Disorder of consciousness

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Disorder_of_consciousness

Disorders of consciousness are medical conditions that inhibit consciousness. Some define disorders of consciousness as any change from complete self-awareness to inhibited or absent self-awareness and arousal. This category generally includes minimally conscious state and persistent vegetative state, but sometimes also includes the less severe locked-in syndrome and more severe but rare chronic coma. Differential diagnosis of these disorders is an active area of biomedical research. Finally, brain death results in an irreversible disruption of consciousness. While other conditions may cause a moderate deterioration (e.g., dementia and delirium) or transient interruption (e.g., grand mal and petit mal seizures) of consciousness, they are not included in this category.

Classification

Patients in such a dramatically altered state of consciousness present unique problems for diagnosis, prognosis and treatment. Assessment of cognitive functions remaining after a traumatic brain injury is difficult. Voluntary movements may be very small, inconsistent and easily exhausted. Quantification of brain activity differentiates patients who sometimes only differ by a brief and small movement of a finger.

Consciousness is a complex and multifaceted concept, divided into two main components: Arousal and Awareness. Arousal is associated with functional brainstem neuron populations projecting to both thalamic and cortical neurons. Therefore, the assessment of reflexes (Using the Glasgow Coma Scale) is important to investigate the functional integrity of the brainstem. Awareness is thought to be related with functional integrity of the cerebral cortex and its subcortical connections. The most important point regarding the classification of disorders of consciousness is, that consciousness cannot be measured objectively by any machine, although many scoring systems have been developed for the quantification of consciousness and neuroimaging techniques are important tools for clinical research, extending our understanding of underlying mechanisms involved. Disorders in consciousness represent immense social and ethical issues because the diagnosis is methodologically complex and needs careful interpretation. Also the ethical framework must be further developed to guide research in these patients.

Locked-in syndrome

Main article: Locked-in syndrome

In locked-in syndrome the patient has awareness, sleep-wake cycles, and meaningful behavior (viz., eye-movement), but is isolated due to quadriplegia and pseudobulbar palsy, resulting from the disruption of corticospinal and corticobulbar pathways. Locked-in syndrome is a condition in which a patient is aware and awake but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles in the body except for the eyes. Eye or eyelid movements are the main method of communication. Total locked-in syndrome is a version of locked-in syndrome where the eyes are paralyzed as well.

Minimally conscious state

Main article: Minimally conscious state

In a minimally conscious state, the patient has intermittent periods of awareness and wakefulness. The criteria for minimally conscious state, that patients are not in a vegetative state but are not able to communicate consistently. This means, that patients have to show limited but reproducible signs of awareness of themself or their environment. This could be following of simple commands, intelligible speech or purposeful behavior (including movements or affective behavior in relation to external stimuli, but not reflexive activity). Further improvement towards full conscious recovery is more likely in this state than in the vegetative state, but still some patients remain in the MCS constantly.

Persistent vegetative state

Main article: Persistent vegetative state

In a persistent vegetative state, the patient has sleep-wake cycles, but lacks awareness, is not able to communicate and only displays reflexive and non-purposeful behavior. The term refers to an organic body that is able to grow and develop devoid of intellectual activity or social intercourse. The diagnosis of the vegetative state should be questioned when there is any degree of sustained and reproducible visual pursuit or fixation or response to threatening gestures. This state reflects an intact brainstem and allied structures but severely damaged white and gray matter in both cerebral hemispheres. The preservation of these structures maintains arousal and automatic functions. The overall metabolism drops in average to 40-50% of the normal range. After four weeks in a vegetative state (VS), the patient is classified as in a persistent vegetative state. Here the metabolism drops to 30-40% of the normal range but seems to be a result of trans-synaptic neuronal degeneration. Although the diagnosis is problematic, the formal absence of any sign of conscious perception or deliberate action is essential. This diagnosis can be further classified as a permanent vegetative state (PVS) after approximately 1 year of being in a vegetative state after traumatic brain injury

Chronic coma

Main article: Chronic coma

Like coma, chronic coma results mostly from cortical or white-matter damage after neuronal or axonal injury, or from focal brainstem lesions. Usually the metabolism in the grey matter decreases to 50-70% of the normal range. The patient lacks awareness and arousal. The patient lies with eyes closed and is not aware of self or surroundings. Stimulation cannot produce spontaneous periods of wakefulness and eye-opening, unlike patients in vegetative state. In medicine, a coma (from the Greek κῶμα koma, meaning deep sleep) is a state of unconsciousness, lasting more than six hours in which a person cannot be awakened, fails to respond normally to painful stimuli, light, sound, lacks a normal sleep-wake cycle and does not initiate voluntary actions. Although, according to the Glasgow Coma Scale, a person with confusion is considered to be in the mildest coma. But cerebral metabolism has been shown to correlate poorly with the level of consciousness in patients with mild to severe injury within the first month after traumatic brain injury (TBI). A person in a state of coma is described as comatose. In general patients surviving a coma recover gradually within 2–4 weeks. But recovery to full awareness and arousal is not always possible. Some patients do not progress further than vegetative state or minimally conscious state and sometimes this also results in prolonged stages before further recovery to complete consciousness.

Although a coma patient may appear to be awake, they are unable to consciously feel, speak, hear, or move. For a patient to maintain consciousness, two important neurological components must function impeccably. The first is the cerebral cortex which is the gray matter covering the outer layer of the brain. The other is a structure located in the brainstem, called reticular activating system (RAS or ARAS). Injury to either or both of these components is sufficient to cause a patient to experience a coma.

