Vitamin A is the term used to denominate the active component retinol and its precursors, carotenoids.

Vitamin A is necessary for proper development and play a fundamental role in growth, bone development, immunologic mechanisms, reproduction and tissue differentiation.

It is also necessary for the synthesis of rhodopsin in the retina (required for night vision).

It contributes to the maintenance of norma l vision and skin. It also takes part in the normal functioning of our immune system, as well as in the process of cell differentiation.

Vitamin A also plays a role in the maintenance of normal mucosae and contributes towards the normal metabolism of iron. Substances that deplete vitamin A are: cholestyramine, colestipol, mineral oil (laxative) and neomycin.

Deficiency symptoms include: night vision issues, loss of skin and mucosa integrity, loss of appetite, growth inhibition, bone defects, loss of taste, among others.

The consequences that may arise from vitamin A deficiency include: night blindness, xerophthalmia (dry eyes), infections, and cutaneous alterations.

When taken in excess, this vitamin may be toxic to the liver, but the "trick" is to:

  1. have the good sense not to overdose on it;

  2. and taking it together with Vitamin D diminishes such risk.

Supplements should be avoided by those who are at risk for lung cancer (smoking) or liver toxicity (alcoholics, patients with liver disease).

Cod fish oil is a good source of these two vitamins and, obviously, omega 3 (EPA and DHA).

Food Sources - Carrots, sweet potatoes, spinach, cabbage, kale, watercress, mango, collard greens, pepper, turnip greens, damascus, cabbage sprouts, broccoli, persimmon, melon, cantaloupe, Savoy cabbage, pumpkin, papaya, liver, vegetable cream, egg yolk, cream, cheese, peppers, kidney, milk.

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Vitamin D may be found in the form of two molecules: cholecalciferol (vitamin D3 and main form) and ergocalciferol (vitamin D2).

The main source of this vitamin is ultraviolet radiation, essential for its production from 7-dehydrocholesterol. The D2 and D3 forms are biologically inactive. A part of the absorbed vitamin D is converted into 25-hydroxyvitamin D in the liver, a biologically little active form, being that the main active form of vitamin D will be produced in the kidneys: 1,25-dihydroxyvitamin D (calcitriol).

Daily sun exposure, without sun protection, as to maintain proper Vitamin D levels:

Vitamin D plays a role on immunity, reproduction, secretion of insulin and differentiation of keratinocytes (epidermal cells that integrate one of the skin layers). It is also involved in the active transport of phosphate in the intestines and calcium homeostasis (in conjunction with the parathyroid hormone, it may lead to loss of bone calcium and increase renal reabsorption of calcium and phosphate).

The risk of vitamin D deficiency may occur in individuals who are not exposed enough to sunlight, or whose vitamin D conversion capabilities is reduced, as is the case of dark-skinned individuals, which contain high levels of melanin (pigment), in the elderly or individuals whose vitamin D requirements are high, as is the case of infants or pregnant women.

Deficiency symptoms include: bone malformation, weakness and excessive sudoresis (sweating). Vitamin D deficiency will originate: rickets in children and osteomalacia in adults, while it can also lead to osteoporosis.

Substances that deplete vitamin D are carbamazepine, phenytoin, phenobarbital, cimetidine, cholestyramine, ranitidine, colestipol, orlistat and mineral oil (laxative).

Important for the levels of calcium and phosphorus in our body, it is not uncommon to currently see vitamin D3 associated with calcium. Since it is fat soluble, it must be taken with full meals.

Together with Vitamin A, chances of overdosing are drastically lower.

Food sources - vegetable cream, egg yolk, milk byproducts, fish liver oils.

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Vitamin E is presented in the form of tocopherols - alpha (α), beta (β), gamma (γ), and delta (δ) - and tocotrienols - alpha (α), beta (β), gamma (γ), and delta (δ). α-tocopherol is the only form that is stored in our body in its active form and, from a nutritional standpoint, it is the most important form.

Vitamin E has an antioxidant function: it prevents the peroxidation of polyunsaturated fatty acids and protects cell membranes from the harmful action of free radicals.

It relieves cramps and muscle strains. It speeds up skin lesions healing, facilitates the absorption of vitamin A by the body and impacts the formation of sex and red blood cells.

Vitamin E improves the absorption of Vitamin A.

The daily requirement of vitamin E vary according to the consumption of polyunsaturated fats. The greater the consumption of these fats is, the greater the need for vitamin E.

