Nevin S. Scrimshaw

The acceptability of milk and milk products in populations with a high prevalence of lactose intolerance.

1) Most humans, like other mammals, gradually lose the intestinal enzyme lactase after infancy and with it the ability to digest lactose, the principle sugar in milk. At some point in prehistory, a genetic mutation occurred and lactase activity persisted in a majority of the adult population of Northern and Central Europe. 2) Persistence of intestinal lactase, the uncommon trait worldwide, is inherited as a highly penetrant autosomal-dominant characteristic. Both types of progeny are almost equally common when one parent is a lactose maldigester and the other a lactose digester. 3) The incidence of lactose maldigestion is usually determined in adults by the administration in the fasting state of a 50-g dose of lactose in water, the equivalent of that in 1 L of milk. Measurement is made of either the subsequent rise in blood glucose or the appearance of additional hydrogen in the breath. It is also sometimes identified by measuring lactase activity directly in a biopsy sample from the jejunum. For children the test dose is reduced according to weight. Depending on the severity of the lactase deficiency and other factors, the test dose may result in abdominal distention, pain, and diarrhea. 4) The frequency of lactose maldigestion varies widely among populations but is high in nearly all but those of European origin. In North American adults lactose maldigestion is found in approximately 79% of Native Americans, 75% of blacks, 51% of Hispanics, and 21% of Caucasians. In Africa, Asia, and Latin America prevalence rates range from 15-100% depending on the population studied. 5) Whenever the lactose ingested exceeds the capacity of the intestinal lactase to split it into the simple sugars glucose and galactose, which are absorbed directly, it passes undigested to the large intestine. There it is fermented by the colonic flora, with short-chain fatty acids and hydrogen gas as major products. The gas produced can cause abdominal distention and pain and diarrhea may also result from the fermentation products. 6) Among individuals with incomplete lactose digestion, there is considerable variation in awareness of lactose intolerance and in the quantity of lactose that can be ingested without symptoms. A positive standard lactose test is not a reliable predictor of the ability of an individual to consume moderate amounts of milk and milk products without symptoms. In usual situations the quantity of lactose ingested at any one time is much less than in the lactose-tolerance test.(ABSTRACT TRUNCATED AT 400 WORDS)

Total human body protein synthesis in relation to protein requirements at various ages

THE intensity of body and tissue protein metabolism per kg declines with increased adult body size in mammals1. This fall parallels a similar progressive decline in the intensity of energy metabolism2–4. It has also been concluded that protein metabolism per unit of body weight is about four to five times faster in young rats than in adult man1; this pattern of change extends to cellular and subcellular aspects of protein metabolism, such as plasma albumin synthesis, liver RNA content and enzyme activity1,5. Similarly, the rate of protein synthesis per kg total body weight declines during growth and development within a species, such as the rat6. This parameter again parallels the reduction in the intensity of energy metabolism which occurs during the growth period3.

Malnutrition, Learning, and Behavior

No wonder you activities are, reading will be always needed. It is not only to fulfil the duties that you need to finish in deadline time. Reading will encourage your mind and thoughts. Of course, reading will greatly develop your experiences about everything. Reading malnutrition learning and behavior is also a way as one of the collective books that gives many advantages. The advantages are not only for you, but for the other peoples with those meaningful benefits.

Nitrogen Metabolism and Insulin Requirements in Obese Diabetic Adults on a Protein-Sparing Modified Fast

