Functions:  

Vitamin A is a fat-soluble vitamin that helps us see in the dark. It is known as retinol because it produces pigments found in the retina of the eye.  Vitamin A helps promote the health and growth of all cells and tissues found in our body.  It assists in the formation and maintenance of healthy teeth, skin, tissues, and mucous membranes.

History:

In 1913, Yale University scientists Lafayette Mendal and Thomas Osbourne discovered that butter improved the physical development of their laboratory rats.  Further evidence indicated that butter contained a very important fat-soluble nutrient, which helped prevent the weight loss and eventual death of these animals.  Their experiment illustrated that a trace amount of this organic substance was critical for the sustenance of these animals.  This substance was later coined “Vitamin A”, because it was the first vitamin to be isolated.     
  
Deficiency:

Vitamin A deficiency is found among malnourished, elderly, and chronically sick populations in the United States, but it is more prevalent in developing countries.  The first signs of vitamin A deficiency are dry skin, dry hair, chipped fingernails, and decreased resistance to infection. Severe Vitamin A deficiency can lead to severe conditions as:

• Night Blindness is a disorder, where a person has difficulty seeing in dim light.  This condition is caused by an impaired production of rhodopsin, a compound found in the retina, which is responsible for detecting small amounts of light.
• Xerophthalmia causes the eyes to fail to produce tears.  This is caused by the alteration of the eye’s conjunctiva and cornea.  It is a major cause for blindness in developing nations.
• Hyperkeratosis is a goose bump-like appearance of the skin caused by keratin blocking hair follicles of the skin.  This condition initially causes the skin on the forearms and thighs to become rough, dry, and scaly.  It can eventually affect all of the body’s skin.

Food Sources:
Liver, eggs, fish oil, milk fortified with vitamin A, fruits and vegetables (red, orange, and yellow colored), dark-green, leafy vegetables

Recommended Dietary Intake (RDI): 5000 IU of Vitamin A per day for Adults

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Related Links: Vitamin Articles

Functions:

Vitamin D is a fat-soluble vitamin that is found in certain foods and can be produced by our body after exposure to UV rays from sunlight.  This vitamin aids in the absorption of calcium and phosphorus and helps deposit these minerals in teeth and bones.  By promoting calcium absorption, vitamin D helps to form and maintain strong bones.  Studies suggest that vitamin D also helps maintain a healthy immune system and helps regulate cell growth and differentiation.

History:

In 1922, Edward Mellanby, discovered Vitamin D while researching rickets, a bone-related disease.  Mellanby had stated that he could produce rickets in animals such as dogs, by restricting their sun exposure and feed them an exclusive oatmeal diet.  He believed that he could counteract this effect by adding cod liver oil to their diet. 

Deficiency:

Vitamin D deficiency can strongly affect the strength and rigidity of our bones.  It can cause several bone diseases including:

• Rickets is a childhood disease, where the long bones (arms, legs) fail to mineralize, causing stunted growth and deformity. 
• Osteomalacia, a bone thinning condition, exclusively affects adults, where the bone’s minerals are removed from the collagenous matrix.  With time people affected by this condition experience bone softening and pain.  Muscle weakness is commonly felt as well.
• Osteoporosis, a similar condition, is characterized by reduced bone mineral denstiy.  The bone mineral density (BMD) is to scientifically measure bone density and determine the fracture risk for those with osteoporosis.  According to the National Osteoporosis Foundation, elderly women are most susceptible to conditions of osteoporosis

Food Sources:
Fish (cod, salmon, mackerel, tuna), fortified milk, margarine, pudding, breakfast cereals, eggs, beef liver, and cheese.