Vitamin E deficiency is not frequent, but, if that is the case, it may lead to the onset of peripheral neuropathy (dysfunction of peripheral nerves).

Substances that deplete vitamin E are: cholestyramine, colestipol, mineral oil, orlistat, sucralfate, phenobarbital, phenytoin, carbamazepine.

Vitamin E may increase the effects of warfarin in thinning the blood.

As with all fat-soluble vitamins, it should be taken with a full meal.

Food Sources - vegetable cream, corn oil, hazelnut, almond, margarine, soybean oil, peanut oil, olive oil, pine nut, peanut, nut, pistachio.

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Unlike other animal species, humans can't synthesise this vitamin, which makes it essential. This vitamin has two biologically active forms - L-ascorbic acid and L-dehydroascorbic acid.

This vitamin is probably the most widely used nutritional supplement, but even those who are familiar with the use of this nutrient may be surprised to discover the ample benefits vitamin C is able to provide.

It is essential for the formation of connective tissue (which holds the body structures together). It contributes to iron absorption and the healing of burns and wounds. Similarly to vitamin E, vitamin C is an antioxidant. Pregnancy, lactation, overactive thyroid gland (thyrotoxicosis), various types of inflammation, surgery and burns can all significantly increase vitamin C requirements of the body and the risk of a deficiency.

Vitamin C also contributes towards the normal formation of collagen for the normal functioning of blood vessels, bones, cartilage, gums, teeth and skin. This vitamin also plays a role in the normal energy producing metabolism, as well as the normal functioning of the nervous system.

It contributes to a normal psychological function and helps the normal function of the immune system, and protection of cells against undesired oxidations.

Initially, symptoms that show a deficiency of this vitamin are: fatigue, anorexia, somnolence, insomnia, irritability, decreased immune function and petechiae (red spots on the skin).

The prolonged deficiency of vitamin C is called scurvy (formation of skin wounds, spongy gums and bleeding mucous membranes).

Substances that deplete vitamin C are: oral contraceptives, aspirin, corticosteroids and furosemide.

Vitamin C plays a role in the reduction of tiredness and fatigue and contributes towards the regeneration of the already used vitamin E, activating it again.

In the case of decrease in the frequency and/or quantity of urine (or even anuria), dehydration or renal failure, the intake of vitamin C must be decreased in order to avoid formation of calculi and crystals.

Food sources - Citrus fruits, kale, Brussels sprouts, watercress, greens, cauliflower, kiwi, papaya, Savoy cabbage, strawberry, broccoli, bell pepper, collard greens, white cabbage, clementines, raspberry, sweet potato, leek, potatoes.

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Vitamin K naturally occurs in two forms: Vitamin K1 (phylloquinone, phytonadione), found primarily in plants, vitamin K2 (menaquinone) synthesized by bacteria in the intestinal tract of humans and various animals or vitamin K3 (2-methyl-1,4-naphthoquinone), the synthetic form.

Vitamin K - Naphthoquinone (anti-hemorrhagic vitamin) is the cofactor of the carboxylase enzyme and plays a key role in blood coagulation with the formation of prothrombin and other factors essential to the coagulation process.

Since vitamin K is soluble in fat, issues interfere with the absorption of lipids, such as celiac disease and cystic fibrosis, may cause a deficiency of vitamin K in children and adults.

Substances that deplete vitamin K are antibiotics, aspirin, phenytoin, phenobarbital, cholestyramine, colestipol, orlistat and mineral oil (as a laxative).

This deficiency may also be developed in people talking anticoagulants to prevent the formation of blood clots.

Main symptoms include is bleeding of the skin, nose, wounds or stomach, accompanied by vomiting. Blood may be present in the urine or faeces. In more severe cases, cerebral haemorrhages may happen in newborns.

Fat-soluble, it follows the general rules for other fat-soluble vitamins, without no known limitations.

Food sources - Spinach, soybean oil, broccoli, turnip, Brussels sprouts, cabbage, lettuce, asparagus, olive oil, butter.

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It plays a cofactor role for several enzymes and takes part in the Krebs cycle, contributing towards the production of energy.

A major function of thiamine is the processing of carbohydrates, proteins and fats.

Cells are not able to use oxygen for energy storage without the presence of vitamin B1.

