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Biomedical subjects

N S Scrimshaw

Publications and source records attributed to N S Scrimshaw.

At least 19 recordsLinked to original sources

Effect of infection on nutritional status.

All infections no matter how mild decrease nutrient intakes and increase nutrient losses even when subclinical. The losses include decreased intestinal absorption, direct loss of nutrients in the gut, internal diversion for metabolic responses to infection and increased BMR when fever is present. Infection influences in this way not only protein and energy status but also that of most other nutrients. The clinical importance of these consequences of infection depends on the prior state of the individual, the nature and duration of the infection and the diet of the individual during the infection, particularly dietary intake during the convalescent period and whether full recovery takes place before another infection occurs. In industrialized countries particular attention must be paid to the nutrition of hospitalized patients since they are frequently debilitated by their primary disease, morbidity, and their nutritional status. Morbidity and mortality are increased by nosocomial infections to which the poorly nourished individual is more susceptible.

Child

Iron deficiency.

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Adult

Nutrition: prospects for the 1990s.

For many decades there has been adequate information for the elimination of acute dietary deficiency diseases. Scurvy, beri-beri, and pellagra, once serious scourges, are now seen only rarely. The severe forms of protein-energy malnutrition, kwashiorkor and marasmus, have also decreased greatly. Nonetheless, mild to moderate forms of protein-energy deficiency, exacerbated by infection, continue to impair growth and development in a majority of the low-income pre-school age populations of most developing countries. Deficiencies of iron, iodine, and vitamin A are still widespread in developing countries. Fortunately, the success of the WHO/UNICEF "Child Survival and Development Revolution" in persuading most developing countries to introduce expanded programs of immunization, growth monitoring, and appropriate feeding of young children, control of diarrheal disease, and specific campaigns against avitaminosis A, iodine deficiency disorders, and the functional consequences of iron deficiency, will accelerate the decline of acute deficiency diseases in the developing world. Diets are changing among the more affluent in these countries, however, and it is time for them to stress dietary goals for the health of rich and poor alike. For the first time there is enough information regarding dietary risk factors for chronic disease to provide an opportunity in the 1990s to accelerate the dietary changes that have already brought significant health benefits to some populations in North America and Europe. The changes, which include a lower dietary intake of fat, particularly saturated fat, less salt, and more green and yellow vegetable and whole grain cereals, can be expected to influence favorably morbidity from cardiovascular diseases and some kinds of cancer. For maximum benefit, these measures need to be combined with the avoidance of obesity, reasonable physical activity, abstention from, or moderate use of, alcohol, and avoidance of tobacco in any form. Since there is already considerable momentum toward these changes in North America and some European countries, the 1990s are likely to see substantial further progress in the reduction of chronic diseases known to be influenced by diet.

Age Factors

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)

Animals

[Lactose tolerance and milk consumption: myths and realities].

The disaccharide lactose, the principal carbohydrate of animal milks, requires the enzyme lactase to split it to glucose and galactose. Undigested lactose passes to the colon where fermentation produces hydrogen and short-chain fatty acids that can cause abdominal distention, pain and sometimes diarrhea. Persistence of intestinal lactase after early childhood, is inherited as a highly-penetrant autosomal dominant genetic characteristic. On the basis of a review of over 560 references, all available data on the primary loss of intestinal lactase in Latin American populations are presented in tabular form. Prevalence of lactose non-digesters in Latin American populations ranges from 45% to 100%. However, this is not a reliable predictor of the acceptability of milk and milk products containing lactose. Milk is being used successfully for the supplementary feeding of children worldwide, and most lactose non-digesters can tolerate at least 240 ml of milk or the lactose equivalent in other products. Lactose maldigestion does not interfere with the absorption of the protein and essential micronutrients in milk. Information is provided on the lactose content of milk and milk products, on the usual milk consumption of Latin American populations, and on worldwide experimental and field observations of milk acceptability. Both adaptation to continued use of milk and milk products and relationships of milk use to various disease states in which intestinal lactase activity may be reduced are discussed. Some types of yoghurts are better tolerated because of the lactase activity of the bacteria used in their fermentation. For unusually intolerant individuals commercial enzyme preparations are available for addition to milk products but for most persons the additional cost is unnecessary.

Adult

The phenomenon of famine.