A protein-sparing modified fast (PSMF), which is a total fast modified by the intake of 1.2–1.4 gm. protein per kilogram ideal body weight (IBW), fluids ad libitum, and vitamin and mineral supplementation, allows effective control of carbohydrate metabolism and hunger. It reduces serum glucose and insulin concentrations in obese diabetic patients and increases free fatty acid and ketone body concentrations; ketonuria appears within 24–72 hours. When this fast was applied to seven obese adult-onset diabetics who were receiving 30–100 units of insulin per day, insulin could be discontinued after 0–19 days (mean, 6.5). In the three patients who had extensive nitrogen-balance studies, balance could be maintained chronically by 1.3 gm. protein per kilogram IBW, despite the gross caloric inadequacy of the diet. The PSMF was tolerated well in an outpatient setting after the initial insulin-withdrawal phase had occurred in the hospital. Significant improvements in blood pressure, lipid abnormalities, parameters of carbohydrate metabolism, and cardiorespiratory, symptoms were associated with weight loss and/or the PSMF. For diabetics with some endogenous insulin reserve, the PSMF offers significant advantages for weight reduction, including preservation of lean body mass (as reflected in nitrogen balance) and withdrawal of exogenous insulin.

Malnutrition, brain development, learning, and behavior☆

Three widely prevalent nutritional deficiencies are recognized to have the potential for permanent adverse effects on learning and behavior: protein-energy, iron, and iodine. Supplementation with adequate protein and calories during the first two years of life improves the cognitive performance of poorly nourished children, and the benefits may be even more robust years later when the children become adolescents and young adults. Iron deficiency is the most common global nutritional problem; among the earliest functions to be affected are those associated with the brain enzymes involved in cognition and behavior. The effects of iron deficiency during infancy appear to be irreversible. At older ages iron deficiency is intellectually and educationally disadvantageous independently of ethnicity and of physical and social environment. Even in areas where cases of cretinism due to iodine deficiency in the mother are few, the linear growth of the infant, its intellectual capacity, and certain other of its neurological functions are permanently compromised to varying degrees. In addition to these three most prevalent forms of deficiency, recent evidence suggests that cows milk and infant formulas may lack sufficient omega-3 fatty acids for optimal development of the preterm infant and the neonate. Nutritional deficiencies are also potential contributors to impaired cognition in the elderly. Investments in education and community development would be more effective if the physical and cognitive capacity of underprivileged populations were not impaired by malnutrition.

Nutrition and Infection Field Study in Guatemalan Villages, 1959–1964

Initially, all three study villages had poor environmental sanitation, little medical care, high mortality, and frequent malnutrition. In one village supplemental feeding of the preschool population without other intervention gave an appreciable but limited improvement in disease incidence and physical growth. A program of preventive medicine and medical care in a second village had no effect on frequency of illness and led to no improvement in physical growth; deaths were fewer. Comparison was to a control village with no added services. Collateral studies increased the usefulness of the basic study and enlarged the results. The broader contribution of the study was better definition of the general health of young children. Most usefully, the size of the problem became measurable by case incidence instead of by the usual dependence on number of deaths. Quantitative information on morbidity revealed a burden of illness on preschool children beyond most estimates; it was greatest in the second year. A publ...

Whole body protein turnover in aging man

Abstract To explore the effects of aging on dynamic aspects of whole body protein metabolism in man, the 15 N-glycine infusion method of Picou and Taylor-Roberts was used to estimate rates of total body protein synthesis and breakdown in both young adults and elderly subjects. Nine healthy elderly subjects, 4 male and 5 female, 65–91 yr old, participated in the study. Results obtained with 4 young men and 4 young women, 18–25 yr old, were used for comparative purposes. Total body protein synthesis and breakdown rates, per day and per unit body weight per day, were lower in women than in men and significantly lower in elderly women than in young women. Urinary creatinine was used to estimate muscle mass, and whole body 40 K to calculate body cell mass. Whole body protein synthesis and breakdown rates, per unit creatinine, were higher in the elderly than in the young adults. Expressed per unit body cell mass, the rates were higher in elderly men than in young men, and a similar, but not statistically significant, difference was observed between elderly and young women. From these results it appears that whole body protein synthesis declines with age in man and is associated with the loss of body cell mass. There is also a redistribution in the pattern of whole body protein synthesis and breakdown as aging progresses, with the visceral organs making a progressively greater contribution to whole body protein metabolism than the skeletal musculature.

