Vitamins

Vitamins are substances present in small dosages in our diet. Vitamins are food components, which provide no energy in contrast to food substances like carbohydrates, fats and proteins, but are essential for a good functioning metabolism (the metabolism).
There are two large groups of vitamins, fat-soluble and water-soluble vitamins. In vivo (in an organism), the most water-soluble vitamins are converted into coenzymes. Coenzymes work together with metabolic enzymes to carry out their biochemical functions. Vitamins can also be operative directly at certain places in the metabolism. Some vitamins get their definite form in the body, the form in which they occur before is called pro-vitamins.
The name vitamin is derived from the Latin words vita (meaning life) and amine (an organic chemical nitrogen containing molecule). This name was used for the first time by Kasimir Funk in 1910. A large part of the vitamins have now been chemically analysed. It has been found, that only one of the vitamins is really an amine, whereas all the other belong to other chemical groups. The name vitamin is therefore not correct, but is used this way.
Whereas vitamins play the same role in all life forms, higher organisms (such as humans) lost their ability to produce vitamins. When a lack of a vitamin occurs an illness can show up which can be treated by the supplementation of the missing vitamin. The illnesses which occurs by the lack of vitamins are called vitamin deficiencies (for example beriberi and scurvy).


List of the different vitamins
Table with Recommended Dietary Allowance (RDA) and maximum safe dose of the vitamins
Look at the vitamins in 3-D structure (Chime / PDB)



List of the different vitamins



Vitamin A



Structure formula vitamin A Retinol
Chemical name: Retinol or All-Trans-Retinol
Molecular formula: C20H30O; Molecular weight: 286.46 g/mole



The pro-vitamin of vitamin A is Beta-carotene (orange dye of carrots).


Structure formula Beta-carotene
Chemical name: Beta-Carotene
Molecular formula: C40H56; Molecular weight: 536.90 g/mole


Vitamin A is a fat-soluble vitamin.
Retinol is probably formed by an oxidative splitting of the beta-carotene in the small intestine. That is why beta-carotene is also called pro-vitamin A.
Beta-carotene is an antioxidant and has in this way cancer preventing properties (if you are not a smoker). Vitamin A has a protective effect on the epithelium.
The effect of vitamin A is essential for the formation of blood capillaries. Therefore it is important for the nutrition supply to all organs. In tissues where most cells are broken down and a continuing replacement of new cells is necessarily (like the skin), a lack of vitamin A is firstly observed. Insufficient capillary formation and an insufficient capillaries position can cause an accumulation of waste products that serve as food for penetrating bacteria. It can cause serious, often deadly inflammations with pus. As a result of a retina disturbance of the eye, night-blindness can arise.


Properties
- Cancer protective properties (beta-carotene for non smokers)
- Prevents and treats skin problems and ageing of the skin
- Improves eyesight and prevents night-blindness
- Improves the regenerating properties of the body
- Stimulates the growth of strong bones, hair, teeth, skin and gums
- Helps against a too fast working thyroid gland


Symptoms when deficiency occur
- Night-blindness
- Continuous headache
- Decreased immunity against infections (especially of the airways)
- Skin problems
- Dry, breakable hair
- Kidney stones


Careful and toxicity
An overdose of vitamin A as retinol is poisonous and women that are pregnant may not use this vitamin. Beta-carotene is not poisonous and this vitamin is considered safe for adult and children. Do not use high doses of retinol or beta-carotene when you are a smoker because this could increase your chance to get lung cancer.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of vitamin A is 0.8 mg (= 800 micro grams). People with specific needs (after illness, when suffering from infections or people with diabetes) need higher dosages. The maximum safe dose per day is 3 mg (= 3000 micro grams).
Important sources of vitamin A are only animal products such as: liver, fish oil, palm oil, butter, margarine and egg yolk.

The Recommended Dietary Allowance (RDA) of beta-carotene is 2 to 6 mg. When a women is pregnant more is needed. The maximum safe dose is 25 mg per day.
Important sources of beta-carotene are green leaf vegetables, carrots and orange vegetables.