Alternative Sources:
Direct sunlight or ultraviolet light helps your body produce this vitamin

Recommended Dietary Intake (RDI): 400 IU of Vitamin D per day for Adults

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Functions:
Vitamin E is a fat-soluble vitamin and powerful antioxidant that protects cellular tissues from the damaging effects of free-radicals.  Free radicals are potentially harmful by-products of energy metabolism, which could contribute to the development of cardiovascular disease and cancer.  Research has shown that Vitamin E may help prevent specific cancers such as colon, breast, and prostate. 

History:
Vitamin E was discovered by two researchers from the University of California, Berkeley.  Dr. Herbert M. Evans, a research physician, and his assistant, Katherine S. Bishop “found” this vitamin in green leafy vegetables.  In their experiment, they were feeding their rats a special diet.  The rats would grow very well, yet all of the female pregnancies, the pups would die.  The rat’s diet was later supplemented with lettuce and wheatgrass, resulting in health pups being born.  Evans and Bishop started to realize that there was some compound, which they named Factor X that helped enhance the pup’s nutrition.
 
After years of research, Drs. Evans and Bishop eventually discovered that Factor X was in the lipid extract of lettuce, which they concluded was fat-soluble.  Unfortunately, the excitement of Vitamin E died away quickly due to the complexity of its structure.  Scientists and researchers had a difficult time extracting and analyzing the compound.  In 1936, Dr. Evans and colleague isolated an alcohol compound called tocopherol.

Deficiency problems:
Vitamin E deficiency is rare among adults and adolescents.  This deficiency affects the nervous system since the brain is most susceptible to the damage of free radicals, which can create problems including difficulty walking, muscle weakness, and reduce reflex response.  Fortunately, this deficiency is very rare, since Vitamin E is found in most all foods.  People unable to absorb fat normal and premature babies are susceptible to this deficiency.  Newborn babies have a low reservoir of vitamin E, based on little migration of the vitamin through the placenta.  Due to this newborns are at an increased risk for vitamin E deficiency. Premature infants, who have vitamin E deficiency, have a high risk of developing blood-related disorders including hemolytic anemia, hemorrhage, and retinopathy.
  
Food sources:
Vegetable oils, Nuts, Seeds, Wheat Germ, Peanut Butter, Salad Dressings, and Leafy-Green Vegetables.

Recommended Dietary Intake (RDI): 15 IU of Vitamin E per day for Adults

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Functions:
Vitamin K is a fat-soluble vitamin that is commonly known as the “clotting” vitamin.  This vitamin’s primary responsibility is to regulate normal blood clotting (through the formation of prothrombin).  Blood clotting occurs instantaneously when there is an injury or tear to any blood vessel.  It regulates this process from helping the body transport calcium. Vitamin K participates in the synthesis of several proteins that are necessary for the functions such as coagulation and anticoagulation.  Vitamin K, by preventing the hardening of arteries, can reduce occurrence of heart disease and heart failure. 

Vitamin K also plays an important role in metabolic processes of bones.  According to most studies, high levels of Vitamin K are associated with high bone mineral density and decreased risk of hip fracture.  Vitamin K supplementation has been observed to improve bone health and reduce risk of bone fracture, especially with elderly women at high risk of osteoporosis.  Vitamin K is also commonly used to reduce of the risk bleeding in various gastrointestinal problems including liver disease and malabsorption.

History:
Contrary to popular belief, this “coagulating” vitamin received the letter K from Koagulation (Danish for Coagulation). Vitamin K was discovered by in 1929 by Danish scientist Henrik Dam.  Dam, at the time was, investigating the properties of cholesterol.  In his experiment, he feed his chickens a cholesterol-free diet, which resulted in the animals developing hemorrhages, which caused them to bleed.  The defects that occurred could not be restored by the simple addition of cholesterol to their diet.  After experimentation, Dam began to realize that there was an additional compound that caused the blood to coagulation.  He discovered that the chickens that were feed a diet, lacking Vitamin K developed hemorrhagic disorders.  He notes a new deficiency syndrome in the young birds that were fed a fat deficient diet.  The characteristic features were a lengthened blood clotting time, anemia and hemorrhage.
  
