Vitamins

·        Fat soluble Vitamins

ü  Vitamin A (Retinol)

ü  Vitamin D (Calciferol)

ü  Vitamin E (Tocopherol)

ü  Vitamin K

·        Water soluble Vitamin

ü  Vitamin C (Ascorbic acid)

ü  Niacin

ü  Biotin

ü  Folic acid

ü  pantothenic acid

ü  Lipoic acid

ü  Vitamin B complex group molecules

§  Vitamin B₁(Thiamin)

§  Vitamin B₂(Riboflavin)

§  Vitamin B₃(Pyridoxin)

§  Vitamin B₄(Cyanocobalamine)

·        

Comparison of two major types of vitamin

Properties	Fat soluble vitamins	Water soluble vitamins
Soluble in fat	Soluble	insoluble
Soluble in water	Insoluble	soluble
Absorption	Along lipids require bile salts	Absorption is simple
Carrier proteins	Present	No carrier protein is present
Storage	Stored in liver	No appreciable storage
Excretion	Not excreted	Excreted
Deficiency	Manifests only when stores are depleted	Manifests rapidly as no storage
Treatment of deficiency	Single large doses may present deficiency	Regular dietary supplements are required
Major vitamins	A,D,E & K	B & C

Vitamin A

Chemistry:

Compounds of vitamin A activity referred to as pterinoids. They are poly isoprenopid compounds with beta-ionone ring or trimethylcyclohexenyl ring compounds.

Precursors of provitamin of vitamin A beta-carotene give rise to two beta-ionone rings connected by poly prenoid or hydrocarbon chain.

Dietary Sources:

Food of animal origin is retinyl esters.

Among Diary sources i.e. butter, milk & cheese. Highest concentration is present in the liver oils of certain species of fish e.g. shark, cod etc. Livers of fresh water fish contains Vitamin A₂

It is also found in deep green, yellow orange fruits & vegetables e.g. carrots and broocoli, kale, pumpkins, sweet potatoes, peach, apricots etc. Recently “spirulina” species of algae are found to be good sources.

Properties:

All yellow crystals of Vitamin A are almost odorless or fish like odor. They have melting point of about 63C⁰ to 64C⁰.They are soluble in alcohol, fixed oils, organic solvents i.e. ether, chloroform etc.

They are stored in air tight containers protected from light. They are made stable by the use of antioxidants from light and oxygen.

Daily requirement:

§  Children……….400 to 600 mg/day

§  Men……………..750 to 1000 mg/day

§  Women……….750 mg/day

Hypervitaminosis:

It is characterized by failure, irritability, anorexia, and loss of weight, vomiting & other GIT disorders. Fever, skin changes, alopecia dry hairs, cracking and bleeding of lips, anemia, headache, pain in bones and joints.

Deficiency:

The major problems areNight blindness, Xerothalmia&keratomalaria.

1.       Small triangular patches on the inner outside of cornea covered by a material like formed termed as bitots spots.

2.       When xerothalmia persists for a drug for a long period of time it progresses to keratomalaria  (softening of cornea) so it becomes dry, rough and scaly.

3.       Retardation of growth accompanied by defects of skull bones on CNS may produce nerve degeneration and paralysis.

4.       Its suitable quantity is required for normal activity of mitochondria and deficiency interferes with oxidative phosphorylation.

Vitamin K

It is also known as Antihaemorragicfactor.It has basically two types;

1.       Vitamin K₁ (mainly obtained from Alfalfa leaves)

2.       Vitamin K₂ (mainly obtained from fish meals and intutinal bacterial flora)

Chemistry:

These are derivatives of phytal chains. First two are natural while other two are synthetic types of Vitamin K.

1.       Vitamin K₁ (Phyeloquinone)

2.       Vitamin K₂ (Farnoquinone)

3.       Vitamin K₃ (Manadione)

4.       Vitamin K₄ (Menadial)

Sources:

It is mainly obtained from green fresh leafy vegetables e.g. Alfalfa, cauliflower, cabbage, tomatoes, soya beans etc.

