Nutrition

The “Nutrition Facts” table indicates the amounts of nutrients which experts recommend to limit or consume in adequate amounts.

Nutrition (also called nourishment or aliment) is the provision, to healthy diet.

The diet of an organism is what it eats, which is largely determined by the perceived palatability of foods. Dietitians are health professionals who specialize in human nutrition, meal planning, economics, and preparation. They are trained to provide safe, evidence-based dietary advice and management to individuals (in health and disease), as well as to institutions. Clinical nutritionists are health professionals who focus more specifically on the role of nutrition in chronic disease, including possible prevention or remediation by addressing nutritional deficiencies before resorting to drugs. While government regulation of the use of this professional title is less universal than for “dietician”, the field is supported by many high-level academic programs, up to and including the Doctoral level, and has its own voluntary certification board,[1] professional associations, and peer-reviewed journals, e.g. the American Society for Nutrition and the American Journal of Clinical Nutrition.

A poor diet may have an injurious impact on health, causing deficiency diseases such as [13]

Contents

[edit] Animal nutrition

[edit] Overview

Nutritional science investigates the metabolic pathways: the sequences of biochemical steps through which substances in living things change from one form to another.

carbon proportions being at varying levels in particular foods. Carnivores consume more nitrogen than carbon while herbivores consume less nitrogen than carbon, when an equal quantity is measured.

The human body and in the plant and animal organisms that humans eat.

The human body consists of elements and compounds ingested, digested, absorbed, and circulated through the feces.

Studies of nutritional status must take into account the state of the body before and after experiments, as well as the experiments 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 favorable for one’s health compared to monotonous diets based on processed foods.[16]

[edit] Nutrients

There are six major classes of nutrients: water.

These nutrient classes can be categorized as either fiber), fats, protein, and water. The micronutrients are minerals and vitamins.

The macronutrients (excluding fiber and water) provide structural material (amino acids from which proteins are built, and lipids from which cell membranes and some signaling molecules are built) and citation needed] for both mechanical and biochemical reasons, although the exact reasons remain unclear.

Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Carbohydrates range from simple essential in the sense that humans cannot make them internally. Some of the amino acids are convertible (with the expenditure of energy) to glucose and can be used for energy production, just as ordinary glucose, in a process known as gluconeogenesis. By breaking down existing protein, some glucose can be produced internally; the remaining amino acids are discarded, primarily as urea in urine. This occurs normally only during prolonged starvation.

Other micronutrients include phytochemicals, which are said to influence (or protect) some body systems. Their necessity is not as well established as in the case of, for instance, vitamins.

Most foods contain a mix of some or all of the nutrient classes, together with other substances, such as toxins of various sorts. Some nutrients can be stored internally (e.g., the fat soluble vitamins), while others are required more or less continuously. Poor health can be caused by a lack of required nutrients or, in extreme cases, too much of a required nutrient. For example, both salt and water (both absolutely required) will cause illness or even death in excessive amounts.[19]

[edit] Carbohydrates

Carbohydrates may be classified as monosaccharides, disaccharides, or polysaccharides depending on the number of monomer (sugar) units they contain. They constitute a large part of foods such as grain-based products. Monosaccharides, disaccharides, and polysaccharides contain one, two, and three or more sugar units, respectively. Polysaccharides are often referred to as complex carbohydrates because they are typically long, multiple branched chains of sugar units.

