The Potential Therapeutic Role of Vitamins

Much interest has been expressed in the therapeutic role of vitamins in cancer patients. This has led a number of alternative and complementary practitioners to advocate the use of high-dose vitamins for cancer patients. It has been know for some time that some vitamin-deficiency states may predispose some individuals to develop cancer. In a study of 29 000 vegetarian Chinese with a high frequency of oesophageal cancer, subjects were given supplements of -carotene and vitamin E. Raising their...

Fibrocalculous Pancreatic Diabetes

In tropical countries there is a form of nonalcoholic chronic pancreatitis characterized by pancreatic exocrine and endocrine insufficiency and associated with pancreatic calcification. This disease, tropical calcific pancreatitis, affects young individuals who are malnourished and present with abdominal pain, extreme emaciation characteristic of protein-energy malnutrition, glucose intolerance, and at a later stage diabetes. The diabetic stage of the illness is referred to as fibrocalcific...

Abnormalities of Hormones and Other Circulating Factors

Growth hormone Obesity is typically accompanied by a decrease in growth hormone (GH) levels and an increase in growth hormone binding protein levels. An inverse relation exists between GH levels and percentage fat mass. GH levels fall with increasing age. GH is released by the anterior pituitary and affects lipid, carbohydrate, and protein metabolism. GH also controls the rate of skeletal and visceral growth. GH is lipolytic in adipose tissue. Animal studies show enhanced catecholamine-induced...

Branched Chain Amino Acids Isoleucine Leucine Valine

Branched chain amino acids (BCAAs) are essential amino acids, which together compose approximately a third of the daily amino acid requirement in humans. BCAAs, and especially leucine, play an important role in the regulation of energy and protein metabolism. BCAAs are primarily oxidized in skeletal muscle and not in the liver. BCAAs donate their amino groups to furnish glutamic acid in muscle in transamination reactions yielding the a-ketoa-cids a-ketoisocaproic acid, a-keto- -methylvaleric...

Tea

D J Baer and S C Chen, US Department of Agriculture, Beltsville, MD, USA Throughout the world, tea is one of the most consumed beverages, second only to water. Based on data from the Tea Association of the United States, the estimated wholesale value of the tea industry increased 273 between 1990 and 2002, and it is now valued in excess of 5 billion. The greatest increase has been in the ready-to-drink market (925 increase). One reason for the popularity in tea consumption is the interest of...

Ideal Body Weight

The estimate of ideal body weight (IBW) is also in part determined by the severity of the CP. The IBW should be aimed at maintaining adequate fat and muscle stores to endure repeated surgeries or a common virus while facilitating daily physical care and management. Weight-for-length is an indicator of nutritional status, which obscures the issue of chronological age and addresses whether the individual is proportionate. IBW can be expressed as this ratio. Those with cerebral palsy should attain...

Breast Feeding Initiatives

In response to concerns about the use of infant formula in environments where lack of breast feeding resulted in large numbers of infant who became severely ill or died, a grassroots global initiative took hold in the 1970s to promote international and national efforts to protect, promote, and support breast feeding. These efforts culminated in 1981 with the nearly unanimous adoption by the World Health Assembly (WHA) of the International Code of Marketing of Breast-Milk Substitutes. This...

Global Breast Feeding Practices

The most comprehensive data on breast feeding come from the Demographic and Health Surveys conducted with support from the US Agency for International Development. These surveys are nationally representative and conducted throughout the developing world. In a number of countries, multiple surveys permit the analysis of trends. Overall, the data show that although the vast majority of women more than 90 in all countries initiate breast feeding, the duration of exclusive breast feeding is far...

Benefits of Breast Feeding

Breast feeding contributes to both maternal and infant nutrition and health through a number of important mechanisms. It provides a complete source of nutrition for the first 6 months of life for normal, full-term infants and provides one-half and one-third of energy needs for the second half of the first year and the second year of life, respectively. It also contributes significantly to protein and micro-nutrient requirements. Numerous studies have shown that during illness, whereas intake of...

Metabolism and Turnover

The primary role of pantothenic acid is in acyl group activation for lipid metabolism, involving thiol acylation of CoA or of ACP, both of which contain 4-phosphopantotheine, the active group of which is -mercaptoethylamine. CoA is essential for oxidation of fatty acids, pyruvate and a-oxogutarate, for metabolism of sterols, and for acetylation of other molecules, so as to modulate their transport characteristics or functions. Acyl carrier protein, which is synthesized from apo-ACP and coenzyme...

Requirements

In the UK, National Food Survey records suggest that during recent decades mean adult daily pan-tothenate intakes have been consistently in the range of 4-6 mg. Since there is little evidence for the magnitude of minimum requirements in humans, the UK committee responsible for the revision of dietary reference values in 1991 suggested that intakes in the range 3-7mgday_1 can be considered as adequate (although no specific values for the reference nutrient intake, estimated average requirement...

Treatment

Once the presumptive diagnosis of celiac disease is made then treatment may be commenced. It is important that the patient does not start to restrict their diet until each of the steps including the biopsy have been completed. Once confirmed, the responsibility for directing the management of the patient lies with the physician. The treatment starts with an explanation of the condition and its cause. It is important that the patient understands that this is a chronic inflammatory condition of...

Cassidy School of Medicine University of East Anglia Norwich UK

All rights reserved. There is a considerable body of evidence to suggest that populations that consume diets rich in fruits and vegetables, whole-grain cereals, and complex carbohydrates have a reduced risk of a range of chronic diseases. This has led to the suggestion that the diversity of substances found in food, particularly plant-derived or plant-based foods, may underlie the protective effects that are attributed to diets high in fruits and vegetables and other plant...

