iDeficiency Disease

A deficiency disease is a condition that develops when the body is deficient in vital nutrients or dietary components like vitamins and minerals. A person's overall health depends on a balanced diet. Any dietary imbalance could lead to either an over or underconsumption of a specific nutrient. An absence of a particular nutrient can lead to a deficiency illness. A vitamin or mineral deficiency can result in an illness called a deficiency disease. The goal of a balanced diet is to give the body all the nutrients it needs. It includes micronutrients like vitamins and minerals as well as macronutrients like protein, carbs, and fat. Consequently, deficiency diseases can be avoided by eating a balanced diet.

Examples of diseases caused by deficiencies include beriberi from a vitamin B₁ deficiency and anaemia from a body deficient in iron.

Nutritional Illness

Nutritional disease, any of the illnesses and ailments that are nutrient-related and cause illness in people. They could include dietary excesses or deficiencies, obesity, eating disorders, and chronic conditions like cancer, cardiovascular disease, high blood pressure, and diabetes mellitus. Additional nutritional diseases include dietary-preventable developmental abnormalities, genetic metabolic conditions that can be treated with diet, the interaction of foods and nutrients with medications, food allergies and intolerances, and potential food supply dangers. This article provides descriptions of each of these categories.

Deficits in Nutrients

The focus of this article will be on the deficiency disease, such as heart disease, stroke, cancer, and diabetes, but chronic undernutrition, which affects more than 925 million people globally, is the most important disease related to nutrition. Weight loss, failure to thrive, and the wasting away of body fat and muscle are the main symptoms of undernutrition, a condition in which there is not enough food to meet energy requirements. One of the many effects of chronic persistent hunger, which affects persons living in poverty in both industrialised and developing nations, is reduced mental function and greater susceptibility to disease. Other effects include low birth weight in infants, inadequate growth and development in children, and impaired growth and development. Asia has the highest prevalence of chronic hunger, but sub-Saharan Africa has the worst starvation conditions. Around 20,000 individuals, mostly children, died from preventable diseases connected to undernutrition every day at the beginning of the twenty-first century. Many of these children's fatalities are caused by their moms' poor nutritional status and the limited opportunities brought on by poverty.

Starvation because of severe food shortages only accounts for a small portion of mortality related to hunger. For instance, throughout the 1990s, natural disasters like droughts and floods were less common causes of global hunger (epidemic collapse of the food supply) than complicated social and political difficulties and the effects of conflict.

Malnutrition is the impairment of function brought on by a sustained lack of total energy or a surplus of nutrients like protein, vital fatty acids, vitamins, or minerals. Fasting, anorexia nervosa, recurrent vomiting (as in bulimia nervosa), difficulty swallowing, impaired digestion and intestinal malabsorption, or long-term conditions that cause loss of appetite (such cancer or AIDS) can all cause this syndrome. Malnutrition can also be caused by a lack of food options, poor eating decisions, or dietary supplement use that is excessive.

Energy-Protein Malnutrition

Protein-Energy Malnutrition (PEM), the most prevalent type of malnutrition worldwide, is the primary symptom of chronic undernutrition. PEM, also referred to as protein-calorie malnutrition, is a continuum in which individuals-often children-consume insufficient amounts of protein, calories, or both. The extremes of the continuum include marasmus, which is complete food deprivation with grossly insufficient levels of both energy and protein, and kwashiorkor, which is characterised by a severe protein deficit.

Marasmus causes a baby to be severely underweight and to have lost most or all of their subcutaneous fat. The child's body has a "skin and bones" appearance, and they are extremely fragile and prone to illnesses. The culprit is a diet that is extremely low in calories across the board (including protein), frequently starting with early weaning to bottled formula made with tainted water. Poor cleanliness and ongoing depletion cause a vicious cycle of gastroenteritis and gastrointestinal tract lining degradation, which obstructs nutritional absorption from the scant food supply and further lowers resistance to infection. Marasmus may lead to death from malnutrition or heart failure if left untreated.

