Nutrition (also called the food or food) is available to cells and organisms, of materials (in the form of food) to support life. Many health problems can be prevented or alleviated with good nutrition.
The diet of an organism refers to what you eat. Dietitians are health professionals who specialize in human nutrition, meal planning, economics, preparation, and so on. They are trained to provide security, evidence-based dietary advice and management to individuals (in health and disease), as well as institutions.
Poor diet can have a detrimental impact on health, causing deficiency diseases such as scurvy, beriberi, and kwashiorkor; health-threatening conditions like obesity and metabolic syndrome, and chronic systemic diseases such as cardiovascular disease, diabetes and osteoporosis.
There are seven main classes of nutrients: carbohydrates, fats, fiber, minerals, proteins, vitamins and water.
These nutrient classes can be classified as either macronutrients (needed in relatively large amounts) and micronutrients (needed in smaller amounts). The macronutrients are carbohydrates, fats, fiber, protein and water. Micronutrients are vitamins and minerals.
The macronutrients (excluding fiber and water) provide energy, measured in joules or kilocalories (often called “calories” and written with a capital C to distinguish calories gram). Carbohydrates and proteins provide 17 kJ (4 kcal) of energy per gram, while fat provides 37 kJ (9 kilocalories) per gram. [1] The vitamins, minerals, fiber and water will not provide energy, but are necessary for other reasons.
Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Carbohydrates ranging from simple monosaccharides (glucose, fructose, galactose) to complex polysaccharides (starch). Fats are triglycerides of different fatty acids monomers bound to glycerol. Some fatty acids, but not all, are essential in the diet: they can not be synthesized in the body. Protein molecules contain nitrogen atoms, in addition to the elements of carbohydrates and fats. The nitrogen-containing monomers of proteins are amino acids and some essential amino acids. Fulfill many functions other than energy metabolism, and when used as fuel, to remove nitrogen from places a burden on the kidneys. Other micronutrients include antioxidants and phytochemicals.
Most foods contain a combination of some or all classes of nutrients. Some nutrients are needed regularly, while others are needed only occasionally. Poor health can be caused by an imbalance of nutrients, either an excess or a deficiency.
Carbohydrates-
A pack of toasted bread is a cheap, high-calorie nutrient (usually unbalanced, ie, deficient in essential vitamins and minerals, due to the removal of bran cereal), a source of food with a long life .
Carbohydrates can be classified as monosaccharides, disaccharides, polysaccharides or the number of monomer (sugar) units they contain. They constitute a large proportion of food such as rice, noodles, bread and other grain-based products. Monosaccharides contain one sugar unit, two disaccharides and polysaccharides of three or more. Polysaccharides are often as complex carbohydrates because they are long chains of sugar units, whereas monosaccharides and disaccharides are simple. The difference is important to have more complex carbohydrates to digest and absorb as their sugar units are processed one by one off the ends of the chains. The increase in blood sugar levels after ingestion of simple sugars is believed to be involved in causing heart and vascular disease. Simple sugars are a major part of modern diets, which leads to more cardiovascular disease in populations. Simple carbohydrates are absorbed quickly, and thus raise blood sugar levels more quickly.
Fat-
A fat molecule is composed of several fatty acids (which contain long chains of carbon and hydrogen atoms) bonded to a glycerol. They are usually found in triglycerides (three fatty acids attached to a glycerol backbone). Fats can be classified as saturated or unsaturated. Saturated fats have all the carbon atoms in their chains of fatty acids bonded to hydrogen atoms, whereas unsaturated fats have some of the carbon atoms bonded twice, so that its molecules are relatively few hydrogen atoms. Unsaturated fats can be further classified as monounsaturated (one double bond) or polyunsaturated (many double bonds). Trans fats are a type of unsaturated fat with trans isomer fatty acids, usually created in an industrial process called (partial) hydrogenation.
Many studies have shown that unsaturated fats, especially monounsaturated fats, are the best in the human diet. Saturated fats, usually of animal origin, are at hand, while trans fats are to be avoided. Saturated and trans fats are usually solid at room temperature (like butter or lard), while unsaturated fats are usually liquid (such as olive oil or linseed oil). Trans fats are very rare in nature but have properties useful in the food processing industry.
Essential fatty acids-
Most fatty acids are not essential, ie, the body can produce when needed. However, in humans, at least two fatty acids are essential and must be included in the diet. A proper balance of essential fatty acids omega-3 and omega-6 fatty acids is important for health. Both “Omega” long-chain polyunsaturated fatty acids are substrates for a class of eicosanoids known as prostaglandins, which have functions throughout the body.
