Nutrition 21525 225972663 2008-07-16T07:37:28Z AThing 751678 /* Metabolic syndrome */ [[Image:Nutrition label.gif|right|thumb|The "Nutrition Facts" table indicates the amounts of nutrients which experts recommend you limit or consume in adequate amounts.]] '''Nutrition''' (also called '''nourishment''' or '''aliment''') is the provision, to cells and [[organism]]s, of the materials necessary (in the form of food) to support [[life]]. Many common health problems can be prevented or alleviated with good nutrition. The ''[[Diet (nutrition)|diet]]'' of an organism refers to what it eats. [[Dietitian]]s are [[health professional]]s who specialize in human nutrition, meal planning, economics, preparation, and so on. They are trained to provide safe, evidence-based dietary advice and management to individuals (in health and disease), as well as to institutions. Poor diet can have an injurious impact on health, causing deficiency diseases such as [[scurvy]], [[beriberi]], and [[kwashiorkor]]; health-threatening conditions like [[obesity]] and [[metabolic syndrome]], and such common chronic systemic diseases as [[cardiovascular disease]], [[diabetes]], and [[osteoporosis]]. == Overview == Nutritional science investigates the [[metabolism|metabolic]] and physiological responses of the body to diet. With advances in the fields of [[molecular biology]], [[biochemistry]], and [[genetics]], the study of nutrition is increasingly concerned with metabolism and metabolic pathways, the sequences of biochemical steps through which the many substances of living things change from one form to another. The [[human body]] contains [[chemical compounds]], such as [[water]], [[carbohydrate]]s (sugar, starch, and [[fiber]]), [[amino acids]] (in [[proteins]]), [[fatty acids]] (in [[lipids]]), and [[nucleic acids]] ([[DNA]]/[[RNA]]). These compounds, in turn, consist of [[chemical element|elements]] such as [[carbon]], [[hydrogen]], [[oxygen]], [[nitrogen]], [[phosphorus]], [[calcium]], [[iron]], [[zinc]], [[magnesium]], [[manganese]], and so on. All of these chemical compounds and elements occur in various forms and combinations (e.g. [[hormones]]/[[vitamins]], [[phospholipids]], [[hydroxyapatite]]), both in the [[human body]] and in organisms (e.g. plants, animals) that humans eat. The human body consists of elements and compounds ingested, digested, absorbed, and circulated through the [[blood]]stream. Except in the unborn fetus, it is the [[digestive system]] which carries out the first steps in feeding the [[Cell (biology)|cell]]s of the body. In a typical adult, about seven liters of digestive juices enter the [[lumen]] of the digestive tract. They break [[chemical bonds]] in ingested molecules and modulate their [[conformation]]s and energy states. Though some molecules are absorbed into the bloodstream unchanged, digestive processes release them from the matrix of foods in which they occur. Unabsorbed matter is secreted in the [[feces]]. Studies of nutritional status must take into account the state of the body before and after experiments, as well as the [[chemical]] composition of the diet and the products of excretion. Comparing the food to the waste can help determine the specific compounds and elements absorbed in the body. Their effects may only be discernible after an extended period of time, during which all food and waste must be analyzed. The number of [[variables]] involved in such [[experiment]]s is high, making nutritional studies time-consuming and expensive, which explains why the science of human nutrition is still slowly evolving. In general, eating a wide variety of fresh, whole (unprocessed), foods has proven favourable compared to monotonous diets based on processed foods. In particular, the consumption of whole plant foods slows digestion and provides higher amounts, and a more favourable balance, of essential nutrients per [[kilocalorie|Calorie]], resulting in better management of cell growth, maintenance, and [[mitosis]] (cell division), as well as better regulation of appetite and blood sugar. Regularly scheduled meals (every few hours) have also proven more wholesome than infrequent, haphazard ones. == Nutrients == {{main|Nutrient}} There are seven major classes of nutrients: [[carbohydrates]] (saccharides), [[fat]]s (triglycerides), [[fiber]] (cellulose), [[minerals]], [[proteins]], [[vitamins]], and [[water]]. These nutrient classes can be generally grouped into the categories of [[macronutrients]] (needed in relatively large amounts), and [[micronutrients]] (needed in smaller quantities). The macronutrients are carbohydrates, fats, fiber, proteins and water. The other nutrient classes are micronutrients. The macronutrients (excluding fiber and water) provide [[Bioenergetics|energy]], which is measured in kilocalories, often called "Calories" and written with a capital C to distinguish them from small [[calorie]]s. Carbohydrates and proteins provide four (4) Calories of energy per gram, while fats provide nine (9) Calories per gram.<ref name=Stryer>{{cite book | author = Berg J, Tymoczko JL, Stryer L | title = Biochemistry | publisher = W. H. Freeman | edition = 5th ed. | location = San Francisco | year = 2002 | isbn = 0716746840 |pages= page 603 }}</ref> Vitamins, minerals, fiber, and water do not provide energy, but are necessary for other reasons. Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Carbohydrates may be simple [[monomer]]s (glucose, fructose, galactose), or large polymers [[polysaccharides]] (starch). Fats are [[triglyceride]]s, made of various [[fatty acid]] monomers bound to [[glycerol]]. Some fatty acids are [[essential fatty acids|essential]], but not all. Protein molecules contain nitrogen atoms in addition to the elements of carbohydrates and fats. The nitrogen-containing monomers of protein, called [[amino acids]], fulfill many roles other than energy metabolism, and when they are used as fuel, getting rid of the nitrogen places a burden on the kidneys. Similar to fatty acids, certain amino acids are [[essential amino acid|essential]]. Other micronutrients not categorized above include [[antioxidants]] and [[phytochemicals]]. Most foods contain a mix of some or all of the nutrient classes. Some nutrients are required on a regular basis, while others are needed less frequently. Poor health can be caused by an imbalance of nutrients, whether an excess or a deficiency. ===Carbohydrates=== {{main|Carbohydrate}} '''Calories/gram: 4''' [[Image:ToastsAsCheapFoodPerCalorie.JPG|thumb|right|150px|A pack of toasted bread is a cheap, high nutrient food source (which too has long shelf life) and may be used (as too dehulled [[rice]]) to combat famines.]] Carbohydrates may be classified as monosaccharides, disaccharides, or polysaccharides by the number of monomer (sugar) units they contain. They are found in foods as [[rice]], [[noodles]] and other [[grain]]-based products, [[potatoes]], ... Monosaccharides contain 1 sugar unit, disaccharides contain 2, and polysaccharides contain 3 or more. Polysaccharides are often referred to as complex carbohydrates because they are long chains of sugar units, whereas monosaccharides and disaccharides are simple carbohydrates. The difference is important to nutritionists because complex carbohydrates take longer to metabolize since their sugar units are processed one-by-one off the ends of the chains. Simple carbohydrates are metabolized quickly and thus raise blood sugar levels more quickly resulting in rapid increases in blood insulin levels compared to complex carbohydrates. ===Fat=== {{main|Fat}} '''Calories/gram: 9''' Fats are composed of [[fatty acid]]s (long carbon/hydrogen chains) bonded to a glycerol. Certain fatty acids are [[essential fatty acids|essential]]. Fats may be classified as saturated or unsaturated. Saturated fats have all of their carbon atoms bonded to hydrogen atoms, whereas unsaturated fats have some of their carbon atoms double-bonded in place of a hydrogen atom. Unsaturated fats are generally healthier than saturated fat. Saturated fat is typically solid at room temperature (such as [[butter]]), while unsaturated fat is a liquid (such as [[olive oil]]). Unsaturated fats may be further classified as monounsaturated (one double-bond) or polyunsaturated (many double-bonds). Trans fats are saturated fats which are typically created from unsaturated fat by adding the extra hydrogen atoms in a process called hydrogenation (also called hydrogenated fat). They are very rare in nature and are the least healthy type of fat. ==== Essential fatty acids ==== {{main|Essential fatty acids}} Most fatty acids are non-essential, meaning the body can produce them as needed, however, at least two fatty acids are essential and must be consumed in the diet. An appropriate balance of essential fatty acids - [[omega-3]] and [[omega-6 fatty