A E Bender Leatherhead UK

All rights reserved. This article is a revision of the previous edition, article by A E Bender, pp. 902-906, 1999, Elsevier Ltd. Fruits and vegetables have considerable potential as a source of nutrients but the amounts eaten vary enormously both within and between countries. Some 3000 species are known to be edible and there are said to be more than 1500 species of wild tropical plants. In the foreword to Traditional Plant Foods, published by the Food and Agriculture...

History of Salt Intake

The fundamental drive to obtain salt can be traced back to the earliest times when humans evolved in a hot African environment with scarce sources of salt. Evidence has been found of salt use during the Neolithic Age, and the Egyptian, Babylonian and Chinese civilizations all had special culinary uses for salt that are well documented. In China, for centuries the production of salt was a major industry. Salt sources were highly valued and were often protected. A tax on salt in the form of a...

Potential Role for Biotin in Gene Expression

In 1995, Hymes and Wolf discovered that biotini-dase can act as a biotinyl-transferase biocytin serves as the source of biotin, and histones are specifically biotinylated. Approximately 25 of total cellular biotinidase activity occurs in the nucleus. Zempleni and coworkers demonstrated that the abundance of biotinylated histones varies with the cell cycle, that biotinylated histones are increased approximately twofold compared to quiescent lymphocytes, and that histones are debiotinylated...

Practical Approach to the Prevention of Caries

The success of fluoridated toothpaste in preventing dental caries has resulted in a change in professional approaches to prevention. Instead of focusing simply on attempts to reverse the main causative factors, attention is now centered on exploiting protective influences. The interaction of the three main causative factors is illustrated in Figure 1. Numerous attempts to change the impact of any of these influences on caries have proved ineffective, except, perhaps, under the most extreme...

Abbreviations

FAO Food and Agriculture Organization See also Alcohol Absorption, Metabolism and Physiological Effects. Carbohydrates Regulation of Metabolism Requirements and Dietary Importance Resistant Starch and Oligosaccharides. Colon Structure and Function. Dietary Fiber Physiological Effects and Effects on Absorption. Fructose. Galactose. Glucose Chemistry and Dietary Sources. Glycemic Index. Small Intestine Structure and Function. Stomach Structure and Function. Sucrose Nutritional Role, Absorption...

Abetalipoproteinemia

This is an autosomal recessive condition with abnormal lipid metabolism, retinitis pigmentosa, neurological deterioration, and acanthocytosis (abnormal red blood cells). The intestines and liver are unable to synthesize triglyceride-rich lipoproteins, chylomi-crons, and very low-density lipoprotein. As a result, there is steatorrhea due to malabsorption of fat together with malabsorption of fat-soluble vitamins. Symptoms can be corrected by substitution of the normal fat intake with...

Abnormalities in Acid Base Balance

Disturbances in acid-base balance are classified as either 'acidosis,' indicating an excess of H+ ions in the blood (reduced pH) or alkalosis, indicating the opposite. In practice, acidosis is the more common, varied, and serious problem. Disturbances in acid-base balance are usually labeled according to their origin. For example, respiratory acidosis reflects a primary problem in gas exchange with impaired excretion of CO2, whereas metabolic acidosis reflects the over-production of fixed acid...

Absorption

As already indicated, although the final end product of protein digestion is amino acids, small peptides are the dominant form of entry of amino acids into enterocytes, where they are further hydrolyzed into amino acids and absorbed into the bloodstream (Figure 4). Thus, the vast majority of products of protein digestion that reach the bloodstream are single amino acids. Amino acid transport systems develop in utero by the end of the first trimester, whereas peptide transport systems can be...

Absorption and Ethyl Alcohol

In food, thiamin occurs mainly as phosphate coen-zymes and the predominant form is TDP (also called thiamin pyrophosphate and cocarboxylase). The phosphate coenzymes are broken down in the gut by phosphatases to give free thiamin for absorption. Thiamin is absorbed mainly from the upper intestine, and less thiamin is absorbed on an empty stomach than when taken with a meal. The latter could be due to the alkaline conditions in the duodenum, which are prevented by the presence of food....

Absorption and Metabolism of Flavonoids

The flavonols and flavones are generally present in plants in the form of glycosides and as such are water-soluble. Thus, some of the flavonol glycosides may be absorbed intact in the small intestine or hydrolyzed by mucosal enzymes and absorbed as aglycones. However, those that pass through the small intestine unabsorbed or reenter the gut from the bile become available for bacterial metabolism in the colon. The colon contains numerous microorganisms and as a result it has significant capacity...

Absorption and Transport

Because carotenoids are hydrophobic molecules, they are associated with lipophilic sites in cells, such as bilayer membranes. Polar substituents such as hydroxyl groups decrease their hydrophobicity and their orientation with respect to membranes. Lycopene and 0-carotene are aligned parallel to membrane surfaces to maintain a hydrophobic environment, whereas the more polar xanthophylls lutein and zeaxanthin become oriented perpendicular to membrane surfaces to keep their hydroxyl groups in a...

Absorption by Human Subjects

Studies of riboflavin absorption by human subjects require a combination of a test dose, usually taken by mouth, and a sampling procedure to estimate the amount absorbed, and possibly also its subsequent fate. The sampling compartment is generally the Covalently bound flavin, not used, excreted Riboflavin glucoside Covalently bound flavin, not used, excreted Riboflavin glucoside Figure 1 Characteristics of the absorption process for riboflavin and its coenzymes. urine, since plasma has proved...