List of the different vitamins


Vitamin B-complex



When the vitamin B-complex was discovered people thought it consisted out of one vitamin. This vitamin got the name vitamin B. Later it was discovered that vitamin B consisted out of more than one vitamin. To distinguish the different vitamins they were numbered 1 to 13. Later on, some vitamins were removed from the B-complex because they were found not to be real vitamins. Finality, 8 vitamins were left, namely:

B1 / Thiamine, B2 / Riboflavin, B3 / Nicotinic acid, B5 / Pantothenic acid,
B6 / Pyridoxine, Biotin, B11 / Folic acid, B12 / Cobalamin

These vitamins from the B-complex are all active in the metabolism of the body. They are all water-soluble and are all precursors of coenzymes.
These vitamins are especially present in meat, bread, potatoes and milk products.


List of the different vitamins



Vitamin B1



vitamin B1 Structural formula Thiamine
Chemical name: Thiamine
Molecular formula: C12H17N4OS; Molecular weight: 265.36 g/mole


Vitamin B1 is a water-soluble and sulphur containing vitamin.
It was discovered in 1901 by Jansen and Donath, Windhaus, van Veen and Okade.
Vitamin B1 is necessary to regulate the metabolism, especially the carbohydrate break down by which energies are obtained. This vitamin alone can keep someone alive without the need of other vitamins and minerals, even under faulty conditions. Deficiencies can cause numerous organic and functional disturbances. When vitamin B1 is lacking and an excess of carbohydrates is present, beriberi arises in different forms. Also an excess of sugar can arouse a lack of vitamin B1. Relative deficiencies occur regularly.


Properties
- Protects against some negative consequences of alcohol use
- Can help in the treatment of nerve disturbances (especially when these are caused by B1 deficiency)
- Can help in the treatment of anemia
- Can improve the flexibility of the mind
- Can help to regulate diabetes when a connection exists to a B1 deficiency
- Helps in the treatment of herpes infections
- Helps to transform sugar into energy in the muscles.


Symptoms in case of deficiencies
- Tiredness
- Weakness in the muscle
- Loss of appetite
- Irritability
- Depressiveness
- Bad memory
- Tingling feeling in the toes and on the soles
- Digestion problems
- Nauseousness
- Beriberi


Careful and toxicity
Thiamine is not considered poisonous but it is advised not to take more than 400 mg per day.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of this vitamin is 1.4 mg.
Heavy drinkers, smokers, pregnant women and women that use the anti-conception pill will have to increase their dosage to 100-300 mg per day. Also raise the dosage when you suffer from stress. This vitamin is most effective as a constituent of a good vitamin B-complex.
The maximum still considered as a safe doses per day is 400 mg.
Vitamin B1 is generally present in the diet. Rich in thiamine are yeast, grain germ, meat, peas and beans.


Specific biochemical mechanism
Vitamin B1 is necessary in the metabolism. It is active in the body as a coenzyme that is called thiamine di-phosphate or thiamine pyrophosphate. It is almost the same molecule as thiamine. The only difference is that there are two phosphate groups attached instead of a hydrogen atom (see image below).


This coenzyme prepares pyruvate for the further breakdown in the citric acid cycle. This coenzyme helps to decarboxylate (= to split off a carbon atom) pyruvate as part of the enzyme pyruvate dehydrogenase complex. It is also a part of the enzyme alpha-ketoglutarate dehydrogenase complex that is also active in the citric acid cycle. In that way it regulates especially the carbohydrate breakdown in which energies are obtained.


List of the different vitamins


Vitamin B2



vitamin B2 structural formula Riboflavin
Chemical name: Riboflavin, Lactoflavin or E101
Molecular formula: C17H20O6N4; Molecular weight: 376.4 g/mole


Vitamin B2 is a water-soluble vitamin just like vitamin B1 and is also active in the breakdown of carbohydrate, protein and fat.


Properties
- Helps the metabolism of fats, proteins and carbohydrates
- Promotes good eyesight
- Promotes a well functioning of the reproductive system
- Promotes athletic performances
- Offers protection against anaemia


Symptoms in case of deficiencies
- Burst of the skin and mucous membrane
- Redness of the tongue
- Eczema on the skin and genital organs
- Burning feeling on the skin
- Tiredness
- Sometimes difficulties in the formation of blood
By absence of vitamin B2, a partial damage of the tissue respiration arises. As a consequence of that a standstill of the growth, belly abnormalities, abnormalities of the lips, curved grown finger nail, atrophy of the tongue and stomach and intestine ailment.


