Science of Unitary Human Beings


Groups of people across the globe have varying frequencies of polymorphic genes, which are genes with any of several differing nucleotide sequences. Water-soluble vitamins Fat-soluble vitamins Major minerals Trace minerals What are calories? On the other hand, humans in the past century have made considerable efforts to reduce negative impacts and provide greater protection for the environment and other living organisms, through such means as environmental law, environmental education, and economic incentives. Serum albumin levels are not useful in predicting imminent kwashiorkor development in moderate PEM cases. Diabetes and triglycerides are related to high carbohydrate eating and Insulin surges.

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Human digestive system

It has also been suggested that serum albumin levels below 2. Serum albumin determinations are relatively easy and cheap to perform, and unlike the other biochemical tests mentioned below, they can be done in modest laboratories in many developing countries.

Levels of two other serum proteins, pre-albumin and serum transferrin, are also of use and not too difficult to determine. Levels of both are reduced in kwashiorkor and may be useful in judging its severity.

However, serum transferrin levels are also influenced by iron status, which reduces their usefulness as an indicator of kwashiorkor. Levels of retinol binding protein RBP , which is the carrier protein for retinol, also tend to be reduced in kwashiorkor and to a lesser degree in nutritional marasmus.

However, other diseases, such as liver disease, vitamin A and zinc deficiencies and hyperthyroidism, may also influence RBP levels. Other biochemical tests that have been used or recommended for diagnosing or evaluating PEM have limited usefulness. These include tests for: These tests are not specific, and most cannot be performed in ordinary hospital laboratories. All children with severe kwashiorkor, nutritional marasmus or marasmic kwashiorkor should, if possible, be admitted to hospital with the mother.

The child should be given a thorough clinical examination, including careful examination for any infection and a special search for respiratory infection such as pneumonia or tuberculosis. Stool, urine and blood tests for haemoglobin and malaria parasites should be performed. The child should be weighed and measured. Often hospital treatment is not possible. In that case the best possible medical treatment available at a health centre, dispensary or other medical facility is necessary.

If the child is still being breastfed, breastfeeding should continue. Treatment is often based on dried skimmed milk DSM powder. The child should receive ml of this mixture per kilogram of body weight per day, given in six feeds at approximately four-hour intervals. Each feed is made by adding five teaspoonfuls of DSM powder to ml of water. Attention to providing all micronutrients is important.

The milk mixture should be fed to the child with a feeding cup or a spoon. If cupor spoon-feeding is difficult - which is possible if the child does not have sufficient appetite and is unable to cooperate or if the child is seriously ill the same mixture is best given through an intragastric tube. The tube should be made of polyethylene; it should be about 50 cm long and should have an internal diameter of 1 mm.

It is passed through one nostril into the stomach. The protruding end should be secured to the cheek either with sticky tape or zinc oxide plaster. The tube can safely be left in position for five days. The milk mixture is best given as a continuous drip, as for a transfusion. Alternatively, the mixture can be administered intermittently using a large syringe and a needle that fits the tube.

The milk mixture is then given in feeds at four-hour intervals. Before and after each feed, 5 ml of warm, previously boiled water should be injected through the lumen of the tube to prevent blockage. There are better mixtures than plain DSM. They can all be administered in exactly the same way by spoon, feeding cup or intragastric tube.

Most of these mixtures contain a vegetable oil e. The vegetable oil increases the energy content and energy density of the mixture and appears to be tolerated better than the fat of full cream milk.

Casein increases the cost of the mixture, but as it often serves to reduce the length of the hospital stay, the money is well spent. A stock of the dry SCOM mixture can be stored for up to one month in a sealed tin.

To make a feeding, the desired quantity of the mixture is placed in a measuring jug, and water is added to the correct level. Stirring or, better still, whisking will ensure an even mixture. As with the plain DSM mixture, ml of liquid SCOM mixture should be given per kilogram of body weight per day; a 5-kg child should receive ml per day in six ml feeds, each made by adding five teaspoonfuls of SCOM mixture to ml of boiled water.

A ml portion of made-up liquid feed provides about 28 kcal, 1 g protein and 12 mg potassium. Children with kwashiorkor or nutritional marasmus who have severe diarrhoea or diarrhoea with vomiting may be dehydrated. Intravenous feeding is not necessary unless the vomiting is severe or the child refuses to take fluids orally. Rehydration should be achieved using standard oral rehydration solution ORS , as is described for the treatment of diarrhoea see Chapter For severely malnourished children, unusually dilute ORS often provides some therapeutic advantage.

Thus if standard ORS packets are used which are normally added to 1 litre of boiled water, in a serious case a packet might be added to 1. Even in tropical areas temperatures at night often drop markedly in hospital wards and elsewhere.