Absorption Distribution and Elimination

Following oral ingestion, caffeine is rapidly and virtually completely absorbed from the gastrointestinal tract into the bloodstream. Mean plasma Figure 1 Chemical structures of caffeine and the dimethyl-xanthines. (A) Purine ring nomenclature according to E. Fischer (B) caffeine (C) theobromine (D) theophylline (E) paraxanthine. From Dews (1984). concentrations of 8-10 mgl-1 are observed following oral or intravenous doses of 5-8mgkg-1. The plasma kinetics of caffeine can be influenced by a...

Absorption of Folates

Food folates mainly consist of reduced polygluta-mates, which are hydrolyzed to monoglutamates in the gut prior to absorption across the intestinal mucosa. The conjugase enzyme that hydrolyzes dietary folates has been found on the luminal brush border membrane in the human jejunum and has equal affinity for polyglutamates of various chain lengths. Transport is facilitated by a saturable carrier-mediated uptake system, although changes in luminal pH and the presence of conjugase inhibitors,...

Absorption of Fructose

Dietary fructose is ingested as the simple monosaccharide and also as part of the disaccharide sucrose. Sucrose is hydrolyzed by sucrase at the intestinal brush border to yield one molecule of glucose and one of fructose. Glucose is rapidly absorbed via a sodium-coupled cotransporter and arrives at the liver via the portal circulation. Fructose absorption is accomplished primarily by a fructose-specific hex-ose transporter, GLUT-5. This transporter is found in the jejunum on both the brush...

Absorption of Glucose and Fructose

The glucose product of sucrose digestion is transported across the epithelial cell membrane more rapidly than is free glucose, a phenomenon that may be related to specific glucose transporters that are not dependent on sodium. The fructose released by sucrose digestion is absorbed more slowly across the brush border membrane by a process called facilitated diffusion (carrier-mediated). Fructose appears to be absorbed better when ingested with glucose (separately or combined in sucrose) than it...

Absorption Transport and Storage

Iodine is usually ingested as an iodide or iodate compound and is rapidly absorbed in the intestine. Iodine entering the circulation is actively trapped by the thyroid gland. This remarkable capacity to concentrate iodine is a reflection of the fact that the most critical physiological role for iodine is the normal functioning of the thyroid gland. Circulating iodide enters the capillaries within the thyroid and is rapidly transported into follicular cells and on into the lumen of the follicle....

Access Devices and PN Concentrations

PN is administered into the venous system either through peripheral venous lines or through centrally placed access devices. Lower concentrations of dextrose and amino acids may be administered through peripheral veins for a short duration of therapy. Such formulas usually do not provide the patient's full nutrition needs, may require large volumes of fluid, and can only be used for short durations due to the difficulty of maintaining peripheral intravenous access. Osmolarity of peripheral...

Acetaldehyde Metabolism

Acetaldehyde is highly toxic but is rapidly converted to acetate. This conversion is catalyzed by aldehyde Table 6 Classes of aldehyde dehydrogenase isoenzymes Liver > kidney > muscle > heart aKm supplied is for acetaldehyde ALDH also oxidizes other substrates. Adapted with permission from Kwo PY and Crabb DW (2002) Genetics of ethanol metabolism and alcoholic liver disease. In Sherman DIN, Preedy VR and Watson RR (eds.) Ethanol and the Liver. Mechanisms and Management, pp. 95-129. London...

Acid

Acid is secreted by the gastric gland parietal cells via the action of the gastric H+ K+ ATPase, a transmembrane proton pump. In nonstimulated parietal cells the pump is present in cytoplasmic vesicles (the tubulovesicles) separated from the apical membrane. Electron microscopy studies have shown that these vesicles are in fact small stacks of cisternae and should be called tubulocisternae. On stimulation the pumps are transported in vesicles to the apical membrane along the actin cytoskeleton...

Acidic Side Chains Aspartic Acid and Glutamic Acid

These are dicarboxylic acids, although at physiological pH they exist almost entirely in the anionic form and so should be referred to as aspartate and glutamate. They are mainly found on the surfaces of proteins. The free amino acids play a central role in transamination reactions, equilibrating rapidly with their corresponding keto acids oxaloacatate and 2-oxoglutarate. Glutamate is a precursor for the inhibitory neurotransmitter 7-aminobutyric acid (GABA). The monosodium salt of glutamate is...

Acids and Bases

Acids are substances that dissociate to donate H+ (eqn 2 ) the stronger the acid, the more readily it dissociates. The dissociation constant (pKa) is the pH at which 50 of the acid is dissociated. At pH values greater than pKa more H+ will dissociate the lower the pKa, the stronger the acid. A base is a substance that accepts hydrogen ions. In the following text the term 'fixed acid' is used to describe formed acid, and 'volatile acid' is used to describe the potential acid load imposed by...

Acknowledgements

This article is adapted with Permission from Cegielski JP, Mc Murray DN. The Relationship between Malnutrition and Tuberculosis.'' Int J Tuberc Lung Dis 2004 8(3) 286-298. See also Ascorbic Acid Deficiency States. Cytokines. Immunity Effects of Iron and Zinc. Malnutrition Primary, Causes Epidemiology and Prevention Secondary, Diagnosis and Management. Tuberculosis Nutritional Management. Vitamin D Physiology, Dietary Sources and Requirements. Zinc Physiology Deficiency in Developing Countries,...

Acknowledgments

The author thanks The Hong Kong Polytechnic University and The World Cancer Research Fund International for financially supporting this work. See also Antioxidants Diet and Antioxidant Defense. Further Reading Ames BN and Wakimoto P (2002) Are vitamin and mineral deficiencies a major cancer risk Nature Reviews 2 694-704. Asplund K (2002) Antioxidant vitamins in the prevention of cardiovascular disease a systematic review. Journal of Internal Medicine 251 372-392. Benzie IFF (2003) Evolution of...