Traditionally, simple carbohydrates were believed to be absorbed quickly, and therefore to raise blood-glucose levels more rapidly than complex carbohydrates. This, however, is not accurate.[25]

[edit] Fiber

Dietary fiber is a carbohydrate (or a polysaccharide) that is incompletely absorbed in humans and in some animals. Like all carbohydrates, when it is metabolized it can produce four Calories (kilocalories) of energy per gram. However, in most circumstances it accounts for less than that because of its limited absorption and digestibility. Dietary fiber consists mainly of cellulose, a large carbohydrate polymer that is indigestible because humans do not have the required enzymes to disassemble it. There are two subcategories: soluble and insoluble fiber. Whole grains, fruits (especially plums, prunes, and figs), and vegetables are good sources of dietary fiber. There are many health benefits of a high-fiber diet. Dietary fiber helps reduce the chance of gastrointestinal problems such as constipation and diarrhea by increasing the weight and size of stool and softening it. Insoluble fiber, found in whole wheat flour, nuts and vegetables, especially stimulates peristalsis – the rhythmic muscular contractions of the intestines which move digesta along the digestive tract. Soluble fiber, found in oats, peas, beans, and many fruits, dissolves in water in the intestinal tract to produce a gel which slows the movement of food through the intestines. This may help lower blood glucose levels because it can slow the absorption of sugar. Additionally, fiber, perhaps especially that from whole grains, is thought to possibly help lessen insulin spikes, and therefore reduce the risk of type 2 diabetes. The link between increased fiber consumption and a decreased risk of colorectal cancer is still uncertain. [26]

[edit] Fat

A molecule of dietary fat typically consists of several punicic acid, in addition to providing energy, represent potent immune modulatory molecules.

Saturated fats (typically from animal sources) have been a staple in many world cultures for millennia. Unsaturated fats (e. g., vegetable oil) are considered healthier, while trans fats are to be avoided. Saturated and some trans fats are typically solid at room temperature (such as citation needed]

[edit] Essential fatty acids

Most fatty acids are non-essential, meaning the body can produce them as needed, generally from other fatty acids and always by expending energy to do so. However, in humans, at least two fatty acids are linoleic acid (LA) in the human 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 is one reason why a balance between omega-3 and omega-6 is believed important for cardiovascular health. In industrialized societies, people typically consume large amounts of processed vegetable oils, which have reduced amounts of the essential fatty acids along with too much of omega-6 fatty acids relative to omega-3 fatty acids.

The conversion rate of omega-6 DGLA to AA largely determines the production of the 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 mitosis (i.e. cell division).

[edit] Protein

Most essential amino acids needed for humans.

Proteins are the basis of many animal body structures (e.g. muscles, skin, and hair). They also form the enzymes that control chemical reactions throughout the body. Each molecule is composed of non-essential (the animal can produce them from other nitrogen-containing compounds). About twenty amino acids are found in the human body, and about ten of these are essential and, therefore, must be included in the diet. A diet that contains adequate amounts of amino acids (especially those that are essential) is particularly important in some situations: during early development and maturation, pregnancy, lactation, or injury (a burn, for instance). A complete protein source contains all the essential amino acids; an incomplete protein source lacks one or more of the essential amino acids.

It is possible to combine two incomplete protein sources (e.g. rice and beans) to make a complete protein source, and characteristic combinations are the basis of distinct cultural cooking traditions. However, complementary sources of protein don’t need to be eaten at the same meal to be used together by the body.[27] Sources of dietary protein include meats, tofu and other soy-products, eggs, legumes, and dairy products such as milk and cheese. Excess amino acids from protein can be converted into glucose and used for fuel through a process called gluconeogenesis. The amino acids remaining after such conversion are discarded.

[edit] Minerals

Dietary minerals are the goiter.

[edit] Macrominerals

Many elements are essential in relative quantity; they are usually called “bulk minerals”. Some are structural, but many play a role as electrolytes.[28] Elements with recommended dietary allowance (RDA) greater than 200 mg/day are, in alphabetical order (with informal or folk-medicine perspectives in parentheses):

  • Calcium, a common electrolyte, but also needed structurally (for muscle and digestive system health, bone strength, some forms neutralize acidity, may help clear toxins, provides signaling ions for nerve and membrane functions)
  • chloride ions; very common electrolyte; see sodium, below
  • ATP and related reactions (builds bone, causes strong peristalsis, increases flexibility, increases alkalinity)
  • Phosphorus, required component of bones; essential for energy processing[29]
  • Potassium, a very common electrolyte (heart and nerve health)
  • verification needed] leading to high blood pressure and osteoporosis.
  • Sulfur, for three essential amino acids and therefore many proteins (skin, hair, nails, liver, and pancreas). Sulfur is not consumed alone, but in the form of sulfur-containing amino acids
[edit] Trace minerals