It is essential for the metabolism of proteins, fats, lipids, nucleic acid (molecules carrying genetic information into cells), carbohydrates and cell breathing. It also participates in the biosynthesis of a large number of cells, such as neurotransmitters (chemicals produced by neurons), such as acetylcholine.

Currently, the lack of vitamin B1 occurs mainly in alcoholics due to existing deficit regarding the level of intake, absorption and storage of nutrients. It may also occur in populations with high intake of refined grains.

Pathologies arising from the lack of this vitamin are called Beriberi and Korsakoff syndrome (neuropathy - condition that affects the nerves). In adults, the signs of deficiency are mainly manifested on the bervous and cardiovascular systems.

Symptoms include: confusion, asthenia (weakness), peripheral paralysis, lower limb pain (cramps), muscle fatigue, emotional instability, depression, irritability and anorexia.

Vitamin B1 (thiamine) is soluble in water and insoluble in alcohol. A good reason to leave alcohol aside, since it prevents the digestion of Thiamine in the intestine.

Tea, coffee and raw fish should also be kept away when taking the vitamin, since these destroy thiamine.

Substances that deplete vitamin B1 are: urosemide, antibiotics, oral contraceptives, phenytoin (antiepileptic).

Food sources - while grain bread, liver, soy, pork, lima beans, black eye peas, kidney, liver, fava beans, chick peas, brown rice, corn flour, white beans, peas, leeks, striped bass, snapper, egg yolk, spaghetti, mackerel, veal, eel, kale, gilt-head (sea) bream.

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Riboflavin may present in the form of Mononucleotide flavin (FMN) or flavin adenine dinucleotide (FAD).

Riboflavin acts as an intermediary for the electron transfer in several oxidation-reduction reactions. It participates in the metabolic reactions of carbohydrates, lipids and proteins and the production of energy.

It acts as a cofactor of essential enzymes for the conversion of pyridoxine (vitamin B6) and folic acid (B9) in their coenzyme forms and the transformation of tryptophan into niacin.

The lack of riboflavin does not normally occur per se, but rather in combination with deficiencies of other water-soluble vitamins.

The signs of deficiency of this vitamin: glossitis (red tongue), angular stomatitis (cracks at the corners of the mouth), pruritus (itching), flaking skin and seborrhoeic dermatitis (inflammation of skin). The vascularization of the cornea associated with photophobia, vision loss and itching may also occur.

In children, a deficiency in riboflavin may lead to growth retardation.

Substances that deplete vitamin B2 are: antibiotics, chlorpromazine, amitriptyline, adriamycin and phenobarbital.

Food sources - liver, kidney, almond, egg yolk, soy, cheese, whole grain bread, egg, lentils, peas, mushrooms, meat, beans, fava beans, yogurt, milk, kale, Brussels sprouts, corn flour.

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Niacin can present in the form of NAD (Nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate).

The coenzymes NAD and NADP play a key role in redox reactions that are encompassed in energy metabolism process of glucides (carbohydrates or sugars), lipids and proteins. The coenzyme NAD integrates the glycogen synthesis process.

The main function of Vitamin B3 is the release of energy in the food, required for the functioning of the body.

It contributes towards the revitalisation of skin, for the good function of the digestive tract, being quite necessary for the maintenance of the nervous system, aiding in the formation of neurotransmitter, relieving anxiety and insomnia.

Some studies have shown that it is quite efficient in the reduction of cholesterol. It reduces triglycerides and lowers the level of LDL ("bad") cholesterol, increasing the level of HDL ("good") cholesterol.

It stimulates circulation and reduces high blood pressure.

In addition, it also acts as detoxifying agent, eliminated toxins, pollutants, and drugs from the body.

The condition that arises from a niacin deficiency is called pellagra, characterized by the appearance of dermatitis, dementia, diarrhoea, tremors and tongue ulcers.

Other symptoms may include: muscular weakness, anorexia, indigestion and rashes. There may also be central nervous lesions that cause disorientation, confusion and neuritis. The membranes of the oral cavity and the gastrointestinal tract may be affected, with irritation and inflammation.

B3 (Niacin) is particularly synergistic with Thiamine (B1) and Riboflavin (B2) and helps the release of energy in the digestion of starchs and sugars and - as a coenzyme - is required for cell respiration.

Substances that deplete vitamin B3 are: antibiotics, isoniazid and 5-fluorouracil (chemotherapy).