Acute Phase Response

The development of injury, infection, or cancer cachexia elicits an acute phase response. This is one of the most basic responses of the body to defend itself against injury. Phylogenetically, this response could be considered the most primitive response of the body. This stereotypical response is similar for injury from an accident, burn, infection, foreign objects, and, in some cases, from a tumor. Unfortunately, this response does not occur for most tumors, but it is seen when the malignancy...

Adaptation

A G Dulloo, University of Fribourg, Fribourg, J Jacquet, University of Geneva, Geneva, 2005 Elsevier Ltd. All rights reserved. Throughout much of evolutionary history, the mammalian species have been faced with periodic food shortages, specific nutrient deficiencies, and, sometimes, food abundance. Within such a lifestyle of famine and feast, it is conceivable that adaptive mechanisms operating through adjustments in energy expenditure and in management of the body's main energy-containing...

Addressing Nutrition in Refugees

Due to the nature of displacement and the loss of livelihoods, refugee populations are extremely vulnerable. Often, refugees settle in camps with support from the international community and host government. In some cases, refugees may live in open situations in which they integrate into the local community. In almost all cases, refugees are dependent on outside assistance, although the level of need depends on the level of self-reliance the refugees are able to achieve. In some instances,...

Adequacy of Nutritional Therapy

Carefully executed diet therapy for individuals with PKU is widely considered to be safe as well as efficacious in preventing mental and neurological impairment. However, it cannot be assumed that largely synthetic diets supplemented with individual vitamins, minerals, and trace elements will confer the same benefits as diets composed of whole foods. Synthetic diets may have an inherent inability to supply all essential nutrients. In addition, patients who are noncompliant or partially...

Adolescents 1019 Years

Adolescent girls are at special nutritional risk, especially for iron deficiency anemia, with menstruation taking place while growth is still not complete. Few intervention studies have been done on adolescent girls, and those that have focused on anemia prevention. Well-supervised intermittent iron supplementation to adolescent girls in schools or the workplace can reduce their prevalence of anemia. Although iron supplements have been shown to be important for correcting iron deficiency anemia...

Adrenal Cortex

Serum cortisol levels are slightly raised, without diurnal variation, and may not suppress with dexa-methasone overnight. Urinary 17-hydroxy and 17-keto steroids are decreased by 30-50 , but urinary-free cortisol may be increased. Corticotrophin-releasing factor (CRF) stimulation causes a subnormal corticotrophin rise but a normal or supernormal serum cortisol response. Levels of CRF in the cere-brospinal fluid are elevated. These changes in the hypothalamic-pituitary-adrenal axis are very...

Adults

The progressive increase in prevalence of lactose maldigestion increases with age, reaching reported adult levels of approximately 70 of the world's adult population. The exceptions are populations of Northern and Central Europeans and some Middle Eastern populations as well as groups of primarily European descent in Australia, New Zealand, and North America. Thus, minority populations in North America and Europe, as well as adult populations in most developing countries, are lactose...

Advancing

Between the ages of 20 and 50 years, there is a gradual rise in serum cholesterol concentrations. In the USA, for example, the serum cholesterol increases on average about 50mgdl 1 (1.295mmoll-1). This change may be related in part to increasing obesity, according to the mechanisms described above. However, even in people who do not gain weight with advancing age, serum cholesterol concentrations usually rise to some extent. Available evidence indicates that this rise results from a decrease in...

Advantages and Limitations of Anthropometric Measurements

Anthropometric measurements are noninvasive. Compared with other methods of assessing nutritional status, the measurements are quick and easy to make using relatively cheap and simple equipment. They can be made by relatively unskilled people. Anthropometric measurements cannot identify protein and micronutrient deficiencies, detect small disturbances in nutritional status, nor identify small changes in the proportions of body fat to lean body mass. Some anthropometric measurements may not be...

Aeromonas and Plesiomonas shigelloides

Aeromonas is another aquatic organism that prefers brackish and fresh water. It is generally accepted as a cause of FP, after initial doubts, in both adults and children. A profuse watery diarrhea is typical, although a dysentery-like syndrome is sometimes associated with it. The incubation period is 18-24 h. Sporadic infections are more common than full-blown outbreaks. Consumption of raw shellfish should be avoided (not only for aeromonas). Plesiomonas shigelloides is also an aquatic...

Age Specific Prevalence

Age-Specific prevalence data suggest a progressive decrease in lactose absorption with age in African American children studied in the United States. This progressive decrease was seen in a study of 409 African American children 13 months to 12 years of age. The population was stratified by age to have approximately equal representation in each 12-month category. The mean age of the children studied was 6.6 years. The study subjects were drawn from four well child clinic sites and a private...

Aging

ALA deficiency has been found in patients on long-term gastric tube-feeding that included large amounts of skim milk without ALA supplementation. These patients, who were in nursing homes, Table 9 Effects of polyunsaturated fatty acids on several genes encoding enzyme proteins involved in cell growth, early gene expression, adhesion molecules, inflammation, -oxidation, and growth factors3 Function and gene Linoleic acid a-Linolenic acid Arachidonic acid Eicosapentaenoic acid Docosahexaenoic...

Alanine

Alanine and glutamine are the principal amino acid substrates for hepatic gluconeogenesis and ureagen-esis. Alanine is produced in peripheral tissues in transamination processes with glutamate, branched chain amino acids, and other amino acids following its release in the systemic circulation, alanine is predominantly taken up by the liver and to a lesser extent by the kidney. Here, alanine can be deami-nated to yield pyruvate and an amino group, which can be used for transamination processes,...