acid|omega-6]] fatty acids - has been discovered to be important for maintaining health. Both of these unique "omega" long-chain [[unsaturated fat|polyunsaturated fatty acids]] are [[substrate (biochemistry)|substrates]] for a class of [[eicosanoids]] known as [[prostaglandins]] which function as hormones. The omega-3 [[eicosapentaenoic acid]] (EPA) (which can be made in the body from the omega-3 essential fatty acid [[alpha-linolenic acid]] (LNA), or taken in through marine food sources), serves as building block for series 3 prostaglandins (e.g. weakly-[[inflammatory|inflammation]] PGE3). The omega-6 dihomo-gamma-linolenic acid (DGLA) serves as building block for series 1 prostaglandins (e.g. anti-inflammatory PGE1), whereas arachidonic acid (AA) serves as building block for series 2 prostaglandins (e.g. pro-inflammatory PGE 2). Both DGLA and AA are made from the omega-6 [[linoleic acid]] (LA) in the body, or can be taken in directly through food. An appropriately balanced intake of omega-3 and omega-6 partly determines the relative production of different prostaglandins, which partly explains the importance of omega-3/omega-6 balance for cardiovascular health. In industrialised societies, people generally consume large amounts of processed vegetable oils that have reduced amounts of essential fatty acids along with an excessive amount of omega-6 relative to omega-3. The rate of conversions of omega-6 DGLA to AA largely determines the production of the respective prostaglandins PGE1 and PGE2. Omega-3 EPA prevents AA from being released from membranes, thereby skewing prostaglandin balance away from pro-inflammatory PGE2 made from AA toward anti-inflammatory PGE1 made from DGLA. Moreover, the conversion (desaturation) of DGLA to AA is controlled by the enzyme [[desaturase|delta-5-desaturase]], which in turn is controlled by hormones such as [[insulin]] (up-regulation) and [[glucagon]] (down-regulation). Because different types and amounts of food eaten/absorbed affect insulin, glucagon and other hormones to varying degrees, not only the amount of omega-3 versus omega-6 eaten but also the general composition of the diet therefore determine health implications in relation to essential fatty acids, [[inflammation]] (e.g. immune function) and [[mitosis]] (i.e. cell division). Good sources of essential fatty acids include: [[fish]], [[flax seed]]s, [[hemp seed]]s, [[soy bean]]s, [[pumpkin seed]]s, [[sunflower seed]]s, and [[walnut]]s. === Fiber === {{main|Dietary fiber}} '''Calories/gram: 0''' Dietary fiber consists mainly of [[cellulose]], a large carbohydrate polymer, that is indigestible because humans do not have enzymes to digest it. Whole grains, fruits (especially [[plum]]s, [[prune]]s, and [[fig]]s), and vegetables are rich in dietary fiber. It provides bulk to the intestinal contents and stimulates [[peristalsis]] (rhythmic muscular contractions passing along the digestive tract). Consequently, a lack of dietary fiber in the diet leads to [[constipation]] (failure to pass motions). Fiber is (severely) lacking in the average North American diet. ===Protein=== {{main|Protein in nutrition}} '''Calories/gram: 4''' [[Image:LemonChicken2.jpg|right|thumb|Most [[meats]] such as [[Chicken (food)|chicken]] contain all the [[essential amino acids]] needed for humans.]] Protein is composed of [[amino acids]], that are the body's structural (muscles, skin, hair etc.) materials. The body requires amino acids to produce new body protein (protein retention) and to replace damaged proteins (maintenance) that are lost in the urine. In animals, amino acid requirements are classified in terms of [[essential amino acid|essential]] (an animal cannot produce them) and [[non-essential amino acid|non-essential]] (the animal can produce them from other nitrogen containing compounds) amino acids. Consuming a diet that contains adequate amounts of essential (but also non-essential) amino acids is particularly important for growing animals, who have a particularly high requirement. Dietary sources of protein include [[meat]]s, [[tofu]] and other [[soy]]-products, [[egg (food)|eggs]], [[grain]]s, [[legume]]s, and [[dairy product]]s such as [[milk]] and [[cheese]]. Proteins can be converted into carbohydrates through a process called [[gluconeogenesis]]. ===Minerals=== {{main|Dietary mineral}} '''Calories/gram: 0''' Dietary minerals are the [[chemical element]]s required by living organisms, other than the four elements [[carbon]], [[hydrogen]], [[nitrogen]], and [[oxygen]] which are present in common [[organic chemistry|organic molecules]]. The term "mineral" is archaic, since the intent of the definition is to describe ions, not [[chemical compound]]s or actual [[mineral]]s. Some dietitians recommend that these heavier elements should be supplied by ingesting specific foods (that are enriched in the element(s) of interest), compounds, and sometimes including even minerals, such as [[calcium carbonate]]. Sometimes these "minerals" come from natural sources such as ground [[oyster]] shells. Sometimes minerals are added to the diet separately from food, such as mineral supplements, the most famous being iodine in "[[iodized salt]]". ====Macrominerals==== A variety of elements are required to support the biochemical processes, many play a role as [[electrolyte]]s or in a structural role.<ref>Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN 1-57259-153-6.</ref> In human nutrition, the dietary bulk "mineral elements" ([[Recommended Dietary Allowance|RDA]] > 200 mg/day) are in alphabetical order (parenthetical comments on folk medicine perspective): * [[Calcium]] (for muscle and digestive system health, builds bone, neutralizes acidity, clears toxins, helps blood stream) * [[Chloride]] * [[Magnesium]] required for processing ATP and related reactions (health, builds bone, causes strong peristalsis, increases flexibility, increases alkalinity) * [[Phosphorus]] required component of bones (see [[apatite]]) and energy processing and many other functions (bone mineralization)<ref>D. E. C. Corbridge "Phosphorus: An Outline of its Chemistry, Biochemistry, and Technology" 5th Edition Elsevier: Amsterdam 1995. ISBN 0-444-89307-5.</ref> * [[Potassium]] required [[electrolyte]] (heart and nerves health) * [[Sodium]] electrolyte * [[Sulfur]] for three essential amino acids and many proteins and cofactors (skin, hair, nails, liver, and pancreas health) ====Trace minerals==== A variety of elements are required in trace amounts, unusually because they play a role in [[catalysis]] in [[enzymes]].<ref name=lipp>Lippard, S. J. and Berg, J. M., Principles of Bioinorganic Chemistry, University Science Books: Mill Valley, CA, 1994.</ref> Some trace mineral elements (RDA < 200 mg/day) are (alphabetical order): * [[Cobalt]] required for biosynthesis of [[vitamin B12]] family of [[coenzyme]]s * [[Copper]] required component of many redox enzymes, including [[cytochrome c oxidase]] * [[Chromium]] required for sugar metabolism * [[Iodine]] required for the biosynthesis of [[thyroxin]] * [[Iron]] required for many proteins and enzymes, notably [[hemoglobin]] * [[Manganese]] (processing of oxygen) * [[Molybdenum]] required for [[xanthine oxidase]] and related oxidases * [[Nickel]] present in [[urease]] * [[Selenium]] required for [[peroxidase]] (antioxidant proteins) * [[Vanadium]] (There is no established RDA for vanadium. No specific biochemical function has been identified for it in humans, although vanadium is found in lower organisms.) * [[Zinc]] required for several enzymes such as [[carboxypeptidase]], [[Alcohol dehydrogenase#In_humans|liver alcohol dehydrogenase]], [[carbonic anhydrase]]. Zinc is pervasive. Iodine is required in larger quantities than the other trace minerals in this list and is sometimes classified with the bulk minerals. Sodium is not generally found in dietary supplements, despite being needed in large quantities, because the ion is very common in food. ===Vitamins=== {{main|Vitamin}} '''Calories/gram: 0''' [[dietary mineral|Mineral]] and/or [[vitamin]] deficiency or excess may yield symptoms of diminishing health such as [[goitre]], [[scurvy]], [[osteoporosis]], weak [[immune system]], disorders of cell [[metabolism]], certain forms of cancer, symptoms of premature [[aging]], and poor [[psychology|psychological health]] (including [[eating disorders]]), among many others.<ref>Shils ''et al.'' (2005) ''Modern Nutrition in Health and Disease'', Lippincott Williams and Wilkins. ISBN 0-7817-4133-5.