An intestinal microorganism possesses high Antihaemorragic concentration which may be 11 to 38 times as active as alfalfa. The names of the microorganisms are Bacillus cereus, Bacillus subtilis, Bacillus mycoids, Bacteriaumproteus, mycobacterium tuberculosis, Sarcinalutea and Staphylococcus aureus etc.

Daily requirement:

50 to 100 mg/day should be available in normal diet.

Deficiency:

Prolong use of broad spectrum antibodies and sulfa drugs lead to fall of prothrombin level in plasma an abnormal long coagulations times and tendency to spontaneous haemorrage.

Functions:

1.       It is very important to maintain adequate plasma level of the protein prothrombin (factor ӏӏ) and three other essential clotting factors i.e. proconvertin (factor VII), autoprothrombin (factor IX) andstuart power factor (factor X).

2.       During clotting the circulating thrombin i.e. required for the production of thrombin which converts fbrin into fibrinogen.

3.       It is involved in the production of two anticoagulant proteins as proteins C & S.

4.       It is administerded with bile in pre-operative and post-operative jaundiced patients to main tain normal protein levelk in blood.

5.       It is necessary cofactor in oxidative phosphorylation being associated with mitochondrial lipids. The normal process of oxidative process of phosphorylation is released when vitamin K is added to them.

Hypervitaminosis:

Administration of large quantities of medicine may result in toxicity as hemolysis, hyperbilirubinemia and brain damage.

Vitamin E

Chemistry:

It was discovered in 1936. It is also known as antisterility factor or tocopherol. It is greenish yellow odorless, viscous, oily liquid, free soluble in organic solvents and fixed oils.

Different degrees of antisterility factors;

§  Processes antioxidant purposes

§  Include a group of 8 compounds

§  Among these α, β, γ and δ are important.

Basic structure of tocopherol shows that;

§  Chromane ring i.e. tocol

§  Trimethyltridecyl i.e. saturated hydrocarbon side chain)

Methyl substituted tocol derivatives;

1.       α-tocopherol  (5,7,8-trimethyl tocol)

2.       β-tocopherol  (5,8-dimethyl tocol)

3.       γ-tocopherol  (7,8-dimethyl tocol)

4.       δ-tocopherol  (8-methyl tocol)

Sources:

Tocopherols are abundant in wheat germs, rice germs, corn germs, lettuce, soyas, cotton seed oil. There is an evidence that some green leafy vegetables and rose hips contains more vitamin E than wheat germ.

Biochemical role of Vitamin E:

1.       It is a powerful natural antioxidant.

2.       Free radicals are greatly generated in living systems products of oxidative detoriation of poly unsaturated fat would attack biomembranes, while vitamin E converts free radicals into non harmful form.

3.       Protects RBC’s from hemolysis by preventing the peroxidation. It keeps the structural and functional integrity of all cells.

4.       It shows down aging process which is due to cumulative effects of free radicals.

5.       It ppt’s in nucleic acid metabolism b/c of tocopherols are component of cytochrome reductase segment of terminal respiratory chain.

6.       It has a role in the regulation of protein synthesis.

7.       It has been investigated to have an effect on enzymes e.g. creatine kinase and liver Xanthine oxidase.

Requirement:

·         Males 10mg/day

·         Females 08mg/day

·         During pregnancy its requirement is about 10mg/day. While during lactation 12mg/day.

Deficiency:

Human deficiency has not been reported.

In volunteers the vitamin E deficiency produced increase fragility of RBC’s, muscular weakness and creatine urea.

Hypervitaminosis:

It is observed only in large doses in animal causes reversible symptoms as skeletal muscle weakness, GIT disorders and disturbances of reproductive functions.

Vitamin B₁

Chemistry:

It consists of Thiazole ring and pyridine ring. It is also called Thiamin.

Sources:

Ø  Richest sources include dried yeast (03 to 06 mg/100g)

Ø  Rice polishing (2 to 3 mg), wheat germ (1.5 to 2.5 mg)

Ø  Whole cereals (0.4 to 0.1 mg), while in leguminous oils, seed and meat (0.3 to 0.4 mg)

Requirement:

·         Total concentration of thiamin in the body of an adult is in the range of 20 to 25 mg.

·         Its daily requirement is 1 to 1.5 mg/day.