When a child is transitioned from high-protein breast milk to a carbohydrate food source with insufficient protein, they frequently develop the sickness known as Kwashiorkor, which is a Ghanaian term for the illness that the first child contracts when the new child is born. Children with this condition, which is characterised by edoema (fluid retention) in the abdomen, are frail, grow slowly, and are more prone to infectious illnesses, which can cause deadly diarrhoea. Apathy, hair darkening, and dry, peeling skin with sores that do not heal are some more signs of kwashiorkor. Edoema, an enlarged fatty liver, and intestinal parasites can all mask weight loss, and there might not be any wastage of body fat and muscle.

Kwashiorkor and marasmus can also happen to hospitalised patients receiving intravenous glucose for a prolonged period of time, such as when recovering from surgery, or to people who have conditions that cause them to lose their appetite or have nutrient malabsorption. People who suffer from eating disorders, cancer, AIDS, and other conditions that impair nutrient absorption or cause appetite loss may lose muscle and organ tissue in addition to fat reserves.

There are three parts to PEM treatment:

1. It is necessary to treat life-threatening illnesses, such as infections and fluid and electrolyte imbalances.
2. Nutritional status should be recovered as fast and safely as feasible; within one or two weeks, a starved kid may have rapid weight gain.
3. The emphasis of treatment then switches to ensuring long-term nutritional recovery.

The degree of malnutrition, the promptness of therapy, and the appropriateness of continuous assistance all influence how quickly and well patients recover. Starvation has the potential to decrease brain development and intellectual performance, especially during the first year of life, and these effects may not entirely recover.

Carbohydrates

In most cases, there is no specific amount of carbohydrates that must be consumed daily, including simple sugars, complex carbohydrates like starches, and the indigestible plant carbohydrates known as dietary fibre. The simple carbohydrate glucose is necessary as fuel for several cells, including brain cells. Glucose synthesis depends on the breakdown of amino acids derived from body and dietary protein as well as the chemical glycerol, which is derived from fat, if dietary carbohydrates are insufficient. Long-term carbohydrate insufficiency leads to an increase in the creation of organic chemicals known as ketones (a state known as ketosis), which gives the breath a unique sweet aroma.

The daily consumption of 50 to 100 grammes of carbohydrates can prevent ketosis and other undesirable effects of a very-low-carbohydrate diet; however, it is advised and typical of human diets to obtain at least half of the daily energy from carbohydrates, or at least 250 grammes of carbohydrates (1,000 calories in a 2,000-calorie diet). Intake of dietary fibre is also provided through a diversified diet that includes fruits, vegetables, legumes, and whole-grain cereals, all of which are high in carbs.

Fatty Acids

Additionally, there is a minimal requirement for fat, but only for the omega-3 and omega-6 fatty acids alpha-linolenic acid and linoleic acid, not for total fat. In hospitalised patients given only intravenous fluids devoid of fat for weeks, in patients with illnesses that interfere with fat absorption, in babies given low-fat formula, and in young children given non-fat milk or low-fat diets, deficiencies of these two fatty acids have been seen. Dry skin, hair loss, and sluggish wound healing are all signs of a shortage. You can get the few grammes of essential fatty acids you need each day by eating around a tablespoon of polyunsaturated plant oils every day. Omega-3 fatty acids are also abundant in fatty fish. Even those who adopt a low-fat diet typically eat enough fat to suit their needs.

Vitamins

Although diseases caused by vitamin insufficiency have been described in humans and experimental animals, in the human experience, numerous deficiencies are typically present at once. A lack of one of the eight B-complex vitamins may influence the functioning of other B-complex vitamins since they work in concert in many enzyme systems and metabolic pathways.