Alcohol Dehydrogenase Isoenzymes

ADH is a zinc metalloprotein with five classes of isoenzymes that arise from the association of eight different subunits into dimers (Table 5). A genetic model accounts for these five classes of ADH as Figure 2 Chemical structures of acetaldehyde and acetate, the products of ethanol metabolism. Figure 3 Pathways of ethanol metabolism. Figure 3 Pathways of ethanol metabolism. products of five gene loci (ADH1-5). Class 1 isoenzymes generally require a low concentration of ethanol to achieve...

Allium Organosulfur Compounds

There is increasing epidemiological evidence that other organosulfur compounds in addition to those derived from glucosinolates can protect against Table 3 Case-control studies of stomach, colon, and rectal cancer showing inverse, null, or positive associations for the consumption of different types of phytochemical-rich fruit and vegetables Fruit or vegetable type No. of studies Table 3 Case-control studies of stomach, colon, and rectal cancer showing inverse, null, or positive associations...

Alternative Feeding Routes

Many children with CP are not able to meet some or all of their calorie needs by mouth due to one or more of the following conditions oral motor dysfunction, excessive energy needs, recurrent infections, illnesses, and orthopedic surgical interventions. Consequently, if the gastrointestinal tract is functioning, supplemental or total tube feedings may be indicated. Early intervention with enteral nutrition may prevent protein-energy malnutrition and its complications. Studies have shown...

Aluminum Induced Bone Disease

AIBD is characterized either by a low turnover osteomalacia or by an aplastic disease. Chemical analyses have shown these conditions to be present when bone aluminum levels are between 12 and 500 mgg-1. High levels of the metal in diseased bones have also been demonstrated using aluminum-specific histochemical bone stains. Aluminum-induced osteodystrophic osteomalacia develops in the absence of hypophosphatemia. The condition does not respond to vitamin D therapy, but it may be prevented by...

Amides Asparagine and Glutamine

Although they are uncharged, these molecules are strongly polar. They are often found on the surface of proteins, where they can form hydrogen bonds with water or with other polar molecules. The conversion of glutamate to glutamine is central to the disposal of ammonia and to the maintenance of acid-base balance. Glutamine is a precursor for the synthesis of purines and pyrimidines. It is also a precursor for gluconeogenesis, and it is the main source of energy for enterocytes and leucocytes....

Breast Feeding Recommendations

Both the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF) recommend exclusive breast feeding for 6 months and continued breast feeding together with provision of safe, appropriate, and hygienically prepared complementary foods until 2 years of age or beyond. The American Academy of Pediatrics Section on Breastfeeding also recommends exclusive breast feeding for 6 months. Breast feeding is defined as exclusive if breast milk is the sole source of infant nutrition...

Amino Acid Flux Concentration and Function

Many amino acids have specific functions or support specific functions by serving as precursors or substrates for reactions in which vital end products are produced. The availability of amino acids to serve these purposes is determined by the rate at which they are released into the plasma and other pools in which these reactions take place, as well as by the rate of disappearance through excretion, protein synthesis, or conversion to other amino acids. The rate of this release, referred to as...

Amino Acids

Amino acids yield 4 kcal g when oxidized for energy. Nitrogen content varies somewhat, depending on the individual amino acid formulation and mixture of amino acids. Mixtures of buffered essential and nonessential amino acids are available as stock concentrations ranging from 3 to 20 . Specialty amino acid products are also available for specific disease states or pediatric populations. For example, formulations containing a higher concentration of branched-chain amino acids may be considered...

Analysis

The analysis of amino acids is based on chromato-graphic techniques. Traditional amino acid analyzers involved separation of the amino acid mixture on a column of ion-exchange resin using a series of sodium or lithium citrate buffers of increasing pH. The column effluent was then reacted with ninhy-drin and passed through a spectrophotometer that would detect and quantify a series of peaks. This method is still used, although high-performance liquid chromatography (HPLC) hardware is usually...

Anthocyanins

Anthocyanins are widespread in nature, predominantly in fruits and flower tissues, in which they are responsible for the red, blue, and purple colors. They are also found in leaves, stems, seeds, and root tissue. In plants, they protect against excessive light by shading leaf mesophyll cells. Additionally, they play an important role in attracting pollinating insects. The most common anthocyanins are pelargonidin, cyanidin, delphinidin, peonidin, petunidin, and malvidin, which are predominantly...

Anthropometric Assessment

Growth delay is one of the main characteristics of Down's syndrome, but impaired growth velocity is particularly evident at certain stages of development. Fetal growth has usually been reported to be relatively normal and the length of the neonate is often within normal limits, allowing for gestation. Some studies have reported prenatal growth delay, and a major Italian study comparing neonatal length, weight, head circumference, and weight length squared reported all percentiles of growth...

Anthropometry

In infancy, the most common routine measurement is weight. It is simple to do, the required equipment is reasonably cheap, and it provides a convenient global summary of the infant's size. Birth weight in particular is a useful proxy for fetal growth. An advantage of weight is that it relates closely to the mother's own perception of her child's size. Infant length is more difficult to measure for several reasons. The optimal equipment is a length board with a sliding footboard, which is...

Antiarrhythmic Effects of n3 Fatty Acids Ala Epa and DHA

Studies have shown that n-3 fatty acids, more so than n-6 PUFA, can prevent ischemia-induced fatal ventricular arrhythmias in experimental animals. n-3 fatty acids make the heart cells less excitable by modulating the conductance of the sodium and other ion channels. Clinical studies further support the role of n-3 fatty acids in the prevention of sudden death due to ventricular arrhythmias which, in the US, account for 50-60 of the mortality from acute myocardial infarction and cause 250 000...