Though the vitamin K was discovered in 1929, a pure form of the vitamin was isolated and analyzed in 1939.  It was now established that this vitamin played a vital role in proper blood clot formation.  The independent efforts of scientists Henrik Dam and Edward Adelbert Doisy led to discovery of structure and true chemical properties of Vitamin K, which played a vital role proper blood clotting.  In 1943, the Nobel Prize for was shared by Danish scientist Henrik Dam and American research Edward Doisy for discovering the chemical nature of Vitamin K.  Doisy was Doisy was successful at the isolation of vitamin K from hexane extracts.

Deficiency problems:
Vitamin K deficiency is usually rare among adults.  However, based on our society’s eating habits we have limited Vitamin K intake.  Vitamin K deficiency can lead to excessive bleeding and poor blood clotting, which can be detrimental in a severe cut or tear. Bleeding (hemorrhage) can occur from an arm, in the stomach, nose, skin (bruises).  Newborns are susceptible to life-threatening brain bleeds. The resulting thin blood will not adequately coagulate or clot to stop the bleed. Like other fat-soluble vitamins, Vitamin K deficiency, can weaken bones through poor bone mineralization, increasing the risk of developing severe osteoporosis.   
   
Food sources:
Vitamin K is found in green leafy vegetables including cabbage, cauliflower, spinach, broccoli, parsley, etc.  Smaller traces are found in meat, eggs, cereal, milk and other dairy products.

Alternative sources:
Vitamin K is found in green leafy vegetables including cabbage, cauliflower, spinach, broccoli, parsley, etc.  Smaller traces are found in meat, eggs, cereal, milk and other dairy products.

Recommended Dietary Intake (RDI): 120 ?g of Vitamin K per day for Adults

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Functions:
Vitamin C is a water-soluble vitamin that affects the body in many different ways.  It is required for the synthesis of collagen, an important protein used to create blood vessels, scar tissue, skin, tendons, and ligaments.  Vitamin C is necessary for the repair and maintenance of these parts and helps heal wounds.  Vitamin C is actively involved in the formation of norepiephrine, a neurotransmitter that is critical in brain function.
 
Vitamin C, a powerful antioxidant, in small amounts in can combat the damage created by free radicals, which are negative by-products of metabolic activity.  The accumulation of these free radicals has been associated to the aging process.  Studies over time have shown that free radicals contribute to the development of ailments such as heart disease, macular degeneration, and cancer. 

History:
In 1747, Scottish surgeon James Lind explained that a special nutrient (vitamin c) found in citrus foods, prevented scurvy.  In his experiments, he administered lemon juice to sailors that were infected with scurvy.  After multiple treatments, his patients were healed from this condition.  He later documented his findings in his book The Treatise of the Scurvy.  Lind was credited with the discovery of Vitamin C. 

Vitamin C was isolated and identified by a team of Hungarian scientists in 1932.  It was later coined the title “ascorbic acid”, which literally means “no scurvy”.  Szent-Gyogyi, was later awarded a Nobel prize in 1937, for his work.  Vitamin C was the first vitamin to be artificially synthesized in 1935 by Zurich scientist Dr. Tadeusz Reichstein. 

In 1971, Vitamin C received a great deal of attention due to the efforts of another Nobel Prize winner Linus Pauling.  Dr. Pauling believed in vitamin C had many beneficial attributes on the body, which he published several best selling books.  One of his most well-known books, Vitamin C and the Common Cold, illustrates the immune-enhancing effects of ascorbic acid on the body. 

Deficiency problems:
Vitamin C, like other water-soluble vitamins, can not be synthesized nor stored by the body.  The excess amounts are excreted by body with urine.  In order to prevent the harmful effects of vitamin C deficiency, you should constantly replenish your body with these nutrients.  Vitamin C deficiency can cause scurvy, a disease with symptoms including bleeding gums, skin discoloration, loose teeth, slow wound healing, joint pain, and anemia.  Fortunately, scury is a rare condition found in the United States.  Iron with vitamin C can cure scurvy-related anemia. 