1. Vitamin A

In the developing world, particularly in Africa and Southeast Asia, vitamin A deficiency is a major concern. In the world's poorest nations, hundreds of thousands of children lose their vision each year as a result of a vitamin A deficit. A shortage of any severity can weaken the immune system, lowering disease resistance. A vitamin A deficiency's early symptoms include night blindness, abnormal eye dryness, and eventually scarring of the cornea (a disorder known as xerophthalmia). Dry skin, hardening of epithelial cells in other parts of the body (including mucous membranes), and impeded growth and development are other signs. Giving children a single, big dosage of vitamin A every six months is reducing the incidence of vitamin A insufficiency in many places where it is endemic. The usage of this so-called golden rice is debatable, but it has the potential to significantly lower the incidence of vitamin A insufficiency because it contains beta-carotene, a precursor to vitamin A.

2. Vitamin D

Without sufficient food sources of vitamin D, a deficiency of the vitamin can happen when exposure to sunlight is restricted. Vitamin D (also known as vitamin D hormone) is synthesised in the body in a series of steps, beginning in the skin by the action of sunlight's ultraviolet rays on a precursor compound. Rickets, a condition marked by poor bone mineralization, development retardation, and skeletal abnormalities like bowed legs, is brought on by a lack of vitamin D in youngsters. Osteomalacia, the adult variant of rickets, causes weak bones as well as weak muscles. A lack of vitamin D may potentially be a factor in the osteoporosis-related bone weakening. People at risk for vitamin D insufficiency include those with dark skin, especially those who reside in northern latitudes, those with minimal sun exposure (including ladies who entirely cover their bodies for religious reasons), the elderly or homebound, and those who are homebound or have dark skin. Since vitamin D is not naturally present in many foods, fortifying milk and other foods with the vitamin-such as margarine, cereals, and breads-has helped safeguard people that do not receive enough sun exposure. The aged, who produce and activate vitamin D less effectively even when exposed to sunshine, may benefit from additional vitamin D as a means of preventing bone fractures.

3. Vitamin E

Although vitamin E insufficiency is uncommon in people, it can occur in preterm infants and those who have poor fat metabolism or absorption. Hemolysis, or the fragility of red blood cells, is apparent in the former; in the latter, where shortage is more severe, neuromuscular dysfunction involving the spinal cord and retina may cause reflex loss, unsteadiness, and sluggishness of the muscles, as well as visual abnormalities. Vitamin E doesn't appear to have a specific metabolic function, but it is a crucial component of the antioxidant system that prevents lipid peroxidation, guarding cells, and their membranes from the harmful effects of free radicals (also known as reactive oxygen and nitrogen species), which are produced metabolically or come into the body from the environment. As consumption of polyunsaturated fatty acids rises, so does the need for vitamin E. To guard against oxidative damage to the lungs, people who smoke or are exposed to air pollution may also require additional vitamin.

4. Vitamin K

Both bone metabolism and the production of prothrombin and other blood-clotting components in the liver depend on vitamin K. Bacteria in the colon create a version of the vitamin that can be partially utilised. Even in the absence of injury, a vitamin K shortage impairs blood coagulation and results in internal bleeding. In affluent nations, new-borns typically receive vitamin K intramuscularly or orally within six hours of delivery to prevent a condition known as newborn haemorrhagic illness due to inadequate transport of the vitamin across the placenta. Adults rarely suffer from vitamin K shortage, except for syndromes characterised by poor fat absorption, liver disease, or while taking certain anticoagulant medications that affect vitamin K metabolism. Patients with antibiotic-killed gut flora may experience bleeding from vitamin K insufficiency.

5. Thiamine

Beriberi is a disease that has been endemic in areas where white rice has been the main food source and is caused by a protracted thiamine (vitamin B1) deficiency. In locations where white rice or wheat make up the majority of the diet and thiamine lost during milling is not replenished through enrichment, thiamine insufficiency is still a problem. Loss of appetite, mental symptoms such as confusion and other mental symptoms, sore calf muscles, muscle weakness, poor coordination, tingling, and paralysis are signs of the dry form of beriberi. Edoema and the potential for an enlarged heart and heart failure are both present in wet beriberi. In communities that consume a lot of raw fish and have gut microorganisms that produce the thiaminase enzyme, thiamine insufficiency can also arise. Wernicke-Korsakoff syndrome, a disorder characterised by rapid eye movements, lack of muscle coordination, mental confusion, and memory loss, is a symptom of thiamine insufficiency that is largely associated in the developed world with prolonged drinking and poor food.

