vitamins

What are vitamins?Vitamins and minerals are substances that are

found in foods we eat. Vitamins are necessary for growth and vitality. They

are found in all natural foods. We must obtain vitamins from foods or dietary supplements.

Vitamins are organic substances necessary for life. Vitamins are essential to the normal functioning of our bodies, and except for a few exceptions, cannot be made by our bodies.

There are thirteen vitamins classified as either water soluble (C and B complex) or fat soluble (A, D, E and K).

What are the functions of vitamins? energize our metabolismregulate our metabolismhelp form blood clots when we bleedenable cell growthhelp us see in color instead of black and

white

Two kinds of vitamins

Water-soluble Vitamina Fat-soluble Vitamin

Fat Soluble VitaminsA fat-soluble vitamin is a vitamin that can be

stored in the liver and fat tissues of your body until your body needs them. Vitamins A, D, E and K are fat-soluble vitamins. Fat-soluble vitamins can be stored in your body for up to six months

Fat-soluble vitamins are absorbed, together with fat from the intestine, into the circulation

Vitamin A (fat-soluble)

Sources: Dairy products, eggs, liver. Can be converted by the body from the beta-carotene found in green vegetables, carrots and liver.

Uses: Maintains the health of the epithelium and acts on the retina's dark adaptation mechanism.

Deficiency leads to: Keratinisation of the nasal and respiratory passage epithelium, night blindness

Retinol Retinoic Acid

Vitamin AIt plays an important role in the formation and

maintenance of healthy skin, hair, and mucous membranes. Vitamin A also helps us to see in dim light and is necessary for proper bone growth, tooth development, and reproduction.

Vitamin A, also called Retinol, plays an important role in cell division and gene expression. Also, the eyes and mucous membranes of the mouth, nose, throat and lungs depend on vitamin A to remain moist.

Beta-carotene, an antioxidant that the body converts to vitamin A. Beta-carotene, or provitamin A, comes from fruits and vegetables.

Vitamin D (fat-soluble)

Sources: Fish liver oils,egg yolks, dairy produce. Vitamin D is formed in the skin when it is exposed to sunlight

Uses: Has a role in the absorption of calcium, which is essential for the maintenance of healthy bones. It's also great for forming strong teeth.

Deficiency leads to: Rickets

Vitamin DVitamin D plays a critical role in the body’s use of calcium and

phosphorous. It increases the amount of calcium absorbed from the small intestine and helps form and maintain bones. Children especially need adequate amounts of vitamin D to develop strong bones and healthy teeth.

Vitamin D, also called Calciferol, is a vitamin that dissolves in the body's fat. Vitamin D is found in food, but also can be made in your body after exposure to ultraviolet rays from the sun. There are several different forms of vitamin D. Each form has a different activity.

Vitamin D is a steroid hormone that functions to regulate specific gene expression following interaction with its intracellular receptor. The biologically active form of the hormone is 1,25-dihydroxy vitamin D3 (1,25-(OH)2D3, also termed calcitriol). Calcitriol functions primarily to regulate calcium and phosphorous homeostasis.

Vitamin E (fat-soluble)

Sources: Pure vegetable oils; wheatgerm, wholemeal bread and cereals, egg yoke, nuts sunflower seeds

Uses: Protects tissues against damage; promotes normal growth and development; helps in normal red blood cell formation

Deficiency leads to: May cause muscular dystrophy

Vitamin E (α-tocopherol)

Vitamin E Vitamin E acts as an antioxidant, protecting vitamins A and C, red blood cells and

essential fatty acids from destruction. Research from a decade ago suggested that taking antioxidant supplements, vitamin E in particular, might help prevent heart disease and cancer

Vitamin E does a lot of things. It is believed that vitamin E may also prevent blood cells from sticking to each other and to the blood vessels they travel. This will help promote clear and flexible blood vessels and lower blood pressure. Vitamin E is absorbed from the intestines packaged in chylomicrons. It is delivered to the tissues via chylomicron transport and then to the liver through chylomicron remnant uptake. The liver can export vitamin E in VLDLs. Due to its lipophilic nature, vitamin E accumulates in cellular membranes, fat deposits and other circulating lipoproteins. The major site of vitamin E storage is in adipose tissue.