Brain death

Main article: Brain death

Brain death is the irreversible end of all brain activity, and function (including involuntary activity necessary to sustain life). The main cause is total necrosis of the cerebral neurons following loss of brain oxygenation. After brain death the patient lacks any sense of awareness; sleep-wake cycles or behavior, and typically look as if they are dead or are in a deep sleep-state or coma. Although visually similar to a comatose state such as persistent vegetative state, the two should not be confused. Criteria for brain death differ from country to country. However, the clinical assessments are the same and require the loss of all brainstem reflexes and the demonstration of continuing apnea in a persistently comatose patient (< 4 weeks). Functional imaging using PET or CT scans, typically show a hollow skull phenomenon. This confirms the absence of neuronal function in the whole brain. Patients classified as brain dead are legally dead and can qualify as organ donors, in which their organs are surgically removed and prepared for a particular recipient.

Brain death is one of the deciding factors when pronouncing a trauma patient as dead. Determining function and presence of necrosis after trauma to the whole brain or brain-stem may be used to determine brain death, and is used in many states in the US.

Methodological problems

Metabolic studies are useful, but they are not able to identify neural activity within a specific region to specific cognitive processes. Functionality can only be identified at the most general level: Metabolism in cortical and subcortical regions that may contribute to cognitive processes.

At present, there is no established relation between cerebral metabolic rates of glucose or oxygen as measured by PET and patient outcome. The decrease of cerebral metabolism occurs also when patients are treated with anesthetics to the point of unresponsiveness. Lowest value (28% of normal range) have been reported during propofol anesthesia. Also, deep sleep represents a phase of decreased metabolism (down to 40% of the normal range) In general, quantitative PET studies and the assessment of cerebral metabolic rates depends on many assumptions. PET, for example, requires a correction factor, the lumped constant, which is stable in healthy brains. There are reports that a global decrease of this constant emerges after a traumatic brain injury. But, not only the correction factors change due to TBI. Another issue is the possibility of anaerobic glycolysis that could occur after TBI. In such a case, the glucose levels measured by the PET are not tightly connected to the oxygen consumption of the patient's brain. Third point regarding PET scans is the overall measurement per unit volume of brain tissue. The imaging can be affected by the inclusion of metabolically inactive spaces e.g. cerebrospinal fluid in the case of gross hydrocephalus, which artificially lowers the calculated metabolism. Also, the issue of radiation exposure must be considered in patients with already severely damaged brains and preclude longitudinal or follow-up studies.

Ethical issues

Disorders of consciousness present a variety of ethical concerns. Most obvious is the lack of consent in any treatment decisions. Patients in PVS or MCS are not able to decide for the possibility of withdrawal of life-support. It is also a general question whether they should receive life-sustaining therapy and, if so, for what duration. The problems regarding a patient's consent also account for neuroimaging studies. Without patient's consent, such studies are perceived as unethical. Additionally, only few patients have created advance directives before losing decision-making capacity. Typically, approval must be obtained from family or legal representatives depending on governmental and hospital guidelines but, even with the consent of representatives, researchers have been refused grants, ethics committee approval and publication.

Social issues arise from the enormous costs associated with people who have disorders of consciousness, especially chronic comatose and vegetative patients, when recovery is highly unlikely and treatment in the ICU is considered futile by clinicians. In addition to the aforementioned problems, the question rises why medical resources were being used not for the broader public good but for patients who seemed to have only little to gain from them. Nevertheless, the irreversibility of these conditions remains an open question. Some studies demonstrated that some patients with disorders of consciousness may be aware despite clinical unresponsiveness. These findings could have a major impact on ethical and social issues.

Altered level of consciousness

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Altered_level_of_consciousness

 

Altered level of consciousness
An intracranial hemorrhage, one cause of altered level of consciousness

An altered level of consciousness is any measure of arousal other than normal. Level of consciousness (LOC) is a measurement of a person's arousability and responsiveness to stimuli from the environment. A mildly depressed level of consciousness or alertness may be classed as lethargy; someone in this state can be aroused with little difficulty. People who are obtunded have a more depressed level of consciousness and cannot be fully aroused. Those who are not able to be aroused from a sleep-like state are said to be stuporous. Coma is the inability to make any purposeful response. Scales such as the Glasgow coma scale have been designed to measure the level of consciousness.

An altered level of consciousness can result from a variety of factors, including alterations in the chemical environment of the brain (e.g. exposure to poisons or intoxicants), insufficient oxygen or blood flow in the brain, and excessive pressure within the skull. Prolonged unconsciousness is understood to be a sign of a medical emergency. A deficit in the level of consciousness suggests that both of the cerebral hemispheres or the reticular activating system have been injured. A decreased level of consciousness correlates to increased morbidity (sickness) and mortality (death). Thus it is a valuable measure of a patient's medical and neurological status. In fact, some sources consider level of consciousness to be one of the vital signs.