6. Riboflavin

Without concurrent nutritional shortage, riboflavin (vitamin B₂) deficiency, also known as ariboflavinosis, is unlikely. An inflamed, magenta-coloured tongue and skin splits at the corners of the mouth are signs of prolonged riboflavin deficiency after several months. Riboflavin is given to jaundiced newborns receiving light therapy since the vitamin is easily damaged by ultraviolet radiation. The main dietary sources of riboflavin, milk, milk products, and cereals, are packed to shield them from light.

7. Niacin

Pellagra symptoms start to appear about two months after niacin is removed from the diet. Diarrhoea, dermatitis, and dementia are the three symptoms that define pellagra, and if it is allowed to worsen untreated, death will result. Pellagra, which affects people who eat mostly maize, was widespread in parts of the southern United States in the early 1900s and is still present in some areas of India, China, and Africa. Most of the niacin found in maize and other cereal grains is bound and so poorly absorbed. Niacin that has been bonded to maize is released by soaking it in lime water, a method that Native American populations have used for generations to prevent pellagra. Additionally, unlike other grains, maize has little tryptophan, an amino acid that can be partially converted to niacin. Even if niacin intake is insufficient, tryptophan-rich high-quality protein in the diet can guard against niacin insufficiency.

8. Vitamin B₆

The body requires vitamin B₆ (pyridoxine and related substances) for several vital processes, including the creation of neurotransmitters and the metabolism of proteins. Dermatitis, microcytic hypochromic anaemia (tiny, pale red blood cells), immune system impairment, depression, disorientation, and convulsions are a few signs of deficiencies. Although severe vitamin B₆ deficiencies are uncommon, marginal deficiencies are more common, particularly in older people who may have a decreased capacity to absorb the vitamin. Alcoholics are at risk for deficiency, particularly those who also have cirrhosis and hepatitis. The metabolism of vitamin B6 is disrupted by several medications, including the isoniazid treatment for tuberculosis.

9. Vitamin B₁₂

Two B vitamins, vitamin B₁₂ and folic acid (folate), have a number of interconnected roles, most notably in DNA synthesis. People who are deficient in either vitamin consequently have many of the same symptoms, including weakness and exhaustion brought on by megaloblastic anaemia, a condition in which red blood cells are big and immature due to a lack of DNA for cell division. A lack of folic acid also impairs the production of platelets and white blood cells, which results in chronic diarrhoea, and disrupts cell division along the gastrointestinal system. Early in pregnancy, inadequate vitamin intake may result in neural tube abnormalities in the developing foetus. So, in addition to ingesting folic acid-rich foods like fresh fruits and vegetables (particularly leafy greens) and legumes, women who can become pregnant are encouraged to take 400 micrograms of folic acid daily from supplements, fortified meals (such fortified cereals), or both. Methotrexate, a cancer medication, disrupts the metabolism of folic acid, leading to adverse effects like diarrhoea and hair loss. Alcohol abuse, which prevents the vitamin from being absorbed, can also cause a folic acid shortage.

Megaloblastic anaemia (big, immature red blood cells) is brought on by vitamin B₁₂ (cobalamin) deficiency and is brought on by folic acid deficiency because both interfere with normal DNA synthesis. An untreated vitamin B₁₂ shortage can lead to nerve degeneration and eventually paralysis because vitamin B₁₂ maintains the myelin coating that shields nerve fibres. Over 1,000 g of folic acid per day can potentially worsen an underlying vitamin B₁₂ deficiency by masking it. Weakness, exhaustion, soreness, shortness of breath, numbness or tingling feelings, mental abnormalities, and eyesight issues can all be signs of vitamin B₁₂ insufficiency. The only trustworthy sources of vitamin B₁₂ are animal products. Vegans, who consume no foods of animal origin, run the danger of lacking in vitamin B₁₂ and must get the vitamin from fortified meals or supplements. A vitamin shortage is unusual in persons who routinely consume animal products, unless there is an issue with absorption. Vitamin B₁₂ needs to be attached to intrinsic factor, which the stomach secretes, to be absorbed. The ability to absorb the vitamin is constrained if intrinsic factor is lacking (because of the autoimmune condition known as pernicious anaemia) or if the stomach fails to produce enough hydrochloric acid. Injections or high oral dosages of vitamin B₁₂ can be used to treat pernicious anaemia, which most frequently affects the elderly.