</ref> As of 2005, twelve vitamins and about the same number of minerals are recognized as "essential nutrients", meaning that they must be consumed and absorbed&mdash;or, in the case of [[vitamin D]], alternatively synthesized via [[UVB radiation]]&mdash;to prevent deficiency symptoms and death. Certain vitamin-like substances found in foods, such as [[carnitine]], have also been found essential to survival and health, but these are not strictly "essential" to eat because the body can produce them from other compounds. Moreover, thousands of different [[phytochemicals]] have recently been discovered in food (particularly in fresh vegetables), which have many known and yet to be explored properties including [[antioxidant]] activity (see below). Other essential nutrients include [[essential amino acid]]s, [[choline]] and the [[essential fatty acid]]s. === Water === [[Image:TapWater-china.JPG|thumb|right|A manual water [[pump]] in China]] {{main|Drinking water}} '''Calories/gram: 0''' About 70% of the non-fat mass of the [[human]] body is made of water{{Fact|date=April 2008}}. To function properly, the body requires between one and seven [[liter]]s of water per [[day]] to avoid [[dehydration]]; the precise amount depends on the level of activity, temperature, humidity, and other factors{{Fact|date=April 2008}}. With physical exertion and heat exposure, water loss will increase and daily fluid needs may increase as well. It is not clear how much water intake is needed by healthy people, although some experts assert that 8–10 glasses of water (approximately 2 liters) daily is the minimum to maintain proper hydration.<ref>{{cite web |url=http://www.bbc.co.uk/health/healthy_living/nutrition/drinks_water.shtml |title=Healthy Water Living|producer=BBC|accessdate=2007-02-01}}</ref> The notion that a person should consume eight glasses of water per day cannot be traced back to a scientific source.<ref>[http://ajpregu.physiology.org/cgi/content/full/283/5/R993 "Drink at least eight glasses of water a day." Really? Is there scientific evidence for "8 × 8"?] by Heinz Valdin, Department of Physiology, Dartmouth Medical School, Lebanon, [[New Hampshire]]</ref> The effect of water on weight loss and constipation is also still unknown.<ref>[http://www.factsmart.org/h2o/h2o.htm Drinking Water - How Much?], Factsmart.org web site and references within</ref> Original recommendation for water intake in 1945 by the [[Food and Nutrition Board]] of the [[National Research Council]] read: "An ordinary standard for diverse persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods."<ref>Food and Nutrition Board, National Academy of Sciences. Recommended Dietary Allowances, revised 1945. National Research Council, Reprint and Circular Series, No. 122, 1945 (Aug), p. 3-18.</ref> The latest dietary reference intake report by the [[United States National Research Council]] in general recommended (including food sources): 2.7 liters of water total for women and 3.7 liters for men.<ref>[http://www.iom.edu/report.asp?id=18495 Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate], Food and Nutrition Board</ref> Specifically, [[Pregnancy|pregnant]] and [[breastfeeding]] women need additional fluids to stay hydrated. According to the [[Institute of Medicine]]&mdash;who recommend that, on average, women consume 2.2 litres and men 3.0 litres&mdash;this is recommended to be 2.4 litres (approx. 9 cups) for pregnant women and 3 litres (approx. 12.5 cups) for breastfeeding women since an especially large amount of fluid is lost during nursing.<ref>[http://www.mayoclinic.com/health/water/NU00283 Water: How much should you drink every day? - MayoClinic.com<!-- Bot generated title -->]</ref> For those who have healthy kidneys, it is rather difficult to drink too much water, but (especially in warm humid weather and while exercising) it is dangerous to drink too little. People can drink far more water than necessary while exercising, however, putting them at risk of [[water intoxication]], which can be fatal. Normally, about 20 percent of water intake comes from food, while the rest comes from drinking water and beverages ([[Caffeine|caffeinated]] included). Water is excreted from the body in multiple forms; through [[urine]] and [[feces]], through [[sweat]]ing, and by exhalation of [[water vapor]] in the breath. === Other nutrients === '''Calories/gram: 0''' Other micronutrients include antioxidants and phytochemicals. These substances are generally more recent discoveries which: have not yet been recognized as vitamins; are still under investigation; or contribute to health but are not necessary for life. Phytochemicals may act as antioxidants, but not all phytochemicals are antioxidants. ==== Antioxidants ==== {{main|Antioxidant}} Antioxidants are a recent discovery. As cellular [[metabolism]]/energy production requires oxygen, potentially damaging (e.g. [[mutation]] causing) compounds known as radical oxygen species or [[free radicals]] form as a result. For normal cellular maintenance, growth, and division, these free radicals must be sufficiently neutralized by antioxidant compounds, some produced by the body with adequate [[precursor (chemistry)|precursors]] ([[glutathione]], [[Vitamin C]] in most animals) and those that the body cannot 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 their subgroup polyphenols comprise of the majority of antioxidants, some 4,000 known, and therefore there is much overlap. Different antioxidants are now known to function in a cooperative network, e.g. vitamin C can reactivate free radical-containing [[glutathione]] or vitamin E by accepting the free radical itself, and so on. Some antioxidants are more effective than others at neutralizing different free radicals. Some cannot neutralize certain free radicals. Some cannot be present in certain areas of free radical development (Vitamin A is [[fat-soluble]] and protects fat areas, Vitamin C is [[water]] soluble and protects those areas). When interacting with a free radical, some antioxidants produce a different free radical compound that is less dangerous or more dangerous than the previous compound. Having a variety of antioxidants allows any byproducts to be safely dealt with by more efficient antioxidants in neutralizing a free radical's [[butterfly effect]]. ==== Phytochemicals ==== {{main|Phytochemical}} [[Image:Blackberry fruits10.jpg|thumb|200px|[[Blackberry|Blackberries]] are a source of [[polyphenol antioxidants]]]] A growing area of interest is the effect upon human health of trace chemicals, collectively called [[phytochemicals]]. These nutrients are typically found in edible plants, especially colorful fruits and vegetables, but also other organisms including seafood, algae, and fungi. The effects of phytochemicals increasingly survive rigorous testing by prominent health organizations. One of the principal classes of phytochemicals are [[polyphenol antioxidant]]s, chemicals which are known to provide certain health benefits to the [[cardiovascular system]] and [[immune system]]. These chemicals are known to down-regulate the formation of [[reactive oxygen species]], key chemicals in [[cardiovascular disease]]. Perhaps the most rigorously tested phytochemical is [[zeaxanthin]], a yellow-pigmented carotenoid present in many yellow and orange fruits and vegetables. Repeated studies have shown a strong correlation between ingestion of zeaxanthin and the prevention and treatment of [[age-related macular degeneration]] (AMD).<ref>Seddon JM ''et al.'' JAMA. 1994; 272: 1413-1420; Schepens Eye Institute/Harvard Medical School, Nov. 11, 2003. See http://www.mdsupport.org/library/zeaxanthin.html.</ref> Less rigorous studies have proposed a correlation between zeaxanthin intake and [[cataracts]].<ref>Lyle, B. J., J. A. Mares-Perlman, ''et al.'' (1999). "Antioxidant intake and risk of incident age-related nuclear cataracts in the Beaver Dam Eye Study." Am J Epidemiol 149(9): 801-9; Yeum, K. J., A. Taylor, ''et al.'' (1995). "Measurement of carotenoids, retinoids, and tocopherols in human lenses." Invest Ophthalmol Vis Sci 36(13): 2756-61; Chasan-Taber, L., W. C. Willett, ''et al.'' (1999). "A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women." Am J Clin Nutr 70(4): 509-16; Brown, L., E. B. Rimm, ''et al.'' (1999). "A prospective study of carotenoid intake and risk of cataract extraction in US men." Am J Clin Nutr 70(4): 517-24.</ref> A second carotenoid, lutein, has also been shown to lower the risk of contracting AMD. Both compounds have been observed to collect in the retina when ingested orally, and they serve to protect the rods and cones against the destructive effects of light. Another caretenoid, beta-[[cryptoxanthin]], appears to protect against chronic joint inflammatory diseases, such as [[arthritis]]. While the association between serum blood levels of beta-cryptoxanthin and substantially decreased joint disease has been established, neither a convincing mechanism for such protection nor a cause-and-effect have been rigorously studied.<ref>Am J Clin Nutr, Vol. 82, No. 2, 451-455, August, 2005 (inflammatory polyarthritis); Am J Epidemiology 2006 163(1).