Food and Nutrition
Redox system
The oxidation can be understood from several points of view. Thus, the addition of oxygen to form a molecule is an oxidation. Talmbién it is the oxidation of hydrogen to form water. Each accompanied by an oxidation process or opposite reaction, reduction, which in the case of water, oxygen is the reduced component.
A more general intepretar oxidation-reduction reactions is to remember that are based on the release of electrons (oxidation) and the addition of electrons (reduction) of the atoms in a molecule. The electrons are never free, they are transferred to an electron acceptor that he comes to be reduced in the process. For example, iron in the respiratory chain cytochromes undergoes reductions and oxidations terminal based on the addition or release electrons, respectively.
Free radicals and reactive oxygen species
Free radicals are chemical species that have an unpaired electron, and can therefore be regarded as highly reactive fragments of molecules. According to this concept in the biochemistry of free radicals, the major reactants in the cell are formed by oxygen radicals and their derivatives, as well as transition metals such as iron in the redox states of ferric and ferrous and copper in the cuprous and cupric. Read the rest of this entry »
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Lipid metabolism
The dietary fat is an essential component in the diet of humans. It is a concentrated source of energy and essential fatty acids are carriers of other nutrients, also essential, as the fat soluble vitamins (A, D, E and K). The bioavailability of lipid soluble components of the diet depends on the capacity of absorption of fats
Much of the dietary lipids are found as triglycerides. On average, 40% of energy requirements of the diet of humans in industrialized countries are provided by the triacylglycerols, which are hydrolyzed in the intestine to fatty acids and monoacylglycerols, molecules that are absorbed, and transported reesterifican blood reaching the liver and adipose tissue.
Absorption of triacylglycerols
In the cells of the intestinal mucosa triacylglycerols, diacylglycerols, monoacylglycerols, glycerol and free fatty acids are converted into triacylglycerols and bind to cholesterol in the diet, along with a specific protein to form chylomicrons. These compounds, which contain apolipoprotein C-II (apo C-II), leaving the intestinal mucosa into the lymphatic system, enter the blood and reach the muscle and adipose tissue. Read the rest of this entry »
Metabolism of these proteins
Proteins constitute a large group of natural nitrogen compounds. Comprise DNA, RNA, polysaccharides and lipids, five kinds of complex biomolecules found in cells and tissues. They are the main building (in the form of amino acids) to muscles, blood, skin, hair, nails and internal organs, become part of hormones, enzymes and antibodies, and serve as a source of heat and energy.
Proteins
Protein turnover
Almost all proteins of the organism are in constant dynamic synthesis (1-2% of total protein), from amino acids, and degradation to new amino acids. This activity causes a net nitrogen loss per day in the form of urea, which corresponds to about 35-55 grams of protein. When dietary intake compensates the loss is said that the body is in nitrogen balance.
Nitrogen balance can be positive or negative. Is positive when the nitrogen intake exceeds losses, as in growth, pregnancy, recovering from illness. Is negative if the nitrogen intake is less than losses, such as in malnutrition, anorexia prolonged postraumatismos, burns, an essential amino acid deficiency.
Degradation pathways of proteins
There are two pathways by which proteins are degraded by proteases (cathepsins). Read the rest of this entry »
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Carbohydrate metabolism
The brain needs a continuous supply of glucose to its normal operation, although sometimes it can be adapted to lower levels of normal, or even use ketone bodies from the fractionation of fats. Red blood cells also require glucose basically spend their metabolism and functions. Are important examples of tissues that need adequate regulation of blood sugar maintenance, a process is certainly complicated, and involved in several metabolic pathways
The concentrations of blood glucose in adults are usually between 72.0 – 99.0 mg/100 mL (4.0-5.5 mmol / L). But when you eat a meal containing carbohydrates, blood glucose may rise to 135.0 mg / 100 mL, for a certain period of time. In one phase of fast, can be as low as 54.0 – 63.0 mg/100 mL. If blood sugar levels are around 180.0 mg / 100 mL, as in diabetes mellitus, or higher levels, as some individuals in serious pathological conditions, comes to appear glucose in the urine (glycosuria).
There are several processes involved in carbohydrate metabolism, which are presented below.
Glycolysis
Glycolysis is called a set of enzymatic reactions in metabolize glucose and other sugars, releasing energy in the form of ATP. Aerobic glycolysis, which is performed in the presence of oxygen, producing pyruvic acid, and anaerobic glycolysis in the absence of oxygen, lactic acid. Read the rest of this entry »
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Diets
Diet is the regulation of food intake as a hygienic measure or treatment. Momentary deprivation of any kind of food may be total (NPO) or partial, which may refer to solid foods (fluid diet) or liquid (dry diet).
Dietary therapy can be understood as a pyramid. At the base metabolic settle the biochemical basis of the human body, essential nutrients and their dynamics interrelaciones.El component is formed immediately above the needs of the life cycle of various nutrients in relation to growth, development, maturation and maintenance. Finally, at the apex of the pyramid is therapeutic nutrition, considering the changes that an individual needs specific treatment for their disease.
Therefore, the principles of dietary therapy in humans have significance only in terms of a normal nutrition. The diet is established only when there is a specific disease that can be solved by understanding what it means normal nutrition and metabolism.