Physiological role of thiamin:

1.       The co-enzyme form is thiamin pyrophosphate (TPP) it is used in oxidative decarboxylation of alpha-ketoacids e.g. pyruvate carboxylase.

2.       A component of pyruvate dehydrogenase (an enzyme) that catalyze the breakdown of the pyruvate to acetyl CoA and CO₂.

3.       Biochemical reactions require TPP in the decarboxylation of alpha-ketoglutarates to succinyl CoA and CO₂.

4.       Second group of enzymes that use TPP as coenzyme as Transketolase in the Hexose monophosphate shunt pathway of glucose.

5.       The main role of carbohydrate metabolism so its requirement is increased along with higher intake of carbohydrate.

6.       In patients on parenteral nutrition who receive all their calories in the form of glucose than thiamin requirements are high.

Deficiency & Manifestations:

It results in severe Neuromuscular syndromes i.e. beriberi which may be classified into many types;

§  Dry beriberi

§  Wet beriberi

§  Acute beriberi

The signs and symptoms of clinical beriberi are loss of strength, fatigue, headache, dizziness, nervousness, loss of appetite, dyspepsia etc.

Deficiency:

Other forms of thiamin deficiency which are seen clinically are alcoholic poly neuritis with motar and sensory defects in chronic in alcoholics. Alcohol utilization needs large doses of thiamin. At the same time alcoholics take less nutritive food leading to deficiency.

Vitamin B₂

Chemistry:

It is also called Riboflavin. It is an orange yellow compound. Chemically it contains o-ribitol (ribose alcohol) attached to heterocyclic parent ring structure that is dimethyl isoallorazine or simply it is 7, 8-dimethyl-10-isoallorazine.

Dietary sources:

Rich sources are liver, dried yeast, egg, whole milk and milk powder. Good sources are fish, whole cereals and green leafy vegetables.

Requirement:

 A daily dietary intake of about 1.1 to 1.7 mg/day is required. Increased quantity is needed during pregnancy and lactation.

Toxicity:

It is not reported but large doses result in light yellow de-coloration of urin.

Functions:

1.       Riboflavin make two co-enzymes B₂ monophosphate usually called flavin mononucleotide and other is flavin dinucleotide.

2.       FMN is the co-enzyme of cytochrome C reductase, L-aminoacid dehydrogenase etc.

3.       FAD is the co-enzyme of Xanthine oxidase, liver, aldehyde oxidize and acyl CoA dehydrogenase.

4.       The formation of FMN and FAD is increased by the thyroid hormone and adrenal steroids. The enzyme containing riboflavin are called flavor protein, they carry out redox reactions.

Vitamin B₆

Chemistry:

Pyridoxine is one of the compounds that can be called vitamin B₆, along with pyridoxal and pyridoxamine. It differs from pyridoxamine by the substituent at the '4' position. Its hydrochloride salt pyridoxine hydrochloride is often used. They mostly exhibit vitamin activity inter-convertible in-vivo.

Source:

Vitamin B₆ is widely distributed in foods in both its free and bound forms. Good sources include meats, whole grain products, vegetables, nuts and bananas.

Requirement:

·         Males……….1.3 mg/day

·         Females……1.5 mg/day

Requirement is increased during pregnancy and lactation.

Functions:

·         The primary role of vitamin B₆ is to act as a coenzyme to many other enzymes in the body that are involved in metabolism. This role is performed by the active form, pyridoxal phosphate.

Vitamin B₆ is involved in the following metabolic processes:

                                                                i.      Amino acid, glucose and lipid metabolism

                                                              ii.      Neurotransmitter synthesis

                                                             iii.      Histamine synthesis

                                                            iv.      Hemoglobin synthesis and function

                                                              v.      Gene expression

·         It involves in the lipid metabolism as well.

·         It also causes Gluconeogenesis.

Deficiency:

The classic clinical syndrome for B₆ deficiency is a seborrhoeic dermatitis-like eruption, atrophic glossitis with ulceration, angular cheilitis, conjunctivitis, intertrigo, and neurologic symptoms ofsomnolence, confusion, and neuropathy.

Toxicity:

Adverse effects have only been documented from vitamin B₆ supplements and never from food sources.