VITAMINS

​

Smt. A. P. Itkapalle

Head

B. Sc. T. Y.

Introduction

• The term vitamin refers to an essential dietary factor that is

required by an organism in small amounts and whose absence

results in deficiency diseases.

• The organisms cannot synthesis vitamins.
• Therefore, vitamins are necessary for life.
• The role vitamins in animal body are not definitely established.
• Vitamins are not the energy source.
• However certain vitamins become part of the enzyme action.
• Generally vitamins are present in fresh and natural foods in

appropriate amounts.

Classifications of vitamins

There are about 25 vitamins which have been arbitrarily

classified into two groups.

• Fat soluble groups: These contain vitamins A, D, E and K.
• Water soluble groups:- These contains rest of the vitamins like B, C etc.

Vitamins are designated by alphabets like A, B, C, D, E etc

in order to their discovery.

Furthermore, the subgroup of an individual vitamin is designated

by the subscripts eg. A₁, A₂, B₁, B₂, B₆, B₁₂, D₁, D₂ etc.

However vitamin H (Biotin) is an exception as it is insoluble

both fat and water.

Vitamin A

• The existence of the fat soluble factor vitamin A, which occurs in

butter, eggs fat and cod liver, was established in 1915 by feeding

experiments.

• Several naturally occurring compounds having vitamin A skeleton

like β-carotene are converted in vivo into this vitamin ie Vitamin A.

• There are two types of vitamins A₁ and A₂.

Vitamins A₁

The IUPAC name of vitamin A₁ is retinol that corresponds to

aldehyde while retinoic acid that corresponds to acid.

Structure of vitamin A₁

Occurrence of Vitamins A₁

• Vitamin A₁ is a fat soluble vitamin which occur free and as esters

in fats in fish livers and in blood.

• It is also present in carrots, green vegetables, sweet potatoes,

tomatoes, apricot, salad, cabbage in which it is present in the form

of carotenes (Provitamins) which in vivo are converted into

vitamin A₁

Deficiency diseases of Vitamins A₁

• Vitamins A₁ influences growth in animals and apparently increase

resistance to disease.

• Its deficiency in animals may cause night blindness but prolonged

deficiency of this may lead to hardening of the conjunctive,

softening of cornea which is termed as xerophthalmia and may

lead to complete blindness in some cases.

• Its deficiency also produces dryness of skin and hair.
• Excess of vitamin A₁ can be injurious.
• The symptoms of excess vitamin A1 are bone fragility, nausea,

weakness and dermatitis.

Vitamins A₂

• It is known as retinol 2.
• It is found in certain fish oils especially from fresh water fish.

Vitamins D

• Vitamins D represents a group of fat soluble vitamins which are

structurally related to sterols.

• Five vitamins D₁, D₂, D₃, D₄ and D₅ have been isolated.
• In fact vitamin D₁ has found to be a moleculat compound of D₂ and

lumisterol.

• All these types of vitamin D can be prepared from irradiation

of specific sterols called provitamins. Vitamin D₂ is called as

ergocalciferol.

Occurrence of Vitamins D

• Vitamin D₂ is formed in nature by irradiation of specific sterols.
• However, other sources are cod liver oil and other fresh liver oils,

hen’s eggs and milk of mammals.

• The amount of D₂ in liver of fish depends upon the season and

also upon the biological conditions of the environment in which

fish is living.

Deficiency diseases of Vitamins D

• The deficiency of vitamin D₂ causes rickets which is a disease

mainly occurring in children.

• This disease is characterized by a softening and bending of bones.
• But these conditions respond rapidly to vitamin D₂.
• Therefore, vitamin D₂ is known as antiractitic factor.

Vitamin E and Tocopherols

• Vitamin E represents a group of eight compounds which are

collectively called tocopherols namely α, β, γ, δ, ε-, ε-₁₁ and η.

• Out of these, the most biologically active compound is α-tocopherols

whereas α and β- tocopherols exhibit about half the activity of

α-compounds.

Occurrence of Vitamin E

• It is widely distributed in nature in plant and animal tissues.
• This vitamin occurs in
• wheat germ oil (which contain α and β- tocopherols),
• cotton seed oil (which contain γ- tocopherols),
• soyabean oil (which contain δ- tocopherols),
• oil and rice.
• In animals, it occurs mainly in the livers of horses and cattles and

in small amounts in the muscles of heart, kidney, placenta egg.

Deficiency diseases of Vitamin E

• It causes antisterlity. Due to this antisterlity factor, vitamin E is

called as tocopherol.

• It causes increase in the number of leucocytes ie WBC of the

blood, causing blood anaemia.

• It causes increased excretion of creative and pentose sugar (ribose)

in urine which is primarily due to degeneration of muscles.

• It also increases concentration of RNA and DNA in the bone

marrow.

Vitamin K

• The term vitamin K originally referred to the two compounds

vitamin K₁ and K₂ .

• They were related structurally but differed in both the length and

the degree of unsaturation of an isoprenoid side chain.

• In 1939, vitamin K₁was first obtained in pure state by Dam et al

and Doisy et. al. from alfalfa

• K₂ was isolated by Doisy et. al. From putrefied fish meal.
• Subsequently vitamin K₂ was detected in number of bacteria.