These are the hormones, in some respects. The omega-3 eicosapentaenoic acid (EPA), which can be done in the human body from omega-3 essential fatty acid alpha-linolenic acid (LNA), or taken in through marine food sources, serves as basis for the series 3 prostaglandins (eg weakly-inflammation PGE3). The omega-6 dihomo-gamma linolenic acid (DGLA) serves as the basis for the series 1 prostaglandins (eg anti-inflammatory PGE1), whereas arachidonic acid (AA) serves as a basis for the series 2 prostaglandins (for example, pro-inflammatory PGE 2).
Both DGLA and AA can be made from the omega-6 linoleic acid (LA) in the human body, or can be taken directly through food. Proper balanced intake of omega-3 fatty acids and omega-6 partly determines the relative production of different prostaglandins: one reason for a balance between omega-3 and omega-6 is important for cardiovascular health. In industrialized societies, people tend to consume large amounts of processed vegetable oils, which have reduced amounts of essential fatty acids, along with much of omega-6 fatty acids in relation to omega-3 fatty acids.
The rate of conversion of Omega-6 fatty acid DGLA to AA largely determines the production of prostaglandins PGE1 and PGE2. Omega-3 EPA prevents AA from being released from the membranes, thereby skewing prostaglandin balance away from pro-inflammatory PGE2 (fact AA) to anti-inflammatory PGE1 (made from DGLA). Moreover, the conversion (desaturation) of DGLA to AA is controlled by the enzyme delta-5-Desaturation, which in turn is controlled by hormones such as insulin (up regulation) and glucagon (down regulation). The amount and type of carbohydrate consumed, along with some types of amino acids may influence processes of insulin, glucagon and other hormones, the proportion of omega-3 versus omega-6 has effects throughout health in general and specific effects on immune function and inflammation, and mitosis (ie cell division).
Good sources of essential fatty acids are most vegetables, nuts, seeds and marine oils, [2] Some of the best sources are fish, flax seed oils, soybeans, pumpkin seeds, sunflower seeds and nuts.
Fiber-
Fiber is a carbohydrate (or a polysaccharide) that are incompletely absorbed in some humans and other animals. Like all carbohydrates, when it is metabolized can produce four calories (kcal) of energy per gram, but in fact, is less than that because of its limited absorption. Dietary fiber consists mainly of cellulose, a carbohydrate polymer that is large indigestible because humans lack the enzymes.
There are two subcategories: soluble and insoluble fiber. Whole grains, fruits (especially plums, prunes and figs) and vegetables are rich in dietary fiber. Fiber is important for digestive health and is designed to reduce the risk of colon cancer. You can help relieve both constipation and diarrhea. The fiber provides the bulk of intestinal contents and stimulates peristalsis insoluble fiber: the rhythmic muscular contractions passing along the digestive tract. Some soluble fibers to produce a highly viscous solution, a gel, which slows the movement of food through the intestines. Fiber, especially grain, can help reduce the peaks of insulin and reduce the risk of diabetes.
Protein-
Most meats such as chicken contain all the essential amino acids necessary for human beings.
Main article: Protein in nutrition Proteins are the basic structures of many animal body (eg, muscle, skin and hair). Each molecule consists of amino acids, sometimes thousands, which are characterized by the inclusion of nitrogen and sometimes sulfur.
The body requires amino acids to produce new protein (protein retention) and to replace damaged proteins (maintenance). Excess amino acids are removed, usually in the urine. For all animals, some amino acids are essential (an animal can not produce internally) and some are not essential (the animal may produce other compounds that contain nitrogen).
About twenty amino acids found in the human body, and about ten of them are essential, and therefore should be included in the diet. A diet containing adequate amounts of amino acids (especially those that are essential) is especially important when there is a greater need in the development and maturation, pregnancy, lactation, or injury.
A complete source of protein containing all essential amino acids, a source of incomplete protein lacks one or more of the essential amino acids. It is possible to combine two sources of incomplete proteins (eg, rice and beans) to make a complete protein source. Sources of dietary protein are meat, tofu and other soy products, eggs, cereals, legumes, and dairy products like milk and cheese. A few amino acids of the protein can be converted into glucose and used for fuel through a process called gluconeogenesis. The amino acids remaining after this conversion is discarded.
Minerals-
Dietary minerals are chemical elements required by living organisms, except the four elements carbon, hydrogen, nitrogen and oxygen that are present in common organic molecules. The term “mineral” is archaic, since the intent is simply to describe the less common elements in the diet: heavier than the four just mentioned, including several metals, and often occur as ions in body. Some dietitians recommend that these be presented from foods that occur naturally, or at least as complex compounds or sometimes even from natural sources, inorganic (such as calcium carbonate from oyster shells field). Moreover, minerals are often artificially added to the diet as a supplement, the most famous being iodine in iodized salt.