10. Pantothenic Acid

Since meals contain so much pantothenic acid, a deficit is unlikely to occur under normal circumstances. Only those fed semi-synthetic diets low in the vitamin or subjects administered a pantothenic acid antagonist have shown signs of deficiency. Fatigue, irritability, sleep issues, gastrointestinal discomfort, and neurological symptoms like tingling in the hands are all indications of a deficit. During World War II, vitamin deficiency was thought to be the cause of "burning feet" syndrome, which is characterised by tingling and numbness in the toes as well as other neurological symptoms, and which only responded to pantothenic acid treatment.

11. Biotin

Biotin deficiency is uncommon, and this may be in part because bacteria in the colon may synthesise the vitamin; however, it is unknown how important this source is. People who consistently consume a lot of raw egg white have been found to have a biotin shortage because raw egg white includes a glycoprotein called avidin that binds to biotin and stops it from being absorbed. Biotin supplements can be used to treat a rare genetic disorder that prevents some infants from being able to absorb a version of the vitamin from food. The absorption of biotin may be hampered by long-term usage of several anticonvulsant medications. Skin rash, hair loss, and finally brain problems are signs of insufficiency.

12. Vitamin C

Ascorbic acid, another name for vitamin C, serves as a cofactor in many different enzyme systems and as a water-soluble antioxidant. These enzyme systems include those that are responsible for the creation of neurotransmitters and connective tissue. Precise haemorrhages (petechiae) under the skin, bleeding gums, joint discomfort, and sluggish wound healing are all signs of scurvy, a condition brought on by a lack of vitamin C. Scurvy is uncommon in modern nations, but it can occasionally occur in persons who follow restrictive diets, especially those with few fruits and vegetables or newborns who are given boiled cow's milk without any additional vitamin C sources. While recommended intakes, which aim to give adequate antioxidant protection, are closer to 100 mg per day, scurvy can be avoided with very little amounts of vitamin C (10 milligrams [mg] per day). An individual's demand for vitamin C may increase due to disease conditions, chemicals in the environment, medications, and other pressures. For instance, smokers may need an extra 35 mg of vitamin C daily to maintain vitamin C levels that are comparable to those of non-smokers.

Minerals

1. Iron

The majority of the world's population has some degree of iron deficiency, making it the most prevalent of all nutritional deficiencies. The most at risk are premenopausal women and young children. Iron is mostly used to make haemoglobin, the blood's red pigment that transports oxygen from the lungs to other tissues. Bleeding can deplete the body's iron stores since each millilitre of blood includes 0.5 mg of iron (as a component of haemoglobin). Microcytic hypochromic anaemia, which is characterised by small red blood cells with less haemoglobin than normal, develops when iron levels are reduced. Fatigue, weakness, apathy, pale complexion, trouble breathing under stress, and a weak response to cold temperatures are all signs of severe iron deficiency anaemia. Iron deficiency throughout childhood might impact behaviour, learning capacity, as well as growth and development. The risk of pregnancy problems and maternal death is increased by severe anaemia. When iron reserves present from birth are depleted and milk, which is low in iron, is a main source of nutrition, iron deficiency anaemia is most prevalent. It is also more common in women during their childbearing years due to blood loss from menstruation and the additional iron requirements of pregnancy. Adults may develop intestinal bleeding and consequent iron deficiency anaemia as a result of tumours, haemorrhoids, ulcers, or long-term aspirin use. Iron insufficiency in both children and adults is made worse in underdeveloped nations by blood loss brought on by hookworm and other illnesses, combined with insufficient dietary iron consumption.