Occurrence of Vitamin K

• Vitamin K₁ occurs in all green, leafy tissues, but the best sources

are alfalfa, carrot tops, cabbage and spinach.

• Vitamin K₂ occurs principally in bacteria and also in putrefied fish

meal.

Deficiency diseases of Vitamin K

• The average daily requirement of vitamins K₁ and K₂ for man is

almost 1 mg.

• Both K1 and K2 are antihaemorrhagic vitamins because they are connected with the enzymes which are involved in blood clotting.
• Vitamin K₁ and K₂ are helpful in blood co-agulation by activating prothrombin, the precursor of thrombin for the formation of blood clotting enzyme.
• The deficiency of vitamins K₁ and K₂lengthens the time of blood clotting.

Vitamin B

Vitamin B is not one vitamin but a group of water soluble vitamins

which are found in yeast, liver, rice polishing etc.

Occurrence of Vitamin B₁

• Vitamin B₁ is a water soluble vitamin which occurs abundantly in

the outer coats of the seeds of many plants including the cereal

grains like rice, wheat etc.

• It is also found in some animal organs, viz- liver and kidney in

small quantity.

• It also occurs in yeast, milk, ground nuts, eggs all green

vegetables, roots fruits and daily products (except butter).

• In animal tissues and in yeast, it occurs primarily as the co-enzyme

thiamine pyrophosphate or co-carboxylase.

Deficiency diseases of Vitamin B₁

A deficiency of vitamin B1 in man produces the classic diseases

known as beri-beri (a type of paralysis). Beri-beri is of two types

• Dry beri-beri:
• This takes place in case of lesser deficiency of thiamine.
• In this type of disease, weight, neuritis, pain in the arms and legs

and decrease in blood pressure.

• The person suffering from dry beri-beri responds rapidly to

thiamine administration.

Wet beri-beri:

• This takes place in the case of serve deficiency of thiamine.
• In this case, the entire nervous system is affected and results in a

type of paralysis, leading to edema and impaired cardiac function.

• The wet type of beri-beri is more common infants.

Vitamin B₂

• Since vitamin B2 is chemically related to the yellow water soluble

pigments known as flavins and it was also isolated from milk.

• It was also known as lactoflavin.

Occurrence of Vitamin B₂

• Vitamin B₂ is widely distributed in plants and chemicals.
• It is present in yeast, vegetables, milk, eggs, wheat, liver, kidney,

meat etc.

• The primary source of vitamin B₂ is plant material, although

commercial production by yeast and certain microorganisms is

practiced.

Deficiency diseases of Vitamin B₂

• The symptoms of vitamin B₂ deficiency are difficult to observe in

man.

• A sign such as a dark red tongue, dermatitis, and cheilosis similar

to those of niacin deficiency in human system also reduces growth

and causes general weakness.

Vitamin B₆

• Actually, vitamin B₆ is not one vitamin but a groups of three

vitamins, namely pyridoxine, pyridoxal and pyridoxamine.

• These three vitamins are interconvertible in the form of their

phosphates.

• Generally, pyridoxine is referred to as vitamin B₆.
• As this vitamin is antidermatitic factor for rats, it is also

known as adermin.

Occurrence of Vitamin B₆

• The three forms of vitamin B₆ occur abundantly in various plants

and animal sources, cereal grains, molasses and yeast are especially

rich sources of all three forms.

• Pyridoxal and pyridoxamine also occur in nature as their phosphate

derivatives which are the co-enzyme forms of vitamin.

Deficiency diseases of Vitamin B₆

• In rats and many other animals, the initial vitamin B₆ deficiency

causes severe dermatitis.

• However, extreme deficiency in these animals also causes

convulsions similar to those of epilepsy and indicates a profound

disturbance in central nervous system.

• It also serves as growth factor for many bacteria.

• In man deficiency diseases of Vitamin B₆ causes nervousness,

insomnia, irritability, stomatitis (inflammation of the mucous

membrane of the mouth) and also causes general weakness.

• Vitamin B₆ is also employed to stop nausea and vomiting in

pregnancy and for treatment of epilespsy and acne or dermatitis.

Vitamin B₁₂

Vitamin B₁₂ is the first natural product which contains cobalt.

Occurrence of Vitamin B₁₂

• Vitamin B₁₂ is not present in plant kingdom but is found in all

animal tissues especially in the liver of ox, sheep, horse, pig,

fish, etc.

• It is also present in cow dung and urine. It is synthesized by

certain micro-organisms.

• Milk, eggs, cheese and meat contain 1 – 5 μg/100 g of material.

Deficiency diseases of Vitamin B₁₂

• It is essential growth factor for many micro-organisms.
• Its deficiency in man causes pernicious anaemia which is followed

by degradation of spinal cord.

• These disease doses not arise due to the absence of vitamin B₁₂ in

diet but due to the lack of secretion in stomach called intrinsic

factor which is essential for the assimilation of vitamin B₁₂.

• The same symptoms also appear in the case of folic acid

deficiency.

• Thus, patients respond to either of the two vitamins.
• However, B₁₂ is considered to be more beneficial than folic acid.

Wish you

all

Happy diwali