Peter L. Pellett

Plant proteins in relation to human protein and amino acid nutrition.

Plant protein foods contribute approximately 65% of the per capita supply of protein on a worldwide basis and approximately 32% in the North American region. These sources of protein are discussed in relation to their amino acid content, human amino acid requirements, and dietary protein quality. Mixtures of plant proteins can serve as a complete and well-balanced source of amino acids for meeting human physiological requirements. This short review ends with a list of series of myths and realities concerning the relationship between plant protein and human nutrition and a list of some nutritional issues of concern to the health professional and informed consumer.

Lysine fortification: past, present, and future.

Fortification with lysine to improve the protein value of human diets that are heavily based on cereals has received support from the results of these recent studies [1,2]. Support also comes from examination of average food and nutrient availability data derived from food balance sheets. Whereas nutritional status is influenced by the nutrient content of foods consumed in relation to need, the requirements for protein and amino acids are influenced by many additional factors [10, 12, 14, 28, 29]. These include age, sex, body size, physical activity, growth, pregnancy and lactation, infection, and the efficiency of nutrient utilization. Even if the immune response was influenced by the added lysine, adequate water and basic sanitation would remain essential. Acute and chronic undernutrition and most micronutrient deficiencies primarily affect poor and deprived people who do not have access to food of adequate nutritional value, live in unsanitary environments without access to clean water and basic services, and lack access to appropriate education and information [30]. A further variable is the possible interaction between protein and food energy availability [31]. This could affect the protein value of diets when food energy is limiting to a significant degree. Thus, the additional effects of food energy deficiency on protein utilization could well be superimposed on the very poorest. The improvement of dietary diversity must be the long-term aim, with dietary fortification considered only a short-term solution. The former should take place as wealth improves and the gaps between rich and poor diminish. Although such changes are taking place, they are highly uneven. Over the last several decades, increases have occurred in the availability of food energy, total protein, and animal protein for both developed and developing countries. However, for the very poorest developing countries over the same period, changes have been almost nonexistent, and the values for some nutritional indicators have even declined. For estimated lysine value, the developed countries showed increases in per capita availability from 5,400 to 6,167 mg per day and the developing countries from 2,400 to 3,454 mg per day, while in contrast, the very poorest countries remained static at about 2,400 to 2,500 mg per day. Thus, although lysine fortification may be theoretically only a short-term solution, in the very poorest countries changes in wealth such that dietary diversity and lysine availability may increase by natural progression remain remote. If we can justify using lysine to fortify animal feed in the rich regions of the world for economic gain, perhaps we should now consider adding lysine to the flour consumed by the deprived people in the poorest regions of the world to improve both their nutrition and their resistance to disease.

Observations on nutritional marasmus in a newly rich nation.

A study was performed in a pediatric hospital in Tripoli, Libya where the familial backgrounds of 50 marasmic infants were compared with those of a group of 50 essentially healthy infants of similar age. Families with marasmic infants had more children but lived in smaller homes than the comparison families. Total income was similar in both sets of families and major consumer items such as television sets, cars, and refrigerators were widely present in both groups. Families with marasmic infants, however, had less literate mothers who tended to breastfeed for shorter periods and to feed purchased pureed baby foods more frequently. The causation of marasmus in these circumstances is probably unhygienic infant feeding despite the availability of clean water and modern kitchen facilities. All 3 factors, adequate housing, adequate income, and an adequately educated mother appear to be necessary simultaneously before infantile marasmus can be prevented.

Impact of Lysine-Fortified Wheat Flour on Morbidity and Immunologic Variables among Members of Rural Families in Northwest Syria

Background Previous studies have shown an effect of lysine fortification on nutrition and immunity of poor men, women, and children consuming a predominantly wheat-based diet. Objective To examine the lysine value of diets and the effect of lysine fortification on functional protein status, anthropometry, and morbidity of men, women, and children in rural Syria. Methods At baseline of a two-phase study using 7-day household food intake inventories (n = 98), nutrient availabilities per adult male equivalent were estimated. In the intervention phase, a 16-week double-blind trial, households (n = 106) were randomly assigned to control and lysine groups. Hematologic and anthropometric data were collected from men (n = 69; 31 control, 38 lysine), women (n = 99; 51 control, 48 lysine), and children (n = 69; 37 control, 32 lysine) at baseline, 12 weeks, and 16 weeks. Total CD3 T lymphocytes as well as T lymphocytes bearing the receptors CD4, CD8, and CD56, IgM, IgG, IgA, complement C3, C-reactive protein, serum albumin, prealbumin, transferrin, retinol-binding protein, hemoglobin, and hepatitis B surface antigen were determined. Health status and flour usage were monitored. Paired- and independent-sample t-tests and chi-square tests were performed. Results Mean nutrient availability per adult equivalent was 2,650 ± 806 kcal, 70.1 ± 26.4 g protein, 65 ± 14% cereal protein, and 41.9 ± 0.8 mg lysine per gram of protein. Complement C3 was significantly higher in men receiving lysine than in controls (p < .05). Among women, there were significant differences between the control and lysine groups in diarrhea period prevalence (total number of diarrheal episodes during the period of intervention divided by the total number of observations), (20 in the control group, 6 in the lysine group; p = .014), the mean number of days ill (0.4 ± 0.7, control, 0.14 ± 0.4, lysine, p = 0.03), and the number of diarrheal episodes per person per year (1.39 in the control group, 0.47 in the lysine group). No other significant differences between the lysine and the control groups were observed. Conclusions Lysine fortification of wheat flour demonstrated a positive effect on diarrheal morbidity in women. The effect could be attributed to an improvement in protein utilization but possibly also to a direct effect of lysine in gastrointestinal tract. Studies in populations with higher diarrheal prevalence and significant dietary lysine deficiency are needed to determine whether the reported effects on diarrheal prevalence are replicable and whether they are pharmacological or nutritional. It would be particularly desirable to study the effect of lysine on diarrhea in preschool children, who have much higher morbidity and mortality rates from this disease than school-age children or adults.