Macrominerals-
Many elements are essential in quantity, also called “bulk minerals”. Some are structural, but many play a role as electrolytes. [3] Elements of the recommended dietary allowance (RDA) of more than 200 mg / day are as follows, in alphabetical order (with the prospect of informal or folk medicine in parentheses):
• Calcium, a common electrolyte, but also structural (for muscle and digestive system health, builds bone, neutralizes acidity, clears toxins, helps blood)
• Chlorine and chloride ions, a common electrolyte, see sodium, then
• Magnesium is necessary for the processing of the ATP and the reactions (builds bone, causes strong peristalsis, increases flexibility, increases alkalinity)
• Phosphorus, a necessary element of the bones, essential for energy transformation
• potassium, a common electrolyte (a healthy heart and veins)
• sodium, a common electrolyte, generally not found in dietary supplements, despite being needed in large quantities, because the ions are very common in foods, usually as sodium chloride or common salt
• Sulfur for three essential amino acids, and hence many proteins (skin, hair, nails, liver and pancreas)
Oligominerals-
Many elements are needed in trace amounts, usually because they play a catalytic role in enzymes. Some trace mineral elements (RDA <200 mg / day) are, in alphabetical order:
• Cobalt required for biosynthesis of vitamin B12 family of coenzymes
• Copper required component of many redox enzymes, including cytochrome c oxidase
• Chromium for sugar metabolism
• Iodine is necessary for the biosynthesis of thyroxine; needed in greater quantity than others in this list, and sometimes classified with macrominerals
• iron necessary for many enzymes, and hemoglobin and other proteins
• Manganese (processing of oxygen)
• Molybdenum for oxidases and xanthine oxidase
• Nickel present in urease
• Selenium for peroxidase (antioxidant proteins)
• Vanadium (speculative: there is no RDA for vanadium. No specific biochemical function has been identified as in humans, although vanadium is found in lower organisms.)
• Zinc required for several enzymes, such as Carboxypeptidase, liver alcohol dehydrogenase, carbonic anhydrase
Vitamins-
As with the aforementioned minerals, twelve vitamins are recognized as essential nutrients needed in the diet for good health. (Vitamin D is the exception: it can alternatively be synthesized in the skin, in the presence of UVB radiation.) Some compounds are vitamins, as recommended in the diet, such as carnitine, are indispensable to the survival and health, but these are not strictly “essential” because the human body has the capacity to produce other compounds. In addition, thousands of different phytochemicals have recently been discovered in food (especially fresh vegetables), which can have desirable properties including antioxidant activity (see below). Other essential nutrients such as vitamins unclassified include essential amino acids (see above), choline, essential fatty acids (see above), minerals and discussed in the previous section.
Vitamin deficiencies can lead to disease: goitre, scurvy, osteoporosis, deterioration of the immune system, disorders of cell metabolism, certain forms of cancer, symptoms of premature aging, and poor psychological health (including eating disorders ), among many others.
Excess of some vitamins is also dangerous to health (especially vitamin A), and mineral deficiency or excess can have serious health consequences.
Water-
Approximately 70% of the fat-free mass of the human body is made of water. [Edit] To function properly, the body requires between one and seven liters of water per day to avoid dehydration, the exact amount depends on the level of activity, temperature, humidity and other factors. [edit] With the physical effort and exposure to heat, water loss will increase and daily fluid needs may increase as well.
It is unclear how much is needed to water intake by healthy people, although some experts say that 8-10 glasses of water (about 2 liters) daily is the minimum adequate to maintain hydration. The notion that a person should consume eight glasses of water per day can not be traced back to a scientific source. The effect of water intake on weight loss and constipation is still unclear.
Original recommendation for water intake in 1945 by the Food and Nutrition, National Research Council read: “A common pattern for the various persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods. ” The final report of the dietary reference intakes of the United States in the National Research Council recommended (including food sources): 2.7 liters of total water for women and 3.7 liters for men.
Specifically, pregnant and lactating women need more fluids to keep hydrated. According to the Institute of Medicine, which recommended that, on average, women consume 2.2 liters and 3.0 liters for men is recommended to be 2.4 liters (about 9 cups) for pregnant women and 3 liters ( approx. 12.5 cups) for breastfeeding women since an especially large amount of fluid is lost during lactation
For those who have healthy kidneys, it is quite difficult to drink too much water, [citation needed], but (especially in the humid and warm in the exercise) is dangerous to drink too little. People can drink far more water than necessary in the exercise, however, putting them at risk of water intoxication, which can be fatal. In particular, large quantities of deionized water are dangerous.