Definition

Scales and terms to classify the levels of consciousness differ, but in general, reduction in response to stimuli indicates an altered level of consciousness:

Levels of consciousness

Level	Summary (Kruse)	Description
Metaconscious	Preternatural	People who possess the ability to monitor and control their own cognitive processes in addition to meeting all the criteria indicative of a normal level of consciousness. In the field of cognitive neuroscience, metacognitive monitoring and control have been viewed as functions of the prefrontal cortex, which receives sensory input signals from divergent cortical regions and implements control through feedback loops which are established utilizing the underlying mechanisms of neuroplasticity (see chapters by Schwartz & Bacon and Shimamura, in Dunlosky & Bjork, 2008).
Conscious	Normal	Assessment of LOC involves checking orientation: people who are able promptly and spontaneously to state their name, location, and the date or time are said to be oriented to self, place, and time, or "oriented X3". A normal sleep stage from which a person is easily awakened is also considered a normal level of consciousness. "Clouding of consciousness" is a term for a mild alteration of consciousness with alterations in attention and wakefulness.
Confused	Disoriented; impaired thinking and responses	People who do not respond quickly with information about their name, location, and the time are considered "obtuse" or "confused". A confused person may be bewildered, disoriented, and have difficulty following instructions. The person may have slow thinking and possible memory time loss. This could be caused by sleep deprivation, malnutrition, allergies, environmental pollution, drugs (prescription and nonprescription), and infection.
Delirious	Disoriented; restlessness, hallucinations, sometimes delusions	Some scales have "delirious" below this level, in which a person may be restless or agitated and exhibit a marked deficit in attention.
Somnolent	Sleepy	A somnolent person shows excessive drowsiness and responds to stimuli only with incoherent mumbles or disorganized movements.
Obtunded	Decreased alertness; slowed psychomotor responses	In obtundation, a person has a decreased interest in their surroundings, slowed responses, and sleepiness.
Stuporous	Sleep-like state (not unconscious); little/no spontaneous activity	People with an even lower level of consciousness, stupor, only respond by grimacing or drawing away from painful stimuli.
Comatose	Cannot be aroused; no response to stimuli	Comatose people do not even make this response to stimuli, have no corneal or gag reflex, and they may have no pupillary response to light.

Altered level of consciousness is sometimes described as altered sensorium.

Glasgow Coma Scale

Main article: Glasgow Coma Scale

The most commonly used tool for measuring LOC objectively is the Glasgow Coma Scale (GCS). It has come into almost universal use for assessing people with brain injury, or an altered level of consciousness. Verbal, motor, and eye-opening responses to stimuli are measured, scored, and added into a final score on a scale of 3–15, with a lower score being a more decreased level of consciousness.

Others

The AVPU scale is another means of measuring LOC: people are assessed to determine whether they are alert, responsive to verbal stimuli, responsive to painful stimuli, or unresponsive. To determine responsiveness to voice, a caregiver speaks to, or, failing that, yells at the person. Responsiveness to pain is determined with a mild painful stimulus such as a pinch; moaning or withdrawal from the stimulus is considered a response to pain. The ACDU scale, like AVPU, is easier to use than the GCS and produces similarly accurate results. Using ACDU, a patient is assessed for alertness, confusion, drowsiness, and unresponsiveness.

The Grady Coma Scale classes people on a scale of I to V along a scale of confusion, stupor, deep stupor, abnormal posturing, and coma.

Pathophysiology

Although the neural science behind alertness, wakefulness, and arousal are not fully known, the reticular formation is known to play a role in these. The ascending reticular activating system is a postulated group of neural connections that receives sensory input and projects to the cerebral cortex through the midbrain and thalamus from the reticular formation. Since this system is thought to modulate wakefulness and sleep, interference with it, such as injury, illness, or metabolic disturbances, could alter the level of consciousness.

Normally, stupor and coma are produced by interference with the brain stem, such as can be caused by a lesion or indirect effects, such as brain herniation. Mass lesions in the brain stem normally cause coma due to their effects on the reticular formation. Mass lesions that occur above the tentorium cerebelli normally do not significantly alter the level of consciousness unless they are very large or affect both cerebral hemispheres.

Diagnosis

Assessing LOC involves determining an individual's response to external stimuli. Speed and accuracy of responses to questions and reactions to stimuli such as touch and pain are noted. Reflexes, such as the cough and gag reflexes, are also means of judging LOC. Once the level of consciousness is determined, clinicians seek clues for the cause of any alteration. Usually the first tests in the ER are pulse oximetry to determine if there is hypoxia, serum glucose levels to rule out hypoglycemia. A urine drug screen may be sent. A CT head is very important to obtain to rule out bleed. In cases where meningitis is suspected, a lumbar puncture must be performed. A serum TSH is an important test to order. In select groups consider vitamin B12 levels. Checking serum ammonia is particularly advised in neonatal coma to discern inborn errors of metabolism.

Differential diagnosis

A lowered level of consciousness indicate a deficit in brain function. Level of consciousness can be lowered when the brain receives insufficient oxygen (as occurs in hypoxia); insufficient blood (as occurs in shock, in children for example due to intussusception); or has an alteration in the brain's chemistry. Conditions of the heart and conditions of the lungs can alter consciousness. Metabolic disorders such as diabetes mellitus and uremia can alter consciousness. Hypo- or hypernatremia (decreased and elevated levels of sodium, respectively) as well as dehydration can also produce an altered LOC. A pH outside of the range the brain can tolerate will also alter LOC. Exposure to drugs (e.g. alcohol) or toxins may also lower LOC, as may a core temperature that is too high or too low (hyperthermia or hypothermia). Increases in intracranial pressure (the pressure within the skull) can also cause altered LOC. It can result from traumatic brain injury such as concussion. Ischemic stroke and brain bleeding are other causes of altered consciousness. Infections of the central nervous system may also be associated with decreased LOC; for example, an altered LOC is the most common symptom of encephalitis. Neoplasms within the intracranial cavity can also affect consciousness, as can epilepsy and post-seizure states. A decreased LOC can also result from a combination of factors. A concussion, which is a mild traumatic brain injury (MTBI) may result in decreased LOC.

Treatment

Treatment depends on the degree of decrease in consciousness and its underlying cause. Initial treatment often involves the administration of dextrose if the blood sugar is low as well as the administration of oxygen, naloxone and thiamine.