The establishment of a diet needs, therefore, accommodate the following questions:
Disease. How the disease affects the body and its normal metabolic functioning?
How dietary therapy and why the diet should be modified in terms of nutritional components to meet the needs caused by that particular disease?
How these dietary guidelines necessary nutritional changes affect daily food choice?.
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Nutrition and Metabolic Diseases
Among the disorders that can be considered as metabolic diseases, those due to inborn errors of metabolism have received considerable attention in recent times.
Congenital metabolic defects leading to a wide range of diseases, relatively rare, occurring as a consequence of inherited deficiencies of particular proteins with enzymatic function, transport, structural, receiver, etc..
Many patients suffering from congenital metabolic disorders can receive various treatments helpful. In some cases the benefit is relatively insignificant, but many others can be achieved very favorable results. The basis of many treatments is essentially nutritional.
According to Aquino Sanjurjo P and L (Nutrition and inborn errors of metabolism, in: Diagnosis and Treatment of Inherited Metabolic Disease. Eds Sanjurjo P and A Baldellou, Ed Ergon, 2001), “Nutrition is the most important therapeutic tool for this type pathology, waiting for gene therapy, and that in a poetic way, these real biological models, which are inborn errors of metabolism will return the favor to the general nutrition, giving important insights achieved through both empiricism as binomial nutrition research / EIM. “
Nutrition and Organic Disease
Extensive reviews epidemiological, clinical and laboratory indicate that diet influences the development of a wide range of organic diseases. It seems very clear to the cardiovascular and hypertension, and very suggestive for certain forms of cancer, especially of the esophagus, stomach, large intestine, breast, lung and prostate, also, that certain dietary patterns predispose to dental caries and some liver diseases and that a positive energy balance produces obesity and increases the risk of diabetes mellitus non-insulin dependent. However, the evidence is not so wide as to draw conclusions about the influence of specific dietary patterns in the presence of osteoporosis and chronic kidney disease.
Most organic diseases in which nutritional factors play an important role, have genetic and environmental determinants. But at present, are not clearly characterized all environmental risk factors, and not yet identified the most susceptible genotypes. Moreover, not yet fully aware of the possible relationships between genetic and environmental mechanisms, in the development of disease. It is clear that dietary factors are important in the etiology of various organic diseases and that dietary modifications can reduce the risk. However, for most diseases is not yet possible to estimate quantitatively, not only the total risk, but also the benefits. Read the rest of this entry »
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Considered conditionally essential nutrients
Compounds are physiologically essential, usually produced in adequate quantities by endogenous synthesis, but that under certain conditions need to be provided exogenously. For these compounds have not been established minimum daily intake requirements.
They are:
A) Amino acids: arginine, carnitine, glycine, glutamine and taurine.
O amino acids needed in its endogenous synthesis, preformed carbon chains and substituent groups derived from other amino acids such as glycine, serine and cysteine.
a) Nucleotide: for the synthesis of nucleic acids in some rapidly growing tissues (intestine, bone marrow and lymphocytes).
b) lipid compounds: fatty acids polyunsaturated long chain fatty acid derivatives essential for preterm infants and adults with cirrhosis.
c) Choline: quaternary ammonium base, ethanolamine derivative by methylation of adenosylmethionine.
d) Inositol: carbohydrate derivative, which can be essential in the preterm infant.
Arginine
Is a basic amino acid. It is synthesized from glutamate, after passing through by ornithine. Read the rest of this entry »
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Nucleic Acids and Nucleotides
The purine and pyrimidine nucleotides are extremely important metabolites involved in many cellular functions. These functions include acting as precursors of nucleic acids, as energy stores, afectores, group transfer agents and mediators of hormonal and neurotransmitter actions.
Previous concepts
Nucleic acids. Are complex molecules of high molecular weight containing nitrogenous bases (purines and pyrimidines), five-carbon sugar (ribose and deoxyribose) and phosphate.
Base. Can be defined as a substance which combines with acids to form neutral salts. Also, as a substance which increases the ion concentration on the contrary hidroxilo.o decreasing concentration of hydrogen ions when dissolved in water.
Purines
Are nitrogenous bases: adenine, guanine and hypoxanthine have a double structure comprising a ring of six carbon and other five-carbon ring.
Nucleosides
Purines can exist as free bases or a pentose sugar, usually ribose or deoxyribose, linked by the N9 position to form a nucleoside. For example, adenine is the free base and adenosine, the nucleoside is the free base guanine and guanosine, the nucleoside. The nucleoside of hypoxanthine called inosine. Read the rest of this entry »
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Phytochemicals
Phytochemicals (phyto = plant) is the generic name is known to a number of substances found in plants, although mainly used to refer to their bioactive compounds that have no nutritional value.
In general, the physiological effects of a complete plant food are higher than those with each of the individual compounds, doubts arise when you are aware of phytochemicals or combinations thereof having a Preventica action on humans. However, certain compounds are known to provide specific health benefits, including certain antioxidant properties that protect against the effects of aging and some chronic diseases such as cancer and cardiovascular diseases.
These bioactive compounds include carotenoids, phenolics such as flavonoids and catechins, phytoestrogens such as isoflavones and lignans, glucosinolates, phytosterols, terpenoids, and saponins. For most of the phytochemicals, not yet well known, molecular, and their interactions with other dietary components. Read the rest of this entry »
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