Nutrition in agricultural development in Aleppo Province Syria 1. Farm resources, rainfall and nutritional status

Surveys were conducted on the growth of children in eight rural villages in high and low rainfall zones of Aleppo Province Syria as part of an investigation to collect base line data on diet, socioeconomic status and agricultural development. Fifty percent of the children in both zones were below 90% of international reference standards in weight for age, and there was also a high prevalence of stunting with 17% of preschool children being below 90% height for age. Weight for height values were, however, generally close to reference standards in both zones. For school age children, mean weight for height and weight for age data showed superiority in the high rainfall zone, though weight for age deficits increased with age in both zones. The validity of using international reference standards was supported by the finding that 95, 7–8 year old Syrian children from more privileged backgrounds attending a private school in Aleppo approximated the median values for well‐nourished, healthy children in the Unite...

Prediction of true limiting amino acids using available protein scoring systems

Mixed diets based on parboiled wheat, milk, rice and lentils were prepared and supplemented with the probable limiting amino acids, either individually or in combination. The amino acid composition, net protein utilization and the true limiting amino acid were determined on each diet. Results were compared with scores obtained using the FAO/WHO (1973) and other possible patterns as reference standards. The 1973 pattern is superior to all others in predicting the true limiting amino acid for test diets in which the first limiting amino acid was either lysine or methionine. The correlation between the scores obtained by use of the FAO/WHO (1973) reference pattern and NPU values with rats was also higher than for any of the other scoring system tested.

Recommended proportions of foods in home‐made feeding mixtures

Tabular data are presented on the recommended proportions of staples and supplements for the preparation of home made feeding mixtures. Optimum proportions are presented for 78 combinations originating from 13 staples and six supplements widely consumed on a world wide basis. Calculations were made so as to reach an adequate level of NDpCal percent (6.5–7.0) with the minimum quantity of the more expensive supplement. This follows the procedure of Cameron and Hofvander (1976) in their Manual on feeding infants and young children, however, newer data is used for the protein and amino acid composition of the foods together with the more accurate FAO/WHO (1973) scoring system rather than the no longer acceptable FAO/WHO (1957) procedure. An improved formula for the calculation of NDpCal percent was also used. The new data show, in general, smaller proportions of supplements to reach the same protein‐calorie value and would thus be of lower cost.

Nutritional problems of the Arab world

Population growth within the Arab World at nearly 3.0 percent per annum is one of the largest in the world. Food production is barely keeping pace with this increase and the area remains dependent on imported grains. The diet of the region is based on wheat as a staple. Although specific nutrient deficiencies do exist, in general if food energy needs are met so also will be needs for most nutrients. The major nutritional problem of the area remains protein‐energy malnutrition of the young child. This appears to be more related to hygienic and socio‐economic factors than to a lack of protein in the diet. In this connection the role of commercial activity in the feeding of infants and its relationship to infantile malnutrition is discussed. The solutions to nutritional problems in the area are considered to lie more in the areas of population control, and in agricultural, political and social reforms than in specific nutrition intervention programs.

Growth status of children in north west Syria: A comparison of three rural livelihood groups

Undernutrition, a multifactorial phenomenon, has severe consequences. A study was conducted in Syria to compare nutritional differences in children from three rural livelihood groups: a “barley-livestock” group in the southeast (Khanasser), and an “olive/fruit tree” group and an “irrigation” group in the northwest of Aleppo province (Afrin). An anthropometric assessment was conducted on 541 rural children from 207 rural households and 199 urban children (2–10 years) from a middle income urban group. Comparisons were made with the 1978 NCHS/WHO (National Center for Health Statistics/ World Health Organization) international growth reference (WHO, 1995) and a –2 SD Z-score was used as a cut-off. Prevalence rates and mean Z-scores were calculated and independent sample t-tests used to compare totals and age-group disaggregated children (both boys and girls). Total stunting prevalence was highest in the barley-livestock group (23%) and lowest in the irrigation group (12.5%). Girls in the barley-livestock group displayed the highest rates of stunting (28.3%), followed by the boys (22%) and the girls (21.08%) in the olive/fruit tree group. The prevalence of underweight children was highest in the barley-livestock and olive/fruit tree livelihood groups (14.29% and 13.25%, respectively). Wasting rates were very low. The rates of stunting and underweight were higher in the barley-livestock and olive/fruit tree groups, as compared with the country-level estimates of 20.8 percent and 12.9 percent respectively, in children under five. A comparison of rates and mean scores indicates that, amongst rural groups, there was considerable variation: the barley-livestock and olive/fruit tree group, belonging to drier and poorer areas, exhibited higher rates and lower mean scores.

Protein quality of homemade weaning food mixtures: 2. Amino acid composition versus biological methods

Protein quality of fourteen different homemade weaning food mixtures, already evaluated by biological procedures, was also estimated on the basis of amino acid composition. Amino acids were determined by ion‐exchange chromatography with the exception of tryptophan, which was estimated from published values for the component ingredients. Amino acid scores were calculated using the FAO/WHO (1973) pattern as well as the new FAO/WHO/UNU (1986) reference patterns for the infant and young child and were compared with the protein values determined biologically. Agreement was high. In addition, comparison was made between estimated intakes and the newly published requirement values for essential amino acids. It was concluded that all mixtures would meet protein and amino acid needs if they were supplied at sufficient levels to meet food energy needs.