</ref> Similarly, a red phytochemical, [[lycopene]], has substantial credible evidence of negative association with development of prostate cancer. The correlations between the ingestion of some phytochemicals and the prevention of disease are, in some cases, enormous in magnitude. Even when the evidence is obtained, translating it to practical dietary advice can be difficult and counter-intuitive. Lutein, for example, occurs in many yellow and orange fruits and vegetables and protects the eyes against various diseases. However, it does not protect the eye nearly as well as zeaxanthin, and the presence of lutein in the retina will prevent zeaxanthin uptake. Additionally, evidence has shown that the lutein present in egg yolk is more readily absorbed than the lutein from vegetable sources, possibly because of fat solubility.<ref>Am J Clin Nutr, Vol. 70, No. 2, 247-251, August 1999.</ref> At the most basic level, the question "should you 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 actually is the chemical that gives tomatoes their red color). It is more highly concentrated, however, in processed tomato products such as commercial pasta sauce, or [[tomato soup]], than in fresh "healthy" tomatoes. Yet, such sauces tend to have high amounts of salt, sugar, other substances a person may wish or even need to avoid. The following table presents phytochemical groups and common sources, arranged by family: <br clear=all> {| class="wikitable" ! Family !! Sources !! Possible Benefits |- | [[flavonoid]]s||[[Berry|berries]], [[herbs]], [[vegetables]], [[wine]], [[grapes]], [[tea]]||general [[antioxidant]], oxidation of [[LDL]]s, prevention of [[arteriosclerosis]] and [[heart disease]] |- | [[isoflavone]]s ([[phytoestrogens]])||[[soy]], [[red clover]], [[kudzu root]]||general [[antioxidant]], prevention of [[arteriosclerosis]] and [[heart disease]], easing symptoms of [[menopause]], [[cancer|cancer prevention]]<ref>Note that some isoflavone studies have linked isoflavones to increased cancer risk.</ref> |- | [[isothiocyanate]]s||[[cruciferous vegetables]]||[[cancer|cancer prevention]] |- | [[monoterpene]]s||[[citrus]] peels, [[essential oil]]s, [[herbs]], [[spices]], [[green plants]], [[atmosphere]]<ref>Monoterpenes are enormously widespread among green plant life (including [[algae]]). Many plants, notably coniferous trees, emit beneficial monoterpenes into the atmosphere.</ref>||[[cancer|cancer prevention]], treating [[gallstones]] |- | [[organosulfur compounds]]||[[chives]], [[garlic]], [[onion]]s||[[cancer|cancer prevention]], lowered [[LDL]]s, assistance to the [[immune system]] |- | [[saponin]]s||[[bean]]s, [[cereal]]s, [[herbs]]||[[Hypercholesterolemia]], [[Hyperglycemia]], [[Antioxidant]], [[cancer|cancer prevention]], [[Anti-inflammatory]] |- | [[capsaicinoid]]s||[[chile pepper|all ''capiscum'' (chile) peppers]]||topical [[pain relief]], [[cancer|cancer prevention]], cancer cell [[apoptosis]] |} ===Intestinal bacterial flora=== {{main|Gut flora}} It is now also known that the [[human digestion]] system contains a population of a range of [[gut flora|bacteria and yeast]] such as ''[[Bacteroides]]'', ''[[L. acidophilus]]'' and ''[[E. coli]]'' which are essential to [[digestion]], and which are also affected by the food we eat. Bacteria in the gut fulfill a host of important functions for humans, including breaking down and aiding in the absorption of otherwise indigestible food; stimulating cell growth; repressing the growth of harmful bacteria, training the immune system to respond only to pathogens; and defending against some diseases. ===Balanced diet=== Balanced diet is a diet which consists of all the nutrients in a required proportion with water and roughage. ===Junk food=== Junk food is a slang name for food items containing limited nutritional value. It includes food high in salts, fats, sugar, and calories, and low nutrient content. == Sports nutrition == {{main|Sports nutrition}} ===Protein=== The protein requirements of athletes, once the source of great controversy, has settled into a current consensus. Sedentary people and recreational athletes<ref>The definition of recreational athlete here is taken from Burke and Deakin's ''Clinical Sports Nutrition''(3rd Edition, McGraw-Hill Australia Pty Ltd, 2006 ): people exercising two to three hours a week at less than 55% maximum VO2 uptake.</ref> have similar protein requirements, about 1 gram of protein per kilogram of body mass. These needs are easily met by a balanced diet containing about 70 grams of protein for a 70 kg (150 pound) man or 60 grams of protein for a 60 kg (130 pound) woman. People who exercise at greater intensity, and especially those whose activity grows muscle bulk, have significantly higher protein requirements. According to ''Clinical Sports Nutrition'' (see footnote above), active athletes playing power sports (such as football), those engaged in muscle-development training, and elite endurance athletes, all require approximately 2 grams of protein per day per kilogram of body weight, roughly double that of a sedentary persons. Older athletes seeking primarily to maintain developed muscle mass require 2 to 3 g per day per kg. Protein intake in excess of that required to build muscle (and other) tissue is broken-down by [[gluconeogenesis]] to be used as energy. ===Water and salts=== Maintaining hydration during periods of physical exertion is key to good performance. While drinking too much water during activities can lead to physical discomfort, dehydration in excess of 2% of body mass (by weight) markedly hinders athletic performance. It is recommended that an athlete drink about 400-600 mL 2-3 hours before activity, during exercise he or she should drink 150-350mL every 15 to 20 minutes and after exercise that he or she replace sweat loss by drinking 450-675 mL for every 0.5 kg body weight loss during activity.{{Fact|date=February 2007}} Some studies have shown that an athlete that drinks before they feel thirsty stays cooler and performs better than one who drinks on thirst cues, although recent studies of such races as the Boston Marathon have indicated that this recommendation can lead to the problem of overhydration.{{Fact|date=February 2007}} Additional carbohydrates and protein before, during, and after exercise increase time to exhaustion as well as speed recovery. Dosage is based on work performed, lean body mass, and environmental factors, especially ambient temperature and humidity. ===Carbohydrates=== The main fuel used by the body during exercise is carbohydrates, which is stored in muscle as glycogen- a form of sugar. During exercise, muscle glycogen reserves can be used up, especially when activities last longer than 90 min.{{Fact|date=February 2007}} When glycogen is not present in muscles, the muscle cells perform anaerobic respiration producing lactic acid, which is responsible for fatigue and burning sensation, and post exercise stiffness in muscles.{{Fact|date=February 2007}} Because the amount of glycogen stored in the body is limited, it is important for athletes to replace glycogen by consuming a diet high in carbohydrates. Meeting energy needs can help improve performance during the sport, as well as improve overall strength and endurance.<br /> There are different kinds of carbohydrates--simple or refined, and unrefined. A typical American consumes about 50% of their carbohydrates as simple sugars, which are added to foods as opposed to sugars that come naturally in fruits and vegetables. These simple sugars come in large amounts in sodas and fast food. Over the course of a year, the average American consumes 54 gallons of soft drinks, which contain the highest amount of added sugars.<ref>William D. McArdle, Frank I. Katch, Victor L. Katch. Exercise Physiology: Energy, Nutrition, and Human Performance. Lippincott Williams & Wilkins, 2006.</ref> Even though carbohydrates are necessary for humans to function, they are not all equally healthful. When machinery has been used to remove bits of high fiber, the carbohydrates are refined. These are the carbohydrates found in white bread and fast food.<ref>[http://www.bbc.co.uk/health/healthy_living/nutrition/basics_carbos.shtml BBC - Health - Healthy living - Bread, cereals and potatoes<!-- Bot generated title -->]</ref> ==Longevity== {{main|Healthy diet}} ===Whole plant food diet=== Heart disease, cancer, obesity, and diabetes are commonly called "Western" diseases because these maladies were once rarely seen in developing countries. [[The China Study|One study in China]] found some regions had essentially no cancer or heart disease, while in other areas they reflected "up to a 100-fold increase" coincident with diets that were found to be entirely plant-based to heavily animal-based, respectively.