Careful and toxicity
Riboflavin is poisonous in very high doses. Rarely occurring symptoms are itch and a burning feeling on the skin.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of this riboflavin is 1.6 mg.
An increased dosage is necessary for pregnancy, breast-feeding, using medicine and heavy drinking. Take vitamin B2 as a part of a B-complex preparation. Mostly it is advised to raise the dosage of vitamin B2 under stress to 100 to 300 mg. The maximum safe dose per day has been determined at 400 mg per day.
Rich in vitamins B2 are liver, kidney, egg yolk, cheese, yeast, milk, leaf vegetables and meat.


Specific biochemical mechanism
Vitamin B2 is just as vitamin B1 a water-soluble vitamin and it is also active in the carbohydrate, protein and fat breakdown. In the body riboflavin is transformed into the coenzyme that is called Flavin Adenine Dinucleotid, FAD.

Structural formula coenzyme FAD
In this image, the coenzyme FAD is represented. Indicated red is vitamin B1. This coenzyme is active as a redox potential. This means that in this molecule energy can be stored. It is active in the citric acid cycle.


List of the different vitamins


Vitamin B3



There are two forms of vitamin B3 nicotinic acid and nicotinamide.

Chemical name: Niacin or Nicotinic acid
Molecular formula: C6H5NO2; Molecular weight: 123.11 g/mole



Chemical name: Niacin or Nicotinamide
Molecular formula: C6H6N2O; Molecular weight: 122.13 g/mole


Vitamin B3 is a vitamin from the vitamin B family and is water-soluble.
This vitamin helps in the energy production and promotes a well-functioning of the nervous system.


Properties
- Prevents and treats schizophrenia
- Promotes the cell respiration
- Gets energy from sugar, fat and protein
- Keeps the skin clean
- Keeps the nerves, the tongue and the digestive system healthy
- Can lower the cholesterol levels and in this way offer protection against heart conditions
- Is considered as an antioxidant
- Can prevent migraine
- Lowers the blood pressure


Symptoms in case of deficiencies
- Dermatoid (skin illness)
- Diarrhoea
- Dementia
- Pellagra: This is an ailment with the above-mentioned symptoms that sixty year ago occurred often in South America. This illness was caused by vitamin B3 deficiency.


Careful and toxicity
Avoid doses, higher than approximately 120 mg, unless under supervision of a physician. Symptoms of high doses are depressiveness, bad functioning of the liver, getting red and headache.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of this vitamin has been determined at 15 to 18 mg.
Dosages of 20 to 100 mg per day can have a positive effect.
The maximum safe dose for this vitamin is different for the two different forms.
For nicotinic acid the maximum safe dose is 120 mg and for nicotinamide this is 300 mg per day.
Important sources of vitamin B3 are: whole grain products, brown rice, milk, cheese, meat, fish and cashew nut.


Specific biochemical mechanism
This vitamin helps in the energy production and promotes a well-functioning of the nervous system. In the body niacin is converted into a coenzyme which is called nicotinamine adenine dinucleotide, NAD.
In the image below NAD is represented in which vitamin B3 is indicated in red.

This coenzyme is active as a redox potential, this means that in this molecule energy can be stored and subsequently be taken. The energy is in the form of hydrogen atoms. Because NAD is always recycled by "recharging" (in the catabolism) and using (in the anabolism), only little (18 mg) of this vitamin is necessary in our daily diet. The coenzyme is active in the citric acid cycle and in the glycolysis.


List of the different vitamins


Vitamin B5




Chemical name: Pantothenic acid
Molecular formula: C9H16O5N; Molecular weight: 218.23 g/mole


Vitamin B5 is just as all vitamin from the vitamin B complex, water-soluble.
Pantothenic acid can be transformed in the body in coenzyme A (CoA). This coenzyme breaks down the protein from our food to individual amino acids. This coenzyme also helps to produce human protein from these amino acid building blocks. Coenzyme A is also active in converting carbohydrates into body energy, for example in the beginning of the citric acid cycle in the decarboxylation reaction.