The serum lipoprotein and cholesterol concentrations of Central and North Americans with different dietary habits.

Abstract 1.1. The total cholesterol and beta-lipoprotein measurements of the blood sera of a group of rural Central American subjects subsisting on a largely vegetarian and very low fat diet have been compared with those of urban Guatemalan and North American subjects who habitually eat large amounts of fat. 2.2. The rural Central American subjects, both male and female, were shown to have lower mean cholesterol levels at all ages studied than did the other groups. There was little evidence of the typical North American increase of serum cholesterol level with age among these Central Americans. There was no sex-determined difference of mean cholesterol levels by decade among the rural Central American subjects. The cholesterol levels of urban Guatemalans living in a good economic status were similar to those of North Americans. 3.3. The serum lipoprotein differences observed among the groups were variable. They were only slightly and irregularly lower in the rural Central American males than in the North Americans and the beta-lipoproteins of the females of this group were frequently at higher levels than those of the North Americans. The urban Guatemalans showed lipoprotein levels as high or higher than those of the North American group. 4.4. These cholesterol and lipoprotein level differences could not be explained by the greater leanness of the Central Americans although this factor could be shown to have a small effect. 5.5. The greater leanness of the rural Guatemalan group taken with higher caloric consumption of that group suggests that the serum lipoprotein levels may be dependent upon the magnitude of energy turnover whereas the serum cholesterol levels are increased by energy accretion or fat deposition. 6.6. The differences in dietary fat intake among the groups do not serve to explain the serum lipid differences because they do not permit an explanation of the dissociation of cholesterol and lipoprotein measurements which is unique in the rural Guatemalans. 7.7. These Guatemalan populations appear to be a useful place to evaluate the relative importance of serum beta-lipoprotein and cholesterol levels in atherogenesis.

The role of exogenous histamine in scombroid poisoning

Abstract In order to investigate the role of histamine as a causative factor in scombroid poisoning, four subjects received grapefruit juice with or without graded doses of histamine in a randomized double-blind fashion for 10 days. Eight subjects received tuna sandwiches with or without histamine in the same manner. Clinical symptoms and vital signs were recorded daily. Histaminase activity was measured in plasma eosinophils and serum. Results demonstrated that although vital signs and histaminase activity showed no consistent pattern of change at any histamine dose, characteristic symptoms of scombroid poisoning (severe headaches and facial flushing) were noted at the 100-, 150-, and 180-mg doses of histamine. These findings suggest that histamine is responsible for the symptoms seen in scombroid poisoning.

Soybean protein in human nutrition: an overview.

The nutritional value of processed soy protein in human protein nutrition is reviewed on the basis of growth, nitrogen balance and metabolic studies in infants, children, adolescents and adults. When well processed soy products serve as the major or sole source of the protein intake, their protein value approaches or equals that of foods of animal origin, and they are fully capable of meeting the long term essential amino acid and protein needs of children and adults. The significance of the sulfur amino acid content of soy protein for practical human nutrition is also examined. For young children and adults, under conditions of normal usage of soy protein, it is concluded that methionine supplementation of good quality products is unnecessary and possibly undesirable. For feeding of the newborn, the limited data available suggest that supplementation of soy-based formulas with methionine may be beneficial. However, the appropriate level of supplementation is considerably less than that suggested from results obtained in rat feeding studies. At total protein intakes that approximate current dietary protein allowances, well processed soy protein products can replace meat and fish proteins without reducing the utilization of dietary nitrogen in adults, and they can serve as nutritionally valuable protein sources in cereal-based diets for child feeding. The value of long term studies concerned with tolerance to and acceptability of new soy protein products in adults is emphasized, and favorable results with two isolated soy protein products are described. The data indicate that properly processed soy protein foods are well tolerated and of good protein value for humans of all ages.