<ref name = "Campbell-China">Campbell T., Campbell T. The China Study, Dallas: Benella Books, 2005</ref> In contrast, diseases of affluence like cancer and heart disease are common throughout the United States. Adjusted for age and exercise, large regional clusters of people in China rarely suffered from these "Western" diseases possibly because their diets are rich in vegetables, fruits and whole grains.<ref name = "Campbell-China"/> The United Healthcare/Pacificare nutrition guideline recommends a whole plant food diet, and recommends using protein only as a condiment with meals. A ''[[National Geographic]]'' cover article from November, 2005, entitled ''The Secrets of Living Longer'', also recommends a whole plant food diet. The article is a lifestyle survey of three populations, [[Sardinia]]ns, [[Okinawa]]ns, and [[Seventh-day Adventist Church|Adventist]]s, who generally display longevity and "suffer a fraction of the diseases that commonly kill people in other parts of the developed world, and enjoy more healthy years of life. In sum, they offer three sets of 'best practices' to emulate. The rest is up to you." In common with all three groups is to "Eat fruits, vegetables, and whole grains." The ''National Geographic'' article noted that an [[NIH]] funded study of 34,000 [[Seventh-Day Adventist Church|Seventh-day Adventist]]s between 1976 and 1988 "...found that the Adventists' habit of consuming beans, soy milk, tomatoes, and other fruits lowered their risk of developing certain cancers. It also suggested that eating whole grain bread, drinking five glasses of water a day, and, most surprisingly, consuming four servings of nuts a week reduced their risk of heart disease." ===The French "paradox"=== {{main|French paradox}} It has been discovered that people living in France live longer. Even though they consume more saturated fats than Americans, the rate of heart disease is lower in France than in North America. A number of explanations have been suggested: * Reduced consumption of processed carbohydrate and other junk foods; * Ethnic genetic differences allowing the body to be harmed less by fats;{{Fact|date=February 2007}} * Regular consumption of [[red wine]]; or * Living in the South requires the body to produce less heat, allowing a slower, and therefore healthier, metabolic rate. {{Fact|date=February 2007}} * More active lifestyles involving plenty of daily exercise, especially walking; the French are much less dependent on cars than Americans are. * Higher consumption of artificially produced trans-fats by Americans, which has been shown to have greater lipoprotein impacts per gram than saturated fat.<ref>{{cite web|first=Pierre| last=Ducimetière| publisher=BMJ| url= http://circ.ahajournals.org/cgi/reprint/115/16/2231 | title=Understanding the Complexity of Trans Fatty Acid Reduction in the American Diet}}</ref> However, a growing number of French health researchers{{Fact|date=August 2007}} doubt the theory that the French are healthier than other populations. Statistics collected by the WHO from 1990-2000 show that the incidence of heart disease in France may have been underestimated and in fact be similar to that of neighboring countries.<ref>{{cite web | first=Pierre | last=Ducimetière | publisher=BMJ | url=http://www.bmj.com/cgi/content/full/320/7229/249/a | title=Rates of coronary events are similar in France and southern Europe }} </ref> == Malnutrition == {{main|Malnutrition}} Malnutrition refers to insufficient, excessive, or imbalanced consumption of nutrients. In developed countries, the diseases of malnutrition are most often associated with nutritional imbalances or excessive consumption. Although there are more people in the world who are malnurished due to excessive consumption, according to the United Nations [[World Health Organization]], the real challenge in developing nations today, more than starvation, is combating insufficient nutrition — the lack of nutrients necessary for the growth and maintenance of vital functions. ===Illnesses caused by improper nutrient consumption=== {| class="wikitable" bgcolor="black" |- ! NUTRIENTS ! DEFICIENCY ! EXCESS |- | [[Calories]] | [[Starvation]] | [[Obesity]], [[diabetes mellitus]], [[Cardiovascular disease]] |- | [[Simple carbohydrates]] | [[Marasmus]], [[starvation]] | [[diabetes mellitus]] |- | [[Complex carbohydrates]] | [[Marasmus]], [[starvation]] | [[Obesity]] |- | [[Saturated fat]] / [[trans fat]] | none | [[Cardiovascular disease]], |- | [[Unsaturated fat]] | [[Rabbit starvation]] | [[Obesity]] |- | [[Cholesterol]] | none | [[Cardiovascular disease]] |- | [[Protein]] | [[Marasmus]] | [[Ketoacidosis]], [[Rabbit starvation]], [[kidney disease]] |- | [[Sodium]] | [[hyponatremia]] | [[Hypernatremia]], [[hypertension]] |- | [[Iron]] | [[Anemia]] | [[Hepatitis C]], [[cirrhosis]], [[heart disease]] |- | [[Iodine]] | [[Goiter]], [[hypothyroidism]] | [[Iodine#Toxicity of iodine | Iodine Toxicity]] (goiter, hypothyroidism) |- | [[Vitamin A]] | [[Xerophthalmia]] and Night Blindness | [[Hypervitaminosis A]] (cirrhosis, hair loss, birth defects) |- | Vitamin B<sub>1</sub> | [[Beri-Beri]] | |- | [[Riboflavin| Vitamin B<sub>2</sub> ]] | Cracking of skin and Corneal Unclearation | |- | [[Niacin]] | [[Pellagra]] | [[dyspepsia]], [[cardiac arrhythmias]], birth defects |- | [[Vitamin B12| Vitamin B<sub>12</sub> ]] | Pernicious Anemia | |- | [[Vitamin C]] | [[Scurvy]] | |- | [[Vitamin D]] | [[Rickets]] | [[Hypervitaminosis D]] (dehydration, vomiting, constipation) |- | [[Vitamin E]] | | [[Hypervitaminosis E]] (anticoagulant: excessive bleeding) |- | [[Vitamin K]] | [[Hemorrhage]] | |} === Mental agility === {{main|Nootropic}} Research indicates that improving the awareness of nutritious meal choices and establishing long-term habits of healthy eating has a positive effect on a cognitive and spatial memory capacity, potentially increasing a student's potential to process and retain academic information. Some organizations have begun working with teachers, policymakers, and managed foodservice contractors to mandate improved nutritional content and increased nutritional resources in school cafeterias from primary to university level institutions. Health and nutrition have been proven to have close links with overall educational success (Behrman, 1996). Currently less than 10% of American college students report that they eat the recommended five servings of fruit and vegetables daily.<ref name="ACHA-p195">American College Health Association. (2007) American College Health Association national college health assessment spring 2006 reference group data report (abridged). Journal of American College Health, 55(4), 195-206.</ref> Better nutrition has been shown to have an impact on both cognitive and spatial memory performance; a study showed those with higher blood sugar levels performed better on certain memory tests.<ref>Benton, D., & Sargent, J. (1992/7). Breakfast, blood glucose and memory. Biological Psychology, 33(2-3), 207-210. </ref> In another study, those who consumed yogurt performed better on thinking tasks when compared to those who consumed caffeine free diet soda or confections.<ref>Kanarek, R. B., & Swinney, D. (1990/2). Effects of food snacks on cognitive performance in male college students. Appetite, 14(1), 15-27.</ref> Nutritional deficiencies have been shown to have a negative effect on learning behavior in mice as far back as 1951.<ref>Whitley, J., O'Dell, B., & Hogan, A. (1951). Effect of diet on maze learning in second-generation rats. folic acid deficiency. Journal of Nutrition, 45(1), 153. </ref> :"Better learning performance is associated with diet induced effects on learning and memory ability".<ref>Umezawa, M., Kogishi, K., Tojo, H., Yoshimura, S., Seriu, N., Ohta, A., et al. (1999). High-linoleate and high-alpha-linolenate diets affect learning ability and natural behavior in SAMR1 mice. The Journal of Nutrition, 129(2), 431-437.</ref> The "nutrition-learning nexus" demonstrates the correlation between diet and learning and has application in a higher education setting. :"We find that better nourished children perform significantly better in school, partly because they enter school earlier and thus have more time to learn but mostly because of greater learning productivity per year of schooling."<ref>Glewwe, P., Jacoby, H., & King, E. (2001). Early childhood nutrition and academic achievement: A longitudinal analysis. Journal of Public Economics, 81(3), 345-368.</ref> :91% of college students feel that they are in good health while only 7% eat their recommended daily allowance of fruits and vegetables.<ref name="ACHA-p195"/> :Nutritional education is an effective and workable model in a higher education setting.<ref>Managed food service contractors react quickly to the demands of their clients achievement: A longitudinal analysis. Journal of Public Economics, 81(3), 345-368.