Properties
- Promotes wound healing
- Helps the body in producing energy
- Decreases stress
- Regulates the immune system
- Prevents tiredness
- Lowers cholesterol levels and offers in this way protection against heart conditions
- Helps preventing and treating arthritis
- Can prevent baldness and greyness of the hair
- Some hormones can only be formed if sufficient levels of vitamin B5 are present in the body


Symptoms in case of deficiencies
- Vomiting
- Cramps
- Tiredness
- Insomnia
- Decreased immunity to infections
- Stomach ache


Careful and toxicity
There are no harmful effects known for vitamin B5, but use doses of more than 300 mg per day only under medical supervision. Some people get stomach disorders when using doses of more than 10 g.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of this vitamin is 6 mg per day.
For a medical application the vitamin can best be taken in a vitamin B-complex preparation up to 300 mg per day.
A normal dosage to prevent illnesses is approximately 100 mg per day. The maximum safe dose per day has been determined at 1000 mg.
Vitamin B5 is present in the following foods: yeast, whole grain products, green vegetables, mushrooms, meat, organ meat, silver skin rice, eggs and nuts.


List of the different vitamins


Vitamin B6




Chemical name: Pyridoxine
Molecular formula: C8H11NO3; Molecular weight: 169.18 g/mole


Vitamin B6 is just like all vitamins from the vitamin B complex water-soluble.
Pyridoxine together with Folic acid and vitamin B12 takes care of the uptake of iron in the body. It is active in the formation of red blood cells. These three vitamins are also important for a good functioning of the nervous system and they are active in the amino acid metabolism.
In the body this vitamin is present as the coenzyme that is called PLP (Pyridoxal 5'-phosphate). This coenzyme is active in the glycogen metabolism especially in the glycogen breakdown. PLP together with the enzyme phosphorylase takes care that glycogen can be broken down.


Properties
- Improves the immune system
- Helps to regulate diabetes
- Is active in the uptake of proteins and fats
- Helps to fight nauseousness
- Helps to prevent skin and nerve abnormalities
- Treats the symptoms of the premenstrual syndrome (PMS) and the menopause
- Decreases tensions in the muscle
- Works as a natural diuretic
- Helps to protect against cancer


Symptoms in case of deficiencies
- Anaemia
- Nerve illness
- Skin problems


Careful and toxicity
Pyridoxine is poisonous in dosages above 200 mg per day. These high doses can lead to serious damages of the nerves. Long periods of high dosages intake of vitamin B6 (25-50 mg per day) can lead to excess levels of this vitamin.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of this vitamin is 1.6 to 2 mg.
It must always be taken in a vitamin B-complex preparation with equal dosages vitamin B1 and B2.
Avoid intake of more than 50 mg per day unless under medical supervision. Don't use this vitamin for long periods in high dosages (25-50 mg per day). The maximum safe dose is 200 mg per day.
Foods rich of vitamin B6 are: vegetables, potatoes, bananas, whole grain products, milk, eggs, nuts, fish and meat.


List of the different vitamins


Vitamin B11/ Folic acid




Chemical name: Folic acid
Molecular formula: C19H19N7O6; Molecular weight: 441.40 g/mole


Folic acid is just as all vitamin from the vitamin B family water-soluble.
Folic acid can be transformed in the body in a coenzyme that is called tetrahydrofolate (THF).
Folic acid stimulates the formation of gastric juice and is important for a well functioning liver.
This vitamin is active in the metabolism of proteins and fats, it is necessary for the formation of red blood cells (it prevents particular forms of anaemia) and it helps in the metabolism of the brain.
Folic acid is also necessary for the metabolism of DNA and RNA.
This vitamin is indispensable in cell division processes of the body and extra folic acid is for that reason advised to women in pregnancy or women who want to become pregnant.