2. Iodine

The most frequent cause of avoidable brain injury, which affects an estimated 50 million people globally, is iodine deficiency illnesses. Severe iodine shortage during pregnancy may hinder foetal development and increase the risk of miscarriage and stillbirth as well as cretinism (irreversible mental retardation accompanied by small stature and developmental abnormalities). Less severe cognitive and neuromuscular abnormalities are among the more widespread effects of chronic iodine shortage. Iodine can be found in abundance in the water, but away from coastal locations, the amount in food varies and mostly depends on the amount in the soil. As the thyroid gland tries to absorb more iodide, the form of iodine that the body uses, from the blood in order to synthesise thyroid hormones, it enlarges and finally develops into a goitre, a noticeable lump at the front of the neck. Some foods, such as cassava, millet, sweet potatoes, some beans, and members of the cabbage family, contain compounds known as goitrogens that prevent the synthesis of thyroid hormones; these compounds, which are destroyed by cooking, can play a significant role in people who depend on goitrogenic foods as staples and have coexisting iodine deficiency. The global iodine status has significantly improved since a plan of universal salt iodization was introduced in 1993. However, millions of people continue to be at danger who live in iodine-deficient regions, primarily in Central Africa, Southeast and Central Asia, and even in central and eastern Europe.

3. Zinc

Zinc, a component of many enzymes, controls gene expression and contributes to the structural integrity of proteins. The first case of zinc insufficiency in humans was discovered in Egypt and Iran in the 1960s, where zinc therapy helped young males and children with stunted growth and underdeveloped genitalia. The region's cuisine, which was abundant in whole grains, legumes, and unleavened breads and foods that contain fibre and other compounds that prevent the absorption of zinc, was blamed for the region's mineral deficiency. The practise of eating clay, which hinders the absorption of zinc, iron, and other nutrients, also contributed to zinc insufficiency. Acrodermatitis enteropathica, a hereditary zinc-responsive condition, and individuals fed intravenous solutions deficient in zinc have both been linked to severe zinc insufficiency. Skin lesions, diarrhoea, increased susceptibility to infections, night blindness, diminished taste and smell acuity, poor appetite, hair loss, sluggish wound healing, low sperm count, and impotence are some signs of zinc deficiency. The levels of zinc are lowest in those who are protein-energy malnourished and are highest in diets strong in protein, particularly red meat and seafood. Young children, expectant mothers, the elderly, severe vegetarians, alcoholics, and those with malabsorption syndromes are at risk for zinc insufficiency even in wealthy nations.

4. Calcium

The skeleton acts as a reservoir for calcium needed in the blood and elsewhere, therefore almost all of the calcium in the body is found in the bones and teeth. A sufficient calcium intake is essential for bone growth and calcification during childhood and adolescence. Low calcium consumption during infancy, particularly during the adolescent growth spurt, may increase one's risk of developing osteoporosis later in life, a condition characterised by decreased bone mass. Bones lose density over time, which makes them brittle and less able to sustain everyday stresses. This can lead to fractures, particularly hip fractures, which can be incapacitating or even fatal. In industrial civilizations, postmenopausal women are particularly susceptible to osteoporosis. Osteoporosis is a hereditary disease that is not caused by a lack of calcium; the risk of the condition can be reduced by ensuring appropriate calcium intake throughout life and participating in frequent weight-bearing exercise. Although not as much as bone-conserving medications, adequate calcium consumption appears to decrease bone loss in the early postmenopausal years.

5. Fluoride

Fluoride helps to mineralize bones and teeth and prevents dental decay. Dental caries rates and the natural fluoride content of water were found to be inversely correlated in epidemiological studies conducted in the United States in the 1930s and 1940s. Children older than six months are advised to take prescription fluoride supplements in locations with low fluoride levels in the drinking water. Dentists may also occasionally brush their patients' teeth with fluoride rinses or gels. For both children and adults, who continue to benefit from consuming fluoride, fluoridated toothpaste is a significant source of fluoride.