Normally, about 20 percent of water intake comes from food, while the rest comes from drinking water and a variety of beverages (caffeinated included). The water leaves your body in multiple ways, including urine and feces, sweat, and water vapor in exhaled air.
Other nutrients
Other micronutrients include antioxidants and phytochemicals. These substances are generally more recent discoveries that: have not yet been recognized as vitamins, are still under investigation, or contribute to health but are not necessary for life. Phytochemicals can act as antioxidants, but not all antioxidants are phytochemicals.
Antioxidants-
Antioxidants are a recent discovery. As cellular metabolism / energy production requires oxygen, potentially damaging (eg mutation causing) compounds known as free radicals can be formed. Most of these are oxidizing (ie, electron acceptor), and some react very strongly.
For the maintenance of normal cell growth and division, these free radicals must be sufficiently neutralized by antioxidant compounds. Some are produced by the human body with adequate precursors (glutathione, vitamin C) and that the body can not produce may only be obtained through the diet through direct sources (Vitamin C in humans, vitamin A, vitamin K) or produced by the body from other compounds (Beta-carotene converted to vitamin A by the body, Vitamin D synthesized from cholesterol by sunlight).
Phytochemicals (section below) and its subgroup of polyphenols are the most antioxidants, about 4,000 are known. Antioxidants are known to work in a cooperative network, eg vitamin C can reactivate free radical-containing vitamin E, glutathione, or acceptance of free radical itself, and so on. Some antioxidants are more effective than others in different neutralize free radicals. Some can not neutralize certain free radicals. Some may not be present in certain areas of development of free radicals (vitamin A is fat soluble and protects fat areas, Vitamin C is water soluble and protects those areas). Interacting with a free radical, some antioxidants produce a compound of the free radicals that are less dangerous or more dangerous than the previous site. Having a variety of antioxidants allows any byproducts to be safely dealt with by more efficient antioxidants in neutralizing free radicals in a butterfly effect.
Phytochemicals-
Blackberries are a source of polyphenol antioxidants
One area of growing interest is the effect on human health of trace chemicals, collectively called phytochemicals. These nutrients typically found in edible plants, especially fruit and vegetables, but also other bodies including seafood, algae and fungi. The effects of phytochemicals increasingly survive rigorous testing by prominent health organizations. One of the major classes of phytochemicals are polyphenol antioxidants, chemicals that are known to provide certain benefits to the health of the cardiovascular system and immune system. These substances are known to down-regulate the formation of reactive oxygen species, key chemicals in cardiovascular disease.
Perhaps the more rigorous test is a carotenoid phytochemical zeaxanthin-yellow pigment present in many fruits and orange and yellow vegetables. Repeated studies have shown a strong correlation between ingestion of zeaxanthin and the prevention and treatment of macular degeneration (AMD). Less rigorous studies have suggested a correlation between zeaxanthin intake and cataracts. A second carotenoid, lutein, has also been shown to reduce the risk of AMD. Both compounds have been observed to collect in the retina when ingested orally, and which serve to protect the rods and cones against the destructive effects of light.
Another carotenoid, beta-cryptoxanthin, appears to protect against all chronic inflammatory diseases such as arthritis. Although the association between blood levels of serum beta-cryptoxanthin and substantially decreased joint disease has been established, neither a convincing mechanism for such protection nor a cause-effect has been rigorously studied.
Similarly, red phytochemical, lycopene, has credible evidence of negative association with the development of prostate cancer.
The correlations between the ingestion of some phytochemicals and disease prevention are, in some cases, the enormous magnitude.
Even when evidence is obtained, the translation into practice dietary advice can be difficult and counter-intuitive. Lutein, for example, occurs in many yellow and orange fruits and vegetables protects against various eye diseases. However, it does not protect the eyes and near zeaxanthin, and the presence of lutein in the retina will prevent zeaxanthin uptake. In addition, evidence has shown that the lutein present in egg yolk is absorbed more easily than the lutein from vegetable sources, possibly because of fat solubility. In the most basic level, the question ‘to eat eggs? ” is complex to the point of dismay, including misperceptions about the health effects of cholesterol in egg yolk, and its saturated fat content.
As another example, lycopene is prevalent in tomatoes (and in fact is the chemical that gives tomatoes their red color). Is more concentrated, however, in processed tomato products such as commercial pasta sauce or tomato soup, than in fresh “healthy” tomatoes. However, such sauces tend to have high amounts of salt, sugar, other substances a person may want or need to avoid.
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