Food sources - peanut, tuna, mackerel, lean meat, bonito, gilt-head (sea) bream, liver, sardines, swordfish, kidney, fava beans, peas, whole wheat bread.

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Formerly, adenine was called Vitamin B4. Nevertheless, it's no longer considered a real vitamin.

However, the two B vitamins, niacin and riboflavin, bind with adenine to form the essential cofactors called nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD) respectively.

Adenine is a purine that has a wide variety of biochemical roles, participating in cellular respiration, in the form of adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD). In the synthesis of proteints, it takes part as a chemical compound of DNA and RNA.

When the adenine is absent from the body can be detected polyneuritis (multiple concurrent inflammation of nerves different regions of the body) resulting in a decrease in the amount of white blood cells or leukocytes.

Food sources - cereal grains, yeast and liver, among other foods.

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Pantothenic acid occurs in the form of D-pantothenic acid. In food, it found as a coenzyme A component.

Pantothenic acid is a precursor for coenzyme A, which is essential in cell metabolism. It is important for the production of adrenal hormones and antibodies.

Thus, it participates in energy metabolism of carbohydrates, fatty acids, cholesterol, phospholipids (components of cell membranes), steroid hormones, and porphyrins (organic molecules) to the hemoglobin and choline. Coenzyme A is also a receptor for the acetate group of amino acids, vitamins and sulfonamides (antibiotics).

There are no known effects caused by a deficiency in this vitamin because its deficiency is rare because it is ubiquitous in food, both from animal and vegetable origin.

In deficiencies, vague symptoms may be observed, such as irritability, insomnia, somnolence periods, fatigue, loss of appetite, abdominal pain, pain in arms and legs, muscle spasms and neuromuscular degeneration (neuropathy may be an indication of alcohol consumption).

In the liver, Vitamin B5 deficiency creates inflammation and damages that may occur in the respiratory and intestinal mucosas of the gastric system. Children with a deficiency in Vitamin B5 may cause growth delays and cartilage formation deficiencies.

Pantothenic acid plays a role in the reduction of tiredness and fatigue and helps in normal mental performance.

Substances that deplete vitamin B5 are: oral contraceptives, amitriptyline, imipramine and desipramine (antidepressants).

Signs and symptoms: cramping, abdominal pain and cramps, fatigue, insomnia, malaise, reduced antibody production.

Food Sources - liver, brewer's yeast, peanuts, mushrooms, egg, wheat germ, herring, broccoli, corn, avocado, milk.

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Vitamin B6 naturally occurs under three forms: Pyridoxine (original shape), Pyridoxal phosphate (PLP) and pyridoxamine phosphate (PMP), which are phosphorylated forms.

Vitamin B6 contributes to the normal energy-producing metabolism and helps the normal function of the nervous system (serotonin, dopamine, and noradrenaline).

Vitamin B6 has a role in normal homocysteine metabolism and the normal metabolism of protein and glycogen. This vitamin contributes to a normal psychological function and is involved in red blood cell formation.

Vitamin B6 plays a role in the normal functioning of the immune system and contributes to the reduction of fatigue and fatigue. Vitamin B6 is also involved in regulation of hormonal activity and contributes to the normal synthesis of cysteine.

Some of the factors that may interfere with this vitamin's metabolism are the use of some medicine and alcoholism.

Substance that deplete vitamin B6: antibiotics, oral contraceptives, isoniazid, penicillamine and medicine for the treatment of Parkinson's disease.

A deficiency in this vitamin can cause changes in the central nervous system, leading to the appearance of symptoms such as irritability, depression and disorientation.

Other symptoms associated with pyridoxine deficiency are: glossitis, ulcers in the oral cavity and angular stomatitis.

Vitamin B6 should be taken in conjunction with other B vitamins.

Food sources - liver, lentils, egg yolk, nut, soy, sardines, hazelnut, brown rice, sea bream, tuna, leek, salmon, striped bass, mackerel, potato, peanut, yeast.

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There are eight forms of Biotin, however only D-Biotin is naturally produced and biologically active.

Biotin acts as a coenzyme of gluconeogenesis and of the synthesis of fatty acid oxidation. It also takes part in amino acid degradation (through its deamination) and purine synthesis.

It is necessary for DNA replication and important to the health of hair and nails.

This vitamin's deficiency is rare, except in patients with hereditary disorders of biotin metabolism, liver disease and during pregnancy (due to increased needs). It can also occur in those who eat of raw egg whites for prolonged periods (from weeks to years) because there is a protein found in egg white (avidin) which binds to biotin and prevents its absorption, or in those who have been given intravenous feeding was given without biotin supplementation.