The seriously malnourished child has difficulty maintaining his or her temperature and may easily develop a lower than normal body temperature, termed hypothermia. Untreated hypothermia is a common cause of death in malnourished children. At home the child may have been kept warm sleeping in bed with the mother, or the windows of the house may have been kept closed. In the hospital ward the child may sleep alone, and the staff may keep the windows open.

He or she must be kept in warm clothes and must be kept covered with warm bedding, and there must be an effort to ensure that the room is adequately warm. Sometimes hot-water bottles in the bed are used.

The child's temperature should be checked frequently. Although it is useful to establish standard procedures for treating kwashiorkor and nutritional marasmus in any hospital or other health unit, each case should nevertheless be treated on its own merits. No two children have identical needs. Infections are so common in severely malnourished children that antibiotics are often routinely recommended.

Benzyl-penicillin by intramuscular injection, 1 million units per day in divided doses for five days, is often used. Ampicillin, mg in tablet form four times a day by mouth, or amoxycillin, mg three times a day by mouth, can also be given.

Gentamycin and chloramphenicol are alternative options but are less often used. In areas where malaria is present an antimalarial is desirable, e. In severe cases and when vomiting is present, chloroquine should be given by injection.

If anaemia is very severe it should be treated by blood transfusion, which should be followed by ferrous sulphate mixture or tablets given three times daily. If a stool examination reveals the presence of hookworm, roundworm or other intestinal parasites, then an appropriate anthelmintic drug such as albendazole should be given after the general condition of the child has improved. Severely malnourished children not infrequently have tuberculosis and should be examined for it.

If the disease is found to be present, specific treatment is needed. On the above regime, a child with serious kwashiorkor would usually begin to lose oedema during the first three to seven days, with consequent loss in weight.

During this period, the diarrhoea should ease or cease, the child should become more cheerful and alert, and skin lesions should begin to clear. When the diarrhoea has stopped, the oedema has disappeared and the appetite has returned, it is desirable to stop tube-feeding if this method has been used. A bottle and teat should not be used. If anaemia is still present, the child should now start a course of iron by mouth, and half a tablet mg of chloroquine should be given weekly.

Children with severe nutritional marasmus may consume very high amounts of energy, and weight gain may be quite rapid. However, the length of time needed in hospital or for full recovery may be longer than for children with kwashiorkor. In both conditions, as recovery continues, usually during the second week in hospital, the patient gains weight.

While feeding of milk is continued, a mixed diet should gradually be introduced, aimed at providing the energy, protein, minerals and vitamins needed by the child. If the disease is not to recur, it is important that the mother or guardian participate in the feeding at this stage. She must be told what the child is being fed and why. Her cooperation with and follow-up of this regime is much more likely if the hospital diet of the child is based mainly on products that are used at home and that are likely to be available to the family.

This is not feasible in every case in a large hospital, but the diet should at least be based on locally available foods.

Thus in a maize-eating area, for example, the child would now receive maize gruel with DSM added. For an older child, crushed groundnuts can be added twice a day, or, if preferred by custom, roasted groundnuts can be eaten. A few teaspoonfuls of ripe papaya, mango, orange or other fruit can be given. At one or two meals per day, a small portion of the green vegetable and the beans, fish or meat that the mother eats can be fed to the child, after having been well chopped.

If eggs are available and custom allows their consumption, an egg can be boiled or scrambled for the child; the mother can watch as it is prepared. Alternatively, a raw egg can be broken into some simmering gruel. Protein-rich foods of animal origin are often relatively expensive. They are not essential; a good mixture of cereals, legumes and vegetables serves just as well.

If suitable vitamin-containing foods are not available, then a vitamin mixture should be given, because the DSM and SCOM mixtures are not rich in vitamins. The above maize-based diet is just an example.

If the diet of the area is based on rice or wheat, these can be used instead of maize. If the staple food is plantain or cassava, then protein-rich supplements are important.

After discharge, or if a moderate case of kwashiorkor has been treated at home and not in the hospital, the child should be followed if possible in the out-patient department or a clinic. It is much better if such cases can visit separately from other patients i. A relaxed atmosphere is desirable, and the medical attendant should have time to explain matters to the mother and to see that she understands what is expected of her.

It is useless just to hand over a bag of milk powder or other supplement, or simply to weigh the child but not provide simple guidance. Satisfactory weight gain is a good measure of progress. At each visit the child should be weighed. Weight is plotted on a chart to provide a picture for the health worker and the mother. Out-patient treatment should be based on the provision of a suitable dietary supplement, but in most cases it is best that this supplement be given as part of the diet.

The mother should be shown a teaspoon and told how many teaspoonfuls to give per day based on the child's weight. Many supplements, especially DSM, are best provided by adding them to the child's usual food such as cereal gruel rather than by making a separate preparation.