6. Sodium

Even without the addition of table salt (sodium chloride), foods typically contain enough levels of sodium. Furthermore, salt insufficiency is uncommon, even in people on low-sodium diets, due to the body's highly evolved sodium-conservation mechanisms. Depletion of sodium can happen as a result of chronically excessive perspiration, vomiting, diarrhoea, or kidney illness. Muscle cramps, nausea, vertigo, weakness, and eventually shock and coma are all signs of hyponatremia, or low blood sodium. After engaging in lengthy, high-intensity exercise in the heat, sodium balance can be recovered by consuming salty foods and beverages (often referred to as sports drinks). It should also be sufficient to consume a litre of water containing two millilitres (a third teaspoon) of table salt.

Similar circumstances to sodium depletion cause the body to lose chloride. A condition known as metabolic alkalosis (excessive alkalinity in bodily fluids) is brought on by severe chloride deficiency.

7. Potassium

Because potassium is frequently incorporated into meals, dietary deficiencies are uncommon. Some diuretics, nevertheless, deplete potassium and are used to treat hypertension. The mineral can also be lost through persistent vomiting, diarrhoea, or laxative use. Weakness, loss of appetite, cramping in the muscles, and confusion are all signs of a potassium deficit. Heart arrhythmias may arise from severe hypokalemia (low blood potassium). Potassium-rich foods, including bananas or oranges, as well as potassium chloride supplements, which should only be taken under medical supervision, can help replace mineral losses.

Lack of Water (Dehydration)

The majority of the body is made up of water, which makes up more than half of body weight. Adults typically need to drink 2 to 4 litres of fluid per day in cool regions, depending on their level of activity, and 8 to 16 litres per day in extremely hot conditions to replenish fluid losses. Dehydration may occur if drinking enough water is insufficient to quench thirst, if the thirst mechanism is malfunctioning, as during vigorous exercise, or if there is an excessive amount of fluid loss, as with diarrhoea or vomiting. Dehydration is defined as a loss of fluid of at least 1 to 2 percent of body weight by the time thirst becomes obvious, therefore there is already some degree of dehydration present. Dry mouth, sunken eyes, poor skin turgor, cold hands and feet, weak and rapid heartbeat, rapid and shallow breathing, confusion, tiredness, and coma are symptoms that can advance swiftly if not treated. A fatality may result from a fluid loss that exceeds 10% of body weight. Dehydration can be especially dangerous for persons who are elderly (whose thirst feeling may be reduced), unwell, and those who travel by plane. Children and infants with chronic malnutrition who get gastroenteritis could become critically dehydrated from vomiting or diarrhoea. An oral or intravenous solution of glucose and salts is used as treatment.

Toxicities of Nutrients

Each nutrient is required within a range that is safe or acceptable, above which there is a danger of negative effects. Even water can become poisonous if consumed in extremely large doses. Overconsumption of some nutrients, including iron, can result in severe toxicity and even death. For the majority of nutrients, chronic toxicity is a concern associated with routinely consuming too much of them. Use of isolated amino acids can result in imbalances and toxicities, and prolonged overconsumption of the caloric-producing nutrients (carbohydrate, fat, and protein) and alcohol raises the risk of obesity and some chronic diseases (see below). The risk of injury from consuming too much vitamins or minerals in food is, however, minimal for the majority of people.

1997 saw the U.S. For a few nutrients, the Institute of Medicine created a reference value known as the Tolerable Upper Intake Level (UL), which is now serving as a model for other nations. The upper limit (UL) is the maximum daily nutrient intake that practically all members of the general population can consume without running the risk of negative health effects; it does not apply to those who are under a doctor's care. Most ULs for newborns, young children, and teenagers are far lower than the "safe intakes" for adults that are discussed below:

1. Vitamins

In comparison to water-soluble vitamins, which, with the exception of vitamin B₁₂, are easily eliminated in the urine if consumed in excess, fat-soluble vitamins, especially vitamins A and D, have a higher potential for toxicity because they can be retained in the liver and fatty tissue. Nevertheless, consuming supplements or food that has been enriched with water-soluble vitamins might be dangerous.