Properties
- Improves the milk production when breast feeding
- Can help to protect against cancer
- Improves skin health
- Is a natural painkiller
- Improves appetite
- Gives babies and children immunity against infections
- Is necessary for the production of DNA and RNA
- Helps preventing the developmental birth defect Spina bifida


Symptoms in case of deficiencies
- Weak feeling
- Apathy
- Exceptional tiredness
- Insomnia
- Irritability
- Dementia
- Birth defect Spina bifida


Careful and toxicity
Folic acid is poisonous in high dosages. In high dosages it can cause serious neurological problems. Do not take this vitamin if you have a lack of vitamin B12 in the form of anaemia. High doses can cause insomnia and hinder the uptake of zinc in the blood.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of this vitamin is 0.20 - 0.36 mg.
Heavy drinkers, pregnant women, elderly people and people on a lowered fat diet have a chance to develop a deficiency. For these groups a supplement of 0.4 - 0.9 mg is recommended. It is advised to take folic acid in a good multivitamin- and mineral tablet.
The maximum safe doses of folic acid is 1 mg per day.
Important food sources of vitamin B11 are: leaf vegetables, eggs, lentils, rice, bread, wheat germ, liver, kidneys, bananas, oranges and peaches.


List of the different vitamins


Vitamin B12




Chemical name: Cobalamin
Molecular formula: C63H88CoN14O14P; Molecular weight: 1355.4 g/mole


Vitamin B12 is like all the vitamins from the B family water-soluble.
Cobalamin is together with vitamin B6 (pyridoxine) and B11 (folic acid) responsible for the uptake of iron in the blood and are necessary for the formation of red blood cells. Deficiencies of these vitamins can lead to anaemia. These three vitamins are also important for a well functioning nervous system and plays a role in the amino acid metabolism.


Properties
- Necessary for the maintenance of the nervous system
- Improves the memory and concentration
- Necessary for the use of fats, carbohydrates, and proteins
- Gives more energy
- Promotes healthy growth for children
- Can give protection against cancer
- Protects against allergens and poisonous elements


Symptoms in case of deficiencies
- Anaemia
- Menstruation problems
- Mental deterioration
- Trembling/ shaking


Careful and toxicity
Vitamin B12 is not considered as poisonous. Yet it is advised not to take more than 200 mg per day.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of this vitamin is 0,001 mg (= 1 micro gram).
Dosages of 5 - 50 micro grams are sufficient for most people, take higher dosages only on advice of an expert. The best way to take this vitamin is as a constituent of a B-complex tablet. The maximum recommended safe dose is 200 mg per day.
Nutrients rich in vitamin B12 are only animal products like: eggs, cheese, pot cheese, milk, fish and meat.


Specific biochemical function
In the body vitamin B12 can be converted into a coenzyme (coenzyme B12) by a addition of a ribose- and an adenine molecule as a rest group. In the image below coenzyme B12 is shown with the rest group represented in red.



Molecular formula: C72H100CoN18O17P; Molecular weight: 1579.60 g/mole

This coenzyme is necessary for the function of two enzymes. Firstly for an enzyme which functions in the fatty acid metabolism, namely methylmalonyl-CoA mutase. This enzyme is one of the enzymes that is responsible for the breakdown of fatty acids with an odd number of carbon atoms.
Secondly coenzyme B12 is necessary for the biosynthesis of the amino acid methionine, together with the enzyme homocystein methyltransferase. This enzyme puts a methyl group at homocystein by which methionine arises.


List of the different vitamins


Vitamin C




Chemical name: L-Ascorbic Acid, L-ascorbate, or E300
Molecular formula: C6H8O6; Molecular weight: 176.12 g/mole


Vitamin C is a water-soluble vitamin. L-Ascorbic acid has as a redox system a task in the oxidative breakdown of the unsaturated fatty acids (linolenic acid).
Vitamins C also increase the activity of white blood cells and for this reason promotes a better healing of infections. Vitamin C is easily affected by oxygen (in the presence of heat) and is one of the most sensitive vitamins. Vitamin C deficiently is also the cause of spring tiredness.