The mother should be asked how many times a day she feeds the child. If he or she is fed only at family mealtimes and the family eats only twice a day, then the mother should be told to feed the child two extra times. If facilities exist and it is feasible, the SCOM mixture can be used for out-patient treatment. It is best provided ready mixed in sealed polyethylene bags. Most deaths in children hospitalized for kwashiorkor or nutritional marasmus occur in the first three days after admission.

Case fatality rates depend on many factors including the seriousness of the child's illness at the time of admission and the adequacy of the treatment given. In some societies sick children are taken to hospital very late in the disease, when they are almost moribund.

In this situation fatality rates are high. The cause and the severity of the disease determine the prognosis. A child with severe marasmus and lungs grossly damaged by tuberculous infection obviously has poor prospects.

The prospects of a child with mild marasmus and no other infection are better. Response to treatment is likely to be slower with marasmus than with kwashiorkor.

It is often difficult to know what to do when the child is cured, especially if the child is under one year of age. There may be no mother or she may be ill, or she may have insufficient or no breastmilk. Instruction and nutrition education are vital for the person who will be responsible for the child. If the child has been brought by the father, then some female relative should spend a few days in the hospital before the child is discharged.

She should be instructed in feeding with a spoon or cup and told not to feed the child from a bottle unless he or she is under three months of age. The best procedure is usually to provide a thin gruel made from the local staple food plus two teaspoonfuls of DSM or some other protein-rich supplement and two teaspoonfuls of oil per kilogram of body weight per day. Instruction regarding other items in the diet must be given if the child is over six months old.

The mother or guardian should be advised to attend the hospital or clinic at weekly intervals if the family lives near enough within about 10 km or at monthly intervals if the distance is greater. Supplies of a suitable supplement to last for slightly longer than the interval between visits should be given at each visit.

The child can be put on other foods, as mentioned in the discussion of infant feeding in Chapter 6. It is essential that the diet provide adequate energy and protein. Usually kcal and 3 g of protein per kilogram of body weight per day are sufficient for long-term treatment. Thus a kg child should receive about kcal and 30 g of protein daily. It should be noted that a marasmic child during the early part of recovery may be capable of consuming and utilizing to kcal and 4 to 5 g of protein per kilogram of body weight per day.

There is little doubt that a disorder due mainly to energy deficiency does occur in adults; it is more common in communities suffering from chronic protein deficiency. The patient is markedly underweight for his or her height unless grossly oedematous , the muscles are wasted, and subcutaneous fat is reduced. Mental changes are common: It is difficult to attract the patient's attention and equally hard to keep it. Appetite is reduced, and the patient is very weak.

Some degree of oedema is nearly always present, and this may mask the weight loss, wasting and lack of subcutaneous fat. Oedema is most common in the legs, and in male patients also in the scrotum, but any part of the body may be affected. The face is often puffy. This condition has been termed "famine oedema" because it occurs where there is starvation resulting from famine or other causes.

It was commonly reported in famines in Indonesia and Papua New Guinea. Frequent, loose, offensive stools may be passed. The abdomen is often slightly distended, and on palpation the organs can be very easily felt through the thin abdominal wall.

During palpation there is nearly always a gurgling noise from the abdomen, and peristaltic movements can often be detected with the fingertips. It is not uncommon for adult kwashiorkor patients to regard their physical state as a consequence of abdominal upset.

For this reason, strong purgatives, either proprietary or herbal, and peppery enemas are sometimes used by these patients before they reach hospital, which may greatly aggravate the condition. The hair frequently shows changes. The skin is often dry and scaly, and may have a crazy-pavement appearance, especially over the tibia.

Swelling of both parotid glands is frequent. On palpation the glands are found to be firm and rubbery. Anaemia is nearly always present and may be severe. The blood pressure is low. There is usually only a trace of albumin in the urine. Oedema may also be caused by severe anaemia. In adult PEM there is less dyspnoea than in anaemia and usually no cardiomegaly.

Other features such as hair changes and parotid swelling are common in adult PEM but not in anaemia. However, the two conditions are closely related.

In contrast to adult kwashiorkor or famine oedema, which is not very prevalent, the adult equivalent of nutritional marasmus is very common. There are five major causes. Any older child or adult whose diet is grossly deficient in energy will develop signs almost exactly like those of nutritional marasmus, and if the condition progresses it may often be fatal. In the case of famines, the condition may be termed starvation see Chapter Famines and severe food shortages resulting from war, civil disturbance or natural disasters such as droughts, floods and earthquakes may result in nutritional marasmus in children and a similar condition in adults, who suffer from weight loss, wasting, diarrhoea, infectious diseases, etc.