Food pyramid (nutrition)

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Food_pyramid_(nutrition) 

The USDA's original food pyramid, from 1992 to 2005

A food pyramid is a representation of the optimal number of servings to be eaten each day from each of the basic food groups. The first pyramid was published in Sweden in 1974. The 1992 pyramid introduced by the United States Department of Agriculture (USDA) was called the "Food Guide Pyramid" or "Eating Right Pyramid". It was updated in 2005 to "MyPyramid", and then it was replaced by "MyPlate" in 2011.

Swedish origin

The "Basic Seven" developed by the United States Department of Agriculture

Amid high food prices in 1972, Sweden's National Board of Health and Welfare developed the idea of "basic foods" that were both cheap and nutritious, and "supplemental foods" that added nutrition missing from the basic foods. Anna-Britt Agnsäter, chief of the test kitchen for Kooperativa Förbundet (a cooperative Swedish retail chain), held a lecture the next year on how to illustrate these food groups. Attendee Fjalar Clemes suggested a triangle displaying basic foods at the base. Agnsäter developed the idea into the first food pyramid, which was introduced to the public in 1974 in KF's Vi magazine. The pyramid was divided into basic foods at the base, including milk, cheese, margarine, bread, cereals and potato; a large section of supplemental vegetables and fruit; and an apex of supplemental meat, fish and egg. The pyramid competed with the National Board's "dietary circle", which KF saw as problematic for resembling a cake divided into seven slices, and for not indicating how much of each food should be eaten. While the Board distanced itself from the pyramid, KF continued to promote it.

Food pyramids were developed in other Scandinavian countries, as well as West Germany, Japan and Sri Lanka. The United States later developed its first food pyramid in 1992.

Food pyramid published by the WHO and FAO

The World Health Organization, in conjunction with the Food and Agriculture Organization, published guidelines that can be effectively represented in a food pyramid relating to objectives in order to prevent obesity, improper nutrition, chronic diseases and dental caries based on meta-analysis though they represent it as a table rather than as a "pyramid". The structure is similar in some respects to the USDA food pyramid, but there are clear distinctions between types of fats, and a more dramatic distinction where carbohydrates are categorized on the basis of free sugars versus sugars in their natural form. Some food substances are singled out due to the impact on the target issues that the "pyramid" is meant to address. In a later revision, however, some recommendations are omitted as they automatically follow other recommendations while other sub-categories are added. The reports quoted here explain that where there is no stated lower limit in the table below, there is no requirement for that nutrient in the diet.

A "simplified" representation of the "Food Pyramid" from the 2002 Joint WHO/FAO Expert Consultation recommendations

Dietary factor	1989 WHO Study Group recommendations	2002 Joint WHO/FAO Expert Consultation recommendations
Total fat	15–30%	15–30%
Saturated fatty acids (SFAs)	0–10%	<10%
Polyunsaturated fatty acids (PUFAs)	3–7%	6–10%
n-6 PUFAs		5–8%
n-3 PUFAs		1–2%
Trans fatty acids		<1%
Monounsaturated fatty acids (MUFAs)		By difference
Total carbohydrate	55–75%	55–75%
Free sugars	0–10%	<10%
Complex carbohydrate	50–70%	No recommendation
Protein	10–15%	10–15%
Cholesterol	0–300 mg/day	< 300 mg/day
Sodium chloride (Sodium)	< 6 g/day	< 5 g/day (< 2 g/day)
Fruits and vegetables	≥ 400 g/day	≥ 400 g/day
Pulses, nuts and seeds	≥ 30 g/day (as part of the 400 g of fruit and vegetables)
Total dietary fiber	27–40 g/day	From foods
Non-starch polysaccharide (NSP)	16–24 g/day	From foods

All percentages are percentages of calories, not of weight or volume. To understand why, consider the determination of an amount of "10% free sugar" to include in a day's worth of calories. For the same amount of calories, free sugars take up less volume and weight, being refined and extracted from the competing carbohydrates in their natural form. In a similar manner, all the items are in competition for various categories of calories.

The representation as a pyramid is not precise, and involves variations due to the alternative percentages of different elements, but the main sections can be represented.

USDA food pyramid

History

Main article: History of USDA nutrition guides

The USDA's food pyramid from 2005 to 2011, MyPyramid

The USDA food pyramid was created in 1992 and divided into six horizontal sections containing depictions of foods from each section's food group. It was updated in 2005 with black and white vertical wedges replacing the horizontal sections and renamed MyPyramid. MyPyramid was often displayed with the food images absent, creating a more abstract design. In an effort to restructure food nutrition guidelines, the USDA rolled out its new MyPlate program in June 2011. My Plate is divided into four slightly different sized quadrants, with fruits and vegetables taking up half the space, and grains and protein making up the other half. The vegetables and grains portions are the largest of the four.

A modified food pyramid was proposed in 1999 for adults aged over 70.

Vegetables

A vegetable is a part of a plant consumed by humans that is generally savory but is not sweet. A vegetable is not considered a grain, fruit, nut, spice, or herb. For example, the stem, root, flower, etc., may be eaten as vegetables. Vegetables contain many vitamins and minerals; however, different vegetables contain different balances of micronutrients, so it is important to eat a wide variety of types. For example, orange and dark green vegetables typically contain vitamin A, dark green vegetables contain vitamin C, and vegetables like broccoli and related plants contain iron and calcium. Vegetables are very low in fats and calories, but ingredients added in preparation can often add them.

Grains

These foods provide complex carbohydrates, which are a good source of energy and provide much nutrition when unrefined. Examples include corn, wheat, pasta, and rice.