Antinutrients

Phytic acid and phytates are antinutrients that are found in all cereals. They reduce mineral availability (see above). Tannins are polyphenolic compounds that are found in most cereals. Tannins can bind to protein, reducing its digestibility. Tannins can also inhibit the activity of digestive enzymes. In addition, cereals contain specific protease inhibitors, but the levels are low in comparison with those found in some seed legumes. The tannins and protease inhibitors are unlikely to have any...

Antioxidant and Prooxidant Actions of Ascorbate

Chemically, ascorbate is a potent reducing agent, both reducing hydrogen peroxide and also acting as a radical trapping antioxidant, reacting with superoxide and a proton to yield hydrogen peroxide or with the hydroxy radical to yield water. In each case the product is monodehydroascorbate, which, as shown in Figure 1, undergoes dismutation to ascorbate and dehydroascorbate. In studies of ascor-bate depletion in men there is a significant increase in abnormalities of sperm DNA, suggesting that...

Antioxidant Defense

An antioxidant can be described in simple terms as anything that can delay or prevent oxidation of a susceptible substrate. Our antioxidant system is complex, however, and consists of various intracel-lular and extracellular, endogenous and exogenous, and aqueous and lipid-soluble components that act in concert to prevent ROS formation (preventative antioxidants), destroy or inactivate ROS that are formed (scavenging and enzymatic antioxidants), and terminate chains of ROS-initiated...

Antioxidant Defense System

Although zinc is not itself an antioxidant, there are several ways in which it participates in the antiox-idant defense system of the body, with important implications for health. It can bind to thiol groups in proteins, making them less susceptible to oxidation. By displacing redox-reactive metals such as iron and copper from both proteins and lipids it can reduce the metal-induced formation of hydroxyl radicals and thus protect the macromolecules. Its role in inducing MT has already been...

Appetite Regulation and Expression

Traditionally it has been thought that appetite is influenced solely by body components or by metabolism. These influences are commonly referred to as the glucostatic, aminostatic, thermostatic, or lipostatic hypotheses. Each suggests that a single variable such as glucose, amino acids, heat generation, or adipose tissue stores plays the major role in modulating the expression of appetite. It can be accepted that all four variables can be monitored and each can exert some influences over food...

Applications

Extent and Physiological Implications of Protein Turnover In the human adult, approximately 300 g of protein turnover occurs each day (4g kg day) that is, three or four times the daily dietary intake. Rates vary between tissues with rapid turnover in visceral tissues and those with slow turnover in muscle. Liver and intestine account for approximately 8 of the lean body mass (LBM) and up to 50 of whole body protein turnover, with skeletal muscle, at 55 of the LBM, accounting for only...

Approaches

N Finer, Luton and Dunstable Hospital NHS Trust, Luton, UK 2005 Elsevier Ltd. All rights reserved. Weight loss and weight loss maintenance require a decrease in energy intake (diet), an increase in energy expenditure (exercise and physical activity), or both. Dietary management should encourage healthy eating, that is, an appropriately balanced intake of macro-and micronutrients. For most obese individuals this will entail not just a decrease in total energy intake, but specifically a decrease...

Approaches to Evaluating Bioactive Food Components

As new technologies, such as metabolomics, develop that allow better understanding of cell metabolism and interaction among nutrients within cell systems, food constituents that have previously gone unnoticed are gaining recognition for their potential roles in maintaining health and decreasing risk of chronic disease. Some food components appear to work in concert with other nutrients and chemicals and are highly active at nanogram concentration levels in cellular systems involved in...

Arm Fat Area

Arm fat area (AFA) can be derived from measurements of MUAC and TSFT. AMA is a better indicator of total body fat but not percentage body fat, than TSFT alone. The formula used to calculate AFA (with MUAC and TSFT in mm) is AMA can be compared with reference values by age and sex. Theoretically, limb fat area can be calculated for other limbs and the body trunk, but there are no reference values available.

Armed Conflict

A second major class of famine comprises those precipitated or triggered by declared war or armed insurgency, leading to a siege or food blockade by a foreign power (e.g., Allied blockade of Germany in 1915-18 Nazi blockade of Holland precipitating the Dutch Winter Famine of 1944-45, and the Nazi siege of Lenningrad in 1942-44) or, as occurring more in recent years, severe civil war that disrupts normal markets as well as emergency food delivery systems (e.g., the Somalian civil war and famine...

Aromatic Amino Acids Tryptophan Tyrosine and Phenylalanine

These are also bulky and nonpolar, and they may interact with other hydrophobic molecules. The phenolic hydrogen of tyrosine is weakly acidic and can form hydrogen bonds to create cross-links or can be donated during catalysis. Tyrosine residues on certain membrane-bound receptors become phos-phorylated by tyrosine kinase domains, thereby initiating a signal transduction cascade. Tryptophan is important as a precursor of the neurotransmitter 5-hydroxytryptamine (serotonin) and of the...

Artificial Nutritional Support

The presence of severe dysphagia and cognitive and complex physical impairments may render oral feeding unsafe or insufficient to meet nutritional requirements. If the gastrointestinal tract is functional, the options for delivering enteral nutritional support are either via a fine-bore nasogastric tube or via a catheter inserted by percutaneous endoscopic gastrostomy (PEG). Decisions concerning the choice of route are influenced by the anticipated duration of dysphagia and benefits versus...