The second major cause of severe wasting or severe PEM in adults is infections, especially chronic, untreated or untreatable infections. The most common of these now is acquired immunodeficiency syndrome AIDS resulting from infection with the human immunodeficiency virus HIV. As the disease progresses there is marked weight loss and severe wasting. Advanced tuberculosis and many other long-term chronic infections also lead to wasting and weight loss.

A number of malabsorption conditions cause PEM in adults and children. These diseases, of which some are hereditary, result in the inability of the body to digest or absorb certain foods or nutrients. Examples are cystic fibrosis, coeliac disease and adult sprue. Another cause of wasting in people of any age is malignancy or cancer of any organ once it progresses to a stage not treatable by surgical excision.

Cachexia is a feature of many advanced cancers. A group of eating disorders cause weight loss leading to the equivalent of PEM. The most widely described is anorexia nervosa, which occurs much more commonly in females than males, in adolescents or younger adults rather than older persons and in affluent rather than poor societies.

Other psychological conditions may also result in poor food intake and lead to PEM. Treatment of adult PEM includes therapy related to the underlying cause of the condition and therapy related to feeding and rehabilitation, when the cause makes that feasible.

Thus infections such as tuberculosis or chronic amoebiasis require specific therapy which when effective will eliminate the cause of the weight loss and wasting. In contrast, curative treatment is not applicable in advanced AIDS or cancer. Dietary treatment for adult PEM should be based on principles similar to those described for the treatment of severe PEM in children, including those recovering from kwashiorkor or marasmus.

Emergency feeding and the rehabilitation of famine victims described in Chapter 24 have relevance to adult PEM. It is much more difficult than controlling, for example, iodine deficiency disorders IDD and vitamin A deficiency, because the underlying and basic causes, as described above, are often numerous and complex, and because there is no single, universal, cheap, sustainable strategy that can be applied everywhere to reduce the prevalence or severity of PEM.

Part V of this book includes various strategies to reduce the prevalence of PEM. Appropriate nutrition policies and programmes are suggested, and separate chapters deal with, for example, improving food security, protection and promotion of good health, and appropriate care practices to ensure good nutrition. These chapters provide guidance on how to deal with the three underlying causes of malnutrition, namely inadequate food, health and care, which in Chapter 1 were included in the conceptual framework for malnutrition.

Other chapters in Part V discuss solutions to particular aspects of the problem, including improving the quality and safety of foods, promoting appropriate diets and healthy lifestyles, procuring food in different ways and incorporating nutrition objectives into development policies and programmes.

Throughout Part V there is an emphasis on improving the quality of life of people, especially by reducing poverty, improving diets and promoting good health. Improving the energy intakes of those at risk of PEM is vital. In the late s and s it was thought that most PEM was caused mainly by inadequate intake of protein. A great deal of emphasis was placed on protein-rich foods as a major solution to the huge problem of malnutrition in the world.

This inappropriate strategy diverted attention from the first need, which is adequate food intake by children. There is now much less emphasis on high-protein weaning foods and on nutrition education efforts to ensure greater consumption of meat, fish and eggs, which are economically out of the reach of many families who have children with PEM.

Protein is an essential nutrient, but PEM is more often associated with deficient food intake than with deficient protein intake. In general, when commonly consumed cereal-based diets meet energy needs, they usually also meet protein needs, especially if the diet also provides modest amounts of legumes and vegetables. Primary attention needs to be given to increasing total food intake and reducing infection.

Sensible efforts are needed to protect and promote breastfeeding and sound weaning; to increase the consumption by young children of cereals, legumes and other locally produced weaning foods; to prevent and control infection and parasitic disease; to increase meal frequency for children; and, where appropriate, to encourage higher consumption of oil, fat and other items that reduce bulk and increase the energy density of foods fed to children at risk. These measures are likely to have more impact if accompanied by growth monitoring, immunization, oral rehydration therapy for diarrhoea, early treatment of common diseases, regular deworming and attention to the underlying causes of PEM such as poverty and inequity.

Some of these measures can be implemented as part of primary health care. Nutritional anaemias are extremely prevalent worldwide.

Unlike protein-energy malnutrition PEM , vitamin A deficiency and iodine deficiency disorders IDD , these anaemias occur frequently in both developing and industrialized countries. The most common cause of anaemia is a deficiency of iron, although not necessarily a dietary deficiency of total iron intake.

Deficiencies of folates or folic acid , vitamin B 12 and protein may also cause anaemia. Ascorbic acid, vitamin E, copper and pyridoxine are also needed for production of red blood cells erythrocytes. Vitamin A deficiency is also associated with anaemia. Anaemias can be classified in numerous ways, some based on the cause of the disease and others based on the appearance of the red blood cells.