Fruits

In terms of food (rather than botany), fruits are the sweet-tasting seed-bearing parts of plants, or occasionally sweet parts of plants which do not bear seeds. These include apples, oranges, grapes, bananas, etc. Fruits are low in calories and fat and are a source of natural sugars, fiber and vitamins. Processing fruit when canning or making into juices may add sugars and remove nutrients. The fruit food group is sometimes combined with the vegetable food group. Note that a massive number of different plant species produce seed pods which are considered fruits in botany, and there are a number of botanical fruits which are conventionally not considered fruits in cuisine because they lack the characteristic sweet taste, e.g., tomatoes or avocados.

Dairy

Dairy products are produced from the milk of mammals, usually but not exclusively cattle. They include milk, yogurt and cheese. Milk and its derivative products are a rich source of dietary calcium and also provide protein, phosphorus, vitamin A, and vitamin D. However, many dairy products are high in saturated fat and cholesterol compared to vegetables, fruits and whole grains, which is why skimmed products are available as an alternative. Historically, adults were recommended to consume three cups of dairy products per day. More recently, evidence is mounting that dairy products have greater levels of negative effects on health than previously thought and confer fewer benefits. For example, recent research has shown that dairy products are not related to stronger bones or less fractures; on the contrary, another study showed that milk (and yogurt) consumption results in higher bone mineral density in the hip. Overall, the majority of research suggests that dairy has some beneficial effects on bone health, in part because of milk's other nutrients.

Meat and beans

Meat is the tissue—usually muscle—of an animal consumed by humans. Since most parts of many animals are edible, there is a vast variety of meats. Meat is a major source of protein, as well as iron, zinc, and vitamin B12. The category of meats, poultry, and fish include beef, chicken, pork, salmon, tuna, shrimp, and eggs.

The meat group is one of the major compacted food groups in the food guide pyramid. Since many of the same nutrients found in meat can also be found in foods like eggs, dry beans, and nuts, such foods are typically placed in the same category as meats, as meat alternatives. These include tofu, products that resemble meat or fish but are made with soy, eggs, and cheeses. For those who do not consume meat or animal products (see Vegetarianism, veganism and Taboo food and drink), meat analogs, tofu, beans, lentils, chickpeas, nuts and other high-protein vegetables are also included in this group. The food guide pyramid suggests that adults eat 2–3 servings per day. One serving of meat is 4 oz (110 g), about the size of a deck of cards.

Oils and sweets

A food pyramid's tip is the smallest part, so the fats and sweets in the top of the Food Pyramid should comprise the smallest percentage of the diet. The foods at the top of the food pyramid should be eaten sparingly because they provide calories, but not much in the way of nutrition. These foods include salad dressings, oils, cream, butter, margarine, sugars, soft drinks, candies, and sweet desserts. On the 1992–2005 pyramid, the fat circle and sugar triangle are scattered throughout the pyramid to represent the naturally-occurring fats and sugars in various foods. The idea of this is to reduce the temptation to eat so much junk food and excessive fats and sugars, as there is already enough fat and sugar in the rest of the diet. For example, the triangles in the Fruit Group represent the fact that sugar is inevitable in that group.

Criticism and controversy

USDA food pyramid

Inside the pyramid

Certain dietary choices that have been linked to heart disease, such as an 8 oz (230 g) serving of hamburger daily, were technically permitted under the pyramid. The pyramid also lacked differentiation within the protein-rich group ("Meat, Poultry, Fish, Dry Beans, Eggs, and Nuts"). The development of the US food pyramid has been influenced by food lobbyists undermining its credibility.

In April 1991, the U.S. Department of Agriculture (USDA) halted publication of its Eating Right Pyramid, due to objections raised by meat and dairy lobbying groups concerning the guide’s display of their products. Despite the USDA’s explanations that the guide required further research and testing, it was not until one year later—after its content was supported by additional research—that the Eating Right Pyramid was officially released. This time, even the guide’s graphic design was altered to appease industry concerns. This incident was only one of many in which the food industry attempted to alter federal dietary recommendations in their own economic self-interest.

Some of the recommended quantities for the different types of food in the old pyramid have also come under criticism for lack of clarity. For instance, the pyramid recommends two to three servings from the protein-rich group, but this is intended to be a maximum. The pyramid recommends two to four fruit servings, but this is intended to be the minimum.

The fats group as a whole have been put at the tip of the pyramid, under the direction to eat as little as possible, which some people have considered problematic. The guide instructs people to limit fat intake as much as possible, which can cause health problems because fat is essential to overall health. Research suggests that unsaturated fats aid in weight loss, reduce heart disease risk, lower blood sugar, and even lower cholesterol. Also, they are very long sustaining, and help keep blood sugar at a steady level. On top of that, these fats help brain function as well.

Several researchers have said that food and agricultural associations exert undue political power on the USDA. Food industries, such as milk companies, have been accused of influencing the United States Department of Agriculture into making the colored spots on the newly created food pyramid larger for their particular product. The milk section has been described as the easiest to see out of the six sections of the pyramid, making individuals believe that more milk should be consumed on a daily basis compared to the others. Furthermore, the inclusion of milk as a group unto itself implies that is an essential part of a healthy diet, despite the many people who are lactose intolerant or choose to abstain from dairy, and a number of cultures that have historically consumed little if any dairy products. Joel Fuhrman says in his book Eat to Live that U.S. taxpayers must contribute $20 billion on price supports to artificially reduce the price of cattle feed to benefit the dairy, beef and veal industries, and then pay the medical bills for an overweight population. He asks if the USDA is under the influence of the food industry, because a food pyramid based on science would have vegetables at its foundation.

These controversies prompted the creation of pyramids for specific audiences, including a Vegetarian Diet Pyramid.