The major function of vitamin E is to act as a natural antioxidant by scavenging free radicals and molecular oxygen. In particular vitamin E is important for preventing peroxidation of polyunsaturated membrane fatty acids. The vitamins E and C are interrelated in their antioxidant capabilities. Active α-tocopherol can be regenerated by interaction with vitamin C following scavenge of a peroxy free radical. Alternatively, α-tocopherol can scavenge two peroxy free radicals and then be conjugated to glucuronate for excretion in the bile.

Vitamin K (fat-soluble)

Sources: Green vegetablesUses: Used by the liver for the formation of

prothrombinDeficiency leads to: Bleeding due to

delayed clotting times caused by lack of clotting factors. Patients may show signs of bruising easily and have nosebleeds.

Vitamin KNaturally produced by the bacteria in the

intestines, vitamin K plays an essential role in normal blood clotting and helps promote bone health. 

The major function of the K vitamins is in the maintenance of normal levels of the blood clotting proteins, factors II, VII, IX, X and protein C and protein S, which are synthesized in the liver as inactive precursor proteins.

Water-soluble Vitamin

A water-soluble vitamin is a vitamin that dissolves in water. Vitamin C and Vitamin B are water soluble vitamins. Water-soluble vitamins cannot be stored in the body for long periods of time. Water-soluble vitamins travel through your body and the whatever your body doesn't need, comes out in your urine. These kinds of vitamins need to be replaced daily.

Vitamin B1 (thiamine) (water-soluble)

Sources: Yeast, egg yolk, liver, wheatgerm, nuts, red meat and cereals

Uses: Carbohydrate metabolismDeficiency leads to: Fatigue, irritability, loss

of appetite; severe deficiency can lead to beri-beri

Vitamin B1 (Thiamin)Thiamin (also written thiamine) is also known

as vitamin B1 . Thiamin is derived from a substituted pyrimidine and a thiazole which are coupled by a methylene bridge. Thiamin is rapidly converted to its active form, thiamin pyrophosphate, TPP, in the brain and liver by a specific enzyme, thiamin diphosphotransferase.

Thiamin Structure

Thiamin Pyrophosphate (TPP)TPP is necessary as a cofactor for the

pyruvate dehydrogenase and α-ketoglutarate dehydrogenase catalyzed reactions as well as the transketolase catalyzed reactions of the pentose phosphate pathway.

The dietary requirement for thiamin is proportional to the caloric intake of the diet and ranges from 1.0–1.5 mg/day for normal adults. If the carbohydrate content of the diet is excessive then an increase in  thiamin intake will be required.

Vitamin B2 (riboflavin) (water-soluble)

Sources: Dairy products, liver, vegetables, eggs, cereals, fruit, yeast

Uses: Intracellular metabolismDeficiency leads to: Painful tongue and

fissures to the corners of the mouth, chapped lips

Riboflavin

RiboflavinRiboflavin is also known as vitamin B2.

Riboflavin is the precursor for the coenzymes, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). The enzymes that require FMN or FAD as cofactors are termed flavoproteins. Several flavoproteins also contain metal ions and are termed metalloflavoproteins. The normal daily requirement for riboflavin is 1.2–1.7 mg/day for normal adults.

Vitamin B12 (water-soluble)

Sources: Liver, red meat, dairy products and fish

Uses: Essential for manufacturing of genetic material in cells. Involved in the production of erythrocytes

Deficiency leads to: pernicious anemia

Cobalamin

Cobalamin

Cobalamin is more commonly known as vitamin B12. Vitamin B12 is synthesized exclusively by microorganisms and is found in the liver of animals bound to protein as methycobalamin or 5'-deoxyadenosylcobalamin. The vitamin must be hydrolyzed from protein in order to be active. Hydrolysis occurs in the stomach by gastric acids or the intestines by trypsin digestion following consumption of animal meat.

Vitamin C (ascorbic acid) (water-soluble)

Sources: Green vegetables and fruitUses: Essential for the maintenance of

bones, teeth and gums, ligaments and blood vessels. It is also necessary for ensuring a normal immune response to infection

Deficiency leads to: Scurvy

Ascorbic Acid

Ascorbic AcidAscorbic acid is more commonly known as vitamin

C. Ascorbic acid is derived from glucose via the uronic acid pathway.

The active form of vitamin C is ascorbic acid itself. The main function of ascorbate is as a reducing agent in a number of different reactions. is the hydroxylation of proline residues in collagen. Vitamin C is, therefore, required for the maintenance of normal connective tissue as well as for wound healing since synthesis of connective tissue is the first event in wound tissue remodeling. Vitamin C also is necessary for bone remodeling due to the presence of collagen in the organic matrix of bones.