Adults with low levels of Vitamin C have exhibited symptoms including depression, fatigue, weight loss, muscle weakness, high rates of infection, poor healing wounds.  The lining of our respiratory tract rely on vitamin C for protection, respiratory infections and other lung conditions are strongly associated with vitamin C deficiency.
Infants rarely obtain this deficiency due to the high levels of Vitamin C found in breast milk and fortified baby formulas.
Pregnancy, breastfeeding, surgery, and burns can significantly increase the body’s demand for vitamin C.  Thus, leaving one more susceptible to vitamin deficient if these needs aren’t addressed.  Most people are unaware, but smoking can increase one’s Vitamin C requirement by approximately 40-50%.

Food Sources:
Citrus fruits (oranges, limes, grapefruit, strawberries, cantalope) and Vegetables (green or red peppers, tomatoes, broccoli).  It is found in some meat, like liver.

Recommended Dietary Intake (RDI): 90 mg of Vitamin C per day for Adults

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Benefits:
Thiamin, a water-soluble B-complex vitamin, and helps the body to create energy by breaking down carbohydrates and fats.  Thiamine, also known as Vitamin B1 is essential for the normal growth and development, it helps to main proper functioning of the heart, nervous, and digestive systems.  Vitamin B1 helps maintain proper functioning digestive, nervous, cardiovascular systems.  It can be stored in muscle tissue temporarily; depletion can occur as quickly as within 14 days.

History:
Thiamine has been described by Chinese medical texts since 2697BC.  Thiamine was first discovered in 1910 by Japanese scientist Umetaro Suzuki, while researching how rice brain cured patients of berberi.    Robert R. Williams published the first correct formula and synthesis in 1935. After his synthesis, the American Medical Association wanted Williams to name the compound.  Williams named this compound “thiamin”.  The reflect the vitamin’s amine nature the American Chemical Society added an “e” to make it the present name “thiamine” .

Deficiency problems:
Vitamin B1 (Thiamine) deficiency strongly contributes to the development of beriberi.  Beriberi is rare condition found in the United States due to adequate dietary thiamine intake.  People that abuse alcohol are most susceptible to the development of beriberi.  Excessive alcohol usage impairs a body’s nutritional ability and makes it harder to absorb thiamine. 
Adult Beriberi syndrome, a severe thiamine deficiency disease, is characterized by fluid accumulation in legs, fast heart rate, neuropathy, and abnormally large rate.  Continued deficiency can lead to Wernicke-Korsakoff symptom, which acts on the nervous system causing physical imbalance, mental confusion, and psychosis.  
Genetic beriberi is a rare condition that is inherited through family members.  People with genetic beriberi are unable to absorb thiamine from foods.  Due to its gradual development of the disease, most people truly experience the symptoms as adults.  They suffer from ailments such as fatigue, muscle weakness, and possible nerve damage. 

Food sources:
Whole-grain products (bread, rice, pasta, tortillas, breakfast cereals), legumes (beans, lentils), beef, liver, and pork. 

Recommended Dietary Intake (RDI): 0.5 mg per 1000 Kcal for Children, Adolescents, and Adults

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Functions:
Riboflavin (Vitamin B2) is a water soluble vitamin that helps the body produce energy through the metabolism of carbohydrates and fats.  It also helps convert tryptophan (an essential amino acid) into niacin (another B vitamin) and activates vitamin B6.  Riboflavin also aids the body’s antioxidant system to protect against free-radical damage.  It is vital for the body’s various systems such as nervous, reproductive, and immune system. 

History:
In 1879, Vitamin B2 (Riboflavin) was observed at a green pigment found in milk. 