The successor to the Food Pyramid called MyPlate has also received numerous criticisms, but unlike the Food Pyramid, which was very well known, the MyPlate program has yet to become publicly well known, with as many as "3 out of 4 Americans [having] no idea what the government's MyPlate dietary guide [even] is."

MyPlate

Main article: MyPlate

The MyPlate food guide icon

MyPlate is the current nutrition guide published by the United States Department of Agriculture, depicting a place setting with a plate and glass divided into five food groups. It replaced the USDA's MyPyramid guide on June 2, 2011, concluding 19 years of USDA food pyramid diagrams.

Healthy diet

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Healthy_diet

Some healthy foods including beans, grains, cauliflower, cantaloupe, pasta, bread, orange, turkey, fish, carrots, turnips, zucchini, snowpeas, string beans, radishes, asparagus, summer squash, lean beef, tomatoes, and potatoes

A healthy diet is a diet that maintains or improves overall health. A healthy diet provides the body with essential nutrition: fluid, macronutrients such as protein, micronutrients such as vitamins, and adequate fibre and food energy.

A healthy diet may contain fruits, vegetables, and whole grains, and may include little to no ultra-processed foods or sweetened beverages. The requirements for a healthy diet can be met from a variety of plant-based and animal-based foods, although additional sources of vitamin B12 are needed for those following a vegan diet. Various nutrition guides are published by medical and governmental institutions to educate individuals on what they should be eating to be healthy. Nutrition facts labels are also mandatory in some countries to allow consumers to choose between foods based on the components relevant to health.

Recommendations

World Health Organization

The World Health Organization (WHO) makes the following five recommendations with respect to both populations and individuals:

1. Maintain a healthy weight by eating roughly the same number of calories that your body is using.
2. Limit intake of fats to no more than 30% of total caloric intake, preferring unsaturated fats to saturated fats. Avoid trans fats.
3. Eat at least 400 grams of fruits and vegetables per day (not counting potatoes, sweet potatoes, cassava, and other starchy roots). A healthy diet also contains legumes (e.g. lentils, beans), whole grains, and nuts.
4. Limit the intake of simple sugars to less than 10% of caloric intake (below 5% of calories or 25 grams may be even better).
5. Limit salt/sodium from all sources and ensure that salt is iodized. Less than 5 grams of salt per day can reduce the risk of cardiovascular disease.

The WHO has stated that insufficient vegetables and fruit is the cause of 2.8% of deaths worldwide.

Other WHO recommendations include:

• ensuring that the foods chosen have sufficient vitamins and certain minerals;
• avoiding directly poisonous (e.g. heavy metals) and carcinogenic (e.g. benzene) substances;
• avoiding foods contaminated by human pathogens (e.g. E. coli, tapeworm eggs);
• and replacing saturated fats with polyunsaturated fats in the diet, which can reduce the risk of coronary artery disease and diabetes.

United States Department of Agriculture

Main article: History of USDA nutrition guides

Main article: MyPlate

The Dietary Guidelines for Americans by the United States Department of Agriculture (USDA) recommends three healthy patterns of diet, summarized in the table below, for a 2000 kcal diet. These guidelines are increasingly adopted by various groups and institutions for recipe and meal plan development.

The guidelines emphasize both health and environmental sustainability and a flexible approach. The committee that drafted it wrote: "The major findings regarding sustainable diets were that a diet higher in plant-based foods, such as vegetables, fruits, whole grains, legumes, nuts, and seeds, and lower in calories and animal-based foods is more health promoting and is associated with less environmental impact than is the current U.S. diet. This pattern of eating can be achieved through a variety of dietary patterns, including the "Healthy U.S.-style Pattern", the "Healthy Vegetarian Pattern" and the "Healthy Mediterranean-style Pattern". Food group amounts are per day, unless noted per week.

The three healthy patterns

Food group/subgroup (units)	U.S. style	Vegetarian	Med-style
Fruits (cup eq)	2	2	2.5
Vegetables (cup eq)	2.5	2.5	2.5
Dark green	1.5/wk	1.5/wk	1.5/wk
Red/orange	5.5/wk	5.5/wk	5.5/wk
Starchy	5/wk	5/wk	5/wk
Legumes	1.5/wk	3/wk	1.5/wk
Others	4/wk	4/wk	4/wk
Grains (oz eq)	6	6.5	6
Whole	3	3.5	3
Refined	3	3	3
Dairy (cup eq)	3	3	2
Protein Foods (oz eq)	5.5	3.5	6.5
Meat (red and processed)	12.5/wk	–	12.5/wk
Poultry	10.5/wk	–	10.5/wk
Seafood	8/wk	–	15/wk
Eggs	3/wk	3/wk	3/wk
Nuts/seeds	4/wk	7/wk	4/wk
Processed Soy (including tofu)	0.5/wk	8/wk	0.5/wk
Oils (grams)	27	27	27
Solid fats limit (grams)	18	21	17
Added sugars limit (grams)	30	36	29

American Heart Association / World Cancer Research Fund / American Institute for Cancer Research

The American Heart Association, World Cancer Research Fund, and American Institute for Cancer Research recommend a diet that consists mostly of unprocessed plant foods, with emphasis on a wide range of whole grains, legumes, and non-starchy vegetables and fruits. This healthy diet includes a wide range of non-starchy vegetables and fruits which provide different colors including red, green, yellow, white, purple, and orange. The recommendations note that tomato cooked with oil, allium vegetables like garlic, and cruciferous vegetables like cauliflower, provide some protection against cancer. This healthy diet is low in energy density, which may protect against weight gain and associated diseases. Finally, limiting consumption of sugary drinks, limiting energy-rich foods, including "fast foods" and red meat, and avoiding processed meats improves health and longevity. Overall, researchers and medical policymakers conclude that this healthy diet can reduce the risk of chronic disease and cancer.

