 g, 1 to 35 mg, 1.5 to 3.0 mg, 38 to 380 mg per 100 g d.w., respectively. The iron and calcium contents were highest in dishes containing leaves. The consumption of these dishes should be promoted along with research on how to further decrease the associated antinutritional factors of traditional cowpea dishes.     

Commentary: Protein and amino acid needs for adults

The objectives of this study are to: (a) assess Latino's nutrition knowledge, attitudes, behaviors, and sources of nutrition information, and (b) examine the association of these with language use at home. Household‐to‐household interviews were conducted in five predominantly Latino neighborhoods in Hartford, Connecticut in households with at least one child ≤ 12 years of age. The typical Latina respondent was a woman in her early 30s who was the mother of at least one child living in the household (N = 426). The vast majority of Latinos were Puerto Rican (95.8%) and they spoke only Spanish (41.8%), only English (6.1%) or both English and Spanish (52.1%) at home. As many as 73.9% of respondents received food stamps and only 9.2% had more than high school education. Respondents were familiar with the USDA's Food Guide Pyramid (93.4%) and with food labels (93.7%). Fifteen percent knew the recommended servings for breads and cereals and 18.3% reported reading food labels always.

Respondents had a positive nutrition attitude but lacked specific knowledge of terms such as “saturated fat” and “neural tube defects”, and were unable to identify good food sources of folate, calcium, and vitamin A. Friends/relatives, doctor, WIC, and television were the main sources of nutrition information. Speaking only Spanish at home (vs English or English and Spanish) was associated with nutrition knowledge and attitudes, and a more traditional pattern of food consumption.     

Plasma amino acid response after ingestion of different whey protein fractions

Background and objectives The digestion rate of proteins and subsequent absorption of amino acids can independently modulate protein metabolism. The objective of the present study was to examine the blood amino acid response to whey protein isolate (WPI), β-lactoglobulin-enriched WPI, hydrolysed WPI and a flavour-identical control.

Methods Eight healthy adults (four female, four male) were recruited (mean±standard error of the mean: age, 27.0±0.76 years; body mass index, 23.2±0.8 kg/cm²) and after an overnight fast consumed 500 ml of each drink, each containing 25g protein, in a cross-over design. Blood was taken at rest and then every 15 min for 2 h post ingestion.

Results Ingesting the β-lactoglobulin-enriched WPI drink resulted in significantly greater plasma leucine concentrations at 45–120 min and significantly greater branched-chain amino acid concentrations at 60–105 min post ingestion compared with hydrolysed WPI. No differences were observed between WPI and β-lactoglobulin-enriched WPI, and all protein drinks resulted in elevated blood amino acids compared with flavour-identical control.

Conclusions In conclusion, whole proteins resulted in a more rapid absorption of leucine and branched-chain amino acid into the blood compared with the hydrolysed molecular form of whey protein.     

Plasma amino acid response after ingestion of different whey protein fractions

Background and objectives The digestion rate of proteins and subsequent absorption of amino acids can independently modulate protein metabolism. The objective of the present study was to examine the blood amino acid response to whey protein isolate (WPI), β-lactoglobulin-enriched WPI, hydrolysed WPI and a flavour-identical control. Methods Eight healthy adults (four female, four male) were recruited (mean±standard error of the mean: age, 27.0±0.76 years; body mass index, 23.2±0.8 kg/cm(2)) and after an overnight fast consumed 500 ml of each drink, each containing 25g protein, in a cross-over design. Blood was taken at rest and then every 15 min for 2 h post ingestion. Results Ingesting the β-lactoglobulin-enriched WPI drink resulted in significantly greater plasma leucine concentrations at 45-120 min and significantly greater branched-chain amino acid concentrations at 60-105 min post ingestion compared with hydrolysed WPI. No differences were observed between WPI and β-lactoglobulin-enriched WPI, and all protein drinks resulted in elevated blood amino acids compared with flavour-identical control. Conclusions In conclusion, whole proteins resulted in a more rapid absorption of leucine and branched-chain amino acid into the blood compared with the hydrolysed molecular form of whey protein.