Deficiency Problems:
Vitamin B2 deficiency could be related to low vitamin intake or conditions associated with poor absorption in the intestine.  Symptoms of riboflavin include cracking mouth and lips, dry skin, skin rash, sensitive itchy eyes, and inflammation of the tongue.  Low levels of vitamin B2 can cause neurological ailments such as numbness and decreased sensitivity of hands.
 
Food sources:
Vegetables (broccoli, asparagus, spinach), nuts, milk and other dairy products, Meat, and Eggs.
 
Recommended Dietary Intake (RDI): 1.2 mg of Vitamin B2 per day for Adults

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Functions:
Niacin is a water-soluble, B-complex vitamin that plays an important role in energy metabolism, by converting carbohydrates and fats.  It also helps the body to remove harmful toxins, to produce steroid hormones, and to repair DNA.  Vitamin B3 plays an important role in our digestive tract by maintaining smooth muscle tone.  Studies have shown that niacin is effective at reducing cholesterol-levels and improving cardiovascular circulation.
 
History:
Niacin was first synthesized in the 1867.  In 1911, Dr. Cashimir Funk isolated niacin from rice and yeast polishings.  A year later, American medical researcher Joseph Goldberger discovered that pellagra was caused by low niacin levels.
 
As previously stated, low niacin levels are linked to the development of pellagra, first described during the 17th century, in Spain and Italy.  This disease epidemic finally reached America during the 20th century.  It was observed that pellagra largely affected people that largely consumed corn, mostly impoverished more from southeastern United States.  There deficiency was caused by inadequate consumption of tryptophan, an essential amino acid.  Tryptophan, is a precursor molecule of niacin.

Though niacin was isolated in 1867, its true knowledge and benefits were aware in 1937, it became the anti-pellagra factor.

Deficiency problems:
Niacin deficiency is no longer prevalent in the United States, since its epidemic.  It common in populations where corn is the staple diet and lime-free fertilizer is used.  Corn has very low levels of niacin.  The lime found in fertilizer releases tryptophan, which is then converting to niacin in the body.  Low levels of niacin have been associated with symptoms including as diarrhea, skin irregularities, and mental disorientation.  If the deficiency progress, one can develop Pellagra.  Pellagra was originally believed to an infectious disease, as first described by Spanish physician Casal in 1735.  This vitamin deficiency causes skin rashes, dementia, anxiety, severe disorientation, and insomnia.  They can be seen in India, China, and Africa.  Tryptophan is commonly used to treat pellagra now days.

Food sources:
Protein-rich foods (beef, fish, poultry, peanuts, beans), yeasts, milk, eggs, seeds,

Recommended Dietary Intake (RDI): 20 mg of Niacin per day for Adults

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Functions:
Vitamin B5 (Pantothenic acid) is a water-soluble B-complex vitamin.  It, like other members of the B-complex family, helps metabolize fats, proteins, and carbohydrates to produce and release energy.  It is common known as the “anti-stress vitamin”, by supporting the adrenal gland in the release a stress hormone, cortisol. 

Pantothenic acid, helps the adrenal gland produce other important hormones, which aid the body to fight allergies and regulate metabolism.  It is, also, very important in stimulating the immune system to produce more antibodies.  

History:
Pantothenic acid, originally called Bios, was isolated by in 1933 by Dr. R.J. Williams.  He and his coworkers isolated this vitamin from yeast.  Williams, a few years later, surprisingly discovered pantothenic acid in the liver.  The name Pantothenic, given by Williams, is derived from the Greek word pantos, which means"everywhere".  It is appropriately name based on the wide use of this vitamin. After many years of experimentation, pantothenic acid was finally crystallized in 1940.

Deficiency problems:
Vitamin B5 deficiency is very rare and is usually seen in conditions of extreme malnutrition.  Most people have a sufficient level of this vitamin based on their dietary source.  People, who temporarily are low in B5, can feel fatigue, nausea, depression, reoccurring infections, and headaches.  They can experience neurological disorders such as feel burning extremities such as"burning feet" syndrome, numbs, and muscle cramps and weakness.