It is recommended that children consume 25 grams or less of added sugar (100 calories) per day. Other recommendations include no extra sugars in those under two years old and less than one soft drink per week. As of 2017, decreasing total fat is no longer recommended, but instead, the recommendation to lower risk of cardiovascular disease is to increase consumption of monounsaturated fats and polyunsaturated fats, while decreasing consumption of saturated fats.

Harvard School of Public Health

The Nutrition Source of Harvard School of Public Health (HSPH) makes the following dietary recommendations:

• Eat healthy fats: healthy fats are necessary and beneficial for health. HSPH "recommends the opposite of the low-fat message promoted for decades by the USDA" and "does not set a maximum on the percentage of calories people should get each day from healthy sources of fat." Healthy fats include polyunsaturated and monounsaturated fats, found in vegetable oils, nuts, seeds, and fish. Foods containing trans fats are to be avoided, while foods high in saturated fats like red meat, butter, cheese, ice cream, coconut and palm oil negatively impact health and should be limited.
• Eat healthy protein: the majority of protein should come from plant sources when possible: lentils, beans, nuts, seeds, whole grains; avoid processed meats like bacon.
• Eat mostly vegetables, fruit, and whole grains.
• Drink water. Consume sugary beverages, juices, and milk only in moderation. Artificially sweetened beverages contribute to weight gain because sweet drinks cause cravings. 100% fruit juice is high in calories. The ideal amount of milk and calcium is not known today.
• Pay attention to salt intake from commercially prepared foods: most of the dietary salt comes from processed foods, "not from salt added to cooking at home or even from salt added at the table before eating."
• Vitamins and minerals: must be obtained from food because they are not produced in our body. They are provided by a diet containing healthy fats, healthy protein, vegetables, fruit, milk and whole grains.
• Pay attention to the carbohydrates package: the type of carbohydrates in the diet is more important than the amount of carbohydrates. Good sources for carbohydrates are vegetables, fruits, beans, and whole grains. Avoid sugared sodas, 100% fruit juice, artificially sweetened drinks, and other highly processed food.

Other than nutrition, the guide recommends staying active and maintaining a healthy body weight.

Others

David L. Katz, who reviewed the most prevalent popular diets in 2014, noted:

The weight of evidence strongly supports a theme of healthful eating while allowing for variations on that theme. A diet of minimally processed foods close to nature, predominantly plants, is decisively associated with health promotion and disease prevention and is consistent with the salient components of seemingly distinct dietary approaches. Efforts to improve public health through diet are forestalled not for want of knowledge about the optimal feeding of Homo sapiens but for distractions associated with exaggerated claims, and our failure to convert what we reliably know into what we routinely do. Knowledge in this case is not, as of yet, power; would that it were so.

Marion Nestle expresses the mainstream view among scientists who study nutrition:

The basic principles of good diets are so simple that I can summarize them in just ten words: eat less, move more, eat lots of fruits and vegetables. For additional clarification, a five-word modifier helps: go easy on junk foods. Follow these precepts and you will go a long way toward preventing the major diseases of our overfed society—coronary heart disease, certain cancers, diabetes, stroke, osteoporosis, and a host of others.... These precepts constitute the bottom line of what seem to be the far more complicated dietary recommendations of many health organizations and national and international governments—the forty-one "key recommendations" of the 2005 Dietary Guidelines, for example. ... Although you may feel as though advice about nutrition is constantly changing, the basic ideas behind my four precepts have not changed in half a century. And they leave plenty of room for enjoying the pleasures of food.

Historically, a healthy diet was defined as a diet comprising more than 55% of carbohydrates, less than 30% of fat and about 15% of proteins. This view is currently shifting towards a more comprehensive framing of dietary needs as a global need of various nutrients with complex interactions, instead of per nutrient type needs.

Specific conditions

Diabetes

A healthy diet in combination with being active can help those with diabetes keep their blood sugar in check. The US CDC advises individuals with diabetes to plan for regular, balanced meals and to include more nonstarchy vegetables, reduce added sugars and refined grains, and focus on whole foods instead of highly processed foods. Generally, people with diabetes and those at risk are encouraged to increase their fiber intake.

Hypertension

A low-sodium diet is beneficial for people with high blood pressure. A 2008 Cochrane review concluded that a long-term (more than four weeks) low-sodium diet lowers blood pressure, both in people with hypertension (high blood pressure) and in those with normal blood pressure.

The DASH diet (Dietary Approaches to Stop Hypertension) is a diet promoted by the National Heart, Lung, and Blood Institute (part of the NIH, a United States government organization) to control hypertension. A major feature of the plan is limiting intake of sodium, and the diet also generally encourages the consumption of nuts, whole grains, fish, poultry, fruits, and vegetables while lowering the consumption of red meats, sweets, and sugar. It is also "rich in potassium, magnesium, and calcium, as well as protein".

The Mediterranean diet, which includes limiting consumption of red meat and using olive oil in cooking, has also been shown to improve cardiovascular outcomes.

Obesity

Further information: Dieting

Healthy diets in combination with physical exercise can be used by people who are overweight or obese to lose weight, although this approach is not by itself an effective long-term treatment for obesity and is primarily effective for only a short period (up to one year), after which some of the weight is typically regained. A meta-analysis found no difference between diet types (low-fat, low-carbohydrate, and low-calorie), with a 2–4 kilograms (4.4–8.8 lb) weight loss. This level of weight loss is by itself insufficient to move a person from an 'obese' body mass index (BMI) category to a 'normal' BMI.