Many elements are required in trace amounts, usually because they play a catalytic role in enzymes.[30] Some trace mineral elements (RDA < 200 mg/day) are, in alphabetical order:

[edit] Vitamins

As with the minerals discussed above, some vitamins are recognized as essential nutrients, necessary in the diet for good health. (above), and the minerals discussed in the preceding section.

Vitamin deficiencies may result in disease conditions, including goitre, scurvy, osteoporosis, impaired immune system, disorders of cell metabolism, certain forms of cancer, symptoms of premature aging, and poor psychological health (including eating disorders), among many others.[31] Excess levels of some vitamins are also dangerous to health (notably vitamin A), and for at least one vitamin, B6, toxicity begins at levels not far above the required amount. Deficient or excess levels of minerals can also have serious health consequences.

[edit] Water

A manual China

Water is excreted from the body in multiple forms; including water vapour in the exhaled breath. Therefore it is necessary to adequately rehydrate to replace lost fluids.

Early recommendations for the quantity of water required for maintenance of good health suggested that 6–8 glasses of water daily is the minimum to maintain proper hydration.[39]

The EFSA panel also determined intakes for different populations. Recommended intake volumes in the elderly are the same as for adults as despite lower energy consumption, the water requirement of this group is increased due to a reduction in renal concentrating capacity.[36]

For those who have healthy kidneys, it is somewhat difficult to drink too much water,[36]

[edit] Other nutrients

Other micronutrients include antioxidants and phytochemicals. These substances are generally more recent discoveries that have not yet been recognized as vitamins or as required. Phytochemicals may act as antioxidants, but not all phytochemicals are antioxidants.[citation needed]

[edit] Antioxidants

As cellular butterfly effect.

Although initial studies suggested that antioxidant supplements might promote health, later large [42]

[edit] Phytochemicals

A growing area of interest is the effect upon human health of trace chemicals, collectively called cardiovascular disease.

Perhaps the most rigorously tested phytochemical is better source needed] 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 carotenoid, 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,[45] neither a convincing mechanism for such protection nor a cause-and-effect have been rigorously studied. Similarly, a red phytochemical, lycopene, has substantial credible evidence of negative association with development of prostate cancer.

As indicated above, some of the correlations between the ingestion of certain phytochemicals and the prevention of disease are, in some cases, enormous in magnitude. Yet, 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.[46] 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:

Family Sources Possible benefits
Flavonoids tea General heart disease
phytoestrogens) kudzu root General antioxidant, prevention of arteriosclerosis and heart disease, easing symptoms of menopause, cancer prevention [47]
Isothiocyanates Cruciferous vegetables cancer prevention
Monoterpenes Citrus peels, essential oils, herbs, spices, green plants, atmosphere[48] gallstones
Organosulfur compounds onions cancer prevention, lowered LDLs, assistance to the immune system
Saponins herbs Hypercholesterolemia, Hyperglycemia, Antioxidant, cancer prevention, Anti-inflammatory
Capsaicinoids Chili peppers Topical pain relief, cancer prevention, cancer cell apoptosis

[edit] Intestinal bacterial flora

It is now also known that animal citation needed].

[edit] Advice and guidance

[edit] U.S. Government policies

The updated humans.

In the US, 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 established jointly by the 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.[49] Canada’s Food Guide is another governmental recommendation.

[edit] Government programs

Federal and state governmental organizations have been working on nutrition literacy interventions in non-primary health care settings to address the nutrition information problem in the U.S. Some programs include:

The Family Nutrition Program (FNP) is a free nutrition education program serving low-income adults around the U.S. This program is funded by the Food Nutrition Service’s (FNS) branch of the United States Department of Agriculture (USDA) usually through a local state academic institution which runs the program. The FNP has developed a series of tools to help families participating in the Food Stamp Program stretch their food dollar and form healthful eating habits including nutrition education.