Ascorbic Acid

The vitamin (L-ascorbic acid) linked with scurvy is known to be a cofactor for two enzymes that take part in the biosynthesis of collagen, the major connective tissue protein the formation of hydroxypro-line and hydroxylysine residues as catalyzed by prolyl hydroxylase and lysyl hydroxylase enzymes, respectively (Figure 8). Collagen is an essential component of the extracellular matrix. As a cofactor for dopamine- -monooxygenase, L-ascorbic acid is also required for the synthesis of adrenaline...

Aspiration and Gastroesophageal Reflux

Clinical signs of aspiration may include coughing, choking, gagging, inability to handle oral secretions, wet upper airway sounds with poor vocal quality, apnea, food refusal, frequent upper respiratory infections, and aspiration pneumonia. Aspiration of food may occur without physical evidence if the protective cough or gag is not functioning, sensory deficits exist, and or the swallowing mechanism is dysfunctional. This results in what is termed silent aspiration. Although aspiration from...

Assessment

An appropriate assessment of a child's feeding disorder is a critical first step in initiating treatment. The management of complicated feeding disorders usually requires a multidisciplinary team devoted to establishing diagnosis, assessment of need, and developing a thorough treatment plan. This team may include a variety of pediatric specialists, including physicians (e.g., general pediatricians, developmental pediatricians, pediatric gastroenterologists, allergists, and otolaryngologists),...

Assessment of Amino Acid Function

The effectiveness of amino acid supplementation, particularly with respect to clinical effectiveness, can be assessed at four levels. First, the intervention should lead to an increased local or systemic concentration of the amino acid in question. The conversion of amino acids in (interorgan) metabolic pathways can lead to an increase in the levels of amino acids other than the one supplemented, increasing or mediating its functionality. Alternatively, supplementation of one amino acid may...

Assessment of Energy Expenditure

The study of energy metabolism in humans has recently raised a great interest in the regulation of these processes thanks to advances in the construction of open-circuit ventilated hood indirect calorimeters and comfortable respiration chambers. With the only measurement of VO2 (in liters of O2 STPD (standard temperature (0 C), pressure (760mmHg), and dry) per min), metabolic rate (M), which corresponds to energy expenditure, can be calculated (in kilojoules per min) as follows The number 20.3...

Assessment of Gestational Age and Fetal Growth Methods and Limitations

Preterm birth is defined as delivery before 37 completed weeks (259 days). To accurately differentiate between preterm and term delivery it is crucial to have a reliable estimate of gestational age. Sono-graphic determination is the most accurate method to estimate gestational age. When ultrasonography is not available, gestational age can be determined by patient's recall of the time of last menstrual period, physical examination of the size of the uterus, and examination of the neonate. These...

Assessment of Mg Status

Several potential markers for estimating daily Mg requirement have been suggested. Plasma Mg concentration is the most commonly used marker to assess Mg status. In healthy populations, the plasma Mg value is 0.86mmol l and the reference value is 0.75-0.96 mmol l. A low plasma Mg value reflects Mg depletion, but a normal plasma Mg level may coexist with low intracellular Mg. Thus, despite its interest, plasma Mg is not a good marker of Mg status. Ion-specific electrodes have become available for...

Assessment of Niacin Status

Whereas the measurement of B vitamin status has, in recent years, tended to focus on blood analysis, perhaps mainly because of the convenience of sample collection, the development of blood-based status analysis for niacin has lagged behind that of the other components of the B complex. Some studies have indeed suggested that the erythrocyte concentration of the niacin-derived coenzyme NAD may provide useful information about the niacin status of human subjects that a reduction in the ratio of...

Assessment of Nutrition in Children Anthropometry

After the first year of life, children usually follow very predictable gains in weight and height over time. Growth as gain in weight and height remains, with activity, the aspect of energy consumption that the body can reduce if energy intakes are inadequate for all needs. The wide range of normal weights for age in a population means that a single weight in an individual child is not a good indicator of over or under nutrition. Nevertheless, weight change over time is the most widely used...

Assessment of Riboflavin Status

Assessment of status for specific nutrients such as riboflavin is closely bound up with the estimation of requirements in human individuals and groups of subjects, and with the monitoring of human populations for evidence of the adequacy of their intakes. It is often cheaper, easier, and more accurate to collect a sample of blood or urine from an individual and carry out biochemical analyses that determine status than to carry out reliable measurements of intake over a period of time, since the...

Assessment of Total Discretionary Salt

Figure 2 compares the traditional and lithium marker techniques for assessing both total salt intake and the distribution of its sources. When table and cooking salt are combined to form a single value, the percentage contribution of these discretionary sources to the total intake measured by the lithium marker technique is significantly lower in the UK compared with that assessed by traditional methods, which do not consider salt losses during cooking and at the table. This intake in the UK...

Assessment of Vitamin C Status

The early method of assessing vitamin C nutritional status was by testing the extent of saturation of the body's reserves by giving a test dose of 500 mg (2.8 mmol) and measuring the amount excreted in the urine. In a subject with high status, more or less all of the test dose is recovered over a period of 5 or 6 h. More sensitive assessment of status is achieved by measuring the concentration of the vitamin in whole blood, plasma, or leukocytes. Criteria of adequacy are shown in Table 2. The...

Atherogenesis and Endothelial Dysfunction

Atherosclerosis can be considered as a chronic inflammatory disease, which slowly progresses over a period of decades before clinical symptoms become manifest. The atherogenic process comprises interactions between multiple cell types, which initiate a cascade of events involving alterations in vascular production of autocoids, cytokines, and growth factors. The endothelium, because of its location between blood and the vascular wall, has been implicated in the atherogenic process from the...