</ref><ref>Guernsey, L. (1993). Many colleges clear their tables of steak, substitute fruit and pasta. Chronicle of Higher Education, 39(26), A30.</ref> :More "engaged" learning models that encompass nutrition is an idea that is picking up steam at all levels of the learning cycle.<ref>Duster, T., & Waters, A. (2006). Engaged learning across the curriculum: The vertical integration of food for thought. Liberal Education, 92(2), 42.</ref> There is limited research available that directly links a student's Grade Point Average (G.P.A.) to their overall nutritional health. Additional substantive data is needed to prove beyond a shadow of a doubt that overall intellectual health is closely linked to a person's diet, rather than just another [[correlation fallacy]]. === Mental disorders === Nutritional supplement treatment may be appropriate for major [[Clinical depression|depression]], [[bipolar disorder]], [[schizophrenia]], and [[obsessive compulsive disorder]], the four most common mental disorders in developed countries.<ref>{{cite journal |author= Lakhan SE, Vieira KF |title= Nutritional therapies for mental disorders |journal= Nutr J |volume=7 |pages=2 |year=2008 |pmid=18208598 |doi=10.1186/1475-2891-7-2 |url=http://www.nutritionj.com/content/7/1/2}}</ref> === Cancer === Cancer is now common in developing countries. According a study by the [[International Agency for Research on Cancer]], "In the developing world, cancers of the liver, stomach and esophagus were more common, often linked to consumption of carcinogenic preserved foods, such as smoked or salted food, and parasitic infections that attack organs." Lung cancer rates are rising rapidly in poorer nations because of increased use of tobacco. Developed countries "tended to have cancers linked to affluence or a 'Western lifestyle' – cancers of the colon, rectum, breast and prostate – that can be caused by obesity, lack of exercise, diet and age."<ref>{{cite web|first=Michael |last=Coren| url=http://www.cnn.com/2005/HEALTH/03/09/cancer.study/index.html | title=Study: Cancer no longer rare in poorer countries | publisher= [[CNN]] | date=[[2005-03-10]] | accessdate=2007-01-01}}</ref> === Metabolic syndrome === Several lines of evidence indicate lifestyle-induced [[hyperinsulinemia]] and reduced insulin function (i.e. [[insulin resistance]]) as a decisive factor in many disease states. For example, hyperinsulinemia and insulin resistance are strongly linked to chronic inflammation, which in turn is strongly linked to a variety of adverse developments such as arterial microinjuries and [[clot]] formation (i.e. heart disease) and exaggerated cell division (i.e. cancer). Hyperinsulinemia and insulin resistance (the so-called [[metabolic syndrome]]) are characterized by a combination of abdominal [[obesity]], elevated [[blood sugar]], elevated [[blood pressure]], elevated blood [[triglycerides]], and reduced HDL [[cholesterol]]. The negative impact of hyperinsulinemia on prostaglandin PGE1/PGE2 balance may be significant. The state of [[obesity]] clearly contributes to insulin resistance, which in turn can cause [[type 2 diabetes]]. Virtually all obese and most type 2 diabetic individuals have marked insulin resistance. Although the association between overweight and insulin resistance is clear, the exact (likely multifarious) causes of insulin resistance remain less clear. Importantly, it has been demonstrated that appropriate exercise, more regular food intake and reducing [[glycemic load]] (see below) all can reverse insulin resistance in overweight individuals (and thereby lower blood sugar levels in those who have type 2 diabetes). Obesity can unfavourably alter hormonal and metabolic status via resistance to the hormone [[leptin]], and a vicious cycle may occur in which insulin/leptin resistance and obesity aggravate one another. The vicious cycle is putatively fuelled by continuously high insulin/leptin stimulation and fat storage, as a result of high intake of strongly insulin/leptin stimulating foods and energy. Both insulin and leptin normally function as satiety signals to the [[hypothalamus]] in the brain; however, insulin/leptin resistance may reduce this signal and therefore allow continued overfeeding despite large body fat stores. In addition, reduced leptin signalling to the brain may reduce leptin's normal effect to maintain an appropriately high metabolic rate. There is a debate about how and to what extent different dietary factors&mdash; such as intake of processed carbohydrates, total protein, fat, and carbohydrate intake, intake of saturated and trans fatty acids, and low intake of vitamins/minerals&mdash;contribute to the development of insulin and leptin resistance. In any case, analogous to the way modern man-made pollution may potentially overwhelm the environment's ability to maintain [[homeostasis]], the recent explosive introduction of high [[glycemic index]] and processed foods into the human diet may potentially overwhelm the body's ability to maintain homeostasis and health (as evidenced by the metabolic syndrome epidemic). === Hyponatremia === Excess water intake, without replenishment of sodium and potassium salts, leads to [[hyponatremia]], which can further lead to [[water intoxication]] at more dangerous levels. A well-publicized case occurred in 2007, when Jennifer Strange died while participating in a water-drinking contest.<ref>[http://news.bbc.co.uk/1/hi/magazine/6263029.stm BBC NEWS | Magazine |Why is too much water dangerous?<!-- Bot generated title -->]</ref> More usually, the condition occurs in long-distance endurance events (such as [[marathon]] or [[triathlon]] competition and training) and causes gradual mental dulling, headache, drowsiness, weakness, and confusion; extreme cases may result in coma, convulsions, and death. The primary damage comes from swelling of the brain, caused by increased osmosis as blood salinity decreases. Effective fluid replacement techniques include Water aid stations during running/cycling races, trainers providing water during team games such as Soccer and devices such as Camel Baks which can provide water for a person without making it too hard to drink the water. == Processed foods == {{main|Food processing}} Since the [[Industrial Revolution]] some two hundred years ago, the food processing industry has invented many [[technology|technologies]] that both help keep foods fresh longer and alter the fresh state of food as they appear in nature. Cooling is the primary technology used to maintain freshness, whereas many more technologies have been invented to allow foods to last longer without becoming spoiled. These latter technologies include [[pasteurisation]], [[autoclavation]], [[drying]], [[salting]], and separation of various components, and all appear to alter the original nutritional contents of food. Pasteurisation and autoclavation (heating techniques) have no doubt improved the safety of many common foods, preventing epidemics of bacterial infection. But some of the (new) food processing technologies undoubtedly have downfalls as well. Modern separation techniques such as [[milling]], [[centrifugation]], and [[pressing]] have enabled upconcentration of particular components of food, yielding flour, oils, juices and so on, and even separate fatty acids, amino acids, vitamins, and minerals. Inevitably, such large scale upconcentration changes the nutritional content of food, saving certain nutrients while removing others. Heating techniques may also reduce food's content of many heat-labile nutrients such as certain vitamins and phytochemicals, and possibly other yet to be discovered substances.