These classifications are fully discussed in medical textbooks. Some anaemias do not have causes related to nutrition but are caused, for example, by congenital abnormalities or inherited characteristics; such anaemias, which include sickle cell disease, aplastic anaemias, thalassaemias and severe haemorrhage, are not covered here. Based on the characteristics of the blood cells or other features, anaemias may be classified as microcytic having small red blood cells , macrocytic having large red blood cells , haemolytic having many ruptured red blood cells or hypochromic having pale-coloured cells with less haemoglobin.

Macrocytic anaemias are often caused by folate or vitamin B 12 deficiencies. In anaemia the blood has less haemoglobin than normal. Haemoglobin is the pigment in red cells that gives blood its red colour.

It is made of protein with iron linked to it. Haemoglobin carries oxygen in the blood to all parts of the body. In anaemia either the amount of haemoglobin in each red cell is low hypochromic anaemia or there is a reduction in the total number of red cells in the body. The life of each red blood cell is about four months, and the red bone marrow is constantly manufacturing new cells for replacement. This process requires adequate amounts of nutrients, especially iron, other minerals, protein and vitamins, all of which originate in the food consumed.

Iron deficiency is the most prevalent important nutritional problem of humans. It threatens over 60 percent of women and children in most non-industrialized countries, and more than half of these have overt anaemia. In most industrialized countries in North America, Europe and Asia, 12 to 18 percent of women are anaemic. Although deficiency diseases are usually considered mainly as consequences of a lack of the nutrient in the diet, iron deficiency anaemia occurs frequently in people whose diets contain quantities of iron close to the recommended allowances.

However, some forms of iron are absorbed better than others; certain items in the diet enhance or detract from iron absorption; and iron can be lost because of many conditions, an important one in many tropical countries being hookworm infection, which is very common. Nutritional anaemias have until recently been relatively neglected and not infrequently remain undiagnosed.

There are many reasons for the lack of attention, but the most important are probably that the symptoms and signs are much less obvious than in severe PEM, IDD or xerophthalmia, and that although anaemias do contribute to mortality rates they do not often do so in a dramatic way, and death is usually ascribed to another more conspicuous cause such as childbirth.

However, research now indicates that iron deficiency has very important implications, including poorer learning ability and behavioural abnormalities in children, lower ability to work hard and poor appetite and growth. To maintain good iron nutritional status each individual needs to have an adequate quantity of iron in the diet. The iron has to be in a form that permits a sufficient amount of it to be absorbed from the intestines.

The absorption of iron may be enhanced or inhibited by other dietary substances. Human beings have the ability both to store and to conserve iron, and it must also be transported properly within the body. The average male adult has 4 to 5 g of iron in his body, most of it in haemoglobin, a little in myoglobin and in enzymes and around 1 g in storage iron, mainly ferritin in the cells, especially in the liver and bone marrow.

Losses of iron from the body must not deplete the supply to less than that needed for manufacture of new red blood cells. To produce new cells the body needs adequate quantities and quality of protein, minerals and vitamins in the diet. Protein is needed both for the framework of the red blood cells and for the manufacture of the haemoglobin to go with it. Iron is essential for the manufacture of haemoglobin, and if a sufficient amount is not available, the cells produced will be smaller and each cell will contain less haemoglobin than normal.

Copper and cobalt are other minerals necessary in small amounts. Folates and vitamin B 12 are also necessary for the normal manufacture of red blood cells. If either is deficient, large abnormal red blood cells without adequate haemoglobin are produced. Ascorbic acid vitamin C also has a role in blood formation. Providing vitamin A during pregnancy has been shown to improve haemoglobin levels.

Of the dietary deficiency causes of nutritional anaemias, iron deficiency is clearly by far the most important. Good dietary sources of iron include foods of animal origin such as liver, red meat and blood products, all containing haem iron, and vegetable sources such as some pulses, dark green leafy vegetables and millet, all containing non-haem iron.

However, the total quantity of iron in the diet is not the only factor that influences the likelihood of developing anaemia. The type of iron in the diet, the individual's requirements for iron, iron losses and other factors often are the determining factors. Iron absorption is influenced by many factors. In general, humans absorb only about 10 percent of the iron in the food they consume. The adult male loses only about 0. On an average monthly basis, the adult pre-menopausal woman loses about twice as much iron as a man.

Similarly, iron is lost during childbirth and lactation. Additional dietary iron is needed by pregnant women and growing children. The availability of iron in foods varies greatly. In general, haem iron from foods of animal origin meat, poultry and fish is well absorbed, but the non-haem iron in vegetable products, including cereals such as wheat, maize and rice, is poorly absorbed.