Food sources:
Meat, liver, kidney, fish, poultry, whole grain cereals, vegetables (broccoli), beans, and milk

Alterntive source:
The intestinal flora found in our body can manufacture this vitamin.

Recommended Dietary Intake (RDI): 10 mg of Vitamin B5 per day for Adults

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Functions:
Vitamin B6 (Pyridoxine) is a water-soluble that helps produce proteins, which then create cell bodies.  It helps convert tryptophan (an essential amino acid) into Niacin (Vitamin B3) and Serotonin, a biological neurotransmitter.  Vitamin B6 helps the immune system by increasing WBC production to fight infection.  The body needs Vitamin B6, to produce hemoglobin.  Hemoglobin, a major component of red blood cells, bind to oxygen carrying it to all body tissues.  It also increases the amount of oxygen carried by hemoglobin. Thus, vitamin B6 deficiency can result in a form of anemia.  It also helps maintain blood glucose levels within normal range.  When your glucose level is low, your body requires vitamin B6 to convert stored carbohydrates into glucose to maintain normal blood sugar levels.  Recent studies have shown that vitamin B6 decreases homocysteine levels, which has been to heart disease. 

History:
Vitamin B6 was discovered in 1934 by research scientist Paul Gyorgy, during nutrition studies on rats.  Gyorgy has observed this vitamin had cured the rats of scaly dermatitis.  He began further research into the compound, and eventually named it pyridoxine.  A few years later, Gyorgy and his co-workers in 1938 isolated the compound from rice bran.  They soon discovered that pyridoxine could prevent and cure acrodynia, a condition caused by excessive mercury exposure.  In 1939, the vitamin true structure was determined and it was later synthesized. 

Deficiency problems:
Vitamin B6 deficiency is rare, since most people consume foods that contain adequate levels of it.  The condition mostly affects the elderly, due to suboptimal vitamin B6 intake.  It can be seen in individuals that have poor quality diet that are deficient in various vitamins.  It is usually associated with poor absorption of nutrients by the gastrointestinal tract.  It cause be caused by genetic disorder that prevent the metabolism of vitamin B6. 

Symptoms of vitamin B6 deficiency can develop vitamin intake is limited for an extended period of time.  This deficiency can cause dermatitis (scaly, flaking skin), inflamed mouth and lips, glossitis(sore tongue), depression, nervousness, insomnia,  confusion, difficulty walking, poor coordination, and muscle weakness.  Vitamin B6 deficiency can also cause anemia due to the vitamin’s affect on hemoglobin.

Food sources:
Chicken, fish, pork, liver, kidney, whole grains, nuts and legumes. plant foods, meats, whole grains, vegetables, and nuts.

Recommended Dietary Intake (RDI): 2.0 mg of Vitamin B6 per day for Adults

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Functions:
Folate is a water-soluble vitamin that plays an important role in DNA and RNA production, which produce new cell bodies.  Folate is required for DNA replication and can prevent change in DNA that may lead to cancer.. It is actively involved in rapid cell division and growth, during times of infancy and pregnancy.  With the aid of vitamin B12, folate forms hemoglobin, found in red blood cells allowing effective oxygen transportation to surrounding body tissues.  Folate plays a role in reducing homocysteine levels in blood. 

History:
Folate was discovered in 1931 by researcher Dr. Lucy Willis, which she learned prevented anemia during pregnancy.  During her experimentation, she observed that brewer’s yeast reversed anemia.  Folate was identified as the special ingredient found in the yeast.  It was extracted from spinach leaves in 1941.  It was first synthesized in 1946.