Properties
- Antioxidant
- Accelerates the healing of wounds
- Keeps bones, teeth and sexual organs healthy
- Functions as a natural antihistaminic
- Can help to fight infertilities of a man
- Decreases the duration of colds and other virus infections


Symptoms in case of deficiencies
- Scurvy
- Feeling of weakness
- Wounds do not cure well
- Tranquillity
- Bleeding gums
- Receiving bruises easily
- Loose teeth
- Pain in the joints
- No appetite
- Heart problems


Careful and toxicity
Vitamin C can cause kidney stones and gout. When using high doses some people develop diarrhoea and stomach cramps. Even so this vitamin is considered not harmfully even in very high doses. Very high doses vitamins C can raise the cholesterol levels in the blood, through which the chance to develop heart diseases increase.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of vitamin C is 60 mg.
More vitamin C is necessary for smokers (25 mg per cigarette), people under stress, people using antibiotics, people suffer from having an infection, strong drinkers or people that had an accident or an injury.
The maximum safe dose has been determined at 1000 mg per day.
L-Ascorbic acid is present in many fruits, green plants (leaf vegetables), milk and liver.


List of the different vitamins


Vitamin D



There are two forms of vitamin D, vitamin D3 and D2.



Chemical name: vitamin D3 or Cholecalciferol
Molecular formula: C27H44O; Molecular weight: 384.6 g/mole



Vitamin D2 differs only with one double bond and one methyl group from vitamin D3 (indicated with red).



Chemical name: vitamin D2, Calciferol or Ergosterol
Molecular formula: C28H44O; Molecular weight: 396.7 g/mole


Vitamin D is an fat-soluble vitamin.
Vitamin D3 is formed in our body from cholesterol under influence of ultraviolet light. The antirachitic properties of UV-light rest on the formation of vitamin D3.
Vitamin D2 is also formed from cholesterol, but via another pathway and vitamin D2 is vegetable.
Vitamin D2 and D3 have biologically the same function. Therefore vitamin D2 is also used as a food supplement.

Vitamin D is necessary for the development of the skeleton and especially in the phosphate- and citric acid metabolism,. The function of vitamin D is dependent on the presence of the pantothenic acid complex. Lack of vitamin D leads to different rachitic, or rachitic like changes of the skeleton. The basis of the disturbance lies in the process of the growth of the cartilage. Therefore a lack of this vitamin is less striking in adults, but still has an effect on the ongoing cell replacement. Determining for damage is the simultaneous drop of break down processes through lacks of other vitamins (C, B etc.), by which the dangerous pre-rachitic state can arise.
An excess of vitamin D can have harmful effects (hyperavitaminosis).


Properties
- Protects against osteoporosis
- Can help in the treatment of psoriasis
- Strengthens the immune system
- Can help to prevent different forms of cancer
- Necessarily for strong teeth and bluntly


Symptoms in case of deficiencies
- Rachitis
- Pain in the bones
- Muscle weakness and muscle cramp
- Osteoporosis


Careful and toxicity
Vitamin D is the most poisonous vitamin of all vitamins and leads to nauseousness, vomiting, headache, depressiveness and other symptoms. Do not take more than 50 micro grams per day.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of this vitamin is 0,005 mg (= 5 micro grams). The maximum safe dose is 0.05 mg (= 50 micro grams) per day.
Important foods with vitamin D are: fish (oil), yeast, leaf vegetables, meat and dairy products.
Specific biochemical function
The formation of vitamin D from cholesterol under influence of ultraviolet-light.
Vitamin D3 is formed in the body from cholesterol under influence of ultraviolet light. The antirachitic properties of UV light rests on the formation of vitamin D3. From cholesterol, 7-dehydrocholesterol is produced by removing a hydrogen atom from place 7 and 8. This reaction is catalysed by 7-dehydrocholesterol reductase. From this 7-dehydrocholesterol, vitamin D3 (cholecalciferol) is produced under the influence of UV light. See the image below.



Vitamin D2 is also formed from cholesterol, but is vegetable and via another pathway. Vegetable ergosterol is made from cholesterol and this ergosterol is subsequently converted in ergocalciferol (vitamin D2) under influence of UV-light
Vitamin D2 and D3 have biologically the same function. Therefore vitamin D2 is also used as a food supplement.

Vitamin D is active a hormone in the calcium and phosphate metabolism.
Vitamin D is actually a hormone. As vitamin D it is not active yet. It is made active in subsequent metabolic processes, firstly in the liver and after that in the kidneys. In the liver, an OH group is placed on carbon atom number 25 and in the kidneys also an OH group is placed but now on carbon atom number 1. The synthesised hormone is called 1,25-dihydroxycholecalciferol or 1,25(OH)2D. See the image below.