Atherosclerosis and Hemostasis

Despite the reported effects of trans fatty acids on blood lipoproteins, experiments with laboratory animals have not provided evidence that dietary trans fatty acids are associated with the development of experimental atherosclerosis, provided that the diet contains adequate levels of linoleic acid. Similarly, there is no evidence that trans fatty acids raise blood pressure or affect the blood coagulation system. However, there has been no thorough evaluation of the effect of trans fatty acids...

AtRA Catabolism

AtRA induces its own metabolism via cytochrome P450 (CYP) into a variety of initial catabolites, including 5,6-epoxy-atRA, 18-hydroxy-atRA, and 4-hydroxy-atRA. Metabolism of atRA limits its activity conversely, inhibitors of atRA metabolism enhance atRA potency. CYP26A1 may catalyze the major degree of atRA catabolism, as evidenced by null mice dying in mid- to late gestation with serious morphological defects. Two other P450's, CYP26B1 and CYP26C1, also catabolize atRA, but null mice have not...

Attention Span Short Term Memory

Impairment of attention span and short-term memory of a few minutes duration are common following stroke. Attention deficits result in an inability either to focus on immediate events or to establish a new focus unless a current stimulus is removed. As a consequence, an activity that requires a sequence of steps, such as eating a meal with two or three courses, cannot he completed. Lack of concentration is also unhelpful in relearning eating patterns. Removing or minimizing distractions at...

Availability

The presence of micronutrients does not ensure availability for metabolic processes. Mineral availability is reduced by the presence of phytic acid and phytates. Phytic acid (myoinositol 1,2,3,4,5,6-hexakis dihydrogen phosphate) accounts for a substantial proportion (usually over 50 ) of the total phosphorus in cereals, and this phosphorus is not fully available for digestion and absorption. Phytic acid accounts for about 1 of whole-grain cereals. However, phytic Table 12 Mineral and vitamin...

Vitamin Deficiencies

Hyperhomocysteinemia is also caused by B vitamin deficiencies. Deficiencies of folate and vitamin B12 lead to impaired remethylation of homocysteine causing mild, moderate, or severe elevations in plasma homocysteine, depending on the severity of the deficiency, as well as coexistence of genetic or other factors that interfere with homocysteine metabolism (see below). Because riboflavin is required for the synthesis of flavin adenine dinucleotide (FAD), and because FAD serves as a cofactor for...

Vitamin Supplementation

Currently, several large-scale intervention trials are underway to determine if B vitamin supplements (folic acid, B12, B6), which effectively lower blood homocysteine levels, reduce the incidence of vascular disease (Table 3). If proven effective, such supplements would be an inexpensive and relatively Table 3 Intervention trials to determine the effect of B vitamin supplements on homocysteine and the risk of vascular disease Cambridge Heart Antioxidant Study 2 UK 1998 Heart Outcomes...

Baby botulism

Some babies, usually younger than 6 months of age, acquire a form of botulism that is usually mild. It is thought to be caused by ingested spores multiplying in and colonizing the baby's intestine, forming toxin. The initial symptom is often constipation, leading to poor feeding, irritability, neck paralysis, and generalized weakness. Honey is thought to be one cause of baby botulism. Diagnosis The diagnosis is made by the demonstration of botulinus toxin in food, stool, or serum. Growing the...

Bacillus cereus

Background Bacillus cereus is widely distributed in the environment and is not a contaminant of food. It is found in rice and other natural foods, such as herbs and spices, cream, and dry foods. Growth and survival Unlike the staphylococci, B. cereus is a spore-forming organism that survives prolonged boiling. It causes two fairly distinct types of food poisoning, emetic and diarrheic. The diarrheal toxin is heat labile and, like Clostridium perfringens, formed in the gut. The foods commonly...

Bacillus subtilis and Bacillus licheniformis

Bacillus subtilis is a member of the Bacillus genus and is similar to B. cereus, except that its natural habitat is slightly different, and so the foods causing illness also differ. It has been recognized increasingly as a cause of GE, characterized mainly by vomiting. The incubation period is short, 2 or 3 h, although many cases occur within 1 h. Foods implicated include meat and vegetable products such as meat pies, sausage rolls, curries with accompanying rice dishes, and even bread,...

Bacillus thuringiensis

Bacillus thuringiensis is a widely distributed bacterium that during sporulation produces a crystal inclusion which is insecticidal when ingested by the larvae of a number of insect orders. Susceptible orders include Lepidoptera, Diptera, and Colcop-tera. The action of B. thuringiensis was first observed in 1901 as the cause of a disease of silkworms. Several strains of the bacterium have been identified with activity against a range of insects including cabbage looper, tobacco budworm,...

Bacterial Contamination

N Noah, London School of Hygiene and Tropical 2005 Elsevier Ltd. All rights reserved. The burden of gastroenteritis (GE) in the world, in terms of both morbidity and mortality, is enormous. In the developing world (e.g., Southeast Asia), diarrhea vies with acute respiratory tract infection as the leading cause of death in childhood. Even in the more developed world, infectious GE is a significant cause of illness and time lost from work, and death does occur. Infectious intestinal disease in...

Bacterial Overgrowth Syndrome

Bacterial overgrowth occurs due to stasis of luminal contents resulting from strictures, fistulas, jejunal diverticula, blind loops, pouches, or motility disorders. The intestine becomes excessively colonized with both anaerobic and aerobic organisms. The latter use vitamin B12 and other nutrients for their own metabolism they deconjugate bile salts and in so doing prevent their use in fat absorption. Normal dietary fat should be substituted by medium-chain triglycerides. Hypoalbuminemia (low...