Deficiency problems:
Folate deficiency is rare among the American population.  It is mostly seen in people that abuse alcohol, have a poor dietary intake, or have metabolic defects that prevent folate absorption.  Low levels of folate can hinder DNA synthesis and cell division, which clinically will affect bone marrow, a site of rapid cell division.  This deficiency can also lead to megaloblastic anemia, where few, large red blood cells are produced.  Due to their abnormal size, these blood cells are unable to transport an optimum quantity of oxygen to surrounding tissue.  

Common symptoms of folate deficiency are difficulty walking, shiny and large tongue, difficulty walking, increased risk of osteoporosis/fractures.  Folate deficiency is very similar to B12 deficiency but lacks the neurological damage associated with B12 deficiency.

Food sources:
Leaf vegetables (spinach, turnip greens), dry beans, fortified cereal products, seeds, and liver.

Recommended Dietary Intake (RDI): 0.4 mg of Folic Acid per day for Adults

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Functions:
Vitamin B12 is a water soluble vitamin that is important in the production of red blood cells and healthy nerve cells.  It is required in DNA and RNA replication.  Vitamin B12, with the help of vitamin B6 and folate, control the body’s homocysteine levels.  Excess amounts of homocysteine are associated with increased risks of heart disease and stroke.  Similar to other water-soluble vitamins, vitamin B12 plays an important role in cell division and growth.  It also increases our energy levels by metabolizing fats and carbohydrates.

Recommended Dietary Intake (RDI): 6 micrograms (mcg) of Vitamin B12 per day for Adults

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Functions:
Biotin is a water-soluble vitamin, generally classified as a B-complex vitamin.  Like other B vitamins, it helps body cells to produce energy.  It helps metabolize fats, proteins (amino acids) and carbohydrates in food.  It is important in cell growth, the production of fatty acids, maintains a steady blood sugar levels, and strengthen hair and nails.  It plays a role in the citric acid cycle, a process where biochemical energy in created during aerobic respiration.  It also plays a role in the transfer of carbon dioxide found in the body. Preliminary studies show that biotin may help improve sugar control in those with diabetes, particularly Type 2 diabetes.

History:
In 1916, W.G. Bateman first demonstrated the effects of biotin-deficiency by feeding his laboratory rats large amounts raw egg whites.  Based on their diet, these animals developed dermatitis, hair loss, and neuromuscular dysfunction.  This syndrome was called"egg white injury", which was caused by a glycoprotein found in egg white called avidin.  It was later discovered by Boas that this"egg white injury" could be cured by special liver factor called"protective factor X".  Because biotin cured various skin disorders, it was named vitamin H by Gyorgy in 1931.  H is for Haut, which in German means skin.  Further scientific research demonstrated that avidin caused the"egg white injury" by binding very tightly to biotin, prevents its absorption.  In its raw form, avidin can not be hydrolyzed by proteolytic enzymes.  However, if the egg white is cooked, avidin becomes denatured and can be digested by these enzymes.  In 1943, biotin was successfully synthesized in the US by Harris and colleagues.  In 1949, Goldberg and Leo Sternbach develop a technique for the industrial production of biotin.

Deficiency problems:
Although biotin deficiency is very rare, it can occur if a person experiences intestinal malabsorption, consumes raw egg whites on a regular basis, uses oral antibiotics for a prolonged time, feed intravenous without biotin supplement, or uses certain anti-seizure medications long-term.  

Biotin deficiency can cause symptoms including anemia, chronic fatigue, loss of appetite, poor fat metabolism, nausea, vomiting, hair loss (alopecia), mental depression, high cholesterol (hypercholesterolemia), tongue inflammation, muscle weakness, muscle pain, irregular heartbeart, impaired cognitive skills, drowniness, and insomnia.  This vitamin deficiency can cause dermatologic problems including dandruff, dermatitis, psoriasis, seborrhea, and eczema.
 
Food sources:
Eggs, dry yeast, liver, salmon, kidney, dairy products, liver, yeast breads, cauliflower, and cereals.

Recommended Dietary Intake (RDI): 300 micrograms (mcg) of Biotin per day for Adults

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