This hormone stimulates the production of Ca2+-binding protein and is in this way responsible for the increased uptake of calcium (Ca) and phosphate (Pi) in the blood. Ca2+-binding protein transports calcium ions and phosphate ions from outside of the cell to the inside of the cell.
Hormones in general and also 1,25-dihydroxycholecalciferol occur in low concentrations in the blood, this also explains why only a little of vitamin D (5 micro grams) is necessarily in our daily diet.


List of the different vitamins


Vitamin E




Chemical name: D-Alpha-Tocopherol
Molecular formula: C29H50O2; Molecular weight: 430.7 g/mole


Vitamin E is an fat-soluble vitamin.
Tocopherol has a preventive effect on ageing conditions. It is like vitamin C a strong antioxidant (it makes free radicals harmless). After the fortieth life year the natural immunity against radicals gradually diminishes. Nowadays, after this age more people use extra vitamin E, often 40 times the Recommended Dietary Allowance (RDA). Tocopherol is also necessary for the formation of red blood cells and the structure, recovery and maintenance of muscle and other tissue. It also protects plural unsaturated fatty acids that are essential for the body.


Properties
- Antioxidant
- Protects against nerve conditions
- Enhances the immune system
- Protects against heart and vascular diseases
- Decreases PMS-symptoms
- Treats skin problems and baldness
- Helps preventing miscarriages
- Effective like a natural diuretic
- Prevents thickened scar tissue


Symptoms in case of deficiencies
No known symptoms


Careful and toxicity
High doses can be poisonous. Take doses higher than 350 mg a day only under medical supervision.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) of this vitamin is 10 mg.
Vitamin E is available in many forms (the dry form is favourable for people with skin problems or people who do not tolerate oil). Daily dosages are 250 to 280 mg, but in some cases higher dosages are advised. It is best taken in with a good multivitamin- and mineral tablet.
The maximum safe dose is 350 mg a day.
Important sources of vitamin E are: vegetable oils, soy beans, broccoli, spinach, nuts, whole grain products, eggs and margarine.


List of the different vitamins


Vitamin H/ Biotin




Chemical name: D-Biotin
Molecular formula: C10H16N2O3S; Molecular weight: 244.3 g/mole


Although biotin is also called vitamin H, it is part of the B-family and is also called vitamin B8. Biotin is a water-soluble vitamin. It can be converted in the body into the coenzyme biocytin (Molecular formula: C16H28N4O4S; Molecular weight: 372.5 g/mole).
Biotin helps to release energy from the diet and in the formation of antibodies.
This vitamin is also responsible for a good condition of the skin and hair.
A deficiently of this vitamin occurs sometimes in babies. This is recognizable from a dry and flaky skin.


Properties
- Prevents grey hair
- Lights various forms of muscle pain
- Helps against eczema, dermatitis and other skin problems
- Helps against baldness


Symptoms in case of deficiencies
- Eczema
- Tiredness
- Decline of the metabolism of fat


Careful and toxicity
Biotin is harmless, but it is advised not to use more than 300 mg per day, unless under medical supervision.


Dosage and natural sources
The Recommended Dietary Allowance (RDA) has been determined on 0.15 mg (= 150 micro grams) per day.
The maximum safe dose is 300 mg per day.
Important sources of biotin are: eggs, milk, fruit, nuts, soybeans, brewer's yeast, brown rice, meat and fish.


List of the different vitamins


Vitamin K



There are three forms of vitamin K: K1, K2 and K3.
All three forms have the same basic structure as indicated below. The rest group (R) is different in the three forms.






Chemical name: Vitamin K1 or Phylloquinone
Molecular formula: C31H46O2; Molecular weight: 450.68 g/mole




Chemical name: vitamin K2 or Menaquinine




Chemical name: vitamin K3 or Menadione


Vitamin K is a fat-soluble vitamin.
This vitamin occurs naturally in vegetable food (green leaves) as a vitamin K1 (phylloquinone). In the intestine, it is also produced by our intestinal bacteria as vitamin K2 (menaquinone). Synthetic vitamin K is called vitamin K3 (menadione), our body converts this vitamin in active vitamin K.
Vitamin K is indispensable in the formation of different coagulation factors, and thus also in the coagulation. Until approximately 3 months after birth it is necessarily that this vitamin is supplied in the diet because until then the intestinal flora is insufficient. Nowadays this vitamin is added in infants feeding to prevent intracranial haemorrhage.