Expanded Food and Nutrition Education Program (ENFEP) is a unique program that currently operates in all 50 states and in American Samoa, Guam, Micronesia, Northern Marianas, Puerto Rico, and the Virgin Islands. It is designed to assist limited-resource audiences in acquiring the knowledge, skills, attitudes, and changed behavior necessary for nutritionally sound diets, and to contribute to their personal development and the improvement of the total family diet and nutritional well-being.

An example of a state initiative to promote nutrition literacy is Smart Bodies, a public-private partnership between the state’s largest university system and largest health insurer, Louisiana State Agricultural Center and Blue Cross and Blue Shield of Louisiana Foundation. Launched in 2005, this program promotes lifelong healthful eating patterns and physically active lifestyles for children and their families. It is an interactive educational program designed to help prevent childhood obesity through classroom activities that teach children healthful eating habits and physical exercise.

[edit] Teaching

Nutrition is 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. In many schools a Nutrition class will fall within the Family and Consumer Science or Health departments. In some American schools, students are required to take a certain number of FCS or Health related classes. Nutrition is offered at many schools, and if it is not a class of its own, nutrition is included in other FCS or Health classes such as: Life Skills, Independent Living, Single Survival, Freshmen Connection, Health etc. In many Nutrition classes, students learn about the food groups, the food pyramid, Daily Recommended Allowances, calories, vitamins, minerals, malnutrition, physical activity, healthful food choices and how to live a healthy life.

A 1985 US [51]

[edit] Healthy diets

[edit] 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. arguments for and against this controversial issue.

The United Healthcare/Pacificare nutrition guideline recommends a whole plant food diet, and recommends using protein only as a condiment with meals. A Adventists, 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 Seventh-day Adventists 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.”

[edit] The French “paradox”

The French paradox is the observation that the French suffer a relatively low incidence of coronary heart disease, despite having a diet relatively rich in saturated fats. A number of explanations have been suggested:

  • Saturated fat consumption does not cause heart disease[53]
  • Reduced consumption of processed carbohydrate and other junk foods.[citation needed]
  • Regular consumption of red wine.[citation needed]
  • More active lifestyles involving plenty of daily exercise, especially walking; the French are much less dependent on cars than Americans are.[citation needed]
  • Higher consumption of artificially produced trans-fats by Americans, which has been shown to have greater lipoprotein effects per gram than saturated fat.[54]

However, statistics collected by the World Health Organization from 1990–2000 show that the incidence of heart disease in France may have been underestimated and, in fact, may be similar to that of neighboring countries.[55]

[edit] Sports nutrition

[edit] Protein

Protein milkshakes, made from protein powder (center) and milk (left), are a common bodybuilding supplement.

Protein is an important component of every cell in the body. Hair and nails are mostly made of protein. The body uses protein to build and repair tissues. In addition, protein is used to make hormones and other chemicals in the body. Protein is also an important building block of bones, muscles, cartilage, skin, and blood.

The protein requirement for each individual differs, as do opinions about whether and to what extent physically active people require more protein. The 2005 [57]

[edit] Water and salts

Water is one of the most important nutrients in the sports diet. It helps eliminate food waste products in the body, regulates body temperature during activity and helps with digestion. Maintaining hydration during periods of physical exertion is key to peak 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.[58] Additional carbohydrates and protein before, during, and after exercise increase time to exhaustion as well as speed recovery. The amount of water needed is based on work performed, lean body mass, and environmental factors, especially ambient temperature and humidity. Maintaining the right amount is key.[vague]

[edit] Carbohydrates

The main fuel used by the body during exercise is carbohydrates, which are 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.[citation needed] 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.