These differences may be modified when a mixture of foods is consumed. It is well known that phytates and phosphates, which are present in cereal grains, inhibit iron absorption. On the other hand, protein and ascorbic acid vitamin C enhance iron absorption. Recent research has shown that ascorbic acid mixed with table salt and added to cereals increases the absorption of intrinsic iron in the cereals two- to fourfold.

The consumption of vitamin C-rich foods such as fresh fruits and vegetables with a meal may therefore promote iron absorption. Egg yolk impairs the absorption of iron, even though eggs are one of the better sources of dietary iron. Tea consumed with a meal may reduce the iron absorbed from the meal.

The normal child at birth has a high haemoglobin level usually at least 18 g per ml , but during the first few weeks many cells are haemolysed. The iron liberated is not lost but is stored in the body, especially in the liver and spleen. As milk is a poor source of iron, this reserve store is used during the early months of life to help increase the volume of blood, which is necessary as the baby grows.

Premature infants have fewer red blood cells at birth than full-term infants, so they are much more prone to anaemia. In addition, iron deficiency in the mother may affect the infant's vital iron store and render the infant more vulnerable to anaemia. A baby's store of iron plus the small quantity of iron supplied in breastmilk suffice for perhaps six months, but then other iron-containing foods are needed in the diet.

Although it is desirable that breastfeeding should continue well beyond six months, it is also necessary that other foods containing iron be introduced into the diet at this time. Although most solid diets, both for children and adults, provide the recommended allowances for iron, the iron may be poorly absorbed. Many people have increased needs because of blood loss from hookworm or bilharzia infections, menstruation, childbirth or wounds.

Women have increased needs during pregnancy, when iron is needed for the foetus, and during lactation, for the iron in breastmilk. It is stressed that iron from vegetable products, including cereal grains, is less well absorbed than that from most animal products. Anaemia is common in premature infants; in young children over six months of age on a purely milk diet; in persons infected with certain parasites; and in those who get only marginal quantities of iron, mainly from vegetable foods.

It is more common in women, especially pregnant and lactating women, than in men. In most of the world, both North and South, the greatest attention to iron deficiency anaemia is directed at women during pregnancy, when they have increased needs for iron and often become anaemic. Pregnant women form the one group of the healthy population who are advised to take a medicinal dietary supplement, usually iron and folic acid.

Pregnant and lactating women are a group at especially high risk of developing anaemia. It is only in recent years that the prevalence and importance of iron deficiency apart from anaemia has been widely discussed. Clearly, however, if the causes of iron deficiency are not removed, corrected or alleviated then the deficiency will lead to anaemia, and gradually the anaemia will become more serious.

Increasing evidence suggests that iron deficiency as manifested by low body iron stores, even in the absence of overt anaemia, is associated with poorer learning and decreased cognitive development.

International agencies now claim that iron deficiency anaemia is the most common nutritional disorder in the world, affecting over 1 million people. In females of child-bearing age in poor countries prevalence rates range from 64 percent in South Asia to 23 percent in South America, with an overall mean of 42 percent Table Prevalence rates are usually considerably higher in pregnant women, with an overall mean of 51 percent.

Thus half the pregnant women in these regions, whose inhabitants represent 75 percent of the world's population, have anaemia. Unlike reported figures for PEM and vitamin A deficiency, which are declining, estimates suggest that anaemia prevalence rates are increasing. In most of the developing regions, and particularly among persons with anaemia or at risk of iron deficiency, much of the iron consumed is non-haem iron from staple foods rice, wheat, maize, root crops or tubers.

In many countries the proportion of dietary iron coming from legumes and vegetables has declined, and rather small quantities of meat, fish and other good sources of haem iron are consumed. In some of the regions with the highest prevalence of anaemia the poor are not improving their dietary intake of iron, and in some areas the per caput supply of dietary iron may even be decreasing year by year.

In , geologist and paleontologist Peter Ward and astrobiologist Donald Brownlee published a book entitled Rare Earth: Why Complex Life is Uncommon in the Universe. Ward and Brownlee are open to the idea of evolution on other planets that is not based on essential Earth-like characteristics such as DNA and carbon. Theoretical physicist Stephen Hawking in warned that humans should not try to contact alien life forms.

He warned that aliens might pillage Earth for resources. In November , the White House released an official response to two petitions asking the U. According to the response, "The U. In , the exoplanet Keplerf was discovered, along with Keplere and Keplerc. A related special issue of the journal Science , published earlier, described the discovery of the exoplanets. On 17 April , the discovery of the Earth-size exoplanet Keplerf , light-years from Earth , was publicly announced; [] it is the first Earth-size planet to be discovered in the habitable zone and it has been hypothesized that there may be liquid water on its surface.