A deficiency of this vitamin causing symptoms such as dermatitis, pallor, nausea, alopecia (hair loss), vomiting and anorexia. In infants younger than 6 months symptoms include seborrheic dermatitis and alopecia.

Substances that deplete biotine: primidone, carbamazepine, phenobarbital, fentinoína, valproic acid and antibiotics.

Food sources - brewer's yeast, liver, soy, wheat bran, dried fruit, cooked egg, mushrooms, spinach, banana, strawberries, whole wheat bread, asparagus.

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Folic acid is the synthetic form of this vitamin and is the parent molecule of several derived molecules called folates.

Folic acid is a very stable molecule with high biological activity.

Folates occur naturally as tetrahydrofolic acid, with varying biological activity.

Folate acts as a coenzyme in various metabolic reactions and plays an important role in the metabolism of amino acids. It is essential in the production of nucleic acids, DNA (gene-producing substance) and RNA (substance necessary for the production of proteins), as well as the formation of blood cells and some of the constituents of nerve tissue.

This vitamin is essential for the development and proper functioning of the nervous system and bone marrow.

It is important in growth and development, in the production of new cells, acting together with B12 to form hemoglobin in red blood cells and converting the amino acid homocysteine into methionine.

Folate deficiency is one of the most common.

Alcoholism is one of the situations which predispose folate deficiency, since it reduces the absorption and increases the excretion of this vitamin.

Substances that deplete folate: anti-inflammatory non-steroidal substances (NSAIDS) such as aspirin and ibuprofen, phenytoin, cholestyramine methotrexate, phenobarbital, colestipol, sulfasalazine, and trimethoprim.

Early symptoms of folate deficiency may include fatigue, irritability and anorexia (loss of appetite). Severe deficiency may result in the appearance of megaloblastic anemia (red blood cells and characterized by large and immature white).

The common symptoms of chronic folate deficiency are fatigue, listlessness, headaches, insomnia, difficulty memorising information. Children may also experience developmental delays.

Folate deficiency has also been linked to neurological problems such as dementia and depression.

Food Sources - liver, black-eye peas, soy, white beans, watercress, beans, asparagus, spinach, Savoy cabbage, Fava beans, Brussels sprouts, egg yolk, lentils, beet, broccoli, dried fruits.

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Cobalamin may be presented in the form of cyanocobalamin and hydroxocobalamin (active forms).

Vitamin B12 is essential to cell metabolism, especially the gastrointestinal tract, bone marrow and nervous tissue. It is essential in the synthesis of nucleic acid (molecules carrying genetic information into cells), purines (nucleotide constituent of the DNA molecule) and pyrimidines (nucleotide constituent of the DNA molecule), participating in the transfer of methyl groups.

It acts on the metabolism of proteins, contributing towards the absorption of amino acids by the body.

It has a huge importance in the prevention and fight against anemia. It has a restorative effect on the neurological damagea caused by pernicious anemia.

Cobalamin also participates in the metabolism of carbohydrates and lipids.

Vitamin B12 deficiency leads to the appearance of megaloblastic anemia (characterized by large and immature red and white cells), resulting in changes to the DNA synthesis, which mainly affect the tissue with a higher cell renovation rate (e.g. hematopoietic system). Neuropathy can also occur (nerve damage).

Symptoms include: weakness, fatigue, dyspnoea (shortness of breath when under stress), paresthesia (feeling of heat, cold, tingling ...), glossitis (inflammation of the tongue), anorexia, weight loss, ageusia (loss of taste perception) and anosmia (loss of smell), psychiatric disorders (irritability, memory loss, mild depression, hallucinations).

Another consequence of this deficiency is spinal cord demyelination, which causes irreversible damage to the nervous system.

Substances that deplete vitamin B12: acide-reduction drugs (omeprazole, lansoprazole, ranitidine), oral contraceptives, antibiotics, cholestyramine and metformin.

Vitamin B12 is the only water-soluble vitamin stored by the liver. Therefore, it must be taken together with other Complex B vitamin.

Food sources - horse mackerel, liver, kidney, mackerel, sardines, sarda, gilt-head sea bream, dogfish, egg yolk, tuna, beef, duck, lamb, veal, pork, cheese, cream, milk.

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