[edit] Nutrition literacy

At the time of this entry, we were not able to identify any specific nutrition literacy studies in the U.S. at a national level. However, the findings of the 2003 National Assessment of Adult Literacy (NAAL) provide a basis upon which to frame the nutrition literacy problem in the U.S. NAAL introduced the first ever measure of “the degree to which individuals have the capacity to obtain, process and understand basic health information and services needed to make appropriate health decisions,” – an objective of Healthy People 2010 [59] and of which nutrition literacy might be considered an important subset. On a scale of below basic, basic, intermediate and proficient, NAAL found 13 percent of adult Americans have proficient health literacy, 44% have intermediate literacy, 29 percent have basic literacy and 14 percent have below basic health literacy. The study found that health literacy increases with education and people living below the level of poverty have lower health literacy then those above it.

Another study examining the health and nutrition literacy status of residents of the lower Mississippi Delta found that 52 percent of participants had a high likelihood of limited literacy skills.[60] further delineating priorities for the region.

These statistics point to the complexities surrounding the lack of health/nutrition literacy and reveal the degree to which they are embedded in the social structure and interconnected with other problems. Among these problems are the lack of information about food choices, the lack of understanding nutritional information and its application to individual circumstances, limited or difficult access to healthful foods, and a range of cultural influences and socioeconomic constraints such as low levels of education and high levels of poverty that decrease opportunities for healthful eating and living.

The links between low health literacy and poor health outcomes has been widely documented[60] in order to achieve better health outcomes.

[edit] Malnutrition

Malnutrition refers to insufficient, excessive, or imbalanced consumption of nutrients by an organism. In developed countries, the diseases of malnutrition are most often associated with nutritional imbalances or excessive consumption.

Although there are more organisms in the world who are malnourished due to insufficient consumption, increasingly more organisms suffer from excessive over-nutrition; a problem caused by an over abundance of sustenance coupled with the instinctual desire (by animals in particular) to consume all that it can.

[64]

[edit] Insufficient

Under consumption generally refers to the long-term consumption of insufficient sustenance in relation to the energy that an organism expends or expels, leading to poor health.

[edit] Excessive

Over consumption generally refers to the long-term consumption of excess sustenance in relation to the energy that an organism expends or expels, leading to poor health and, in animals, obesity. It can cause excessive hair loss, brittle nails, and irregular premenstrual cycles for females

[edit] Unbalanced

When too much of one or more nutrients is present in the diet to the exclusion of the proper amount of other nutrients, the diet is said to be unbalanced.

[edit] Illnesses caused by improper nutrient consumption

Nutrients Deficiency Excess
Macronutrients
Calories marasmus cardiovascular disease
Simple carbohydrates None cardiovascular disease
Complex carbohydrates Micronutrient deficiency cardiovascular disease (high glycemic index foods)
Protein Kwashiorkor ketoacidosis (in diabetics)
Saturated fat None cardiovascular disease
Trans fat None cardiovascular disease
Unsaturated fat Fat-soluble vitamin deficiency cardiovascular disease
Micronutrients
Vitamin A night blindness Hypervitaminosis A (cirrhosis, hair loss)
Vitamin B1 Beri-Beri  ?
Vitamin B2 Skin and corneal lesions  ?
Niacin Pellagra cardiac arrhythmias, birth defects
Vitamin B12 Pernicious anemia  ?
Vitamin C Scurvy dehydration
Vitamin D Rickets Hypervitaminosis D (dehydration, vomiting, constipation)
Vitamin E Neurological disease Hypervitaminosis E (anticoagulant: excessive bleeding)
Vitamin K Hemorrhage  ?
Omega-3 fats Cardiovascular Disease Bleeding, Hemorrhages, Hemorrhagic stroke, reduced glycemic control among diabetics
Omega-6 fats None Cardiovascular Disease, Cancer
Cholesterol None Cardiovascular Disease
Macrominerals
Calcium cardiac arrhythmias kidney stones
Magnesium Hypertension Weakness, nausea, vomiting, impaired breathing, and hypotension
Potassium cardiac arrhythmias palpitations
Sodium Hyponatremia hypertension
Trace minerals
Iron Anemia heart disease
Iodine hypothyroidism Iodine toxicity (goiter, hypothyroidism)