On 13 February , scientists including Geoffrey Marcy , Seth Shostak , Frank Drake and David Brin at a convention of the American Association for the Advancement of Science , discussed Active SETI and whether transmitting a message to possible intelligent extraterrestrials in the Cosmos was a good idea; [] [] one result was a statement, signed by many, that a "worldwide scientific, political and humanitarian discussion must occur before any message is sent".

The group contracted the services of the meter Robert C. From Wikipedia, the free encyclopedia. For other uses, see Astrobiology.

Some major international efforts to search for extraterrestrial life. Clockwise from top left: The search for extrasolar planets image: Kepler telescope Listening for extraterrestrial signals indicating intelligence image: Allen array Robotic exploration of the Solar System image: Curiosity rover on Mars.

Planetary habitability , Habitability of natural satellites , and Exobiology. List of planetary systems. Including red dwarfs would increase this to 40 billion. The New York Times. Retrieved 20 November Controversial pieces of evidence for extraterrestrial life". Retrieved 18 February Retrieved 6 January Archived from the original on 24 October Retrieved 10 March Other Worlds, Other Universes.

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International Journal of Astrobiology: The National Academies Press. In Shils, Maurice E. Modern Nutrition in Health and Disease 9th ed. Retrieved 8 August To Utopia and Back: The Search for Life in the Solar System. Retrieved 8 April There is general consensus that extant microbial life on Mars would probably exist if at all in the subsurface and at low abundance.

What are the Properties of Life? The University of Arizona. Retrieved 6 June If any life exists on Mars today, scientists believe it is most likely to be in pockets of liquid water beneath the Martian surface. Milwaukee School of Engineering. Archived from the original on 9 June Retrieved 10 August Origin, Composition, and the Prospects for Life". Archived from the original PDF on 3 July Retrieved 21 December Anaxagoras and the Origin of Panspermia Theory.

Annalen der Chemie und Pharmacie. We must regard it as probably to the highest degree that there are countless seed-bearing meteoritic stones moving through space. Worlds in the Making: The Evolution of the Universe. University College Cardiff Press. Some past speculations on the origin of life: Where are they today?

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Retrieved 25 May Retrieved 26 June University of California, Riverside. Little Evidence of Life on Mars". Archived from the original on 16 April Research conducted in China shows that there have been profound shifts in purchasing practices in relation to income over the past decade. These analyses show how extra income in China affects poor people and rich people in a differential manner, enhancing the fat intake of the poor more than that of the rich 7.

A variable proportion of these fat calories are provided by saturated fatty acids. Only in the two of the most affluent regions i. National dietary surveys conducted in some countries confirm these data. The ratio of dietary fat from animal sources to total fat is a key indicator, since foods from animal sources are high in saturated fat. Data sets used to calculate country-specific FERs can also be used to calculate proportions of animal fat in total fat.

These findings are not strictly divided along economic lines, as not all of the countries in the high range represent the most affluent countries.

Country-specific food availability and cultural dietary preferences and norms to some extent determine these patterns.

The types of edible oils used in developing countries are also changing with the increasing use of hardened margarines rich in trans fatty acids that do not need to be refrigerated. Palm oil is becoming an increasingly important edible oil in the diets of much of South-East Asia and is likely to be a major source in the coming years.

Potential developments in the edible oil sector could affect all stages of the oil production process from plant breeding to processing methods, including the blending of oils aimed at producing edible oils that have a healthy fatty acid composition. Olive oil is an important edible oil consumed largely in the Mediterranean region. Its production has been driven by rising demand, which has increasingly shifted olive cultivation from traditional farms to more intensive forms of cultivation.

There is some concern that the intensive cultivation of olives may have adverse environmental impacts, such as soil erosion and desertification 8.

However, agricultural production methods are being developed to ensure less harmful impacts on the environment. There has been an increasing pressure on the livestock sector to meet the growing demand for high-value animal protein.

Annual meat production is projected to increase from million tonnes in to million tonnes by There is a strong positive relationship between the level of income and the consumption of animal protein, with the consumption of meat, milk and eggs increasing at the expense of staple foods.

Because of the recent steep decline in prices, developing countries are embarking on higher meat consumption at much lower levels of gross domestic product than the industrialized countries did some years ago.

Urbanization is a major driving force influencing global demand for livestock products. Urbanization stimulates improvements in infrastructure, including cold chains, which permit trade in perishable goods.

Compared with the less diversified diets of the rural communities, city dwellers have a varied diet rich in animal proteins and fats, and characterized by higher consumption of meat, poultry, milk and other dairy products.

Table 4 shows trends in per capita consumption of livestock products in different regions and country groups. There has been a remarkable increase in the consumption of animal products in countries such as Brazil and China, although the levels are still well below the levels of consumption in North American and most other industrialized countries.