Famines are sustained, extreme shortages of food among discrete populations sufficient to cause high rates of mortality. Signs and symptoms of prolonged food deprivation include loss of fat and subcutaneous tissue, depression, apathy, and weakness, which progress to immobility and death of the individual, often from superimposed respiratory or other infections. The social consequences of famines are disruption from mass migrations of people in search of food, breakdown of social behavior, abandonment of cooperative effort, loss of personal pride and sense of family ties, and finally a struggle for individual survival. Famines have been common ever since the development of agriculture made human settlements possible. Food shortages due to crop failures caused by natural disasters including poor weather, insect plagues, and plant diseases; crop destruction due to warfare; and enforced starvation as a political tool are by no means the only causative factors. Many of the worst famines have been due to poor distribution of existing food supplies, either because of inequities that result in a lack of purchasing power on the part of the poor or because of political interference with normal distribution or relief movements of food. Europe and Asia, which in the past experienced frequent severe famines, sometimes with deaths in the hundreds of thousands or millions, have now largely eliminated famines through social and technological change. However, in Africa, political and social factors have destroyed the capacity of many populations to survive drought-induced variations in local food supplies and prices. Thus, famines are due to varying combinations of inadequacy of food supplies for whatever reason and the inability of populations to acquire food because of poverty, civil disturbances, or political interference. Despite the role of natural causes, the conclusion is inescapable that modern famines, like most of those in history, are man-made.

Demography

Consequences of hunger for individuals and societies.

Famine and the manifestations of acute hunger that result are an unnecessary disgrace to our global society and serious in their political, economic, and social consequences. Probably more damaging is the chronic undernutrition that afflicts such a large proportion of the populations of developing countries and the hidden hungers of iron deficiency, avitaminosis A, and iodine deficiency disorders that are enormously widespread. Famine in the modern world is almost invariably superimposed on chronic undernutrition that is not solved with emergency relief. Adaptation to this undernutrition requires a reduction in physical activity needed for household and community improvement as well as work output. Iron deficiency interferes with cognitive performance, resistance to infection, and capacity for work. Other nutrient deficiencies add to the damage to the individual and society. Prevention of famine and hunger is not primarily a technological issue, but a moral, political, and social one.

Adaptation, Physiological

Retrospective analysis of data from five long-term, metabolic balance studies: implications for understanding dietary nitrogen and energy utilization.

Daily urinary nitrogen (N) excretion and body weight data of 42 healthy young adults, who received constant, adequate diets for up to 90 days, and maintained constant level of physical activity, were examined retrospectively. From the N excretion data, it was determined that, when corrected for long-term trends, daily variability was random and much larger than variability due to the long-term trends. Thus, N balance data based on commonly used diet periods of about 2 wk adequately estimates population variability. Body weight data for most subjects showed significant changes and many subjects experienced persistent linear changes throughout the entire experimental period. Thus, for most healthy young adults, neither dietary-induced thermogenesis nor changes in the efficiency of energy utilization appears to play a quantitatively important role in the maintenance of body weight (and body composition) in response to relatively modest discrepancies between the level of food intake and energy intake needed to balance initial total energy expenditure. The key importance of food intake regulation and/or physical activity in weight maintenance is emphasized by these findings.

Adolescent

Evaluation of the protein quality of an isolated soy protein in young men: relative nitrogen requirements and effect of methionine supplementation.

The protein nutritional value of an isolated soy protein (Supro-620) was evaluated in a series of nitrogen balance studies in healthy young male MIT students. Experiment 1 involved giving eight subjects graded intakes of the isolated soy protein while seven additional subjects received egg protein. Mean nitrogen intake required for N balance for the isolated soy protein and the egg protein were not significantly different (p greater than 0.1). In experiment 2, nine subjects received soy and the effects on N balance at various levels of L-methionine supplementation were studied. In experiment 3 eight subjects each were studied at two nitrogen intake levels of isolated soy protein/kg/day with methionine supplementation, and an unsupplemented egg protein period included. Results from experiment 2 and 3 at an 82 mg N/kg/day test level showed that N balance for 1.6% supplementation was significantly below that of unsupplemented egg while 1.1% and unsupplemented soy were indistinguishable from egg. No beneficial effects of methionine supplementation were observed when the test nitrogen intake level was 128 mg N/kg/day. These results indicate that for healthy adults, the isolated soy protein is of high nutritional quality, comparable to that of animal protein sources, and that the methionine content is not limiting for adult protein maintenance.

Adult