<ref> {{cite journal|last=Morris|first=Audrey|coauthors=Audia Barnett, Olive-Jean Burrows|title=Effect of Processing on Nutrient Content of Foods|journal=CAJANUS|volume=37|issue=3|pages=pp. 160–164|date=2004|url=http://www.paho.org/English/CFNI/cfni-caj37No304-art-3.pdf|accessdate=2006-10-26|format=[[PDF]]}}</ref> Because of reduced nutritional value, processed foods are often 'enriched' or 'fortified' with some of the most critical nutrients (usually certain vitamins) that were lost during processing. Nonetheless, processed foods tend to have an inferior nutritional profile compared to whole, fresh foods, regarding content of both sugar and high GI starches, [[potassium]]/[[sodium]], vitamins, fibre, and of intact, unoxidized (essential) fatty acids. In addition, processed foods often contain potentially harmful substances such as oxidized fats and trans fatty acids. A dramatic example of the effect of food processing on a population's health is the history of epidemics of [[beri-beri]] in people subsisting on polished rice. Removing the outer layer of rice by polishing it removes with it the essential vitamin [[thiamine]], causing beri-beri. Another example is the development of [[scurvy]] among infants in the late 1800s in the United States. It turned out that the vast majority of sufferers were being fed milk that had been heat-treated (as suggested by [[Pasteur]]) to control bacterial disease. Pasteurisation was effective against bacteria, but it destroyed the vitamin C. As mentioned, lifestyle- and obesity-related diseases are becoming increasingly prevalent all around the world. There is little doubt that the increasingly widespread application of some modern food processing technologies has contributed to this development. The food processing industry is a major part of modern economy, and as such it is influential in political decisions (e.g. nutritional recommendations, agricultural subsidising). In any known profit-driven economy, health considerations are hardly a priority; effective production of cheap foods with a long shelf-life is more the trend. In general, whole, fresh foods have a relatively short shelf-life and are less profitable to produce and sell than are more processed foods. Thus the consumer is left with the choice between more expensive but nutritionally superior whole, fresh foods, and cheap, usually nutritionally inferior processed foods. Because processed foods are often cheaper, more convenient (in both purchasing, storage, and preparation), and more available, the consumption of nutritionally inferior foods has been increasing throughout the world along with many nutrition-related health complications. == Advice and guidance == ===Governmental policies=== [[Image:MyPyramid1.png|right|thumb|The updated [[United States Department of Agriculture|USDA]] [[MyPyramid|food pyramid]], published in 2005, is a general nutrition guide for recommended [[food]] consumption for [[humans]].]] In the US, {{cite web|url=http://en.wikipedia.org/wiki/Dietitian|title=dietitians}} are registered (RD) or licensed (LD) with the Commission for Dietetic Registration and the American Dietetic Association, and are only able to use the title "dietitian," as described by the business and professions codes of each respective state, when they have met specific educational and experiential prerequisites and passed a national registration or licensure examination, respectively. In California, registered dietitions must abide by the {{cite web|url=http://www.leginfo.ca.gov/cgi-bin/displaycode?section=bpc&group=02001-03000&file=2585-2586.8|title=Business and Professions Code of Section 2585-2586.8}}Anyone may call themselves a nutritionist, including unqualified personnel, as this term is unregulated. Some states, such as the State of Florida, have begun to include the title "nutritionist" in state licensure requirements. Most governments provide guidance on nutrition, and some also impose [[mandatory labeling|mandatory disclosure/labeling]] requirements for processed food manufacturers and restaurants to assist consumers in complying with such guidance. In the US, nutritional standards and recommendations are currently controlled by the [[USDA|US Department of Agriculture]]. Dietary and exercise guidelines from the USDA are presented in the concept of a [[MyPyramid|food pyramid]], which superseded the Four Food Groups. The Senate committee currently responsible for oversight of the USDA is the ''Agriculture, Nutrition and Forestry Committee''. Committee hearings are often televised on [[C-SPAN]] as seen here. The [[U.S. Department of Health and Human Services]] provides a sample week-long menu which fulfills the nutritional recommendations of the government.[http://www.mypyramid.gov/downloads/sample_menu.pdf] [[Canada's Food Guide]] is another governmental recommendation. ===Teaching=== Nutrition is [[Teaching|taught]] in schools in many countries. In [[England and Wales]] the [[Personal and Social Education]] and Food Technology curricula include nutrition, stressing the importance of a balanced diet and teaching how to read nutrition labels on packaging. ==History== Humans have evolved as [[omnivore|omnivorous]] [[hunter-gatherer]]s over the past 250,000 years. The diet of early modern humans varied significantly depending on location and climate. The diet in the tropics tended to be based more heavily on plant foods, while the diet at higher latitudes tended more towards animal products. Analysis of postcranial and cranial remains of humans and animals from the Neolithic, along with detailed bone modification studies have shown that cannibalism was also prevalent among prehistoric humans.<ref>Paola Villa, et al. "Cannibalism in the Neolithic" ''Science'' '''233''' July 1986.</ref> [[Agriculture]] developed about 10,000 years ago in multiple locations throughout the world, providing grains such as [[wheat]], [[rice]], and [[maize]], with staples such as [[bread]] and [[pasta]]. Farming also provided milk and dairy products, and sharply increased the availability of meats and the diversity of vegetables. The importance of food purity was recognized when bulk storage led to infestation and contamination risks. [[Cooking]] developed as an often ritualistic activity, due to efficiency and reliability concerns requiring adherence to strict recipes and procedures, and in response to demands for food purity and consistency.<ref>[http://rcw.raiuniversity.edu/biotechnology/MScBioinformatics/generalnutrition/lecture-notes/lecture-01.pdf History of the Study of Nutrition in Western Culture] (copy at [http://www.rain.org/homeschool/nutrition-history-in-western-culture.html])</ref> {{Prose|date=February 2008}} ===Antiquity through 1900=== * The first recorded nutritional experiment is found in the Bible's [[Book of Daniel]]. Daniel and his friends were captured by the king of [[Babylon]] during an invasion of Israel. Selected as court servants, they were to share in the king's fine foods and wine. But they objected, preferring vegetables ([[Pulse (legume)|pulses]]) and water in accordance with their [[Jewish]] dietary restrictions. The king's chief steward reluctantly agreed to a trial. Daniel and his friends received their diet for 10 days and were then compared to the king's men. Appearing healthier, they were allowed to continue with their diet. * c. 475 BC: [[Anaxagoras]] states that food is absorbed by the human body and therefore contained "homeomerics" (generative components), thereby deducing the existence of nutrients. * c. 400 BC: [[Hippocrates]] says, "Let food be your medicine and medicine be your food."<ref name="Smith">[http://bmj.bmjjournals.com/cgi/content/full/328/7433/0-g "Let food by thy medicine...] Richard Smith, ''BMJ 2004;328 (24 January),'', Accessed May 2008</ref> * 1500s: Scientist and artist [[Leonardo da Vinci]] compared [[metabolism]] to a burning candle. * 1747: Dr. [[James Lind]], a physician in the British navy, performed the first [[science|scientific]] nutrition experiment, discovering that [[Lime (fruit)|lime]] juice saved sailors who had been at sea for years from [[scurvy]], a deadly and painful bleeding disorder. The discovery was ignored for forty years, after which British sailors became known as "limeys." The essential [[vitamin C]] within lime juice would not be identified by scientists until the 1930s. * 1770: [[Antoine Lavoisier]], the "Father of Nutrition and Chemistry" discovered the details of metabolism, demonstrating that the [[oxidation]] of food is the source of body heat. * 1790: [[George Fordyce]] recognized [[calcium]] as necessary for fowl survival. * Early 1800s: The elements [[carbon]], [[nitrogen]], [[hydrogen]] and [[oxygen]] were recognized as the primary components of food, and methods to measure their proportions were developed. * 1816: [[François Magendie]] discovers that dogs fed only [[carbohydrates]] and [[fat]] lost their body [[protein]] and died in a few weeks, but dogs also fed protein survived, identifying protein as an essential dietary component. * 1840: [[Justus Liebig]] discovers the chemical makeup of carbohydrates ([[sugar]]s), fats ([[fatty acid]]s) and proteins ([[amino acid]]s.) * 1860s: [[Claude Bernard]] discovers that body fat can be synthesized from carbohydrate and protein, showing that the energy in blood [[glucose]] can be stored as fat or as [[glycogen]]. * Early 1880s: [[Kanehiro Takaki]] observed that Japanese sailors (whose diets consisted almost entirely of white rice) developed [[beriberi]] (or endemic neuritis, a disease causing heart problems and paralysis) but British sailors and Japanese naval officers did not. Adding various types of vegetables and meats to the diets of Japanese sailors prevented the disease. * 1896: Baumann observed [[iodine]] in thyroid glands. * 1897: [[Christiaan Eijkman]] worked with natives of [[Java (island)|Java]], who also suffered from beriberi. Eijkman observed that chickens fed the native diet of white rice developed the symptoms of beriberi, but remained healthy