Properties
Prevents blood clutters.


Careful and toxicity
There it no information known about toxicity.


Dosage and natural sources
Important sources of phylloquinone are: cauliflower, broccoli, spinach, peas, whole grain products, turnip seed oil and non-fat meat.
The Recommended Dietary Allowance (RDA) vitamin K is 0.08 mg (= 80 micro grams). The maximum safe dose is considered as 50 times the RDA, thus 4 mg (= 4000 micro grams).


Specific biochemical function
Vitamin K is indispensable for the formation of thrombin or prothrombin (thrombinogen) and other coagulation factors in the liver.
When vitamin K is missing or when a competitive inhibitor is present (like warfarin, a poison for rats), then abnormal trombine is formed, that only shows 1% to 2% of the normal activity.
Image of warfarin, a rat poison. Warfarin has similarities with vitamin K.


Normal active trombine contain ten amino acids gamma- carboxyglutamate (gla). Abnormally, hardly active trombine on the other hand contain instead of gamma-carboxyglutamate (gla), glutamic acid (glu). From this it became clear that vitamin K functions as cofactor in the post translational processes in the formation of trombine. Vitamin K functions in the conversion of glutamic acid (glu) in gamma-carboxyglutamate (gla), see for this the image below.



In this image it is shown how "glu" is converted into "gla".
Step 1: Vitamin K is in its active hydroquinone form and a H+ ion (a proton) is removed from the "glu" in an oxygen (O2) consuming reaction. Because of this reaction a carbon ion arises on the "glu" molecule.
Step 2: The "glu" carbon ion reacts with CO2 so that "gla" arises.
Step 3 and 4: Active vitamin K in the hydroquinone form is regenerated in two reactions. These reactions are catalysed by the same enzyme that use thiols (like lipoic acid). The rat poison warfarin and also dicoumarol block these regeneration reactions.

In the image above it is shown how vitamin K is re-used. This explains why we only need a little (80 micro grams) of this vitamin in our daily diet.


List of the different vitamins


Table with Recommended Dietary Allowance (RDA) and the maximum safe dose of vitamins


Vitamin

Chemical name

Maximum safe dose per day

Retinol

0.8 mg

3 mg

Beta-Carotene

2 to 6 mg

25 mg

Thiamine

1.4 mg

400 mg

Riboflavin

1.6 mg

400 mg

Nicotinic acid

15 to 18 mg

120 mg

Nicotinamide

15 to 18 mg

300 mg

Pantothenic acid

6 mg

1000 mg

Pyridoxine

1.6 to 2 mg

200 mg

Folic acid

0.2 to 0.36 mg

1 mg

Cobalamin

0,001 mg

200 mg

L-Ascorbic acid

60 mg

1000 mg

Calciferol

0,005 mg

0.05 mg

Tocopherol

10 mg

350 mg

Biotin

0.15 mg

300 mg

Phylloquinone

0.08 mg

4 mg


RDA = Recommended Dietary Allowance
mg = Milligram




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Literature

[1]. Stryer, Lubert;- Biochemistry - fourth edition; New York: W. H. Freeman and Company (1995). ISBN 0-7167-2009-4
[2]. Foot, Donald and Foot Judith G.; - Biochemistry - second edition; New York: John Wiley & Sons, Inc (1995). ISBN 0-471-58651-X.
[3]. Sullivan, Carts; - vitamins & Minerals - First edition; Antwerp: Zetwerk (1998). ISBN 90-5495-144-3
[4]. Mathijssen, Eugene;- Better knowledge is healthier life - First edition; Hema (1998). ISBN 90389 0746x
[5]. Dr. C. Norman Shealy; - Encyclopedia of the Natural Medicines - First edition;
Groningen: TextCase (1999). ISBN 3-8290-1713-8



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