Gluten-related disorders

Further information: Gluten-free diet

Gluten, a mixture of proteins found in wheat and related grains including barley, rye, oat, and all their species and hybrids (such as spelt, kamut, and triticale), causes health problems for those with gluten-related disorders, including celiac disease, non-celiac gluten sensitivity, gluten ataxia, dermatitis herpetiformis, and wheat allergy. In these people, the gluten-free diet is the only available treatment.

Epilepsy

Further information: Ketogenic diet

The ketogenic diet is a treatment to reduce epileptic seizures for adults and children when managed by a health care team.

Research

Further information: Diet and cancer

Preliminary research indicated that a diet high in fruit and vegetables may decrease the risk of cardiovascular disease and death, but not cancer. Eating a healthy diet and getting enough exercise can maintain body weight within the normal range and reduce the risk of obesity in most people. A 2021 scientific review of evidence on diets for lowering the risk of atherosclerosis found that:

low consumption of salt and foods of animal origin, and increased intake of plant-based foods—whole grains, fruits, vegetables, legumes, and nuts—are linked with reduced atherosclerosis risk. The same applies for the replacement of butter and other animal/tropical fats with olive oil and other unsaturated-fat-rich oil. [...] With regard to meat, new evidence differentiates processed and red meat—both associated with increased CVD risk—from poultry, showing a neutral relationship with CVD for moderate intakes. [...] New data endorse the replacement of most high glycemic index (GI) foods with both whole grain and low GI cereal foods.

Scientific research is also investigating impacts of nutrition on health- and lifespans beyond any specific range of diseases.

Research suggests that increasing adherence to Mediterranean diet patterns is associated with a reduction in total and cause-specific mortality, extending health- and lifespan. Research is identifying the key beneficial components of the Mediterranean diet. Studies suggest dietary changes are a factor of national relative rises in life-span. Moreover, not only do the components of diets matter but the total caloric content and eating patterns may also impact health – dietary restriction such as caloric restriction is considered to be potentially healthy to include in eating patterns in various ways in terms of health- and lifespan.

Unhealthy diets

An unhealthy diet is a major risk factor for a number of chronic diseases including: high blood pressure, high cholesterol, diabetes, abnormal blood lipids, overweight/obesity, cardiovascular diseases, and cancer. The World Health Organization has estimated that 2.7 million deaths each year are attributable to a diet low in fruit and vegetables during the 21st century. Globally, such diets are estimated to cause about 19% of gastrointestinal cancer, 31% of ischaemic heart disease, and 11% of strokes, thus making it one of the leading preventable causes of death worldwide, and the 4th leading risk factor for any disease. As an example, the Western pattern diet is "rich in red meat, dairy products, processed and artificially sweetened foods, and salt, with minimal intake of fruits, vegetables, fish, legumes, and whole grains," contrasted by the Mediterranean diet which is associated with less morbidity and mortality.

Dietary patterns that lead to non-communicable diseases generate productivity losses. A true cost accounting (TCA) assessment on the hidden impacts of agrifood systems estimated that unhealthy dietary patterns generate more than USD 9 trillion in health-related hidden costs in 2020, which is 73 percent of the total quantified hidden costs of global agrifood systems (USD 12.7 trillion). Globally, the average productivity losses per person from dietary intake is equivalent to 7 percent of GDP purchasing power parity (PPP) in 2020; low-income countries report the lowest value (4 percent), while other income categories report 7 percent or higher.

Fad diet

Further information: Fad diet

Some publicized diets, often referred to as fad diets, make exaggerated claims of fast weight loss or other health advantages, such as longer life or detoxification without clinical evidence; many fad diets are based on highly restrictive or unusual food choices. Celebrity endorsements (including celebrity doctors) are frequently associated with such diets, and the individuals who develop and promote these programs often profit considerably.

Public health

Most of the people unable to afford a healthy diet in 2021 lived in southern Asia, and in eastern and western Africa

Consumers are generally aware of the elements of a healthy diet, but find nutrition labels and diet advice in popular media confusing.

Vending machines are criticized for being avenues of entry into schools for junk food promoters, but there is little in the way of regulation and it is difficult for most people to properly analyze the real merits of a company referring to itself as "healthy." The Committee of Advertising Practice in the United Kingdom launched a proposal to limit media advertising for food and soft drink products high in fat, salt, or sugar. The British Heart Foundation released its own government-funded advertisements, labeled "Food4Thought", which were targeted at children and adults to discourage unhealthy habits of consuming junk food.

From a psychological and cultural perspective, a healthier diet may be difficult to achieve for people with poor eating habits. This may be due to tastes acquired in childhood and preferences for sugary, salty, and fatty foods. In 2018, the UK chief medical officer recommended that sugar and salt be taxed to discourage consumption. The UK government 2020 Obesity Strategy encourages healthier choices by restricting point-of-sale promotions of less-healthy foods and drinks.

The effectiveness of population-level health interventions has included food pricing strategies, mass media campaigns and worksite wellness programs. One peso per liter of sugar-sweetened beverages (SSB) price intervention implemented in Mexico produced a 12% reduction in SSB purchasing. Mass media campaigns in Pakistan and the USA aimed at increasing vegetable and fruit consumption found positive changes in dietary behavior. Reviews of the effectiveness of worksite wellness interventions found evidence linking the programs to weight loss and increased fruit and vegetable consumption.

Other animals

Animals that are kept by humans also benefit from a healthy diet, but the requirements of such diets may be very different from the ideal human diet.