when fed unprocessed brown rice with the outer bran intact. Eijkman cured the natives by feeding them brown rice, discovering that food can cure disease. Over two decades later, nutritionists learned that the outer rice bran contains vitamin B1, also known as [[thiamine]]. ===1900 through 1941=== * Early 1900s: [[Carl Von Voit]] and [[Max Rubner]] independently measure [[calorie|caloric]] energy expenditure in different species of animals, applying principles of physics in nutrition. * 1906: Wilcock and Hopkins showed that the amino acid [[tryptophan]] was necessary for the survival of rats. He fed them a special mixture of food containing all the nutrients he believed were essential for survival, but the rats died. A second group of rats to which he also fed fed an amount of milk contained something else, [[vitamins]] (from the Heinemann 2e Biology Activity Manual by Judith Brotherton and Kate Mundie). [[Gowland Hopkins]] recognized "accessory food factors" other than calories, protein and [[Dietary mineral|minerals]], as [[Organic compound|organic]] materials essential to health but which the body cannot synthesise. * 1907: [[Stephen M. Babcock]] and [[Edwin B. Hart]] conduct the [[single-grain experiment]]. This experiment runs through 1911. * 1912: [[Casimir Funk]] coined the term [[vitamin]], a vital factor in the diet, from the words "vital" and "amine," because these unknown substances preventing scurvy, beriberi, and [[pellagra]], were thought then to be derived from ammonia. * 1913: [[Elmer McCollum]] discovered the first vitamins, fat soluble [[vitamin A]], and water soluble [[vitamin B]] (in 1915; now known to be a complex of several water-soluble vitamins) and names [[vitamin C]] as the then-unknown substance preventing scurvy. [[Lafayette Mendel]] and Thomas Osborne also perform pioneering work on vitamin A and B. * 1919: Sir [[Edward Mellanby]] incorrectly identified [[rickets]] as a vitamin A deficiency, because he could cure it in dogs with cod liver oil.<ref>[http://www.beyonddiscovery.org/content/view.txt.asp?a=414 Unraveling the Enigma of Vitamin D] - a paper funded by the [[United States National Academy of Sciences]]</ref> * 1922: McCollum destroys the vitamin A in cod liver oil but finds it still cures rickets, naming [[vitamin D]] * 1922: H.M. Evans and L.S. Bishop discover [[Tocopherol|vitamin E]] as essential for rat pregnancy, originally calling it "food factor X" until 1925. * 1925: Hart discovers trace amounts of [[copper]] are necessary for [[iron]] absorption. * 1927: [[Adolf Otto Reinhold Windaus]] synthesizes vitamin D, for which he won the [[Nobel Prize]] in Chemistry in 1928. * 1928: [[Albert Szent-Györgyi]] isolates [[ascorbic acid]], and in 1932 proves that it is vitamin C by preventing scurvy. In 1935 he synthesizes it, and in 1937 he wins a Nobel Prize for his efforts. Szent-Györgyi concurrently elucidates much of the [[citric acid cycle]]. * 1930s: [[William Cumming Rose]] identifies [[essential amino acid]]s, necessary protein components which the body cannot synthesize. * 1935: Underwood and Marston independently discover the necessity of [[cobalt]]. * 1936: [[Eugene Floyd Dubois]] shows that work and school performance are related to caloric intake. * 1938: The chemical structure of vitamin E is discovered by [[Erhard Fernholz]], and it is synthesised by [[Paul Karrer]]. *1940 [[Rationing in the United Kingdom during and after World War II|UK institutes rationing]] according to nutritional principles drawn up by [[Elsie Widdowson]] and others * 1941: The first [[Recommended Dietary Allowance]]s (RDAs) were established by the [[United States National Research Council|National Research Council]]. ===Recent=== * 1992 The U.S. Department of Agriculture Introduces Food Guide Pyramid * 2002 [[Natural Justice|Study shows relation between nutrition and violent behavior]] * 2005 Obesity may be caused by [[adenovirus]] in addition to bad nutrition<ref>[http://news.bbc.co.uk/1/hi/health/854584.stm "Can a virus make you fat?"] at [[BBC News]]; [http://www.scienceblog.com/cms/contagious_obesity_identifying_the_human_adenoviruses_that_may_make_us_fat_9901 "Contagious obesity? Identifying the human adenoviruses that may make us fat"] at [[Science Blog]]</ref> == See also == : ''Main list: [[List of basic nutrition topics]]'' {| style="background-color: transparent; width: {{{width|100%}}}" | width="33%" align="{{{align|left}}}" valign="{{{valign|top}}}" | '''Biology:''' * [[Digestion]] * [[Enzyme]] ''' Dangers of poor nutrition''' * [[Deficiency]] **[[Avitaminosis]] is a deficiency of vitamins. **[[Boron deficiency (medicine)]] **[[Chromium deficiency]] **[[Iron deficiency (medicine)]] **[[Iodine deficiency]] **[[Magnesium deficiency (medicine)]] * [[Diabetes]] * [[Eating disorders]] * [[Illnesses related to poor nutrition]] * [[Malnutrition]] * [[Obesity]] ** [[Childhood obesity]] * [[Starvation]] '''[[Food]]:''' : ''[[Portal:Food|Food (portal)]]'' * [[5 A Day]] * [[Canada's Food Guide]] * [[Fast Food]] * [[Food groups]] * [[Food guide pyramid]] * [[Food supplements]] * [[Fruit]]s * [[Functional food]] * [[Grain]]s * [[Junk Food]] * [[Meat]] * [[Vegetable]]s | width="33%" align="{{{align|left}}}" valign="{{{valign|top}}}" | '''[[Healthy diet]]: ''' * [[Dieting]] * [[Eating]] * [[Healthy eating pyramid]] * [[Nutritional rating systems]] * [[Physicians Committee for Responsible Medicine]] (PCRM) * [[The China Study]] '''Lists:''' * [[List of diets|Diets (list)]] * [[List of food additives]] * [[List of illnesses related to poor nutrition]] * [[List of life extension related topics]] * [[List of publications in medicine#Nutrition|List of publications in nutrition]] * [[List of unrefined sweeteners]] '''[[Nutrient]]s:''' * [[Carbohydrate]]s * [[Dietary mineral]]s ** [[Essential mineral]]s * [[Dietary supplement]]s * [[Essential nutrient]]s * [[Fat]] ** [[Essential fatty acid]]s * [[Macronutrient]]s * [[Micronutrient]]s * [[Nootropic]]s * [[Nutraceutical]]s | width="50%" align="{{{align|left}}}" valign="{{{valign|top}}}" | * [[Phytochemicals]] * [[Protein]] ** [[Complete protein]] ** [[Essential amino acid]]s ** [[Protein combining|Incomplete protein]] ** [[Protein combining]] ** [[Protein in nutrition]] * [[Vitamin]]s ** [[Megavitamin therapy]] ** [[Vitamin C megadosage]] '''Profession:''' * [[Dietitian]] * [[Nutritionist]] '''Tools:''' * [[Nutrition scale]] '''Organizations:''' *[[American Dietetic Association]] *[http://www.nutrition.org American Society for Nutrition] *[[British Dietetic Association]] '''Related topics''' {{main|Health}} * [[Auxology]] * [[Exercise]] * [[General Fitness Training]] * [[Portal:Health|Health (portal)]] * [[Life extension]] * [[Orthomolecular medicine]] * [[Physical fitness]] |} == Further reading == *Galdston, I., ''Human Nutrition Historic and Scientific'' (New York: International Universities Press, 1960)<!-- LCCN RA 605 --> *Mahan, L.K. and Escott-Stump, S. eds. (2000) ''Krause's Food, Nutrition, and Diet Therapy.'' 10th ed. (Philadelphia: W.B. Saunders Harcourt Brace) * Thiollet, J-P, ''Vitamines & minéraux'' (Paris, Anagramme, 2001) *Walter C. Willett and Meir J. Stampfer. 2003. Rebuilding the Food Pyramid. ''Scientific American'' January 2003. ==References== {{reflist}} ==External links== * [http://www.who.int/nutrition/topics/dietnutrition_and_chronicdiseases/en/ Diet, Nutrition and the prevention of chronic diseases] by a Joint [[WHO]]/[[FAO]] Expert consultation (2003) * [http://www.nal.usda.gov/fnic/foodcomp/Bulletins/faq.html United States Department of Agriculture (USDA) Frequently asked questions] * [http://www.foodsec.org/DL/dlintro_en.asp Nutritional Status Assessment and Analysis - e-learning from FAO] === Databases and search engines === * [http://www.nutritiondata.com/ Nutrition Data] * [http://www.nal.usda.gov/fnic/foodcomp/search/ USDA National Nutrient Database for Standard Reference] Search By Food * [http://www.ars.usda.gov/Services/docs.htm?docid=13726 USDA National Nutrient Database for Standard Reference Nutrient Lists] Search By Nutrient === Governmental agencies and intergovernmental bodies === * [http://www.unsystem.org/scn/ UN Standing Committee on Nutrition] - In English, French and Portuguese {{portal|Food}} {{Food science}} {{Allied health professions}} [[Category:Applied sciences]] [[Category:Food science]] [[Category:Health]] [[Category:Health sciences]] [[Category:Nutrition| ]] [[Category:Self-care]] [[bg:Хранене]] [[ca:Nutrició]] [[de:Ernährung]] [[es:Nutrición]] [[eo:Nutrado]] [[fr:Nutrition]] [[fur:Nutrizion]] [[gl:Nutrición]] [[hr:Nutricionizam]] [[iu:ᓂᕿᑦᓯᐊᕙᓕᕆᓂᖅ]] [[it:Nutrizione]] [[he:תזונה]] [[lb:Ernierung]] [[nl:Voedingsleer]] [[ja:栄養学]] [[no:Ernæring]] [[pl:Dietetyka]] [[pt:Nutrição]] [[ru:Диетология]] [[sr:Исхрана]] [[fi:Ravinto]] [[sv:Näringslära]] [[th:โภชนาการ]] [[tr:Beslenme (biyoloji)]] [[zh:营养学]]