As diets become richer and more diverse, the high-value protein that the livestock sector offers improves the nutrition of the vast majority of the world. Livestock products not only provide high-value protein but are also important sources of a wide range of essential micronutrients, in particular minerals such as iron and zinc, and vitamins such as vitamin A.

For the large majority of people in the world, particularly in developing countries, livestock products remain a desired food for nutritional value and taste. Excessive consumption of animal products in some countries and social classes can, however, lead to excessive intakes of fat.

The growing demand for livestock products is likely to have an undesirable impact on the environment. For example, there will be more large-scale, industrial production, often located close to urban centres, which brings with it a range of environmental and public health risks. Attempts have been made to estimate the environmental impact of industrial livestock production. For instance, it has been estimated that the number of people fed in a year per hectare ranges from 22 for potatoes and 19 for rice to 1 and 2, respectively, for beef and lamb 9.

The low energy conversion ratio from feed to meat is another concern, since some of the cereal grain food produced is diverted to livestock production. Likewise, land and water requirements for meat production are likely to become a major concern, as the increasing demand for animal products results in more intensive livestock production systems Despite fluctuations in supply and demand caused by the changing state of fisheries resources, the economic climate and environmental conditions, fisheries, including aquaculture, have traditionally been, and remain an important source of food, employment and revenue in many countries and communities After the remarkable increase in both marine and inland capture of fish during the s and s, world fisheries production has levelled off since the s.

It is therefore very unlikely that substantial increases in total catch will be obtained in the future. In contrast, aquaculture production has followed the opposite path. Starting from an insignificant total production, inland and marine aquaculture production has been growing at a remarkable rate, offsetting part of the reduction in the ocean catch of fish. The total food fish supply and hence consumption has been growing at a rate of 3.

The proteins derived from fish, crustaceans and molluscs account for between The average apparent per capita consumption increased from about 9 kg per year in the early s to 16 kg in The per capita availability of fish and fishery products has therefore nearly doubled in 40 years, outpacing population growth.

As well as income-related variations, the role of fish in nutrition shows marked continental, regional and national differences. In industrialized countries, where diets generally contain a more diversified range of animal proteins, a rise in per capita provision from In this group of countries, fish contributed an increasing share of total protein intake until accounting for between 6.

Over the past four decades, however, the share of fish proteins in animal proteins has declined slightly, because of faster growth in the consumption of other animal products. Currently, two-thirds of the total food fish supply is obtained from capture fisheries in marine and inland waters, while the remaining one third is derived from aquaculture.

The contribution of inland and marine capture fisheries to per capita food supply has stabilized, around 10 kg per capita in the period Any recent increases in per capita availability have, therefore, been obtained from aquaculture production, from both traditional rural aquaculture and intensive commercial aquaculture of high-value species. Fish contributes up to kcal per capita per day, but reaches such high levels only in a few countries where there is a lack of alternative protein foods grown locally or where there is a strong preference for fish examples are Iceland, Japan and some small island states.

More typically, fish provides about kcal per capita per day. Fish proteins are essential in the diet of some densely populated countries where the total protein intake level is low, and are very important in the diets of many other countries.

Worldwide, about a billion people rely on fish as their main source of animal proteins. Dependence on fish is usually higher in coastal than in inland areas.

Recommending the increased consumption of fish is another area where the feasibility of dietary recommendations needs to be balanced against concerns for sustainability of marine stocks and the potential depletion of this important marine source of high quality nutritious food. Added to this is the concern that a significant proportion of the world fish catch is transformed into fish meal and used as animal feed in industrial livestock production and thus is not available for human consumption.

Consumption of fruits and vegetables plays a vital role in providing a diversified and nutritious diet. Alow consumption of fruits and vegetables in many regions of the developing world is, however, a persistent phenomenon, confirmed by the findings of food consumption surveys. Nationally representative surveys in India 12 , for example, indicate a steady level of consumption of only g per capita per day, with about another g per capita coming from roots and tubers, and some 40 g per capita from pulses.

This may not be true for urban populations in India, who have rising incomes and greater access to a diverse and varied diet. In contrast, in China, - a country that is undergoing rapid economic growth and transition - the amount of fruits and vegetables consumed has increased to g per capita per day by In , only 6 of the 14 WHO regions had an availability of fruits and vegetables equal to or greater than the earlier recommended intake of g per capita per day. The relatively favourable situation in appears to have evolved from a markedly less favourable position in previous years, as evidenced by the great increase in vegetable availability recorded between and for most of the regions.

In contrast, the availability of fruit generally decreased between and in most regions of the world. The increase in urbanization globally is another challenge. Increasing urbanization will distance more people from primary food production, and in turn have a negative impact on both the availability of a varied and nutritious diet with enough fruits and vegetables, and the access of the urban poor to such a diet.

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