[edit] Mental agility

Research indicates that improving the awareness of nutritious meal choices and establishing long-term habits of healthful eating have a positive effect on 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.[69]

“Better learning performance is associated with diet induced effects on learning and memory ability”.[70]
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.”[71]
91% of college students feel that they are in good health while only 7% eat their recommended daily allowance of fruits and vegetables.[66]
Nutritional education is an effective and workable model in a higher education setting.[73]
More “engaged” learning models that encompass nutrition is an idea that is picking up steam at all levels of the learning cycle.[74]

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 that overall intellectual health is closely linked to a person’s diet, rather than just another correlation fallacy.

[edit] Mental disorders

Nutritional supplement treatment may be appropriate for major depression, bipolar disorder, schizophrenia, and obsessive compulsive disorder, the four most common mental disorders in developed countries.[75] Supplements that have been studied most for mood elevation and stabilization include eicosapentaenoic acid and docosahexaenoic acid (each of which are an omega-3 fatty acid contained in fish oil, but not in flaxseed oil), vitamin B12, folic acid, and inositol.

[edit] Cancer

Cancer is now common in developing countries. According to a study by the [76]

[edit] 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 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— 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—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 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).

[edit] 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.[77] 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.

[edit] Antinutrient

Antinutrients are natural or synthetic compounds that interfere with the absorption of nutrients. Nutrition studies focus on antinutrients commonly found in food sources and beverages.

[edit] Processed foods

Since the salting, and separation of various components, all of which 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 concentration 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 concentration 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.[78] 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, fiber, 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 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.

[edit] History

Humans have evolved as omnivorous hunter-gatherers 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.[79]

Agriculture developed about 10,000 years ago in multiple locations throughout the world, providing grains such as wheat, rice, potatoes, and maize, with staples such as bread, pasta, and tortillas. 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.[80]

[edit] From antiquity to 1900

Anaxagoras

Around 475 BC, [81]

In the 16th century, scientist and artist vitamin C within lime juice would not be identified by scientists until the 1930s.

Around 1770, oxygen were recognized as the primary components of food, and methods to measure their proportions were developed.

In 1816, glycogen.

In the early 1880s, 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.

In 1896, Eugen Baumann observed thiamine.

[edit] From 1900 to the present

Frederick Hopkins, discoverer of vitamins and Nobel Laureate

In the early 20th century, Carl Von Voit and Max Rubner independently measured caloric energy expenditure in different species of animals, applying principles of physics in nutrition. In 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 were fed an amount of milk containing vitamins.[82] Sir Frederick Hopkins recognized “accessory food factors” other than calories, protein and minerals, as organic materials essential to health, but which the body cannot synthesize. In 1907, Stephen M. Babcock and Edwin B. Hart conducted the single-grain experiment, which took nearly four years to complete.

In 1912, pellagra, were thought then to be derived from ammonia. The vitamins were studied in the first half of the 20th century.

In 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 named vitamin C as the then-unknown substance preventing scurvy. Lafayette Mendel and Thomas Osborne also performed pioneering work on vitamins A and B. In 1919, Sir Edward Mellanby incorrectly identified rickets as a vitamin A deficiency because he could cure it in dogs with cod liver oil.[83] In 1922, Elmer McCollum destroyed the vitamin A in cod liver oil, but found that it still cured rickets. Also in 1922, H.M. Evans and L.S. Bishop discover vitamin E as essential for rat pregnancy, originally calling it “food factor X” until 1925.

In 1925, Hart discovered that trace amounts of citric acid cycle.

In the 1930s, Paul Karrer.

In 1940, National Research Council.