Acute vitamin A poisoning symptoms in adults typically call for a dose of at least 15,000 mg (50,000 IU) of the vitamin and include stomach discomfort, nausea, vomiting, headaches, dizziness, impaired vision, and a lack of coordination in the muscles. Chronic hypervitaminosis A, which typically results from a persistent daily intake of 30,000 mg (100,000 IU) for months or years, can have a variety of negative effects, such as liver damage and a loss of bone density. Young neonates with vitamin A poisoning may have enlargement of the fontanelles (soft patches) as a result of elevated intracranial pressure. The exact threshold for producing birth defects is uncertain, but less than 3,000 mg (10,000 IU) daily appears to be a safe consumption. Large amounts of vitamin A taken by a pregnant woman can also cause developmental problems in a foetus, especially if taken during the first trimester. Although the majority of vitamins contained in food naturally do not have any negative effects, some animals' livers may contain dangerous amounts of vitamin A. For instance, it has been said that eating polar bear liver poisoned early Arctic explorers. The skin may get a yellow tint after consuming a lot of beta-carotene, whether from supplements, carrots, or other high beta-carotene meals, although this does not have the same hazardous effects as preformed vitamin A.

A high vitamin D intake can have a number of detrimental effects, including the hardening of soft tissues and harm to the heart and kidneys. Although it usually isn't a problem, vitamin D intoxication is particularly dangerous for young children. The safe daily intake limit of 50 mg (2,000 IU) may be exceeded by those who consume large amounts of fortified milk or fish or who take numerous supplements.

It has become common practise to supplement with substantial dosages (several hundred milligrammes per day) of vitamin E in the hopes of preventing heart disease and other chronic diseases due to its role as an antioxidant. Such doses-many times the amount typically found in food-seem safe for the majority of people, but there is no proof that they are useful in preventing disease or slowing the ageing process. Daily doses above 1,000 mg are not recommended since they may prevent blood from clotting, which could have hemorrhagic complications.

Niacin (nicotinic acid) in high amounts may cause skin reddening, burning, tingling, and itching in addition to decreasing cholesterol. The first sign of niacin overload is a "niacin flush," and it is this symptom that led to the safe daily consumption recommendation of 35 mg. Numerous grammes of niacin per day have also been linked to liver damage and other negative effects.

Large doses of vitamin B6 have been administered in an effort to cure illnesses like premenstrual syndrome and carpal tunnel syndrome. A severe sensory neuropathy of the extremities, including an inability to walk, has been the most serious adverse consequence from such treatment. Despite the fact that only 1 to 2 mg are needed for excellent health, a daily intake of up to 100 mg is regarded as safe.

Since chemist and Nobel laureate Linus Pauling proposed that the vitamin was preventative against the common cold in 1970, vitamin C pills have become widely used. While many research have failed to establish a meaningful effect on incidence, some studies have demonstrated a modest advantage of vitamin C in lowering the length and intensity of common-cold episodes. Because unabsorbed vitamin C travels through the colon, diarrhoea and other gastrointestinal symptoms are the most frequent adverse effects of high vitamin C intake. The prevention of these digestive effects forms the basis for the recommended daily consumption limit of 2,000 mg. Other potential negative consequences of high vitamin C intake have been researched, but none have been shown in healthy individuals.

2. Minerals

The range of the minerals' optimal dietary intake is typically somewhat constrained. A large intake of one mineral may negatively impact the utilisation or absorption of another due to interactions. Although toxicity from excessive food intake is infrequent, it is more likely to occur if fortified meals or supplements are taken. For some groups, additional concerns include exposure to potentially hazardous quantities of minerals through the environment or at work.