In 1992, The U.S. Department of Agriculture introduced the Food Guide Pyramid. In 2002, a Natural Justice study showed a relation between nutrition and violent behavior[citation needed]. In 2005, a study found that obesity may be caused by adenovirus in addition to bad nutrition.[84]

World leaders are looking at alternatives like genetically modified foods to tackle the problem of world hunger and food shortages.[85]

[edit] Plant nutrition

Plant nutrition is the study of the metabolism. However, this principle does not account for the so-called beneficial elements, whose presence, while not required, has clear positive effects on plant growth.

A nutrient that is able to limit plant growth according to Liebig’s law of the minimum, is considered an essential plant nutrient if the plant cannot complete its full life cycle without it. There are 17 essential plant nutrients.

Macronutrients:

Micronutrients (trace levels) include:

[edit] Macronutrients

Calcium

Calcium regulates transport of other nutrients into the plant and is also involved in the activation of certain plant enzymes. Calcium deficiency results in stunting.

Nitrogen

Nitrogen is an essential component of all proteins. Nitrogen deficiency most often results in stunted growth.

Phosphorus

Phosphorus is important in plant seed formation.

Potassium

Potassium regulates the opening and closing of the Potassium deficiency may cause necrosis or interveinal chlorosis.

Silicon

Silicon is deposited in elasticity

[edit] Micronutrients

Boron

Boron is important in sugar transport, Boron deficiency causes necrosis in young leaves and stunting.

Copper

Copper is important for photosynthesis. Symptoms for copper deficiency include chlorosis. Involved in many enzyme processes. Necessary for proper photosythesis. Involved in the manufacture of lignin (cell walls). Involved in grain production.

Chlorine

Chlorine is necessary for photosynthesis.

Iron

Iron is necessary for photosynthesis and is present as an enzyme cofactor in plants. necrosis.

Manganese

Manganese is necessary for building the foliage.

Molybdenum

Molybdenum is a cofactor to enzymes important in building amino acids.

Nickel

In citation needed]

Sodium

Sodium is involved in the regeneration of C4 plants. It can also substitute for potassium in some circumstances.

Zinc

Zinc is required in a large number of enzymes and plays an essential role in auxin.

[edit] Processes

Plants uptake essential elements from the oxygen. The carbon dioxide molecules are used as the carbon source in photosynthesis.

Although nitrogen is plentiful in the Earth’s atmosphere, very few plants can use this directly. Most plants therefore require nitrogen compounds to be present in the soil in which they grow. This is made possible by largely inert atmospheric nitrogen being changed in a nitrogen fixation process to biologically usable forms in the soil by bacteria.[86]

Plant nutrition is a difficult subject to understand completely, partially because of the variation between different plants and even between different species or individuals of a given clone. Elements present at low levels may cause deficiency symptoms, and toxicity is possible at levels that are too high. Furthermore, deficiency of one element may present as symptoms of toxicity from another element, and vice-versa.

[edit] See also

Balanced Eating:

Biology:

Dangers of poor nutrition

Food:

Food (portal)

Healthy diet:

Lists:

Nutrients:

Profession:

Tools:

Organizations:

Related topics

[edit] References

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[edit] Further reading

  • Curley, S., and Mark (1990). The Natural Guide to Good Health, Lafayette, Louisiana, Supreme Publishing
  • Galdston, I. (1960). Human Nutrition Historic and Scientific. New York: International Universities Press.
  • Mahan, L.K. and Escott-Stump, S. eds. (2000). Krause’s Food, Nutrition, and Diet Therapy (10th ed.). Philadelphia: W.B. Saunders Harcourt Brace. ISBN 0-7216-7904-8.
  • Thiollet, J.-P. (2001). Vitamines & minéraux. Paris: Anagramme.
  • Walter C. Willett and Meir J. Stampfer (January 2003). “Rebuilding the Food Pyramid”. Scientific American 288 (1): 64–71. doi:10.1038/scientificamerican0103-64. PMID 12506426.

[edit] External links

[edit] Databases and search engines



Source: Wikipedia